Arnica montana a grower s guide for commercial production...
Transcript of Arnica montana a grower s guide for commercial production...
Crop & Food Research Report No [Click and type report number here]
Arnica montana a grower‟s guide for commercial production in New Zealand.
B.M.Smallfield & M.H. Douglas
December 2008
A report prepared for
New Zealand Arnica Growers‟ Group
New Zealand Institute for Crop and Food Research Limited Private Bag 4704, Christchurch, New Zealand.
© 2008 New Zealand Institute for Crop and Food Research Limited
Arnica montana a grower,s guide for
commercial production in New
Zealand.
B.M.Smallfield and M.H. Douglas
Disclaimer: The New Zealand Institute for Crop & Food
Research Limited has exercised reasonable skill, care and
diligence in producing this grower guide. It contains general
information only and is not exhaustive on any topic. It is
therefore not intended as a substitute for professional
advice. The Institute cannot accept responsibility for
consequences of actions arising from the use of the
information contained in this publication.
Cover Photo: Arnica montana Variety Arbo in flower 29th Jan
2006 on MAF SFF arnica trial at 600 masl. Styx Creek,
Central Otago. Source: Pauline Seaton.
Contents
1 Introduction 5 1.1 What is arnica? 5 1.2 Objective of this growers‟ guide 2
2 How is arnica used? 3 2.1 Active constituents and quality standards 3 2.2 Traditional source of flowers 6
3 Requirements for growing arnica flowers 6 3.1 Environmental fit 6 3.2 Plant Propagation 6 3.3 Field Establishment 7 3.4 Planting density 8 3.5 7 Weed control 9 3.6 Pests and Disease 11
4 Flower Production 12 4.1 Time of flowering 12 4.2 Effect of Flower maturity on Quality 12 4.3 Flower Harvesting and post harvest handling 12 4.4 Flower Yield and returns 14 4.5 Crop improvement Error! Bookmark not defined.
5 Acknowledgements 14
6 Sources of Information 14
1 Introduction
1.1 What is arnica?
Arnica (Arnica montana L.) is a rhizomatous
herbaceous perennial herb of the daisy family.
The broad spear shaped leaves form a flat
rosette (about 150-300 mm high) and die
down in winter. A flower stalk (20-60 cm high)
rises from the rosette with a number of bright,
orange - yellow daisylike flowers, about 4-8
cm wide. The flowers open progressively
down the flower stalk with the terminal bud
normally producing the largest flower. The
rhizome is dark brown and cylindrical. Usually
curved, it bears leaf scars and on the under
surface wiry rootlets.
The word arnica comes from the Greek “arnakis”, meaning lamb‟s coat, and refers to
the felt-like sepals covered in soft hairs that surround the flower. Arnica montana is
commonly called European arnica or mountain tobacco. It grows wild across Europe
from southern Norway and Latvia southward to Portugal, and east across Europe to the
north Appennine mountains in Italy and south Carpathian mountains in Romania. A
subspecies commonly called Spanish Arnica or Bolós (Arnica montana subsp.
atlantica) is restricted to an area of south-west France the Gallica region of Northern
Spain and into Portugal. Arnica grows naturally on low fertility meadows, peat bogs
heathlands and alpine meadows on acid soils, between 500 and 2500 m in altitude, but
is now a threatened species over most of its natural range.
A niche high value pharmaceutical and medicinal herb, it is used as fresh whole plants,
dried flowers or dried roots. Collection from the wild is often undertaken by Romany
gypsy communities and then traded through dealers and brokers. The pharmaceutical
and medicinal trade names for the dried flowers are Arnica flos (Latin), Fleur d‟Arnica
(Fr), Flor de árnica (Sp), Arnikablüten (Ge) and Fiore de arnica (It) and the trade names
for dried root are Arnicae radix (Latin), Racine d‟Arnique (Fr), Raiz de árnica (Sp),
Arnikawurzel (Ge).
Arnica montana plant in flower.
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1.2 Objective of this growers‟ guide
There is growing international demand for arnica as an ingredient in medicinal,
physiotherapy and sports massage products and in a growing range of cosmeceutical
and personal care products. Most of the world production of dried flowers is however,
still dependant on wild sources. The abundance of arnica has greatly declined in the
wild over much of Europe, due to loss of habitat, changing ecological conditions and
over-harvesting for medicinal purposes (Lange 1998). Aerial fertilisation as a result of
air pollution is also threatening the survival of wild arnica. Legal conservation
protection measures are now in place throughout much of Europe. As demand for
arnica continues to rise, cultivated arnica will increasingly be looked on to supply this
demand.
