HAZELNUT growEr’s

HAZELNUT growEr’s HANdbook

Coordinating author: Lester SnareOrange Agricultural InstituteIndustry & Investment NSW

Hazelnut grower’s handbook

February 2010

Disclaimer

© State of New South Wales through Department of Industry and Investment (Industry & Investment NSW). The information contained in this publication is based on knowledge and understanding at the time of writing (February 2010). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check the currency of the information with the appropriate officer of Industry & Investment NSW or the user’s independent adviser.

Recognising that most of the information in this document is provided by third parties, the State of New South Wales, the author and the publisher take no responsibility for the accuracy, currency, reliability and correctness of any information included in the document provided by third parties.

The product trade names in this publication are supplied on the understanding that no preference between equivalent products is intended and that the inclusion of a product name does not imply endorsement by the Industry & Investment NSW over any equivalent product from another manufacturer.

alWaYs reaD THe laBel

Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this publication.

ISBN 978 1 74256 015 1

jn 9698

H a z e l N U T g R o W e R ’S H a N D B o o k | i

aBOUT THis maNUalThe aim of this manual is to produce an informative resource that supplies primarily hazelnut growers with information relevant to production in australia. as many growers currently process and value-add, sections on postharvest handling and processing are included.

Hazelnut producers in australia have a reputation for producing hazelnuts of excellent quality, free from chemical residues and microbial contamination. The addition of this resource to members of the industry will help to maintain and improve this reputation. This updated edition reflects changes in domestic requirements by consumers and processors but still allows scope for producers to use different growing systems. It also reflects best practices from other hazelnut-producing regions around the world and includes information from australian research programs.

Many hazelnut growers will want to be responsible for their own decision-making, whereas others may not have the confidence or time to do so. The framework presented in this manual aims to help producers optimise their efficiency so that their enterprises can be profitable and sustainable. The resource, where possible, supports best practice management that in turn will increase standards and advance the australian hazelnut industry.

The overall aim is to create confidence for the buyer, consumer and producer that australian hazelnuts are of high quality.

The manual forms part of a package for new members joining the Hazelnut growers of australia Inc. (Hga).

H a z e l N U T g R o W e R ’S H a N D B o o ki i |

acKNOWleDGmeNTs & cONTriBUTOrsI acknowledge the financial support provided by Horticulture australia ltd and the Hazelnut growers of australia Inc. (Hga). Thanks are extended to the growers, propagators and processors who have provided information in the past and more recently for the development of this handbook.

Thanks are also extended to Mr Basil Baldwin, who provided liaison with the Hga and some editorial comment. Mr Rex Bean, former Hga president, provided supporting information on the history of hazelnuts in australia.

I express my appreciation to kerri Fleming and Stephen gottschall, Industry & Investment NSW, for their help and support in the preparation of the manuscript.

Finally, I would like to thank Mike Robbins, I&I NSW, for reviewing the section on irrigation.

Photography

all images supplied by photographers other than the author are acknowledged where known.

Funding

This manual was funded through Horticulture australia ltd, with a matching voluntary financial contribution from Hga.

lester Snare, Industry & Investment NSW Coordinating author

lester Snare (ascDipHort, BappSc) is a Senior Technical officer at orange agricultural Institute, Industry & Investment NSW. His horticultural experience and interests include temperate nut production. Research interests include variety assessment of hazelnuts and, pest and disease issues related to production.

H a z e l N U T g R o W e R ’S H a N D B o o k | i i i

cONTeNTs

WeeD cONTrOl 50

PrUNiNG & sHaPiNG 53

Diseases & PesTs 58

HarvesTiNG 65

POsTHarvesT maNaGemeNT 68

marKeTiNG OF HazelNUTs 73

aPPeNDix a sTaNDarDs FOr aUsTraliaN HazelNUTs iN sHell

76

aPPeNDix B DeTermiNiNG NUT iN-sHell mOisTUre cONTeNT

77

aPPeNDix c NUTriTiONal cOmPOsiTiON OF raW HazelNUT

aBOUT THis maNUal i

acKNOWleDGmeNTs & cONTriBUTOrs ii

HisTOrY OF HazelNUTs iN aUsTralia 1

GeNeral climaTic & sOil reQUiremeNTs

4

WiND sHelTer 13

OrcHarD laYOUT 16

NUTriTiON & FerTilisers 20

irriGaTiON 24

FlOWeriNG & POlliNaTiON 31

varieTies 35

PrOPaGaTiON 41

BUYiNG & PlaNTiNG NUrserY sTOcK 44

| 1H I S To R y o F H a z e l N U T S I N aU S T R a l I a

HISTORY OF HAZELNUTS IN AUSTRALIA

Hazelnuts are not native to australia, and commercial varieties in australia are cultivars of the european hazelnut, Corylus avellana. another species of Corylus admired for human consumption is C. americana, which is not produced commercially. Corylus species belong to the birch family, Betulaceae, and are scattered over temperate regions of the Northern Hemisphere. Reference to hazelnut in this publication generally refers to C. avellana or the european hazelnut.

Hazelnuts were introduced into australia over 150 years ago. The exact time of import is unknown, but it is highly likely that seedlings of hazelnut cultivars were introduced during the early days of white settlement. Nursery catalogues from the 1840s show hazelnut planting material for sale in Tasmania and later in Victoria in the 1880s. These were most likely plants introduced from england. Records from the 19th century and evidence of small remanent orchards reveal that hazelnuts were grown around Bright and Wandiligong, in the Dandenong ranges in Victoria, and in the Hobart region of Tasmania. In NSW, records show plantings at glen Innes and orange.

Through the early part of the 20th century, little development took place and many of the orchards based on seedlings went into decline. Subsistence-like farming seemed to dominate australian agriculture through to the end of the Second World War, by which time commercial hazelnut production in australia had become almost non-existent. although other types of nuts such as almonds were available locally, hazelnuts were sourced from abroad by most processors.

as with many tree crops in australia, peaks and troughs of development related to interest and profitability have paved the way to the current level of development. along the way many personalities—too numerous to mention in this publication—have contributed at varying stages. The contribution of Imre Tokolyi to the development of current australian varieties is considered particularly important.

2 | H a z e l N U T g R o W e R ’S H a N D B o o k

1950s through to the 1970sImre Tokolyi came to australia from Hungary in 1956 and was convinced of the future success of hazelnuts in australia. He set up a small manufacturing enterprise baking continental-style biscuits using various types of nuts, and the business expanded in Victoria. This led to supply contracts with australian airline companies, and by 1973 the biscuit factory had been taken over. Tokolyi’s interest in growing increased, and he germinated thousands of seedlings. The most promising seedlings were selected for yield and suitability to local conditions. These mother plants provided material for several subsequent crosses. a suite of varieties was developed and propagated at the Tokolyi nursery at Hoodles Creek in Victoria.

one of the main varieties grown in australia today, Tokolyi/Brownfield Cosford (TBC) (occasionally referred to as Tokolyi Cosford) is a legacy of Imre Tokolyi.

During this period and through the mid 1970s, State departments of agriculture in Victoria, New South Wales and Tasmania began, or reactivated, trial plantings; major trials started at orange in New South Wales and at Myrtleford and Toolangi in Victoria. knoxfield in Victoria became the centre of considerable research, with Paul Baxter, John kenez and Tony allen being active in field trials and grower education programs.

The late 1970s through to the early 1980s saw changes in State industry organizations, particularly in Victoria and NSW. These organizations suffered from a lack of funds and had only a small membership base. Varietal importation was also an important part of this period, and many named varieties from around the world entered australian quarantine facilities. ennis and Barcelona featured prominently, and in 1988 Harry lagerstedt from oregon State University visited australia and provided further information to australian growers. at this point in time the variety Wanliss Pride featured prominently in Victorian orchards, and there were many productive trees. In later australian research this variety proved to be a variable producer across a range of climates.

In 1988 the australian Nut Industry Council was formed as a peak nut body, and by 1990–1991 the Victorian Nut growers association and NSW Nut growers had ceased to operate and separate nut commodity groups had been formed by their members. This group included the Hazelnut growers of australia ltd, later to become incorporated, together with chestnut and walnut bodies. The australian Nut Industry Council now represents, in addition to the three original groups, the almond, pistachio, pecan and macadamia grower organisations.

The organized structure of commodity-based grower groups allowed those interested in hazelnut production to direct their attentions solely to the hazelnut industry. as a result, development of the industry and specialised research programs recommenced.

| 3H I S To R y o F H a z e l N U T S I N aU S T R a l I a

Subject areas of these projects have included, in the past, hazelnut pollination, varietal identification, fruit set, storage parameters and nutritional composition. In 1995 a program of field research began with funding from the Rural Industries Research and Development Corporation. The key aims of this program were to determine the regional suitability of hazelnut production (i.e. the places in australia where hazelnuts could successfully be grown) and to select those varieties that were the most productive and suitable for development of an australian industry. The key outcomes of this research provided insight into the profitability of hazelnut production.

The combination of confidence in productive capacity and availability of planting material from expanding nursery suppliers led to greater areas of hazelnut being planted in the eastern States through the late 1990s. In 2009 the majority of plantings, in no particular order, consist of Barcelona, ennis and TBC.

Further reading

Jaynes Ra (ed.) (1979) Nut Tree Culture in North America. North Nut growers association Inc., Connecticut

Wilkinson J (2005) Nut Grower’s Guide. landlinks Press, Melbourne

40 year old plus orchard at Stanley in Victoria

H a z e l N U T g R o W e R ’S H a N D B o o k4 |

climatea suitable climate, reliable rainfall and supplementary irrigation are important for good tree growth and the production of high-quality nuts. The preferred climate is characterised by a mild summer and cool winters. exposed sites subject to the drying effects of summer winds should be avoided. Major centres of production in the Northern Hemisphere, Northern Turkey, Italy and Spain lie in the latitude range 40 to 45 °N. Many areas of australia have a similar temperate climate, particularly in Victoria and Tasmania and on the Tablelands of NSW, and also some areas of western Wa and Sa.

Major plantings of hazelnuts in NSW are on the Tablelands and include the Central West, New england, and small areas in the Hunter and at Tumbarumba. North-east Victoria around Bright and Myrtleford supports commercial plantings, as do the hills east of Melbourne.

In the USa commercial production is almost entirely confined to the valley of the Willamette River in Western oregon. The valley has deep, fertile soils protected by the high Cascade Mountains from the cold arctic winds but open to the moderating rain-producing and warming influence of the nearby Pacific ocean. apart from being grown in Mediterranean climates, hazelnuts are also grown on a smaller scale in southern england. This reflects the wide range of conditions suitable for hazelnut culture.

More than 750 mm annual rainfall is required for good production, and in seasons of low rainfall supplementary irrigation is useful during the establishment stage. Supplementary irrigation is used in other parts of the world such as Spain and France, where rainfall can be unreliable.

GENERAL CLIMATIC & SOIL REQUIREMENTS

| 5g e N e R a l C l I M aT I C & S o I l R e q U I R e M e N T S

long periods of chilling are required to ensure fruitfulness and reliable hazelnut yields. Chilling requirements vary for male catkins, female flowers and leaf buds, but about 1200 hours between 0 °C and 7 °C is suitable. Some varieties, such as Tonda di giffoni, may have lower chilling requirements. For female flowers severe frost areas should be avoided, and temperatures below –5 °C should be avoided when the female flowers are opening. low temperatures at pollen shed followed by bursts of substantially warmer weather can cause catkins to dry out, affecting pollen quality.

High summer temperatures during the growing season can cause leaves to scorch and burn and can prevent satisfactory fruiting.

Ideally, hazelnuts require mild to warm summers and some protection from hot drying winds, which may affect the large, soft leaves. During dormancy hazelnuts can tolerate snow and winter frosts down to at least –15 °C. Slope and aspect should be considered; west-facing slopes should be avoided. These slopes can be prone to strong, hot winds in summer causing stress in developing trees.

calculate your region’s chill hours

To break the period of winter rest and maintain fruitfulness, a period of exposure to low temperatures is required. The number of hours required differs for different plant parts: male catkins generally require fewer chilling hours than either vegetative buds or female flower clusters.

Calculation of the average temperature in the coldest month (usually July) will allow for the use of the ready reckoner (Figure 1). This can be used as a general guide; it does not take into account site-specific considerations. For help in obtaining the mean temperature for your area consult the climatology services of the Bureau of Meteorology: climatic data are available online from the bureau’s website. This will provide a guide as to whether hazelnuts are suited to your area. The mean temperature for the coldest month is obtained by first adding the daily maximum to the daily minimum temperature and dividing the number by two. add up the daily mean temperatures for the month and divide by the number of days in the month. This figure can then be used to read from the graph and estimate available chilling.

Figure 1. Winter chill ready reckoner

Mean temperature in July (degrees Celsius)5

1200

800

400

0

10 15


soilsHazelnuts require a well-drained soil approximately 1.8 m deep and preferably with good organic matter levels. The tree has a mainly fibrous root system, but deeper soils allow for greater exploitation of soil resources and heavier production in the mature orchard. Research in australia has shown that alluvial river flats have produced excellent growth.

In areas of shallow soils, particularly over rock, trees have initially grown but then declined. Heavy clays and very sandy soils should be avoided, and a deep loam is preferred. In some areas of NSW on krasnozem soils, acid conditions combined with high manganese levels can be detrimental to growth. The pH of these soils at depth can go as low as 4.5. a neutral to slightly acid soil (pH about 6 to 6.5) is suitable. There are two common measurements of soil acidity or alkalinity: pH as measured in water [pH(w)] and pH(CaCl2) as measured in 0.01 M CaCl2, both at a soil to solution ratio of 1:5. The pH is a logarithmic scale, meaning that pH 4 is 10 times more acid than pH 5 and 100 times more acid that pH 6.

Soil test reports usually provide soil pH results measured in both calcium chloride and water. Both methods are correct. Soils tested in CaCl2 solution register about 0.5 to 0.8 units lower than the same soils tested in water. The calcium chloride test is more useful for long-term monitoring and tends to be used for fertiliser and plant recommendations. It is less subject to seasonal variations and better approximates field conditions.

applications of agricultural lime or dolomite are the usual ways to reduce acidity. lime also adds the nutrient calcium to the soil and dolomite adds calcium and magnesium. lime or dolomite should be applied below pH 5.6 and preferably incorporated some months before planting, but a full soil test will provide greater detail on other factors that should be considered. In established plantings, have

Measuring soil pH

| 7g e N e R a l C l I M aT I C & S o I l R e q U I R e M e N T S

the soil tested at least every 2 years and if necessary topdress with lime or dolomite before the pH drops too low. Note that dolomite should not be used regularly, otherwise exchangeable Ca:Mg ratio levels can also become low.

as well as being mobile in plants and a component of chlorophyll, calcium and magnesium should be kept at sufficient levels in the soil because they usually have a beneficial effect on the physical state of the soil. This relates to their ability to stabilise soil aggregates and their influence on the activity of decay organisms. Stabilisation of soil aggregates is encouraged by the active decay of organic residues. alternatively, excess or high levels of magnesium can lead to collapse of the soil structure, with soils becoming hard and forming crusts. Infiltration rates of water can also be reduced. gypsum (CaS04) can have a role here to loosen the soil, but gypsum addition is only part of the solution: increasing organic matter levels will provide improved soil aggregate stability. a ratio of 3 to 5 parts Ca to one part Mg is desirable.