New Zealand has a good opportunity to commercially cultivate arnica flowers and roots
for the international markets. Trading on its reputation for high quality and its natural
„clean green‟ image in Europe, is an advantage for promoting medicinal herb products.
Arnica was first identified as a potential new crop for Otago when the Dunedin
Botanical gardens were first established in 1863 (Dunlop 2003). Research resumed in
New Zealand in the late 1980‟s and significant progress has been made towards
defining arnica‟s key quality constituents, and agronomic and environmental
requirements in a temperate climate. This booklet aims to give potential growers and
primary processors information on growing the crop in the Southern South Island.
Recent research results are summarised and costs and potential returns are presented.
Crop & Food Research Report No Page 3
2 How is arnica used?
Wild-harvested Arnica montana flowers, roots and the whole plant have a long history
of use as a herbal medicine with flowers being the most important. Arnica heads the
list of phytotherapeutic remedies with as many as 271 preparations (Bisset 1994). The
most frequently used form of the herbal medicine is as a tincture, prepared from 1 part
dried flowers and 10 parts 70% ethanol (Bisset 1994). An arnica oil extract is
traditionally prepared from 1 part of dried flowers and 5 parts vegetable oil with an
ointment containing a maximum of 15% arnica oil. Preparations derived from the dried
flowers are topically applied to reduce the swelling and pain from bruises, sprains,
fractures, rheumatic and joint problems, chilblains and insect bites. The active
constituents have been shown to have strong anti-microbial, anti-inflammatory, anti-
rheumatic, anti-arthritic and anti-hyperlipidaemic properties. They also affect the heart
and circulation. It should not be used for prolonged treatment of damaged skin and
long use can also give rise to eczema. Arnica has also been shown to contain
sensitising agents that may act as allergens in a proportion of the human population.
Internal use should be very carefully controlled or avoided, owing to the toxicity of the
sesquiterpine lactones. In Germany it is used for heart conditions. A prescription from
a qualified practitioner is required for internal use in the United Kingdom and in the
United States it is regarded as unsafe for internal use.
2.1 Active constituents and quality standards
The main chemical constituents responsible for its pharmacological properties are the
sesquiterpene lactones (SL), helenalin and dihydrohelenalin, and their short chain
esters. These are thought to be produced in the glandular trichomes that cover the
surface of the leaves, stems, flowers and seed coat. European arnica contains
principally the helenalin esters where as the subspecies Spanish arnica contains
predominantly dihydrohelenalins and only small amounts of the helenalin esters. There
is some evidence that suggests that helenalins and dihydrohelenins may differ in their
antiinflamatory efficacy and their allergenic side effects, but clinical studies are still
required. The active compounds are extracted by alcohol or vegetable oil and have
been reported at levels ranging from 0.3 to 1% total sequeterpine lactones in flower
heads and at much lower levels in leaf and stem material. New Zealand grown arnica
has total SL levels of 0.66% to 0.94% (Douglas et al 2004), within the same range and
composition as found in Europe and well above a 0.4% suggested minimum standard.
New Zealand research has shown that the level of SL increases as the flower head
matures (Doulgas et al 2004). The SL composition of the arnica flowers also appears
to be most strongly influenced by plant genetics and not affected by growing
environment. The analyses of dried arnica flowers of the Arbo variety harvested from
the MAF SSF arnica trials in 2006-07 season showed SL composition was very similar
at all sites (Table 1). Results from Crop & Food Research plant selection trials also
indicates very little year to year variation in SL composition of arnica flowers.
The plants also contain 0.2-0.35% essential oil. Dried flowers must also meet
quantitative standards for foreign matter (generally not more than 1%), moisture
content (not more than 9 %), total ash not more than 8-9%, maximum counts for yeasts
and moulds, not more than 1% stem and receptacles with attached involucre of not
more than 25-33% (Bisset 1994). Each consignment is also examined macro and
microscopically to confirm botanical authenticity and for presence of adulterants. Many
companies are also actively looking to source spray free or organically certified product.
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Glandular trichomes on the leaf surface of young arnica plants
0
5
10
E F G H
Tota
l S
L (
mg/g
)
Effect of flower maturity on total sequiterpene lactone content (Douglas et al 2004).
Crop & Food Research Report No Page 5
Table 1. Effect of location of the Sesquiterpene lactone composition and total SL content of dried arnica flowers
(plant variety Arbo), 2006 .