When purchasing lime, the most important detail to confirm is the material’s ability to neutralise soil acidity. This is known as the neutralizing value (NV). Normally, the finer the material the greater the NV. Pure calcium carbonate has an NV of 100, which is the standard. Ideally, the NV should be over 95; this figure is usually marked on the bag or supplied in the product description if the product is purchased in bulk.

Use dolomite occasionally but not every time a liming material is required. Test kits that use colour to indicate pH levels are available. The kits are cheap (around $20) and easy to use and will test many samples.

Table 1 provides an estimate of the quantities of lime required to reduce pH.

Table 1. Amounts of lime required to reduced pH in soils of different textures

TO CHANGE pH (w) IN 0 – 15 cm TOpSOIL

t/ha OF FINE AGRICULTURAL LIME

FROM TO SANd SANdY LOAM

LOAM SILTY LOAM

CLAY LOAM

4 6.5 4.5 6.7 8 9 11.25

4.5 6.5 3.3 3.5 6.75 7.5 9

5 6.5 2.25 3.75 5.25 6 7.5

5.5 6.5 1.5 3 3.75 4.5 5.25

6 6.5 0.75 1.5 1.8 2.25 5.25

4 6 3.3 5.25 6.75 7.5 9

4.5 6 2.25 3.75 5.25 6 7.5

5 6 1.5 3 3.75 4.5 6

5.5 6 0.75 1.5 1.8 2.25 5.25

4 5.5 2.25 3.75 5.25 6 7.5

4.5 5.5 1.5 3 3.75 4.5 6

5 5.5 0.75 1.5 1.8 2.25 5.25


Figure 2 shows the relative availability of 12 essential plant nutrients in well-drained mineral soils in temperate regions in relation to soil pH. a pH (CaCl2) range between 5.0 and 6.0 is considered ideal for hazelnuts.

The important indicators evaluated in a typical soil test, and the desirable levels for hazelnut production, are shown in Table 2.

6.0

MOL

YbdE

NUM

COpp

ER &

ZINC

bORO

N

MAN

GANE

SE IRON

SULF

UR

MAG

NESI

UM CALC

IUM

pOTA

SSIU

M pHOS

pHOR

US

NITR

OGEN

medium acid

slightly acid

very slightly acid

very slightly alkaline

slightly alkaline

medium alkaline

strongly acid

strongly alkaline

5.5

5.0

4.5

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Figure 2. Effect of pHCa on availability of plant nutrients. The thicker the band, the more soluble the element is under that level of soil acidity/alkalinity.

Table 2. Typical indicators evaluated in a soil test, and desirable levels for hazelnut production

INdICATOR dESIRAbLE RANGE

pH (CaCl2) 5.5 – 6.5

Organic Carbon % (Walkley & Black) 3.5 – 4.0

Nitrate Nitrogen mg/kg N 10 – 20

Phosphorus Bray mg/kg 30 – 50

EC dS/M < 0.15

CEC cmol(+)/kg > 10

INdICATOR dESIRAbLE RANGE

ExCHANGEAbLE CATIONS

Calcium 65 – 80% (4 – 6 meq/100 g)

Magnesium 10 – 20% (1 – 2 meq/100 g)

Potassium 2 – 6% (0.3 – 0.5 meq/100 g)

Sodium < 2% (0 meq/100 g)

Aluminium < 5% (0 meq/100 g)

CEC (cation exchange capacity) > 10

Calcium/magnesium ratio 3 – 5 (i.e. 3 – 5 parts Ca to one part Mg)

| 9

although all of the indicators in Table 2 are important, cation exchange capacity (CeC) plays an especially important role. CeC is a measure of the soil’s ability to hold nutrients for later use by the hazelnut tree. Soils with a low CeC are often sandy and prone to leaching. a soil with a high CeC is more fertile than a soil with a low CeC. organic matter, which eventually decomposes to humus, has a much greater CeC than, for example, clay, and so increasing organic matter in the nut grove is important for maintaining soil fertility. Fertile soils are considered essential for profitable commercial production.

managing your soil, and soil basics

Hazelnut orchards are unique to some degree in that the harvest period requires the orchard floor to be relatively clear to allow for successful nut collection. This is largely dictated by the type of harvest machinery used. These requirements are also demanding on soil and soil management. With changing climates, summer storm events are predicted to become more intense and orchard floors unprotected at harvest time can be exposed to erosion. Typically, in an established bearing orchard a flail mower is used on orchard ground cover. This helps reduce the height of cover to just above the surface of the soil, chops up leaves and twigs, and prepares the orchard floor for harvest.

observation of the profile can help in managing the soil by giving a good idea of the soil’s advantages and limitations. The ‘soil profile’ refers to the sequence of horizons down to, and including, the parent material. The ‘a horizon’ is the topsoil and where hazelnuts obtain most of their nutrients, and the ‘B horizon’ or ‘subsoil’ is the soil profile’s moisture storage layer. To determine the soil depth, dig suitable holes with an auger, backhoe or shovel to 2 m. a hand auger is portable and can be used later for checking the depth of irrigation as the orchard matures.

A soil pit showing root development and soil characteristics

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Soil structure is largely the physical arrangement of the soil particles, aggregates and pores. Its greatest influence is on the distribution of moisture and oxygen in the soil, which in turn affects the ease of which roots can exploit the soil for nutrients. growers should be wary of soils that have a sand silt or loam topsoil over a clay subsoil. The fibrous roots of the hazelnut tree can be restricted in these soils, which can have poor drainage. lateral drainage at the top of the subsoil can also cause problems for root growth.

The proportion of sand, silt and clay determines soil texture. organic matter and the clay minerals provide the bonds that hold the soil together. In a soil made up of over 60% clay particles, the clay minerals will do most of the bonding. as the proportion of clay in a soil decreases, organic matter becomes increasingly important. a loam soil, for example, which has roughly equal portions of sand silt and clay, is generally a good topsoil and is suitable for hazelnut production.

Colour is often the first clue to determining soil type. a red soil is generally more sandy than a black soil, whereas red clay soils have limited ability to swell. These soils are typically acidic and can become hard-setting. Redness in soils generally indicates good drainage, which can be evidenced by oxidation of the iron content. yellow or mottling of soil colour in a soil profile can indicate poor drainage and the possibility of waterlogging.

soil management

growers should maintain sound cultural practices that will sustain soil structure, minimise erosion, and provide an environment for healthy root development. Soil compaction and low levels of organic matter can cause reduced root growth and reduce tree performance. The use of heavy machinery and harvesters on bare wet ground should be avoided, particularly on soils with high clay content. excess runoff exposes tree roots, which can be exposed to herbicides if the tree strip is sprayed with them.

Basic principles to remember are:

orchards should be planned so that water flow is managed to minimise soil •erosion and nutrient runoff. The topsoil is your most valuable soil and needs to be stable.

aim to keep soil at least 70% covered through the growing season.•

Shorten intermediate slopes with contour banks.•

Contour rip, where necessary, pre-planting. This will increase water entry into the •soil and retard runoff.

on sloping land, plant on the contour if possible.•

| 11

The orchard floor

Permanent sods can be incorporated with the use of a regular herbicide program banded down the row to reduce competition and encourage tree growth. This is particularly important in the early years. Managed inter-rows provide improve soil structure, increase water penetration and maintain organic matter levels. growth can be mown for use as mulch under trees and flail-mowed before nut fall. Flail-mowing after nut harvest is also useful to mulch leaves and eliminate old nuts, which can attract rodents.

a typical sward for cooler tablelands areas might consist of kangaroo rye 20 kg/ha and Haifa white clover at 2 kg/ha. Some sub-clovers may also be suitable. Commercial mixtures are also available and generally consist of a fescue, ryegrass and clover. Clovers have good capacity to fix nitrogen and support the general fertiliser program. optimum sowing time is typically early to mid autumn, with sowing rates up to 50 kg/ha. This figure is important to ensure rapid establishment of effective competition for weeds.

If a pre-planting cover crop is sown then it should be mown before incorporation. Ploughing in a green stalky cover crop is not recommended as it can leave large amounts of plant material, which in dry conditions can take a long time to break down. a typical cover crop may consist of oats at 30 kg/ha combined with vetch 20 kg/ha, or oats at 35 kg/ha plus field peas at 30 kg/ha.

g e N e R a l C l I M aT I C & S o I l R e q U I R e M e N T S


When preparing the area for planting some growers may wish to rip the soil. This may be completed for a range of reasons, depending on soil type and previous ground usage. Ripping can help to remove tree roots from a previous crop. To prepare the area for planting, trees and vegetation can be cleared and the land deep-ripped in both directions to a depth of about half a metre.

on steep slopes, to avoid erosion rip only along the contours. The land should then be levelled and fertilisers and lime added, as determined by soil testing.

Further reading

Baldwin B, gilchrist k and Snare l (2007) Hazelnut Variety Assessment for South Eastern Australia. Project No. US-1259. Rural Industries Research and Development Corporation, Canberra

Brunton B (2006) Soil Wise: Pocket Guide to Looking after Soils. NSW Department of Primary Industries, orange

McMullen B (1995) Soil Management for New South Wales Orchards and Vineyards. NSW Department of Primary Industries, orange

Westwood MN (1978) Temperate-zone Pomology. WH Freeman & Co, San Francisco

Westwood MN (1988) Temperate-zone Pomology: Physiology and Culture. 3rd edition, Timber Press, Portland, oregon

| 13W I N D S H e lT e R

wINd SHELTER

young hazelnut plants are very susceptible to the drying effects of hot winds. The battering effects of persistent winds in summer can damage large leaves. exposed sites subject to the drying effects of summer winds should be avoided. a well-designed windbreak proves its worth when low humidity, high temperatures and strong winds combine to cause unfavourable conditions for newly planted trees. good soil moisture is also required at this time, not only for the hazelnut planting but also for the windbreak.

Hazelnuts are wind pollinated and flower in winter, so any windbreak should allow some air movement for pollen to be carried.

Height is generally the most important factor determining the effectiveness of the windbreak. The taller the windbreak, the greater the area protected. on level ground a windbreak will reduce the speed of the wind on the downwind side for a distance equal to about 25 times the tree height. Maximum reduction of wind speed is obtained at a distance of five to 15 times the tree height downwind of the windbreak.

The windbreak should be sufficiently permeable to allow air through, rather than acting as a solid barrier. It should be planted at right angles to the winds from which protection is needed (Figure 3). Hazelnut orchards are generally worst affected by hot drying winds from the west and north-west. easterly winds can also be persistent. Windbreaks planted north–south are a good compromise, as they provide protection from winds from the western quarter.


Figure 3. Options for windbreak design

Prac tical implicationsWindbreaks should not shade, or compete with, the hazelnut orchard.•

Choose appropriate species. Some species, such as acacia, may harbour pests •like borers or provide perches for birds that may compete for the crop.

Plan windbreaks so that they provide a refuge for beneficial predators.•

If singles rows are used, choose species that retain their foliage to the ground •and make dense growth. The river oak Casuarina cunninghamiana has proven to be a worthy windbreak on the Tablelands of NSW and in other parts of australia. The main disadvantage of single rows is that if a tree is lost a gap is created, reducing the efficiency of the windbreak. Breaks of up to three rows, consisting of one row each of low, medium and tall trees, are most effective.

Include windbreaks in your irrigation design.•

leave enough turning space at the head of the rows for tractor/harvesting •operations.

generally, windbreak trees are planted in late autumn (april–May) or winter, but •delay planting if the ground is very wet. In extremely cold areas a spring planting in September can give better results.

Root pruning may be required if windbreaks compete with the orchard.•

The choice of species is dictated by local experience, conditions and the grower’s •preference for natives or exotics. key considerations are drought, frost tolerance, growth rates and longevity.

For further information consult your State’s department of primary industries or forestry departments. local nurseries specializing in farm trees can also advise.

double row

wind

treble row

wind

| 15W I N D S H e lT e R

Further reading

Cleugh H (2003) Trees for Shelter – a Guide to Using Windbreaks on Australian Farms. Publication Number 02/059, Rural Industries Research and Development Corporation, Canberra

Cremer k (1990) Trees for Rural Australia. Inkata Press, Melbourne

A double row of Casuarina cunninghamiana is an effective windbreak


ORCHARd LAYOUT

a whole-farm plan is an important tool in the establishment and management of the orchard. This optimises the use of natural resources and is the basis of successful management. a whole-farm plan should include a map of the farm and neighbouring areas and a strategic plan for the enterprise.

generally orchards should be:

planned so that water flow is managed to minimise soil erosion•

designed to reduce the effect of any future spray drift on to neighbouring •properties

arranged so that the position of the processing shed is such that complaints •from neighbours are avoided and there is access for transportation of the crop.

establishing the plantingThe layout of varieties in an orchard is a compromise between the benefits of cross-pollination and maximising orchard harvest and orchard management efficiency. good pollination between varieties increases the number and quality of nuts. Incorporating three different polliniser cultivars in the planting that overlap with female bloom will provide good nut set. Planting too many varieties can lead to problems with mixing early and late season varieties and can make labour and machinery operations inefficient.

| 17o R C H a R D l ayo U T

Planting distances

a number of spacings have been used in the past to grow hazelnuts, and in recent years more efficient ways of increasing yields and making better use of the available land area have been adopted. The selection of tree planting distances should take into account the relative vigour of the variety, the soil type, and the width of implements available for use in the orchard. Close plantings may have to be thinned at maturity, but the higher return in the first 10 years may be crucial to the economic survival of a new planting. The three spacings below are typical examples. The first value is the distance between rows.

Plant spacing No. of trees/ha

6 m × 4 m 416

6 m × 6 m 277

6 m × 3 m 555

The higher density plantings like 6 m × 3 m are considered more efficient, as yields have the potential to be double that of the 6 × 6 m spacing within the first 10 years. Trees can be thinned in the long term if excessive shading and crowding occur. The closer planting also allows for better pollination and nut set.

Planting at 6 m between rows and 3 m between trees is also an option, with every second tree removed down the row at 11 to 15 years. This allows for greater earlier revenue return but will involve greater capital input for planting and removal costs. Varieties like Barcelona and TBC, for example, are spreading, whereas ennis and Tonda di giffoni are slightly more erect. In oregon (USa) the recommended spacings include 6 m × 6 m and 5.4 m × 5.4 m.

Planting with a wider spacing along the rows is suitable for the trees when they mature. The alternative method is to double plant and remove every second tree when overcrowding occurs. If the second method is adopted there is greater production in the early years of the orchard, but this needs to be balanced against the cost of the trees and the cost and effort of removing half of them at a later stage. as pollination depends on the movement of air around the trees (i.e. hazelnuts are wind pollinated), there is a limit to how far the pollinisers can be from the main crop. The closer the polliniser is to the main crop trees the better pollination will be. This relationship needs to be considered when high-density plantings are thinned.

If the area of land available to the grower is less of a consideration than the cost of planting material, then it may be prudent to plant at full-width spacing initially, as it is always a difficult decision to remove trees. If land is limited and the grower wishes to maximise the returns in the initial years, then close spacing may be the best option. a close-spaced orchard may be maintained with appropriate pruning, but this will incur higher costs in maintenance.


Poll inationas already mentioned, hazelnuts are not self-pollinating, and it is generally considered that three different varieties with compatible pollen should be planted with the main crop so that there is pollen available over the entire period when the female flowers are receptive. The pollinisers are usually classified as early, medium and late; information on suitable pollinisers of the commercially viable hazelnut varieties is highlighted in the section on ‘Flowering & pollination’.

one polliniser tree to eight of the main variety should ensure wind cross-pollination; in unfavourable seasons a one to five ratio may be beneficial. older orchards may require a smaller number of pollinisers. Research from the USa into pollen movement indicates that trees up to 18 m away from a polliniser will usually bear a good crop.

In locations where there are many orchards the ratio may be less owing to the large quantities of pollen in the area; however, this is not currently the situation in australia, where the density of orchards is low and existing orchards are small. The proportion of pollinisers and how they are planted among the main crop is important, because the nuts of the polliniser trees will need to be separated from those of the main crop when it is sold.

one way of separating polliniser nuts from the main crop during harvest is to choose pollinisers with significantly different sizes, shapes, or cropping times. If the polliniser nuts are significantly smaller or larger than those of the main crop they can be graded out. If they fall earlier or later they may be harvested at a different time, although this will add to costs.

If the polliniser nuts are of a similar size and shape and their fall overlaps that of the main crop, the problem can be reduced by having rows of pollinators that can be harvested at the same time but in a separate run. as the trees mature, mixing of the polliniser and main crop nuts will tend to increase.

Planting schemesThere are variations worldwide in planting schemes for the distribution of main crop and pollinisers. Some planting schemes favour a row or rows of pollinisers interspersed between every three to six rows of the main crop (Figure 4).

In oregon, pollinisers are planted every third row every sixth tree in a staggered design (Figure 5).

The layouts in both figures can be used by australian growers.

| 19

P P P P P P P P P P P P P P P

M M M M M M M M M M M M M M M





P P P P P P P P P P P P P P P


Figure 4. (P = Polliniser, M = Main Variety). One polliniser to every five main variety trees in each row


M P M M M M M P M M M M M P M



M M M M P M M M M M P M M M M



M P M M M M M P M M M M M P M



M M M M P M M M M M P M M M M


Figure 5. Planting scheme used in Oregon. Pollinisers are placed every third row every sixth tree in a staggered design.

a number of australian hazelnut propagators provide their purchasers with detailed planting schemes.

Further reading

Baldwin B, gilchrist k and Snare l (2000) Selecting pollinators for a hazelnut orchard. Australian Nutgrower 14(3), 16–19

Snare l (2008) Hazelnut Production. Primefact 765, NSW Department of Primary Industries, orange

o R C H a R D l ayo U T


NUTRITION & FERTILISERS

leaf analysisestablished hazelnut orchards should be fertilised according to the results of leaf tissue analyses and limed according to the results of soil testing. Soil and leaf analyses provide guides to the availability of nutrients in the soil and uptake by the tree. levels provided by these tests can be compared with the optimum levels set for healthy trees. Standard sampling procedures and quality-assured laboratories will allow growers to better understand tree nutritional trends in the orchard. It is important that analysis interpretation and fertiliser recommendations are linked to an understanding of the soil type, the soil test, and the seasonal cycle of the tree.

leaf analysis can also:

confirm a diagnosis on the basis of symptoms•

predict a nutrient disorder in the current or future crop•

help in the development and adjustment of fertiliser programs•

measure the amounts of nutrient removed from the orchard with a view to •replacement

suggest additional tests to identify a problem.•

Regular testing over a number of seasons allows the grower to assess any trends that are developing and incorporate this information with other observations such as the effects of crop load, alternate bearing patterns and weather. These effects can cause variations in element levels from year to year and need to be considered when interpreting results. leaves can be sampled during early January; leaves should be collected from the mid-shoot of the current season’s growth. Samples can be collected by walking a ‘W’ across the block and collecting leaves randomly. about

| 21N U T R I T I o N & F e R T I l I S e R S

100 leaves are required for laboratory processing, which can be completed by private laboratories or some State departments of primary industries. leaf tissue standards are supplied in Table 3. keep the records of the fertiliser program.

Fer ti l ising Hazelnuts benefit from a balanced nutritional program such as annual applications of a complete NPk fertiliser. Nitrogen, potassium and boron are the elements most commonly deficient in hazelnuts.

Table 3. Plant leaf analysis standards for hazelnuts

NUTRIENT dEFICIENT bELOw NORMAL NORMAL AbOvE NORMAL ExCESSIvE

Nitrogen % < 1.80 1.81 – 2.20 2.21 – 2.50 2.51 – 3.00 > 3.00

Phosphorous % < 0.10 0.11 – 0.13 0.14 – 0.45 0.46 – 0.55 > 0.55

Potassium % 0.50 0.51 – 0.80 0.81 – 2.00 2.01 – 3.00 > 3.00

Sulphur % 0.08 0.90 – 0.12 0.13 – 0.20 0.21 – 0.50 > 0.50

Calcium % < 0.60 0.61 – 1.00 1.01 – 2.50 2.51 – 3.00 > 3.00

Magnesium % < 0.18 0.19 – 0.24 0.25 – 0.50 0.51 – 1.00 > 1.00

Manganese ppm < 20 21 – 25 26 – 650 651 – 1000 > 1000

Iron ppm < 40 41 – 50 51 – 400 401 – 500 > 500

Copper ppm < 2 3 – 4 5 – 15 16 – 100 > 100

Boron ppm < 25 26 – 30 31 – 75 76 – 100 > 100

Zinc ppm < 10 11 – 15 16 – 60 61 – 100 > 100

Fertiliser can be applied using a number of different techniques. This includes broadcasting or banding down tree tows, applying foliar sprays, or application via an irrigation system.

Nitrogen, potassium, and boron are the main elements that have proven to provide increased yields and are discussed here in detail.

Nitrogen

The main nutrient to be supplied as fertiliser, or as organic matter, is nitrogen (N). Plants take nitrogen from the soil during the growing season, and this nitrogen is harvested mainly as protein in the kernels. Therefore, typically, nitrogen needs to be replaced after a crop has been grown. Nitrogen needs to be converted into a mineral form, nitrate, to be available to plants.


The likely nitrogen requirements may be judged by observing the length of new branch growth at the end of the growing season. In established trees this should be about 30 to 50 cm. a more accurate method is to have a leaf analysis completed on a sample of leaves taken in January. Much of the development work with fertilisers has been completed in the USa, and so the following is provided as a guide only. younger trees require less than mature trees: at year 2 about 50 g can be applied, with the rate increasing through to maturity. Nitrogen can be applied (three applications per year) from September through to early December.

The normal requirement for a mature tree is between 450 and 680 g per tree of actual nitrogen per tree (broadcast), depending upon tree densities. If nitrogen is banded under the trees then about 20% less can be used. even distribution around young trees is critical, as improper application can kill trees. Do not apply fertiliser of any kind to the planting hole, as fertiliser application at planting time can burn the developing roots.

If nitrogen is applied in small amounts frequently, the plants will be able to take up most of the nitrogen; this will reduce leaching.

Practical implications:

Do not apply more than 20% of the total annual nitrogen application during •summer. Heavy applications increase vegetative growth, which competes with kernel development.

avoid using uncomposted animal manures, as they can cause problems at •harvest time, especially with sweepers and vacuum machines. Salmonella can also persist in manures that have not been properly composted.

Consider fertigation to fertilise trees in the absence of good rain. Calcium nitrate •and liquid NPk fertilisers may be suitable.

Be sure to calculate the N content of each fertiliser to get the exact rate. For •example, if the N content of a fertiliser is 27%, then to apply 50 g of actual N; 185 g of product should be spread (50 × 100 ÷ 27 = 185).

Try to use non-acidifying nitrogen fertilisers where possible. These include:•

potassium nitrate (13% N)•

calcium nitrate (15.5% N)•

composted poultry manure (3% N).•

Maintain optimum soil organic matter levels to buffer the effect of the fertiliser •on pH levels.

| 23

Potassium

Potassium is important for growth but is normally applied only in autumn in accordance with the results of leaf and soil analyses. Potassium can be low or deficient in some sandy soils and is slower acting and less mobile than nitrogen. The most common potassium fertilisers are muriate of potash (potassium chloride) and sulfate of potash. Potassium deficiency is indicated by the presence of small leaves with some burning on the margins and short nut husks. Care needs to be taken with potassium chloride to avoid its build-up and subsequent salinity problems.

Boron

annual sprays of boron applied in late spring can increase nut set in trees over 6 years old, although a response is not always obtained. Boron deficiency shows up as dieback of shoot tips and dropping of the lowest leaves of new shoots. Research has shown that foliar boron applications can increase nut set by as much as 33% in some situations. Foliar boron can be toxic when used to excess, and applications should not exceed more than 1.1 kg/ha.

Boron availability is reduced under dry conditions, and trees can produce deficiency symptoms in one season despite not having seen the problem for a number of years.

In summary, many growers use a variety of organic and other fertilisers, including pelletised chicken manure and NPk fertilisers. although some growers have found that trees yield good crops without annual applications of fertiliser, because of annual nutrient removal by the crop over time it is unlikely they would continue to maintain these good yields. Response to fertilisers depends on the amounts of available nutrients and other factors such as soil pH. To maximise the production potential of trees, growers should ensure that factors under their control, such as fertiliser programs, provide nutrients at optimum levels.

Further reading

olsen J (1996) Nitrogen management in oregon hazelnuts. In Proceedings of the Fourth International Symposium on Hazelnut. Acta Horticulturae 445, 263–265

olsen J (2001) Hazelnut Nutrient Management Guide. oregon State University. Retrieved on 30/10/09 from http://extension.oregonstate.edu/catalog/pdf/em/em8786-e.pdf

Snare l (2004) Hazelnut leaf nutrition; building your interpretative and diagnostic skills Australian Nutgrower 18(3), 13–17

N U T R I T I o N & F e R T I l I S e R S

Potassium deficiency symptoms


Irrigation is one of the key tasks that growers need to be able to manage in young and mature hazelnut orchards. In simple terms, irrigation is the act of supplying water from dams, rivers or bores to meet crop water needs between rainfall events. When irrigating hazelnuts, we need to calculate the best time to irrigate and how much water to use so that we achieve good yields and sustainably manage the available water supply.

Correct management helps to:

achieve targeted yields•

produce quality kernels•

maintain tree health by reducing moisture stress•

deliver nutrients to the plant for sustained growth (through fertigation).•

In the same way that water stress can lead to reduced yields, catkin drop, and early leaf fall, excessive applications of water can lead to plant health problems, increased pumping costs, leaching of nutrients and wastage of water down the soil profile. good irrigation practice comes from knowledge of your soil characteristics and an understanding of the tree’s growth and development cycle. It is desirable to have good water availability from october (early leaf ) and optimum levels from December onwards as the kernel fills. Stress during this period can reduce the final nut size as the nut develops through shell development to harvest.

IRRIGATION

| 25I R R I g aT I o N

Water qualityan assessment of water quality is an initial important factor when considering the suitability of water for the orchard. Some areas may have marginal water quality; this can reduce yields and damage plants and the soil. The main characteristics to consider include:

electrical conductivity (ec), a measure of salinity• . If salinity is less than 0.8 dS/m then the water is generally suitable for irrigation on well-drained soils.

pH• . Water with pH 6 to 8.5 is generally suitable for irrigation.

chloride• . levels below 140 mg/l (140 ppm) are generally acceptable.

alkalinity• . Highly alkaline water can affect the uptake of calcium and magnesium. levels up to 150 mg/l are acceptable.

calcium carbonate saturation index• . This is an index determined by taking into account pH, salinity, alkalinity and hardness. Figures between –0.5 and +0.5 are usually acceptable.

appearance• . algae can cause blockage of filters and drippers.

Type of deliver yThe irrigation system chosen will depend on many factors, and every grower’s situation will be different. The amount and source of water available, evaporation rates, the composition/profile of the soil, available funding, and orchard harvest management techniques are but a few considerations.

A simple valve station showing the solenoid (blue) and injector points (yellow) for fertigation. A disc filter is on the outlet side.


When choosing a system, consider the advantages and disadvantages and confirm that they are right for you. In australia most hazelnut orchards are generally irrigated with a drip, mini-sprinkler system or sub-surface delivery system. Some of the advantages and disadvantages are highlighted in Table 4.

Table 4. Advantages and disadvantages of irrigation systems for hazelnuts

LOw LEvEL SpRINkLERS dRIp IRRIGATION

AdvANTAGES dISAdvANTAGES AdvANTAGES dISAdvANTAGES

Wind effects minimised•

Suited to most soil types•

Well suited to fertigation•

Easily adapted to automation•

Checking sprinkler operation is •expensive

Good weed control is necessary •for distribution

Greater susceptibility to •physical damage from animals and harvesting equipment

Highly suited to fertigation •and automation

No wearing parts•

Potentially the most water •efficient system

Large water savings in young •plantings due to accurate and even water placement

High frequency of irrigation •means a flexible and frequent water supply system is required

High degree of filtration •necessary

Susceptible to damage from •orchard operations

In young blocks a single lateral with appropriately spaced emitters may suffice for drip irrigation. as trees mature, two drip laterals can be used per row to provide a larger wetted area for the root system. alternatively, if the laterals permit, micro-sprinklers can be added as the trees mature. Some growers prefer to run laterals below the surface, with emitters above ground. This accommodates cross-mowing.

Subsurface drip irrigation (SDI), where drip tape or tube is buried below the soil surface, is highly efficient, as evaporation is reduced. Depth of the tube placement, emitter spacing, flow and soil properties should be considered carefully. The wetting pattern of water in the soil from the emitters must reach the tree roots in both young and mature plantings. It is important that with any system water is available to at least 30% of the root surface area.

Flow meters provide accuracy to the system

| 27

In all of the above systems consider water quality. Use of poor-quality water can create limitations, and filters need to be able to handle worst-case scenarios. as a general guide, filters should be able to remove particles one-quarter the size of the emitter opening, as particles may clump together and clog emitters. Flow meters form part of any system, and records of flow can help detect deviations. amounts of water recorded can be compared with the estimated crop water usage to aid efficient management.

Maintenance is required on all systems, and regular flushing of lines and addition of chlorine will minimise clogging. expert advice is readily available from many equipment suppliers, who will provide designs for the total system.

Basics of irr igation schedulingThere are many methods developed for measuring crop water use. These methods can be grouped into three categories:

plant-based methods• : information from the plant itself, including direct observations

weather-based methods• : data from climatic factors, including sunlight, temperature, wind and humidity

soil-based methods• : methods that monitor how much water is taken up by the plant from the soil.