Location
SL Compounds Methven Weston Waipiata Styx Creek Three Mile Hill Invercargill
Dihydrohelenalin (%) 2.12 3.29 3.80 3.26 4.92 4.91
Helenalin (%) 1.09 1.28 1.01 1.90 1.68 1.37
Acetyl Dihydrohelenalin (%) 1.96 2.52 3.02 3.21 3.11 3.32
Acetyl Helenalin (%) 5.78 6.59 10.36 8.64 8.07 9.61
Methacryloyl Dihydrohelenalin (%)
2.91 2.13 2.88 2.62 2.50 2.03
Methocryloyl Helenalin / Isobutyryl Dihydrohelenalin (%)
20.40 17.66 22.79 17.00 18.82 18.86
Isobutyryl Helenain (%) 19.69 24.87 18.60 18.98 18.60 19.31
Tigloyl Dihydrohelenalin (%) 2.92 2.68 2.54 3.35 2.59 2.04
Tigloyl helenalin (%) 14.28 12.12 14.34 14.40 14.86 13.44
2 Methyl Butyryl Dihydrohelenalin (%)
1.26 1.37 1.16 1.23 0.00 0.73
Iso Valeryl Dihydrohelenalin (%) 1.28 1.41 1.31 1.74 1.62 1.17
2 Methyl Butyryl Helenalin (%) 19.75 17.95 15.52 18.28 17.78 17.35
Iso Valeryl Helenalin (%) 6.55 6.13 2.66 5.39 5.46 5.85
Total SL content (mg/g) 11.48 9.44 8.70 7.67 6.37 7.25
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2.2 Traditional source of flowers
Currently the major source of arnica flowers to the medicinal herb industry is harvested
from the wild in the Balkans, Romania, and Spain. An estimated 50 t of dried flowers
are traded annually in Europe (Lange 1998). This equates to 250-350 t of fresh
flowers. In New Zealand the annual demand is currently between 1.5 and 3 t of dried
flowers. New Zealand companies wish to source locally grown product because of the
increasing difficulties they face sourcing supply from Europe and problems with
adulteration. In addition small quantities of dried root and whole fresh plant are
consumed each year in Europe mainly for use in homeopathic preparations. This
material generally comes from cultivated sources.
3 Requirements for growing arnica flowers
3.1 Environmental fit
The environmental requirements to grow arnica in New Zealand are still not clearly
defined. Arnica is an alpine plant, but in New Zealand survives and flowers well under
cool lowland conditions. We have found from experimental sites at Hamilton, Hastings
and Lincoln the majority of plants failed to produce flowers over three successive
seasons and attributed the lack of flowering to insufficient chilling. The majority of
plants in grower trials at Methven, Rolleston and at 700 m on Banks Peninsula have
consistently produced flowers. Plants also failed to flower over two successive
seasons at a trial site near Westport. Our experience to date suggests the best
environments for growing arnica are the cool and moist regions of Otago and Southland
and possibly up against the foot hills on the Canterbury plains in the area covered by
the NW rain band. In these environments flower yields have been consistent over
several seasons and the plants are generally less susceptible to crown rot disease
problems. Plants have also flowered extremely well in trials on the Otago uplands at
Lee Stream and near Styx Creek at 600 m on the Rock and Pillar Range. The first
season flower yields (2006/07 season) at the Rock and Pillar site were the highest we
have recorded for the cultivar Arbo, averaging 700 kg/ha of dried flowers compared to
less than 200 kg/ha at four other sites. In the next season however, the flower yield
was very poor, possibly because of the effects of a severe drought restricted plant
growth from the conclusion of flowering at the end of January 2007 until the first snow
stopped all growth for the season.
3.2 Plant propagation
Plants are propagated from seed or by division. Arnica seeds are cylindrical in shape,
with a thousand seed weight of 0.9 to 1.3 g. Seed germination can be highly viable, but
is generally less than 80%. The seed is generally only available from specialist herb
seed suppliers in Europe and North America and current seed prices vary from $2000
to $6000/kg. Arnica seed can be imported into New Zealand without a permit, but any
importation of seed for sowing must meet the conditions laid out in the “MAF Standard
155.02.05 Importation of seed for sowing” (http://www.biosecurity.govt.nz/files/ihs/155-
02-05.pdf). Arbo is currently the only named cultivar of Arnica montana. Developed in
the 1980‟s in Germany the seed of Arbo has been imported into New Zealand from the
German licence holder by Crop & Food Research and the NZ Arnica Growers‟ group
for use in the MAF Sustainable Farming Fund Trials.