The key issues remain how much to irrigate and when to irrigate. knowing how much to irrigate requires first establishing how much water is held in the root zone. Not all water that is applied or already in the soil is available to the tree. Some water is held tightly in the soil; this is known as soil moisture tension. Soil moisture tension is a measure of how hard the plant has to work to extract moisture from the soil. It is measured in negative kPa.

an understanding of the following terms helps to identify the behaviour of water in the soil:

field capacity• : this is when the soil profile has been filled (been irrigated or had good rain) and has naturally drained for about 24 hours. The soil moisture tension is approximately 8 kPa at field capacity.

permanent wilting point• : the tree cannot take up any more water, despite there being some water left in the soil. Soil moisture tension is approximately 1500 kPa.

refill point• : driest soil that the plant can extract water without stress occurring, between 40–60 kPa.

readily available water (raW)• : this is the volume of water that is easily available to the tree, between field capacity and refill point, when plants have difficulty sucking up water. Soil moisture tension is between 40 and 60 kPa.

Figure 6 illustrates the above points.

I R R I g aT I o N


dry soil

permanent wilting point

Refill point

Field capacity

Saturated soil

n

o cro

p gro

wth

crop growth slows best crop growth

crop growth slowsFigure 6. Water availability indicator

crop factors

Crop factors are values that relate tree water use at a particular stage of growth to the amount of pan evaporation (epan): for example, if the pan evaporation is 10 mm and the crop factor is 0.8, then the plant water use is 0.8 × 10 = 8 mm. This can also be described as a percentage (i.e. 80% of the evaporation). Figures for pan evaporation can be obtained from the Bureau of Meteorology. Crop factors change with the growth stage of the plant. early in the season, at leaf out, for example, crop factors are generally low and peak before nuts are harvested. The physiological phases for hazelnut in australia are:

vegetative growth, flowering induction, ovary growth• : october, November, December

kernel fill• : January to February

reserve accumulation• : March, april, May.

The right crop factor will need to be determined to some degree through trial and experience. Some crop factors for hazelnuts are presented in Table 5. growers can begin with these, and if the soil is too dry or wet then the crop factor and irrigation frequency can be adjusted. Crop coefficients are other numbers used to relate tree water usage and evapotranspiration figures obtained from automatic weather stations; they can be used in the same way for the purpose of irrigation management.

Table 5. Potential guidelines for distribution of the monthly crop factor for hazelnuts in Australia.

MONTH CROp FACTOR MONTH CROp FACTOR

October 0.30 January 0.70

November 0.40 February 0.55

December 0.62 March 0.35

Adapted from Allen et al. (1998)

From the information above, tree water usage can be calculated:

Tree water use (l/tree) = Crop factor × pan evaporation × planting square (m2)

| 29I R R I g aT I o N

monitoring soil moisture: how much and when to irr igateSoil moisture monitoring allows real-time determination of the moisture level of the soil and should be the primary monitoring tool. It can also be used as a check to determine if the irrigation is reasonable and also whether the crop factors are accurate for your site. Soil moisture should be monitored before and after irrigation and adjusted if soils are too wet below the root zone or if soils are dry after the irrigation.

knowledge of soil moisture content is important for deciding on the first irrigation and when to irrigate after rainfall. Soil moisture tension or total soil water is generally measured. Soil moisture monitoring systems include tensiometers and gypsum blocks to measure soil tension, or more expensive sophisticated capacitance systems to measure total soil water content. Tensiometers and gypsum blocks are cheap, easy to install and allow continuous monitoring. Soil type can affect the accuracy of some sensors (i.e. capacitance probes can be less accurate on cracking clays). Table 6 is a guide to interpreting the results of the tensiometers that are commonly used.

Table 6. Interpreting common tensiometer readings

REAdING (CENTIbARS OR kpA) INTERpRETATION

0 – 8 Soil is saturated (0) to near field capacity (8). Continued low readings indicate water logging.

8 Field capacity.

8 – 25 The best conditions of soil moisture and aeration.

25 – 35 Consider irrigation at critical stages of crop cycle. Ovary growth and kernel expansion.

35 – 50 Mild stress on well drained soils.

50+ Soil is very dry: this will affect yield and kernel quality.

Practical considerations

Whichever system is chosen it is important to have the sensors located in positions that are representative of the soil type, tree health and tree size. overwatering of young trees can cause water logging. When installing sensors it is a good idea to dig under the emitter to establish the wetting pattern. Sensors need to be located at the following depths:

in the middle of the root zone•

near the bottom of the main fibrous root zone•

below the root zone.•


Further reading

Boland a, ziehrl a and Beaumont J (2002) Guide to Best Practice in Water Management – Orchard Crops. Department of Natural Resources and environment. Highway Press, Victoria

Charlesworth P (2005) Soil Water Monitoring: an Information Package. land and Water australia, Canberra

allen g, Pereira l, Raes D and Smith M (1998) Crop evapotranspiration – guidelines for computing crop water requirements. Food and agriculture organisation Irrigation and Drainage paper 56. Retrieved on 30.10.09 from www.fao.org/docrep/X0490e/X0490e00.htm

gispert J, Tous J, Romero a, Plana J, gil J and Company J (2005) The influence of different irrigation strategies and the percentage of wet soil volume on the productive and vegetative behaviour of the hazelnut. Proceedings of the Sixth International Congress on Hazelnut, Acta Horticulturae 686, 333–341

Irrigation australia ltd (n.d.) www.irrigation.org.au

NSW DPI (2002) Irrigation Management Notes: a waterwise on the farm course. NSW Department of Primary Industries, orange

Tensiometer with ceramic tip and vacuum gauge at the top.

| 31F lo W e R I N g & P o l l I N aT I o N

FLOwERING & pOLLINATION

Hazelnuts are wind pollinated and self-incompatible: that is, a tree cannot pollinise itself or any other tree of the same variety. The pollen from the male catkins drifts through the orchard on the wind in winter and is transferred to the open stigmas of the female flower.

Because successful pollination determines the productivity level and viability of the orchard it is essential to plan correctly at the establishment phase. Planting layouts are discussed in the section on ‘orchard layout’. growers need to know which variety will pollinate the main nut-bearing crop and when the pollinisers shed their pollen.

Successful pollination requires:

suitable amounts of pollen•

pollen of a compatible type that is available at the same time as the female •flowers are in bloom

favourable weather conditions. as a winter-flowering plant the hazelnut tree is •well adapted to supply pollen.

maintenance of soil moisture during autumn so that the catkins do not fall.•

Typically, the start of bloom is correlated with temperature: in regions with milder winters (e.g. mild South Coast region of NSW) a given set of varieties will flower first, whereas in colder areas (e.g. the cooler region of orange in NSW) the same set will flower later. australian research indicates that the length of the period of pollen shed is less in later-flowering varieties. The blooming season can take up to 3 months from initial pollen shedding of early varieties to the later full bloom of female flowers.

as mentioned in the section on ‘general climatic & soil requirements’, chilling requirements vary for male catkins, female flowers and leaf buds, but about 1200 hours between 0 °C and 7 °C is suitable.


a range of varieties should be planted to ensure the dissemination of cross-compatible pollen. Table 7 shows the pollen compatibility of some hazelnut varieties. one polliniser tree to eight of the main variety should ensure wind cross-pollination, and in unfavourable seasons a one-to-five ratio may be beneficial. older orchards may require a smaller number of pollinisers. Most overseas orchards use at least two pollinisers to compensate for seasonal variation and to ensure full coverage of the female bloom. The planning of groves for mechanised harvest requires that polliniser placement be made with harvest and marketing requirements firmly in mind.

Hazelnut trees rarely set no nuts, and at flowering time they are generally affected only by severe frosts. Female flowers are extremely frost tolerant and will withstand temperatures down to –15 °C. Persistent rain during the period of pollen shed can reduce the amount of pollen available to female flowers, and some yield reduction may occur. Following the transfer of pollen to the female flower and the germination of pollen down the pollen tube, nut development is suspended until later in summer, when shell, husk and ovule development occur. given the right conditions, shell development proceeds through November–December and the kernels develop quickly through January and February. Successful fertilisation is indicated by development of a kernel.

Some defective nuts, known as blanks, can occur when pollination stimulates the shell to develop and the kernel fails to develop. This is a common defect when fertilisation fails to occur or when embryos abort in the early stages of growth. This may be due to number of factors, including nutrient deficiency (see comment on boron in the section on ‘Soil chemicals & fertilisers’), and low levels of calcium are also possible. environmental reasons and moisture stress are also possible. Typically, these blank nuts tend to fall earlier, and so a degree of separation can be achieved before the main harvest starts.

An expanding male catkin (left). Female flowers at the base of a male catkin showing red stigmas (above).

| 33F lo W e R I N g & P o l l I N aT I o N

Table 7. Pollen compatibilities of some hazelnut varieties

vARIETY pOLLEN SHEd START

pOLLEN SHEd LENGTH (dAYS)

FEMALE bLOOM START

FEMALE bLOOM (dAYS)

Barcelona 20 June 39 15 July 32

Ennis 29 June 38 14 Aug 27

TBC 11 July 31 29 July 28

Lewis 11 July 28 24 July 32

Butler 5 July 28 14 Aug 30

Willamette 2 July 29 20 Jul 33

Turkish Cosford 12 July 21 16 Aug 7

Casina 14 July 25 16 Aug 22

Halls Giant 8 Aug 16 18 Aug 18

Jemtegaard 5 11 Aug 19 26 Aug 16

Tonda Di Giffoni 20 June 30 7 July 31

Source: Baldwin et al. (2007)

Figure 7. Timings of pollen shed and female bloom in different varieties

Source: Baldwin et al. (2007)

Table 7 and Figure 7 show the approximate start and length of pollen shed and female bloom in temperate regions of NSW; the information is adapted from australian research.

Tonda di Giffoni

barcelona

Ennis

willamette

butler

Lewis

TbC

Turkish Cosford

Casina

Halls Giant

Jemtegaard 5

pollen shed

female bloom

22 Ju

ne

15 Ju

ne

29 Ju

ne

6 Ju

ly

13 Ju

ly

3 au

gust

10 a

ugus

t

17 a

ugus

t

24 a

ugus

t

31 a

ugus

t

7 Se

ptem

ber

27 Ju

ly

20 Ju

ly

14 S

epte

mbe

r


compatibility

The genetics of hazelnut fertilization are complex, but in summary the allele (a form of specified gene) of the pollen should be different from the allele of the flower it is pollinating.

Table 8 has been adapted for australian varieties and provides a guide to compatibility for commercial varieties grown in australia. australian specialist nurseries can also offer advice on compatibility and selection of pollinators.

Table 8. Hazelnut compatibility chart

pOLL

EN pA

RENT

bARC

ELON

A

ENNI

S

MON

TEbE

LLO

T.G.d

.L.

T dI G

IFFO

NI

TONd

A RO

MAN

A

NEGR

ET

TONO

LLO

CASI

NA

bUTL

ER

dAvI

ANA

LANS

ING

HALL

’S GI

ANT

J5 dU CH

ILLY

EpSI

LON

TOkO

LYI C

OSFO

Rd

(TbC

)

wIL

LAM

ETTE

LEw

IS

CLAR

k

FEMALE pARENT ALLELES 1 1 1 7 2 10 20

10 1 10 21

3 3 3 5 15

3 8 1 5 3 3 8

3 8

Barcelona 1 2 – – – + – + + – + + + + + + + – + + + +

Ennis 1 11 – – – + + + + – + + + + + + + – + + + +

Montebello 1 2 – – – + – + + – + + + + + + + – + + + +

T.G.D.L. 2 7 + + + – – + + + + + + + + + + + + + + +

T di Giffoni 2 23 + + + + – + + + + + + + + + + + + + + +

Tonda Romana 10 20 + + + + + – – + – + + + + + + + + + + +

Negret 10 22 + + + + + – – + – + + + + + + + + + + +

Casina 10 21 + + + + + – – + – + + + + + + + + + + +

Butler 2 3 + + + + – + + + + – – – + – + + + – – –

Daviana 3 11 + + + + + + + + + – – – + – + + + – – –

Lansing 1 3 – – – + + + + – + – – – + – + – + – – –

Hall’s Giant 5 15 + + + + + + + + + + + + – + + + – + + +

Tonollo 1 2 – – – + – + + – + + + + + + + – + + + +

Jemtegaard #5 2 3 + + + + – + + + + – – – + – + + + – – –

DuChilly 8 10 + + + + + – – + – + + + + + – + + + – –

Tokolyi Cosford (TBC) 5 23 + + + + + + + + + + + + – + + + – + + +

Lewis 3 8 + + + + + + + + + – – – + – – + + – – –

Willamette 1 3 – – – + + + + – + – – – + – + – + – – –

+ = compatible, – = incompatible. Note: When an allele expressed by the pollen is met by the same allele in the female flower, the cross is incompatible. * Both alleles are always expressed in the female flowers but not necessarily in the pollen.

Source: Adapted from S.A. Mehlenbacher and A.N. Miller, Pollinizer Management in a Hazelnut Orchard , Oregon State University (1988)

Further reading

Baldwin B, gilchrist k and Snare l (2007) Hazelnut Variety Assessment for South Eastern Australia. Project No. US-125a. Rural Industries Research and Development Corporation, Canberra

| 35Va R I e T I e S

Selecting the most appropriate hazelnut varieties for planting is an important decision. The two main considerations for a successful profitable planting are the productivity of the tree and the marketability of the nuts. Ideally the varieties planted should both be productive and produce nuts with a market demand. Hazelnuts have multiple uses and traditionally can be sold into two different markets, the in-shell and the kernel market.

in-shellThe in-shell market uses nuts that:

are large, with attractive shells•

have a minimum of fibre•

show limited pubescence on the shell that can make the nut appear dull and •potentially undesirable

ideally have a good shelf life.•

KernelThe kernel market typically uses nuts that can be either blanched (i.e. they have the pellicle or skin removed) or unblanched. The blanched kernel market utilises nuts that ideally have:

round shells that are easy to crack•

plump, bright, white kernels•

pellicle easily removed by heat•

crisp and crunchy texture when dried•

good storage capacity (depends also on storage conditions and moisture content).•

vARIETIES


Hazelnut kernels are covered with a pellicle that varies among varieties in thickness, appearance, and ease of removal. kernels suitable to the raw, unblanched trade ideally have thin pellicles as rough, thick pellicles are unattractive. The pellicle can be readily removed from varieties such as Tonda di giffoni, Willamette and the australia selection TBC. This process involves roasting kernels for 10 to 15 minutes at 135 °C and then rubbing or brushing them.

O ther fac tors More generally, other factors to consider include:

nut size and shape relevant to your end-market•

level of defective nuts and percent kernel•

catkin abundance and quantity of pollen•

blanching capacity•

tree vigour•

tendency of the variety to sucker.•

growers need to determine from buyers what characteristics they require in terms of kernel size, shape, texture, taste, and roasting and blanching ability. Many buyers and processors have specific requirements for their products.

Research in australia has provided information on the productive capacities of a range of varieties. The production features of a range of varieties grown in australia are listed in Table 9. a high kernel percentage is desirable for all commercial varieties. This is the ratio of kernel weight to nut weight and is a function of shell thickness and amount of kernel shrinkage upon drying.

Varieties that have performed with consistency in evaluation trials are Barcelona, TBC, ennis, lewis, Casina and Tonda di giffoni.

a range of planting material has been imported through the australian quarantine Inspection Service and has undergone checks to confirm the absence of pests and diseases. Many of these imported varieties have now been propagated and planted in increasing quantities and are available from australian specialist hazelnut nursery suppliers. Contacts for nurseries are available from the Hazelnut growers of australia Incorporated website.

a number of key varieties are described below. a more comprehensive description of varieties and their performance based on australian experience can be obtained from the further reading list at the end of this section.


Table 9. Production features of a range of varieties grown in Australia

vARIETY pOTENTIAL USE kERNEL % COUNTRY OF ORIGIN

Barcelona (Oregon) Kernel/In-shell 42 USA

Butler Polliniser/In-shell 46 USA

Casina Kernel 55 Spain

Daviana Polliniser 53 England

Ennis In-shell 46 USA

Hall’s Giant Late polliniser 40 Germany

Lewis Kernel 48 USA

Jemtegaard 5 Polliniser – USA

Tonda Gentile delle Langhe (TGDL)

Kernel 46 Italy

Tokolyi/Brownfield Cosford (TBC)

Kernel 44 Australia

Tonda di Giffoni Kernel 48 Italy

Tonda Romana Kernel Italy

Tonollo Kernel/In-shell > 42 Australia

Wanliss Pride Kernel/In-shell 42 Australia/Turkey

Willamette Kernel 50 USA

Adapted from Baldwin B, Snare L, Gilchrist K (1999) A Field Evaluation of the Productivity of Hazelnuts. Project No. USO-1A. Rural Industries Research and Development Corporation. Canberra

varieties

Barcelona (synonym: Fertile de coutard)

This is an old variety that is widely distributed in Western europe and has been the basis of the industry in oregon. In the USa, Frenchmen Felix gillet in the 1880s imported many hazelnut varieties and began distributing varieties from a nursery he established in California. australian imports of this variety have largely come from the USa. Barcelona is vigorous in growth; it has performed well in variety trials in australia and appears to be well adapted to a range of regions. It can be used in the in-shell and kernel markets and blanches reasonably well. Nuts have a 42% crackout kernel by weight. Barcelona is productive and mid-season flowering. Suitable pollinisers are lewis, TBC and Halls giant.


Butler

This selection from the USa has been available in australia for many years. It has been used widely in the USa as a polliniser for ennis since 1957 and can be used in the in-shell market. The attractive, well-sized nuts fall freely from the husk, but the kernels do not blanch well. Butler is productive, compatible with ennis as a polliniser, and matures about 8 days before Barcelona.

casina

Casina is a Northern Spanish variety with small nuts averaging 1.8 to 2 g and suitable for the unblanched market. Casina has a high proportion of catkins shedding mid-season and is a suitable pollinator for many varieties, including Barcelona, TBC and ennis. Casina nuts are enclosed by the nut husk and have a crackout of 56% kernel by weight.

ennis

ennis is an american cultivar known around the world for its large nut size and reliable high yield. Because of its size and attractive colour it is well suited to the in-shell market, although it can be used in other markets. ennis does not blanch well; it has a similar blanching ability to Daviana and a nut weight of up to 4.3 g. In australia ennis falls freely from the husk and releases its pollen relatively late in the season. Pollinisers include Halls giant, Casina and Jemtegaard #5.

lewis

lewis is a high yielding variety for the kernel market; it was released by oregon State University in 1997. lewis trees are early bearing and 75% to 80% of the size of Barcelona trees; they are upright and spreading and may be suited to closer plantings. Nuts are slightly smaller than those of Barcelona, fall free from the husk at maturity, and have a blanching capacity similar to, or slightly better than, that of Barcelona. Pollinisers for lewis include Tonda di giffoni and Halls giant. lewis pollinates ennis and Casina.


Tokolyi Brownfield cosford (TBc)

TBC is most likely an australian seedling and a selection of Imre Tokolyi, who immigrated to australia in 1956. a large, productive planting existed at the Brownfield orchard at acheron in Victoria for many years, and some material was also distributed from this orchard.

TBC is a vigorous, upright tree. australian observations show that it is well adapted to many producing areas in australia. It has produced good yields in australian field trials and produces kernels that are suited to a range of products. The nut is round, blanches well and has a kernel percentage of 43% to 45%. TBC produces pollen mid-season in australia and can pollinise a range of varieties. This variety is one of the few australian varieties with known alleles, which were determined in oregon. TBC is pollinised by Barcelona, lewis and Jemtegaard #5. a proportion of TBC nuts fall with the husk attached; it is typically removed by harvest equipment or later during processing.

Tonda di Giffoni

Tonda di giffoni originates from Central Italy and has a kernel much prized for the confectionery market. The nuts are round, blanch extremely well and have a crackout of 48% kernel by weight. The yield of this variety is reliable and in other parts of the world similar to those of Barcelona and ennis. australian observations show it to be a strong tree with early leaf out and good yields. Both catkins and leaf buds have a low chilling requirement; this may make it suitable to areas with lower chill hours. Pollinisers for this variety include Barcelona, lewis and Halls giant.

Daviana

Daviana originated in england and has been long used as a polliniser for Barcelona in the USa. The nuts of Daviana are medium to large and slightly elongated and do not blanch that well. yields of Daviana are reported to be low overseas, and this is supported by the results of australian studies. observations in australia also show that Daviana is prone to dropping catkins in late autumn and, compared with other varieties, may be more prone to moisture stress. Daviana matures approximately 10 days before Barcelona.


Halls Giant (synonym: merveille de Bollwiller)

Halls giant plays an important role as a late polliniser and is a vigorous erect tree. It is compatible with a range of varieties, with the exception of TBC. Halls giant nuts are a little smaller and thicker shelled than those of ennis, but the nuts can be blanched to some extent. It is a low-yielding variety and resistant to big bud mite.

Jemtegaard #5 (J#5)

Jemtegaard #5, a growers’ selection from oregon, is a useful late pollinator in australia. It is a relatively vigorous variety and will pollinate Barcelona, ennis and TBC. The nuts of J#5 are medium to large. J#5 has good numbers of catkins to ensure ample pollen distribution.

Wanliss Pride

Wanliss Pride is a medium-sized tree with a spreading habit. It was grown in north-east Victoria in the 1920s. It may be a selection of the Turkish variety Imperial de Trebizonde. Reported yields of Wanliss Pride are variable, but the tree appears to grow well as a multi-stemmed plant. The nuts are large, with a distinctive broad base. Some growers report a degree of shrivelling following harvest.

Willamette

Willamette is a vigorous, productive variety for the blanched kernel market. This variety was the first to be released by the hazelnut breeding program at oregon State University and subsequently imported by the australian nursery industry. Willamette yield is slightly higher than that of Barcelona in other parts of the world. The pellicle can easily be removed by dry heat blanching, giving bright white kernels of good quality useful for a range of pastry and confectionery products. Tonda di giffoni is one suitable early polliniser. Both these nuts are suited to the blanched kernel market and mature at similar times.

Further reading

Baldwin B (2007) Identification of Hazelnut Clonal Material. Project NT04010, Horticulture australia ltd, Sydney

Hummer k (2001) Historical notes on hazelnuts in oregon. Proceedings of the Fifth International Congress on Hazelnut. Acta Horticulturae 556, 25–28

Wilkinson J (2005) Nut Grower’s Guide. landlinks Press, Melbourne

| 41P R o Pag aT I o N

a variety of techniques have been used for the vegetative propagation of hazelnut plants. Vegetative or asexual reproduction allows for reproduction of all the genetic information of the parent plant. This provides uniformity and potentially consistent performance in the orchard. Seedlings are an unacceptable means of propagating stock for the commercial hazelnut nut orchard, as they are a result of open pollination and will not reproduce the characteristics of the parent plant.

Production of grafted plants is not common in australia, nor is micro-propagation commonly practised, although both methods are possible with appropriate equipment. effective methods for micro-propagating hazelnuts in tissue culture have been developed in the USa. This method is helping breeding programs and commercial laboratories to fast-track new disease-resistant varieties.

mound (stool) layeringMound or stool layering is the most common and successful way of propagating hazelnuts and producing whips (i.e. rooted suckers) for planting in australia. This involves cutting a plant to ground level in the dormant season and mounding sawdust or other media around the newly developing shoots to encourage roots.

Typically, mother plants are established in nursery rows and allowed to grow until they can support strong suckers. This may take 2 years. In the second or third year all plants are cut back to about 25 millimetres above the ground. Shoots develop from this stump and are hilled with sawdust approximately three times through the growing season. The height of the sawdust is about one-third of the total height of the sucker, or future whip. girdling or ringing the base of the shoot and an application of a rooting hormone (indole butyric acid; IBa) can help in root development. a short length of copper wire is twisted around the stem, causing a restriction that induces root formation.

pROpAGATION


at the end of the growing season shoots should have rooted sufficiently to be separated from the mother plant. The rooted shoots are cut almost to ground level and removed from the stool. The rooted plant, or ‘whip’, is now ready for planting out in the orchard or for growing-on in a nursery, and the rotation from the mother plant can continue. Trench layering where shoots are pinned horizontally to the ground and sawdust is added is a variation of this technique, but it is a far less common practice in australia for commercial nursery production

Stool beds can produce for up to 20 years if maintained in a vigorous condition.

The diagrams in Figure 8 illustrate the process.

Hazelnut whips in the nursery stool bed. Tags provide identification for nursery handling.

| 43P R o Pag aT I o N

1. Rooted mother plant

2. Mother plant grows 1 to 3 years

3. Top removed before new growth

4. Sawdust mounding through summer

5. Root development at end of season

6. Rooted layers or whips ready for planting

Figure 8. The process of producing whips from mound layering

Further reading

Hartmann H and kester D (1996) Plant Propagation. Prentice Hall, New Jersey

1 2

3

4 5 6


The majority of hazelnut trees in australia are propagated vegetatively by mound (stool) layering. This process produces a rooted sucker, or ‘whip’ that is true to type and genetically the same as the parent. Very few nurseries produce grafted trees. Dormant whips are normally supplied from early July through to mid to late august. It is best to order material 1 year ahead to guarantee supply. Details of propagators are available from the Hazelnut growers of australia Inc.

The whipThe following points are provided to help growers and nursery operators to select good quality stock:

Whips should be from stools that are true to type. This means meeting the •specifications for the variety.

The whip should be supplied with a root system that can adequately support it •and supplied free of residual soil. Roots should be not damaged or deformed.

If possible, confirm that the whips are fully dormant before they have been cut •from the stool, and confirm complete defoliation. Ideally, the wood should have hardened all the way to the tip.

The whip should be free from obvious lesions, pests and diseases. Bacterial •blight, mildews and scale are most common. Many growers have unwittingly brought in disease with their plants.

a calliper-measured size of greater than 10 mm at the base of the whip and •about 800 mm high is desirable.

If the whips are packaged in sawdust, avoid putting large pieces of wood in the •mix that may carry wood rots.

bUYING & pLANTING NURSERY STOCk

| 45B U y I N g & P l a N T I N g N U R S e R y S To C k

Plants should be bundled and transported to ensure minimal damage, and tree •roots must remain damp.

Dipping or spraying with a solution of winter oil and copper before shipping will •help with management of pests and diseases (especially bacterial blight).

Nursery operators should comply with any State plant health import regulations •when shipping propagation material interstate, in particular from regions where big bud mite is known to exist.

If delays are envisaged between the collection of plants from the nursery and planting, the whips should be ‘heeled in’ into moist friable soil or a heap of sawdust. This reduces the chances of roots drying out, and planting may then be done over a number of weeks, as weather and time permits. Caution should also be taken to avoid freezing of roots before planting.

Hazelnuts, being deciduous trees, are planted in winter when they are dormant. Planting earlier is preferable, although this is in part controlled by delivery time. Trees need to be settled in the ground before soil and air temperature start to increase. This provides a buffer of time for unexpected delays or bad weather.

early winter planting (July to early august) is preferable to allow the formation of a root system to cope with spring growth.

layoutThe majority of plantings are laid out in a regular pattern normally based on a square, rectangle or triangle. These are established by using a straight baseline, usually next to a fence or roadway. lines at right angles to the base at both ends are established, along with one or two markers in the middle of the block. Right angles are established by using rope or wire in lengths of 3:4:5 proportions. Thirty, forty and fifty-metre lengths are suitable. The 40-metre length is placed on the baseline and the 30-metre one at an approximate right angle. The 30-metre piece is adjusted in either direction to touch the end of the 50-metre piece. The 30-metre piece is now at a right angle to the base line. once these lines are established, upright markers can be placed along the base and right angle lines for sighting.

90°

30 m

40 m

50 m

sighting stakes

on baseline

stakes at tree positions

sighting stakes at right

angle to baseline

6 m

8 m

Row and tree spacing can be established with a tape or marked rope. actual tree position can be marked with small stakes (small dowel can be good), pressure-pack survey paint, or lime.

Figure 9 shows the 3:4:5 triangle used to establish right angles from the baseline. Sighting the stakes allows the entire block to be marked out.

Figure 9. Setting up the right-angle


aligning trees a useful device to ensure that trees are aligned within the row is a planting board (Figure 10). This is a light board about 1 m × 0.1 m in dimensions; it is V-notched in the centre and at both ends. When planting, the centre notch is placed at the peg or lime mark marking the tree location and dowels or pegs are placed at the end notches. The board and the tree peg only are then removed and the hole dug. The board is then relocated using the end pegs and the tree placed at the centre notch. This centres the tree in the hole.

tree peg

locating pegs

1 metre

0.1 m

Figure 10. A planting board

as a general rule, tree planting should not be complicated by unnecessary devices or tree markers. Trees planted 12 to 20 centimetres out of line present no problems with later care.

PlantingTree holes should be large enough to accommodate the root system before planting, so that the roots spread out evenly from the trunk. Damaged or long roots can be trimmed, as long roots may well form suckers. If small white basal buds can be seen at the join of the root and stem, then they should be removed by rubbing off with fingers. This can provide some early relief from sucker management.

Well-rooted hazelnut whips ready for planting


Planting holes can be mechanically dug, but the walls of any hole that is glazed by mechanical action need to be sliced with a shovel. Undesirable glazing of holes can be prevented by digging holes when the soil is dry or slightly moist. Typically, nursery whips can be held in the hole and backfilled around the roots with topsoil. The tree is firmed in with the feet. a longer whip may be planted a little deeper, as hazelnuts have good capacity to develop roots. This is usually not necessary but may be of advantage on exposed sites. Trees should be watered in as soon as possible after planting if the soil is drying out. The top six buds can be left at the top of the whip and the lower buds rubbed off. This directs growth to where it is required and helps in tree structure development. Fertiliser is generally not placed in the hole at planting.

ground that has been suitably prepared to depth and cultivated if necessary can usually be planted with a shovel with relative ease. Well-prepared ground also allows for a mechanical planter to be used with no ill effects upon establishment.