Crop & Food Research Report No Page 7
We have not attempted direct paddock seeding of
arnica because of the lack of synchrony in seed
germination, the low germination percentage of seed
lines plus the cylindrical seed shape makes
mechanical sowing difficult. The preferred method of
establishment for large scale planting is to raise plants
from seed under nursery conditions and transplant into
the field. Arnica plants can be propagated by
scattering the seed onto surface of trays containing a
commercial seed raising mix and then covering with a
thin layer of fine basalt chip. Covering the sown tray
with a layer of newsprint paper helps to retain moisture
during the germination period. Under glasshouse
conditions in August - September (night temperature
10-12 °C; day temperature 20-25 °C), the seeds
germinate in about 14-20 days but germination can be
extremely erratic depending on seed source, quality
and seed treatment.
We have found that the synchrony of germination can be improved by soaking the seed
in tap water for 24 hrs under natural light. After soaking, the seeds can be sown
immediately or dried back and stored for a period. Seedlings are pricked out 2-3 weeks
after germination into cell trays or tubes containing a commercial potting mixture. We
use a free draining mix consisting of 7 parts fine bark, 2 parts peat, 1 part gravel and 1
part horticultural sand and with a slow release fertilizer added. We have also
established that Arnica plants are very susceptible to high soluble salt loadings in
potting mixes and soluble salt levels of commercial potting mixes should be monitored
before use. Under our conditions we also found it was unnecessary to sterilize the
potting mix or to add lime. As part of the MAF SFF project Paul Verdonk, Whitestone
Nurseries at Weston, successfully developed an organic seedling production cell
transplant system.
An alternative method of propagation, that avoids the manual pricking out stage, is to
sow directly into cell trays, sowing 3-4 seeds/cell, and after germination, thin to leave
only one seedling per cell. The thinned plants can be used to fill the blank cells. For
direct cell sowing, seed with a high germination percentage must be used to avoid too
many blank cells. In trials using treated seed with an 80% germination percentage, we
still had a 28% blank cells count, from sowing 3 seeds per cell. The pricked out
seedlings are initially slow to develop and on average 6-8 weeks growth will be needed
prior to transplanting in the field. At the planting out stage the seedlings will have 3-4
pairs of leaves in a rosette, and a firm root ball. More research is required before direct
seeding will be possible.
3.3 Field establishment
The field establishment of seedlings transplants is most reliable when carried out in
spring after the last frost. Late summer/early autumn establishment can be successful
where there is adequate rainfall or access to irrigation and the plants have sufficient
time to grow and get their roots established before the onset of the first frosts. A high
proportion of autumn transplants will flower in the following spring, so the time to first
flower production is reduced with autumn planting. However, flower yield will be lower
than for a spring planted crop, because plants will be smaller. Autumn planting in
environments with hard winter frosts is risky as the seedlings can be killed by the
effects of frost heave.
Arnica seedling in cell tray
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Arnica is very sensitive to soil conditions, and its cultivation should be kept on well
aerated acid land, free of lime, and not too rich in phosphates and nitrogen. Our
experience is that Arnica will grow and produce well on a wide range of soil types from
silts to clay loams, in the cool/moist environment, but with adverse soil conditions (very
wet or very hot and dry) the plants die rapidly with fungal crown rot invasion.
We have only used transplants and have not attempted direct seeding because of
erratic germination. At the planting out stage the seedlings will have 3-4 pairs of leaves
in a rosette, and a firm root ball.
3.4 Planting density
Our research has shown the first
season flower yields are density
dependent but the plant rosettes
will expand as basal buds grow
and a dense ground cover is
achieved by the end of the second
year. The increased flower yield
from plant densities great than 20
plants/m2, is unlikely to cover the
additional costs of the plant
material and establishment. The
risk of plant diseases spreading is
also higher with high plant
densities.
The transplants are best established in 150 cm wide, 4 row beds, with plants at 25 cm
spacing in row and 25-30 cm between rows, and with a 50 cm laneway between beds.
This is equivalent to a plant density of 16 plants/m of bed or 90,000 plants/ha. At this
density, the first year flower yields are less than at higher plant densities (up to 100/m
of bed), but the maximum flower yield was achieved at this density in the second
flowering season. This bed layout also aids management of the crop as it provides
traffic lane ways for weeding, general crop management and flower harvesting without
needing to drive over the crop. We have obtained improved plant survival and flower
yield from establishing plants on raised beds on heavier soils, but for lighter and very
free draining soils flat beds are best. On large scale planting we find a group of 4 to 8
people can plant hand plant between 800 to 1000 plants per hour. With a two row
mechanical punch planter, three people plus a tractor driver can plant 3000 plants/hr.
For mechanical planting the third person is used to replant material that is misplanted
(falls on its side or upside down). For efficient mechanical planting the plants need to
be of uniform size and with not too much top growth plus the beds also need to be level
and with a fine tilth.
Raised beds of Arbo plants Mosgiel, 6 weeks after planting.