Post-planting care

young trees are easily sunburned before the bark on the trunk matures. The most vulnerable area is just above the ground or the mulch layer. Simple protection can be provided by painting the trunk with a mixture of half water and half white water-based paint. Coverage should go all the way to ground level. Varying types of tree guards, such as milk cartons, may also provide some protection from the sun, although generally they may not have the desired height. Foil laminate building insulation (silver side out) has proven to be cost effective and can be stapled around the tree trunk snugly to give protection to the top and base of the trunk. This has the advantage of allowing growers to make guards that suit their tree height. The foil laminate can be cut to length with a utility knife to produce larger quantities. This type of guard will last a couple of seasons until the young tree develops its own self-protection.

Mechanical planting of hazelnuts


other advantages of this approach include:

protection of young trees from herbicides •

safer sucker control. young suckers outside the guard can be controlled with a •contact herbicide without the risk of affecting the young trunk. There is also a degree of protection from rabbit and hare attack.

mulchingThe most common faults observed in establishing the newly planted tree are improper irrigation and lack of weed control. These factors alone cause more stunting and tree loss than any others during the first 2 years. Mulching helps:

reduce evaporation and conserve soil moisture•

modify soil temperature to reduce extremes of both hot and cold•

reduce weed growth•

add organic matter and protect and improve soil structure.•

organic mulches such as wheaten straw or other commercial mulches are suitable. To avoid collar rot, keep the mulch from contacting the trunk. Mulch can be applied thickly at tree planting and reapplied through this period to about years 3 or 4. after this period, mulch can interfere with ground harvesting operations, and experience has shown that vacuum machines and mulches that break down slowly such as wood chips can be a problem.

To be effective, mulch needs to block all light to the weeds; different mulch materials vary in the depth necessary to accomplish this. organic mulches should be maintained in a layer 100 millimetres or more thick.

If rabbits, hares and kangaroos are a problem in your proposed orchard area, some form of tree protection is necessary. a netting fence enclosing the orchard area is the best option, but some individual tree guards can provide protection. guards can be removed once the trees are established.

Tree guards provide protection from sun and herbicide damage in the early years.


i rr igation of young treesIrrigation has been covered in a previous section, but some comments are relevant to young trees in situations where there is inadequate rainfall. young tree roots are very small and may deplete the moisture immediately surrounding each root, even though good moisture is found at the surface close to the tree. The following points should be considered when watering young trees:

Irrigation during the first year should be applied often, at least weekly but for •only a short time.

Short irrigations will replenish dry areas around the roots without waterlogging •the soil.

Inexperienced growers apply either too much water, creating an oxygen •deficiency and drowning the roots, or let the roots become too dry.


wEEd CONTROL

Weed growth around young trees deprives the developing tree of moisture, nutrients and sunlight and can harbour undesirable pests. Weeds need to be controlled by a range of tactics, which typically include surface mulching, tillage, and chemical application. For the majority of growers the key objective is to reduce weed competition and reproduction to levels that the individual can accept. orchard floor management decisions and the management methods used are significantly influenced by location, climatic conditions, soils, irrigation practices, topography, grower preferences and the types of weeds that may be dominating.

a weed management program should start before the trees are planted, because the more difficult-to-control weeds are easier to manage before planting.

If time permits, cultivation pre-planting for 2 years can reduce bad infestations of undesirable weeds. Cultivation should be kept to a minimum: to control weeds a depth of 10 cm should be sufficient.

Weed populations react to the environmental conditions and to the control measures being applied. Failure to adjust management will lead to shifts in the weed population to harder-to-control weeds, such as persistent perennial weeds with long-lived tubers and rhizomes, or the development of herbicide resistance.

| 51W e e D Co N T R o l

standard weed control programWeed control in the orchard is normally associated with a flailing/mowing program and banded herbicide strips. a typical weed control program begins with a non-selective herbicide in late winter or early spring to kill any weeds present. a residual herbicide can then be applied to give control through spring and early summer. Weeds that escape the residual herbicide treatment can be controlled with a non-selective registered knockdown herbicide through summer if necessary.

Chemicals used for weed control in hazelnut fall into different classes with different modes of operation. Pre-emergent herbicides have residual benefits, whereas post-emergent herbicides like paraquat/diquat or glyphosate provide no residual effect. Some pre-emergent and post-emergent herbicides can be combined to give a knockdown and residual effect in one application. Pre-emergent herbicides are generally used on trees older than 3 years; usage should be confirmed on the label.

Herbicides have been placed into groups from a to N: for example, paraquat and diquat are group l herbicides, whereas glyphosate is a group M herbicide. Herbicide resistance is more likely to develop to some groups than to others. When using herbicides, note the letter assigned: the earlier the group is in the alphabet, the higher the risk of development of resistance. Information on resistance is available from the Orchard Plant Protection Guide for Deciduous Fruits in NSW. This publication is available free from Industry & Investment NSW.

Paraquat and diquat herbicides act on contact by destroying the chlorophyll-forming tissue in the plant (usually the leaves); in conditions of rapid growth the effect may be visible after only a few hours. effectiveness is increased when these are applied in overcast weather or late in the afternoon. although only tissue that is actually contacted is affected, caution must be exercised when spraying close to young hazelnut plants, as the spray may destroy sufficient green or tender bark to seriously affect the health of the plant.

Systemic herbicides such as glyphosate are absorbed by the plant, disrupting the function of the root system and ultimately destroying the plant. Care should be exercised around young plants, as sufficient over-spray may be taken up by the green bark to kill the plant. around well-established trees, take care not to spray suckers, as any chemical absorbed in this way will be transferred to the main root system, affecting the health of the whole plant.


Chemical registrations change, so growers should confirm whether the chemical is approved for use. Some key points to take note of when using herbicides include:

alternate chemicals used so that resistance does not become a problem. Monitor •for resistance, especially if using glyphosate. Resistance status can be confirmed by a recognised herbicide resistance-testing service.

Use only pesticides registered or permitted, and observe any withholding •periods. The presence of unacceptable chemical residues can lead to the loss of potential markets.

Minimise the risks of off-target spray drift.•

Maintain records and a spray diary so that the effectiveness of the program can •be monitored. good records can also help processors with any food safety issues.

Herbicides commonly used in the cultivation of hazelnuts in australia include those in Table 10. Current registered products are updated on the Hga website.

Table 10. Herbicides commonly used in the cultivation of hazelnuts in Australia

bRANd NAME ACTIvE CONSITUENT

Spray.Seed® Paraquat,Diquat

Roundup® Glyphosate

Basta® Glufosinate-ammonium

Various trade names Simazine

Further reading

I&I NSW (annually) Orchard Plant Protection Guide for Deciduous Fruits in NSW. Industry & Investment NSW, orange

Weeds australia (n.d.) www.weeds.org.au

| 53P R U N I N g & S H a P I N g

control of suckersTree shaping depends on the tree shape desired by the grower. Typically, that can be a single trunk tree, multiple two- to four-trunk trees, or a multi-stemmed bush. The basic vase shape single-stemmed or several-stemmed tree is the most favoured form for the commercial hazelnut orchard (see below under pruning).

Whichever system is chosen, suckers are undesirable for several reasons:

Suckers divert growth from the main tree structure. energy is wasted on a shoot •that will need to be removed.

an abundance of suckers at the base of the plant traps fallen nuts, which can •contaminate harvest the following year.

excessive sucker growth interferes with the shaping of the tree.•

young fleshy suckers can be attractive to insect attack.•

Suckers act as a site for undesired herbicide uptake, which can affect tree health, •especially with fully systemic herbicides combined with side-boom application.

Suckers can be controlled chemically and mechanically. Chemical control involves spraying the suckers with a knockdown registered herbicide such as paraquat. This is normally applied when suckers are 5 to 10 centimetres tall; best results are achieved in overcast weather. Correct timing is important: application when the sucker is fleshy gives optimum control. Care is necessary not to over-spray on to the trunks of young plants. larger suckers that have become woody will need to be cut out with secateurs. Use of long-handled limb-loppers can be effective to reduce the degree of bending required by the operator.

as the orchard matures and trees settle into cropping, de-suckering becomes less of a task.

pRUNING & SHApING


occasionally the suckering habit of the hazelnut, apart from the role played in nursery production, is used to advantage in the orchard block. If the main nursery whip has failed or succumbed to disease or dieback for whatever reason, the original whip can be cut back and a healthy sucker selected to become the new tree. This applies only to those plants originally planted on their own roots and not grafted.

The Turkish tree hazel, Corylus colurna, has particular value as a non-suckering rootstock. The rootstock selections Newberg and Dundee have been imported into australia as rootstocks, as have a number of interspecific hybrids that may have potential as rootstocks. These stocks are not used widely in commercial production in australia but may be useful for use as ornamental hazelnuts.

Pruning and trainingUnlike other deciduous fruit trees, hazelnuts require a minimum of pruning. Pruning is carried out in late winter and normally after the catkins have shed pollen: this is in about august in temperate areas of australia. Warmer sunny winter days are best; pruning in wet weather should be avoided to avoid spreading bacterial blight on open cuts.

There are two main objectives of pruning. The first is to establish the required shape of the tree so that the long-term management of the grove can be achieved as efficiently and productively as possible. The second is maintenance: pruning on a routine basis maximises fruit production.

Hazelnuts generally crop on 1-year-old shoots, and in the USa in established orchards, 15% to 20% of the orchard may be pruned on a 5- or 6-year rotation plan. Since the crop is born on moderately vigorous 1-year annual twig growth of about 10 cm, care must be taken during the pruning program or yield will be affected.

Pruning is but one factor in triggering an alternate bearing pattern. Insufficient pruning of mature trees, can reduce shoot vigour and diminish cropping potential. excessive shading will reduce flower bud formation, fruit set, yield and nut size.

Trees lightly pruned to encourage vase shape and to allow movement under of machinery under the trees.


Tree shapingThe hazelnut is naturally a suckering plant, with most varieties tending to develop into multi-stemmed bushes. However, many growers believe that, for commercial orchards, a single-trunk tree with an open V-shape is more viable, for several reasons. First, the shape facilitates methods of mechanical harvesting by allowing easier access of equipment under the tree canopy, and fewer nuts are lost by being trapped in the network of stems. Second, the single trunk permits better sunlight penetration, with obvious benefits. Third, general orchard operations such as sucker removal, irrigation, mulching and spraying are rendered easier with the basic vase-shaped tree.

This tree form does have some disadvantages. also, being relatively shallow rooted, the single-trunk hazelnut plant is more vulnerable to storm damage. With respect to yields, field evidence suggests that there is no significant difference between a single-trunk open vase form and a multi-stemmed tree. The initial treatment of whips depends on what is supplied from the nursery. assuming that a single-trunk tree with an open V-shape is required and a strong healthy whip is supplied, the young plant can be headed to about 800 mm high. leave at least four to six buds at the top of the whip, and gently rub off the remaining buds below. as well as establishing the shape of the tree, this process will help to redress the balance between the top of the plant and the root system, which may have been damaged during planting. For the first 2 to 3 years the major object of pruning is to establish an open vase shape with four to six permanent scaffold limbs well spaced down and around the trunk.

mature treesonce a vase shape is established, the inward and crowded growing shoots can be removed. Strong upright water shoots should also be removed annually, as this type of growth can attract aphids. large pruning cuts should be avoided to prevent infections from wood rots.

Tree management now consists of:

allowing the entrance of light into the canopy to maintain fruitfulness and good •rates of photosynthesis

maintaining the basic vase shape that was established during the initial training•

removing diseased shoots that may be affected by bacterial blight•

removing large side shoots or branches to allow for tractor movement up the •row. This will be the case even with a low-profile tractor configuration.

In older plantings where tree vigour has declined, rejuvenation pruning can stimulate new growth and larger cuts will be required. If large cuts are to be made, an angled bench cut can provide direction to form new main limbs. The drawings in Figure 11 show the development of the tree framework.


Figure 11. Development of the tree framework (Kentish Cobnut Association)

1 2 3 4

5 6

1. Bare rooted one year old nursery plant

2. If the tree has grown well the leading shoot can be shortened to encourage buds below to break and develop a vase structure. Remove all suckers

3. Tree height is about 110 cm. Remove central leader and cut to a shoot with an obtuse angle

4. Tree is now four years old and developing good structure. Between years four and five centre upright shoots can be removed or shortened slightly to reduce dominance

5. Continue open centre shape. Remove strong upright shoots and shorten dominant branches to horizontal side shoot. Attain even vigour around the framework

6. Maintain framework branches. Remove crowded upright growth and ensure new cropping wood. Shorter weaker branch tips can be removed and renewed over the years


Further reading

kentish Cobnut association (2001) Pruning Kentish Cobnuts. kentish Cobnut association, Norwich Uk

Single stem tree (left) P Felder Multi-stem tree (right) P Felder


Hazelnut production is affected by fewer pest and diseases issues than commonly affect other temperate-climate fruits. Insect pests, diseases, and domestic animals can, however, constrain production and need to be monitored.

In australia it is difficult to estimate the losses that occur from pest and disease problems, but it has been widely accepted that we do not have many of the key pests that affect overseas production.

Depending upon the region, management strategies, and environmental conditions, hazelnuts may not be affected by a great range of pests. The majority of orchards in australia are unsprayed; this is probably because of their isolation, lack of use of insecticides in the past, and a natural ecological balance. This status of balance is desirable, and the australian industry is well situated to maintain this position.

Pest monitoring and management systems are complex and require an understanding of the pest and available control measures. Integrated pest management systems, in which all available forms of suppression (biological, chemical, physical) are used to lower pest populations safely and economically, are preferred.

only the key diseases and pests are discussed below. a more complete study, Pest and Disease Analysis in Hazelnuts, completed by the author is available via a link from the Hga website.

dISEASES & pESTS

| 59D I S e a S e S & P e S T S

Diseases

Bacterial blight

The key disease in australia is bacterial blight, which causes dieback of young twigs and branches.

The disease is caused by Xanthomonas corylina, a bacterium that affects the buds, leaves, branches and trunk. occasionally it attacks the nuts and spotting is observed on the husks. Varieties that leaf out early—an event that can be associated with early spring rains—are often affected by early blight strikes.

Hazelnut blight is most injurious to trees up to 4 years old. Trees more than 4 years old rarely die following infection, but nut yields may be reduced through the loss of nut-bearing branches. Poor environmental conditions, such as sunscald, poor soil drainage, moisture stress, cold injury, mechanical equipment damage, pruning cuts and general cultural neglect, can contribute to making trees susceptible to blight.

The first infection on current-season stems consists of dark green water-soaked areas on the bark, turning to reddish brown. one- and two-year-old twigs are attacked and killed. Infection occurs through wounds, blighted buds and shoots of the current season’s growth. Dead leaves often cling to diseased stems for longer periods than in a normal leaf fall.

Protective copper-based sprays in late summer, autumn (three-quarter leaf fall), winter and early spring are the current means of control. Copper applications create a protective coating that destroys spores that come into contact with it. a number of copper products are registered for hazelnuts.

In seasons of heavy winter rainfall, two or three applications may be required. Use of a suitable spreader/wetting agent will make these treatments last longer. effective containment of this disease evolves around securing disease-free planting material, using appropriate copper-based sprays, and maintaining good sanitation in the orchard. Removal and destruction of infected plant material, including dead trees, will decrease the chances of inoculums spreading.

armillaria root disease

Armillaria is a soil inhabiting fungus that causes root rots. Species of Armillaria are native to forests worldwide, and most infections arise because orchard blocks are planted on recently cleared land that contains infected native trees (especially wattles).

Foliar symptoms include poor shoot growth, defoliation, branch dieback, premature yellowing and stunted leaves. The presence of white, fan-shaped mycelia (fungal strands) between the bark and the wood indicates infection. In severe cases the wood on the tree can be stringy, and light-golden-coloured mushrooms can grow around infected trees in autumn.

Hazelnut blight


Spread is via roots of the hazelnut coming into contact with other infected roots. Where possible, previously infected root material should be removed from the orchard and burnt. Infection is common in light sandy soils, and the history of new blocks should be considered before they are planted out.

Postharvest diseases

The moulds Aspergillus flavus and Aspergillus parasiticus can produce the toxin aflatoxin. If batches of hazelnuts intended as a human foodstuff are affected by this toxin, the product can no longer be used for human consumption. Hazelnut samples from the Central Tablelands of NSW have been identified with this fungus.

Postharvest handling has a major influence on hazelnut mycoflora, and nuts with fungi are usually colonised by several fungi rather than by a single species. Usually, hot humid conditions lead to mould growth on the nuts and to high levels of aflatoxin. Improper storage conditions can lead to aflatoxin contamination after crops have been harvested.

If a long delay is anticipated, nuts should be stored under controlled conditions to prevent aflatoxin production; this will also keep them dry and protected from insects and rodents.

Decay problems are most commonly related to insufficient drying, or not collecting nuts from the ground quickly enough in damp harvest conditions.

insec t pestsHazelnut plantings are prone to insect attack, and growers should regularly check their plantings for the most commonly occurring insects. aphids, scale and chewing insects all require monitoring. The key pests are presented below.

Fruit tree borer (Maroga melanostigma)

The fruit tree borer Maroga melanostigma can cause severe damage to hazelnuts by ringbarking the tree, weakening laterals, and boring tunnels into the wood. Infestation is usually in the fork of the tree and is evidenced by a fine sawdust-like frass on the surface. Control measures are limited to scraping away the sawdust-like material and flooding the entrance holes with a registered insecticide, or infiltrating the borer hole with a thin piece of wire and piercing the larva.

Aspergillis on the surface of stored hazelnuts


Chemical control to prevent egg laying and damage from the new generation of insects may be an option. effective control is difficult, because the borer is exposed to the insecticide only during the period when it hatches from the egg and before it bores into the tree. external trees in a block tend to be affected first and, where infestation is high, entry points have been observed where larger pruning cuts have been made.

The use of a small parasitoid wasp, Trichogramma, as a biological control agent is currently under investigation in australia.

Aphids on underside of the leaf I&I NSW

Borer larva tunnelling

Hazel aphid (Myzocallis coryli)

Hazel aphid is a common pest in australian hazelnut plantings, and its biology is well documented. aphids feed on the leaves in spring and early summer, causing the leaves to become yellow and drop. In heavy infestations, honeydew is produced, aiding the development of sooty mould in the tree.

Preventive strategies, which encourage biological control, are preferred. ladybird beetles are active and voracious predators of many aphids. oil sprays at bud swell are used in other crops to control aphids and can be used successfully to smother eggs. Use of a registered aphicide will also provide control. over-use of nitrogen can encourage excessive young growth, which is attractive to aphids. Water shoots should be pruned out, and weed hosts controlled, to avoid build-up of high aphid populations.

Big bud mite (Phytoptus avellanae)

Big bud mite, also known as filbert bud mite and hazelnut gall mite, is known to be a problem in most of the major hazelnut-production areas around the world, including australia. Samples from Tasmania have been identified with big bud mite.

Specific plant damage is indicated by enlarged buds: infested terminal buds become swollen and deformed. Big bud mite infestation first becomes obvious during late summer and early autumn. affected buds become spherical and swell to several times their normal size, reaching about 10 mm in diameter. These buds are prone to desiccation and fall from the tree prematurely. If these buds are female buds, then yield can be affected.

Big bud mite: close up of enlarged popcorn-like buds I&I NSW


loose-bud cultivars, including Royal and Daviana, are more sensitive to big bud mite infestation. Varieties such as Butler, ennis, Negret and Tonda gentile delle langhe are reported to be highly susceptible. Studies in europe indicate that a single application of sulfur 80% WP (400 g/100 l) before the peak period of mite migration from old big buds to new buds is effective in keeping mite numbers low.

an alternative to chemical sprays is that swollen buds can be picked off and burned during autumn and winter before the mites emerge in spring.

Over wintering scales

Plum scale (Parthenolecanium corni)

Scales are closely related to aphids, mealy bugs, and whiteflies, which have piercing-sucking mouthparts. large infestations can kill twigs, retard growth, and produce quantities of honeydew. overwintering occurs as an immature scale or as a fertilised female on twigs and branches. The immature scales resume feeding in the spring, and newly mature female scales lay their eggs underneath the scale cover. These eggs hatch in early summer, and crawlers migrate to the undersides of leaves and begin to feed.

Sooty mould development on the honeydew can give the tree a blackened, sticky appearance. Nuts and husks can be occasionally stained, and although the mould is not feeding on the plant it can restrict the light reaching the leaves.

Chemical control is timed to target the overwintering scales, using oil sprays while the trees are dormant in late august. ornamental trees and neglected fruit trees can be alternative hosts, and infested trees should be treated. Infested branches should be removed and burned before crawlers emerge.

lacewings are aggressive predators of scale and can help with biological control.


Noctuid moths

Caterpillars of various species of moth may attack the leaves and the immature nuts.

The family includes pests of crop plants and includes cutworms and armyworms. Some are called ‘semi-loopers’ after the movement of the caterpillar. They live near the soil surface and can chew off young plants above ground level. others climb the trees and feed on leaves and other parts. The sample in the photograph was collected in the Mudgee district of NSW and found to be eating the nut.

Clovers, medics and a wide range of weeds are hosts for noctuid moth larvae.

Noctuid moth larva that has emerged from the nut

BirdsBird damage to hazelnut orchards includes pruning of foliage and buds, ringbarking of trees, and cracking and eating of hazelnuts. Sulfur-crested cockatoos, galahs, little corellas and long-billed corellas are the main bird pests to the hazelnut industry. other species cause damage to growing tips, buds, and mature fruit. These include crows and ravens and a variety of rosellas and parrots. Surveys in australia have indicated that damage caused by birds is higher in nut crops than any other horticultural crops.

Hazelnuts can be removed from the trees before the kernels are mature and also as they are awaiting collection from the ground. Many birds are highly mobile and can readily replace those that are killed in lethal control programs, so these kinds of programs do not often reduce damage. Permits from national parks and wildlife agencies are required to kill most native species. Unless actions are well planned and coordinated they are unlikely to have a lasting effect.

Bird damaged nuts on the orchard floor


management optionsManagement options include scaring, netting, lethal control and birds of prey. Scaring is most commonly practised, and netting may be an option for some growers.

Scaring utilises visual and sound devices to scare birds and can include the use of lPg gas guns, reflective mirrors or tape, flashing or rotating lights. Best results for scaring are achieved when:

combinations of techniques are used•

scaring starts before the birds establish a feeding pattern•

the sound is reinforced by shooting or a threat•

the timing and placement of devices are changed frequently, but not at regular •intervals.

Habituation is the main drawback of all types of scaring. Birds quickly become accustomed to noise or visual cues.

Netting

exclusion netting using throw-over or permanent nets has high up-front costs but may be appropriate where levels of damage are high. a variety of netting options are available. Machines can be used to install and remove drape-over nets of varying width (for example, one, two or four rows). ‘lock-out’ netting provides a continuous cover of netting by joining draped nets without the need for poles and cables. Nets can also be used on infrastructure to prevent birds roosting or nesting. If maintained, netting with ultra-violet stabilisers can provide between 5 and 10 years of protection. Permanent netting is easier to maintain, allows easier spraying of trees, and does not need to be removed before harvest.

Further reading

Snare l and Baldwin B (1997) Hazelnut blight: an overview. Australian Nutgrower 11(3), 12–13

Snare l and knihinicki D (2000) Big bud mite: an issue for australian hazelnut growers. Australian Nutgrower 14 (1), 17–19

Snare l (2006) Pest and Disease Analysis in Hazelnuts. Project No. NT05002, Horticulture australia ltd, Sydney

Teviotdale Bl, Michailides TJ and Pscheidt JW (2002) Compendium of Nut Crop Diseases in Temperate Zones. aPS Press, Minnesota

Tracey J, Bomford M, Hart q, Saunders g and Sinclair R (2007) Managing Bird Damage to Fruit and other Horticultural Crops. Bureau of Rural Sciences, Canberra

| 65H a R V e S T I N g

Hazelnuts mature and drop to the ground in late February to early March. Mature nuts should be brown and ideally free from the husk. Some varieties fall with the husk intact and require some form of mechanical action to remove the husk. TBC is one such variety. Many harvesting machines include husk removal as part of the cleaning process. Production costs are greatly affected by the harvesting technique.

Under dry conditions the nuts can remain on the ground without major deterioration, but moist conditions and rainfall require the nuts to be collected. Rain can cause discolouration and cause the nuts to go darker. This is undesirable, especially if the nuts are to be sold in shell.

Orchard f loor preparationMature orchards require suitable preparation for a trouble-free mechanised harvest, and this preparation starts through summer. any trash or past-season’s nuts need to be flail-mowed or removed. Trash may often include suckers that were removed during summer. This reduces the chances of blocking of any machines and of any of the previous year’s nuts being harvested.

assuming the ground is now prepared, the hazelnuts are either raked manually or mechanically into windows in preparation for pickup. Portable blowing machines or shoulder fans can also be used to blow nuts out from under the trees. In this case some slight soil moisture can help reduce the amount of dust.

HARvESTING


Har vestersInnovation in machinery has led to increased efficiencies in harvesting units, and when orchards are young it may not be economical to commit the capital required for mechanical harvesters. For medium-scale commercial operations mechanical harvesting is essential. Harvesting machine design not only has improved operating times and costs, but also takes into account the quality of the working environment, dust, noise and the operator’s health and safety.

Harvesters can be classified into three different types:

towed vacuum harvesters with aspirating tubes•

towed or tractor-mounted harvesters with automatic pick-up systems•

self-propelled harvesters (aspirating or pickup).•

Vacuum harvesters of various types are usually equipped with one or two aspirating hoses; the operators walk along and pass the tubes over the windrowed nuts, which have either been blown or swept into rows. Recent developments have the tubes fitted to a side-mounted head; this reduces the number of operators required. Towed vacuum harvester rates with or without side pickers vary from 0.2 to 0.4 ha/h.

larger machines can be used in bigger orchards. Three-stage tumbling and a high-volume suction fan give good dirt and trash separation. Nuts can be deposited from the harvester into a trailer or towed bin.

The above mentioned harvesters are all available in australia, and as australian production increases there will be opportunities for growers to share machinery.

This smaller vacuum unit with limited trash separation can be towed with a quad bike (above) Vacuuming a crop in the early years (right)

| 67H a R V e S T I N g

Vacuum harvester fitted with side mounted head

Har vest managementThe following points should be considered to ensure optimum quality:

Picking up nuts as often as possible and practicable will maximize quality. Up to •three passes may be necessary. kernel quality and shelf life will deteriorate the longer nuts are left on the ground.

ensure efficient pickup so that nuts are not left on the ground for the second •pickup.

keep harvest boxes clean to avoid contamination.•

Maintain and adjust harvest equipment to avoid cracking of the shell during •harvest.

If practicable, keep nuts from each harvest round separate. This will provide •separation if the later harvest has quality problems for a range of reasons (e.g. wet weather or machinery breakdown).

Further reading

Monarca D, Cecchini M and antonelli D (2005) Innovations in harvesting machines. In Proceedings of the Sixth International Symposium on Hazelnut, Acta Horticulturae 686, 343–350

Wilkinson J (2009) Food safety begins on the farm. Australian Nutgrower 23(2), 42–43


Following collection, the nuts should be cleaned and dried to approximately 8% to 10% moisture. Depending on how the nuts have been collected (by hand, mechanical sweeper or vacuum sucker), loose grass, dirt and dust need to be removed. To help in the process of rubbish removal, storage bins with grated bottoms can be used. These types of bins also have the advantage of allowing air to circulate between the nuts, allowing some initial drying to occur, especially if the nuts have been collected wet or damp after rain. any husks not already removed from the nut by the harvester will need to be removed at this stage. Some varieties (e.g. TBC) maintain their husks to a greater degree. Ideally, husks should be removed promptly as nuts left in the husk can generate respiratory heat, which can cause an increase in mould and rancidity.

Dr yingThe degree of drying required depends on the end-use of the nut and the anticipated length of storage: for example, some on-sellers in the shell trade sell very quickly and prefer nuts that are not dried or are only partly dried. However, this is more the exception than the rule.

In the case of many confectionery companies, 6% moisture is the maximum required. If drying is not completed correctly the kernel will go rancid and/or mouldy very quickly and will not be suitable for longer storage. Drying can be done either on open racks or by heat fan-forced into a large silo. appendix B provides information on drying.

Small enterprises will often air-dry their own nuts in drying racks and, given the general climatic conditions prevailing during the australian harvest, this may take up to 3 months. The racks should ensure air flow around the nuts and should be situated and in a well-ventilated, warm and vermin-proof shed.

pOSTHARvEST MANAGEMENT

| 69P o S T H a R V e S T M a N ag e M e N T

larger enterprises can use fan-forced drying silos, which have the advantage of allowing the crop to be processed in shorter periods. a benefit of this is that producers can sell the crop into markets directly after harvest in March and april. Most driers operate with fans flowing air up through the nuts in a silo. Temperatures of 32 to 38 °C are commonly used for drying, and equipment for other purposes, such as prune driers or small dehydrators, can also be adapted to dry the nuts. a 2-metre-diameter silo with a 7.8-cubic-metre capacity will hold about 4.7 tonnes of nuts.

after drying, the nuts are graded into various sizes, bagged and sold. Conveyors between the drying operation and nut grader can be used as an inspection table to remove blanks, marked and disfigured nuts and any rubbish not previously removed.

once dried down to about 6% moisture content, the nuts can be stored in onion bags or other types of bags (excluding plastic bags). The nuts can be stored for extended periods, provided that temperature extremes are avoided.

Careful marking is required to ensure a record of nut type and size on each bag. larger enterprises will use silos to store nuts.

Purpose-built drying racks (above) Smaller growers may package nuts into woven poly mesh bags for ease of handling (inset)


Postharvest handling

The following points should be noted with postharvest handling:

shed and equipmentMaintain processing shed in an orderly, sanitary condition. Frequently remove •and dispose of any waste, including rejected nuts. Monitor and control insects, birds, mice and other animals entering the shed. Covered bait stations should be used and located where there is no chance of contamination of nuts. If moth larvae are a problem in storage areas, pheromone traps can be used to reduce populations of egg-laying moths.

ensure no contamination by broken glass, and use covered light fittings.•

keep daily records of nuts processed and their source. These records should •provide the ability to track product from the consumer back to the farm.

Maintain sorting equipment in a sound, clean condition. Sufficient guarding and •lighting is required for efficiency and safety.

avoid high humidity at all cost through the processing chain; humidity is •conducive to mould and development of aflatoxins. The optimum temperature for development ranges from about 37 to 42 °C.

Monitor rejected nuts during sorting by cracking a sample, and record the •reasons for rejection. Nuts are best sorted when dry, at which time defective nuts are easily identified.

Drying, storing and sizing

Monitor moisture content at harvest and then at least weekly during drying, or •daily if using heated air.

Try to avoid using temperatures greater than 5 °C above ambient air •temperature. excessive temperatures cause internal browning and discolouration of the kernel during roasting.

Maintain good air circulation during storage once the desired level of moisture is •achieved.

If growers intend to store nuts, then ensure that there is enough storage to hold at least 50% of the crop. This will become an issue as more mature plantings start to bear. Be aware that some processors crack to order and may not have large storage capacities. Following appropriate drying, hazelnuts can be stored for up to 2 years, but growers must be aware that the shelf life of the processed product will be affected by the length of storage of the kernel.

Nuts are normally graded in a rotating cylindrical size grader with varying sized holes for the nuts to fall through.

| 71P o S T H a R V e S T M a N ag e M e N T

The following sizes, as adopted by the Hga, are standards for australian hazelnut in-shell:

Small: up to 13.00 mm Medium: 13.01 – 18.00 mm

large: 18.01 – 19.50 mm Very large: 19.51 – 22.00 mm

giant: greater than 22.00 mm

a full description of standards for australian hazelnuts in-shell is included in appendix a.

Kernel sizes

In the USa, hazelnut kernels are graded into the sizes shown in Table 11; these are a good guide for australian kernels.Table 11. Hazelnut grading sizes (USA)

CLASSIFICATION MAxIMUM SIZE (MM)

wILL pASS THROUGH A ROUNd OpENING OF THE FOLLOwING SIZE

MINIMUM SIZE (MM)

wILL NOT pASS THROUGH A ROUNd OpENING OF THE FOLLOwING SIZE

Giant No maximum 16

Jumbo 17 15

Extra large 16 14

Large 15 13

Medium 14 12

Small 13 11

Source: Oregon Hazelnuts, Hazelnut Marketing Board (www.oregonhazelnuts.org/downloads/Oregon%20Kernel%20Standard.pdf )

Grading hazelnuts for size


kernels should also be:

well dried and clean•

free from foreign material, mould, rancidity, decay and insect injury•

free from damage caused by chafing or scraping, deformity and internal flesh •discolouration

free from serious damage caused by serious shrivelling and broken kernels.•

crackingMany growers wish to value add and many crack their own nuts. There is a range of cracking machines: they use either drum/roller or disc crackers. These are normally combined with air separation to separate shell from kernel.

growers should be aware of their potential liability to the consuming public if nuts of an unacceptable standard are supplied. Processing facilities should comply with relevant health regulations, which may vary from State to State.

Further reading

DaaF (2004) guidelines for on-farm Food Safety for Fresh Produce. Department of agriculture, Fisheries and Forestry, Canberra

Food Standards australia (n.d.) www.foodstandards.gov.au

oregon Hazelnuts (2006) www.oregonhazelnuts.org/index.php

| 73M a R k e T I N g o F H a z e l N U T S

The major users of hazelnuts in australia rely on imported kernels and nuts. approximately 2000 tonnes of kernel is imported each year, most of which is taken up by the confectionery industry and manufacturers of spreads and other products. Processors of imported nuts rely on regular supplies of product with consistent quality.

Market potential and expansion are being led by research that is showing the health benefits of including nuts as a daily part of one’s diet. Research continues to show that nut oils are heart friendly and help lower levels of bad cholesterol.

australian production is largely from individual growers with orchards under 5 hectares in area. These growers sell small quantities locally and are able to gain premium prices in niche markets or by direct selling. Commercial production is estimated to be less than 50 tonnes, but production is estimated to increase, as many orchards are yet to reach full production. Current growers and new orchards will expand production.

To break into the processing market and to supply larger processors, producers first have to be able to produce nuts in volume and in varieties that processors want. Most users of kernels have their own product specifications, which commonly include size, shape, appearance and quality standards, as well as blanching characteristics.

This last characteristic is important. Through heat application, blanching facilitates removal of the skin. Heating loosens the nut’s skin, and movement of one nut against another or the rubbing action of rubber brushes/rollers in processing causes the skins to come off. No chemicals are used in blanching. This trait is highly desired by many processors and, as mentioned previously, the skin of some varieties is easier to remove by heating than the skin of others. Producers can simply assess skin removal by spreading whole kernels in a single layer on a baking sheet and baking at 135 °C for 15 to 20 minutes. Take care not to over-roast, as the nuts can scorch quickly. To

MARkETING OF HAZELNUTS


remove the skins, wrap the warm hazelnuts in a towel and let them sit for 5 to 10 minutes, then rub vigorously in the towel. This simple test will provide knowledge about your variety. The photos in the ‘Varieties’ section on varieties show blanched kernels with varying degrees of pellicle removal.

larger processors are interested in dealing in large quantities only, such as the standard 20-tonne container load, although there is some ‘spot’ buying by wholesalers. In addition, local producers have to meet international quality standards and be competitive on price. It is important that producers identify their markets and discuss with buyers or processors the specifics of their requirements.

marketsThe two main markets for kernels are:

processed foods: confectionery, desserts, cakes and snack foods•

nuts to be eaten raw.•

Some uses for hazelnut kernels (to name but a few) are outlined in Table 12.

Table 12. Some uses for hazelnut kernels

AppEARANCE COMMENTS USE

Whole roasted or whole natural kernels Flavour intensified when roasted Snack, confectionery, cereal and bakery

Diced/chopped: natural or roasted Uniform distribution and intensified flavour if roasted

Bakery, confectionery, salads, soups, health bars, encrusting material, toppings, dairy products and muesli

Sliced kernels Adds crunchy texture and appearance Decorating cakes, biscuits and as a garnish

Meal Can be used as a gluten-free flour substitute

Bakery, health foods, confectionery, stuffings, ice cream and sauces

Hazelnuts can also be used in oil production and can be included as a component in cosmetics. Shells are used in landscaping as pathway surfaces; they are slow to decompose and burn slowly. appendix C provides basic nutritional information for 100 g of raw hazelnut.

marketing alternatives

a number of potential marketing alternatives are available for hazelnuts from new plantings, particularly with a small production. These include sales through:

grower cooperatives•

supermarket chains•

specialised nut retailers•

other opportunities.•

| 75M a R k e T I N g o F H a z e l N U T S

Turkey is the dominant world trader in hazelnuts, but opportunity exists long term to expand australian hazelnut plantings to take advantage of profitable markets for healthy food and growth in asian economies. This is evidenced by a substantial proportion of the USa in-shell production now being exported to China and Vietnam. often prices are negotiated and contracted before harvest.

a potential competitive advantage for australian-grown product is freshness, availability throughout the year, and freedom from pesticides. To capitalise on these opportunities, the current australian production sector of the industry needs to expand considerably, to work in a collaborative manner, and to market hazelnuts in a manner that meets the needs of the buyers and the consumers.

Further reading

Baldwin B and Simpson M (2003) Hazelnut Market Assessment Study: A Report for Hazelnut Growers Australia Ltd. accessible from the Hga website: www.hazelnuts.org.au

Horticulture australia ltd (n.d.) Nuts for Life Campaign. Going Nuts for Good Health www.nutsforlife.com.au

76 | a P P e N D I X a : S Ta N Da R D S F o R aU S T R a l I a N H a z e l N U T S I N S H e l l

sTaNDarDs FOr aUsTraliaN HazelNUTs iN sHell

(Standards as adopted by the Hazelnut growers of australia Incorporated.)

Packages of nuts offered for sale shall be:1.

free of all foreign material, husks, stalks, and mechanical damage•

free of rancidity, mould and insect injury.•

Not more than 5% of the content of any package containing nuts in shell of any 2. grade shall be blank (i.e. contain no kernel).

The nuts shall be dried so that the moisture content of the kernel is not more than 3. 5% of the kernel mass.

Nuts in shell are graded in accordance with the following sizes:4.

Small: up to 13 mma.

Medium: 13.01 mm to 18 mmb.

large: 18.01 mm to 19.5 mmc.

Very large: 19.51 mm to 22 mmd.

giant: over 22 mm.e.

The nuts shall be adequately packed to withstand transport and packaging. The 6. packaging shall be clean and of a suitability quality, design and construction to avoid causing damage to the nuts. The materials used inside the package, particularly any paper, shall be new and clean, and of a quality to avoid causing any damage to the nuts.

one end of the package, or a card within the bag, containing australian hazelnuts shall bear the following information in characters that are legible and not handwritten:

australian hazelnutsa.

Full name and address of producer (individual, firm or corporation)b.

Name of variety or nutsc.

grade of nutsd.

Net mass (weight of nuts)e.

Moisture content of nutsf.

year nuts were harvestedg.

Note: a. shall be in letters at least 3 cm high; b. to g. shall be in letters at least 1.5 cm high

AppENdIx A

| 77a P P e N D I X B : D e T e R M I N I N g N U T I N - S H e l l M o I S T U R e Co N T e N T

DeTermiNiNG NUT iN-sHell mOisTUre cONTeNT

(Source: Hazelnut Growers Handbook 1998, Hazelnut Growers of Australia Ltd, Melbourne)

How to dry your nuts

Select a sample of 100 nuts from the rack and divide into two lots of 50 nuts. label 1. the two lots of 50 Sample a and Sample B.

Weigh both samples and record the weight on the proforma. Place 2. sample B in a net bag and place back in the rack.

Take 3. sample a and crack all the nuts, keeping the shell and kernel together. Note the number of blanks, shrivelled kernel, mouldy kernel or stained kernel. Record the numbers on the proforma.

Re-weigh 4. sample a (nuts and shell combined). This is known as the WeT WeIgHT of the nuts. Place sample a in a microwave plate and place in microwave (It is easier if you weigh the plate separately and then weigh the plate plus sample a. The final weight of the nuts can then be calculated by subtracting the weight of the plate.) Heat for 1 minute on high power and then reweigh nuts and record result. (Using times longer than 1 minute usually results in the nuts being burned and inconsistent results being obtained.)

Repeat process, weighing and recording the result, until the weight of the sample 5. does not change. This is known as the DRy WeIgHT of the nuts (i.e. no moisture). (Depending on the amount of moisture this may take up to 14 bursts of heat.) Note also that the weight will stabilise, but after 30 seconds on the scales the nuts will start to take up moisture and the weight will be observed to increase.

Calculate the moisture content (MC):6.

a. WeT WeIgHT – DRy WeIgHT = ToTal WeIgHT oF MoISTURe ReMoVeD

b. MoISTURe CoNTeNT (MC) = WeT WeIgHT – DRy WeIgHT × 100

DRy WeIgHT

The moisture content calculated represents the moisture content present in the nuts at the time of selecting the samples, i.e. the moisture level that exists in both sample a and sample B. To calculate the weight when the nuts will be at a 5% moisture content, use the following formula:

c. 5% (MC) = DRy WeIgHT + 5 × DRy WeIgHT

100

To calculate the weight of sample B when it is at 5% MC, it is necessary to use the formula at 6 b. to calculate the DRy WeIgHT of sample B. By transposing the formula, the DRy WeIgHT becomes:

d. DRy WeIgHT = WeT WeIgHT × 100

MC + 100

AppENdIx b


Then use the formula at 6 c. to calculate the weight for 5% MC of sample B. This weight is the weight that sample B should reach when the nuts have been dried sufficiently. Checking the weight of sample B every 4 or 5 days and recording the result is the best way to monitor the level of moisture content. air-drying takes approximately 2 to 3 months to lower the moisture content to the correct level.

The nuts should now be stored in either airtight containers or in a dry, temperature-stable location until used.

recording proforma

SAMpLE A MEASUREMENT SAMpLE b

WET WEIGHT, DATE WET WEIGHT, DATE

No. of blanks WET WEIGHT, DATE

No. of shrivelled kernels WET WEIGHT, DATE

No. of mouldy kernels WET WEIGHT, DATE

No. of stained kernels WET WEIGHT, DATE

WET WEIGHT, DATE

Dish weight WET WEIGHT, DATE

WET WEIGHT, DATE

WEIGHT of dish plus nuts WET WEIGHT, DATE

FINAL WEIGHT should equal 5% MC as calculated below

Microwave heat weight

1st 5th 9th 12th

2nd 6th 10th 13th

3rd 7th 11th 14th

4th 8th

(Remember to subtract the dish weight)

FINal WeIgHT = DRy WeIgHT = WeT WeIgHT – DRy WeIgHT = MoISTURe WeIgHT

MoISTURe CoNTeNT (MC) = WeT WeIgHT – DRy WeIgHT × 100

DRy WeIgHT

5% (MC) = DRy WeIgHT + 5 × DRy WeIgHT

100

FoR SaMPle B:

DRy WeIgHT = WeT WeIgHT × 100

MC + 100

5% (MC) = DRy WeIgHT + 5 × DRy WeIgHT

100

= WeIgHT oF SaMPle B when dried to 5% MC

| 79a P P e N D I X C : N U T R I T I o N a l Co M P o S I T I o N o F R aW H a z e l N U T

AppENdIx C

NUTriTiONal cOmPOsiTiON OF raW HazelNUT

Nutritional composition of raw hazelnut (per 100 g)

ITEM QUANTITY ITEM QUANTITY

Energy (kJ)1 2693 Iron (mg) 3.2

Protein (g) 14.8 Zinc (mg) 2.2

Total fat (g) 61.4 Thiamin (mg) 0.39

Saturated fat (g) 2.7 Riboflavin (mg) 0.17

Monounsaturated fat (g) 48.6 Niacin (mg) 2.20

Polyunsaturated fat (g) 7.1 Folate (µg) 72

Omega 3 fat(mg)2 100 Pantothenic acid (mg)3 0.918

Total carbohydrate (g) 5.1 Vitamin B6 (mg)3 0.563

Carbohydrate sugars (g) 4.4 Vitamin A (µg RE) 1.0

Dietary fibre (g) 10.4 Vitamin E (µg) 15.0

Sodium (mg) 3.0 Copper (mg)3 1.72

Potassium (mg) 680 Manganese (mg)3 6.17

Magnesium (mg) 160 Selenium (µg) 2.4

Calcium (mg) 86.0 Arginine (g)3 2.21

Plant sterols (mg)3 96 Cholesterol 0

1 Kilojoule content includes the energy from dietary fibre2 Meyer B, Tsivis E, Howe PRC, Tapsell L and Calvert GD (1999) Polyunsaturated fatty acid content of foods: differentiating between long and short chain Omega-3 fatty acids. Food Australia 51(3), 81–953 US Department of Agriculture National Nutrient Database for Standard Reference, Release 22. www.nal.usda.gov/fnic/foodcomp/search/

Hazelnut grower’s handbookLester Snare, Orange Agricultural Institute

Industry & Investment NSW

jn 9

698

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