Crop & Food Research Report No Page 9
Plants can be highly variable in their rate of establishment. Some plants may not
develop daughter rosettes within the first six months and others will produce multiple
rosette. Weed control is therefore critical during this establishment period and in drier
areas irrigation maybe required. Under good conditions with progressive daughter
rosette development plants will reach a diameter in excess of 25-30 cm. From a spring
planted crop a percentage of plants may flower in the autumn of the establishment
year. The proportion of plants flowering appears to relate to when the crop was
established and autumn weather conditions. In the MAF SFF trials more plants
flowered in the first autumn at the cooler higher altitude sites than at the warmer
lowland sites.
The fertiliser requirement for the crop is dependent on the existing soil fertility, and as a
standard practice, the soil should be analysed for macro elements prior to crop
establishment, and any deficiencies rectified. We have found the plants will respond to
low to moderate applications of NPKS fertiliser but high levels of fertiliser in spring can
encourage crown rot disease.
3.5 Weed control
There are no herbicides registered for use on Arnica in New Zealand, therefore
planting into a stale seedbed (a seedbed which has had the weeds controlled before
planting and not re-worked) is prudent management. White clover and grass weed
invasion can be a significant problem and once established can quickly smother and kill
the crop. Control of weeds in the lane ways is also critical.
The SFF arnica protect investigated the effectiveness of several types of potential
organic weed methods for controlling weeds including a plant fatty acid herbicide, a
planting through a layer of wood chip mulch, a biodegradable corn starch film, a paper
mat material and synthetic woven weed cloth cloth. Herbicides composed of plant fatty
acids or pine oils can only be used for spot treatment of weeds under AsureQuality
Organic Standards. However, these types of products were not effective with arnica
because the temperatures required for good herbicide action do not occur when arnica
is dormant. The physical barrier systems also gave mixed results. At all sites the
paper barrier and corn starch film failed to survive the growing season. In most cases
both paper mat and the corn starch film material were ripped and blown off the beds by
the first strong NW winds. It would appear that the arnica plants do not establish
quickly enough to anchor these materials. Even though these materials did not survive,
retaining a barrier on the surface for a limited period of time did have some residual
effect on slowing the rate of weed invasion. The woven weed mat was found to provide
effective weed control at all sites. Under the weed mat and wood mulch the plants
Hand planting arnica at Weston and mechanical planting at Styx Creek.
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were to be slightly larger and the barrier also conserved soil moisture under dry
conditions. The disadvantages of the weed mat are holes need to be cut in the
material, plants need to be planted by hand and at the start of the second season it
needs to be taken up or the size of the holes expanded to accommodate the growing
rosette. There is also a disposal issue with the synthetic woven weed mat at the end of
the products life. The corn starch film would offer significant weed control advantages if
a heavier grade of film was more resistant to wind damage. The film is cheaper than
woven weed mat, can be laid with a standard film laying machine and a planter can
punch through the film. The film has a 120 day life and is fully biodegradable. The
corn starch film is currently not certified for organic use in New Zealand.
Organic methods of weed control at Styx Creek site.
Organic Weed control treatments showing wind damage to corn starch film and white recycle paper mat at Three Mile Hill site, 16 December 06.
Crop & Food Research Report No Page 11
3.6 Pests and diseases
Arnica plants are very sensitive to crown rot and fungal diseases, the most serious of
which are Phytophthora and Phoma. During the growing season, individual or patches
of plants can collapse and die suddenly when conditions are unfavourable, particularly
under hot wet or hot dry conditions. The first visible symptom of the disease is that the
plant starts to wilt. There are no fungicides registered for use on arnica. Therefore good
plant hygiene techniques need to be maintained right through the production cycle.
We have found no value in replanting into infected areas as the new plants also often
succumb to crown rot. A proportion of plants taken out by the disease will re-grow from
a surviving piece of rhizome, but often they continue to have a chronic level of infection.
Further work needs to be undertaken to determine how best to manage this disease
plus selection for plant resistance would offer a significant advantage. Patches of
plants killed by disease also provide areas where weeds such as white clover can
establish and spread into and smother healthy plants if not controlled.
No major insect pest problems have been identified to date. The leaves are attacked by
the caterpillars of the magpie moth and the green looper, but damage is relatively
minor. Populations of grass grub larvae have also been found under mature plants but
there has been little evidence of feeding damage to the roots. Aphids can be an issue
on seedlings being propagated in the greenhouse, causing curling and distortion of the
leaf. In some other daisy species the SL‟s have been shown to have insecticidal
properties against some insects.
At several locations rabbits have caused minor damage,
digging up plants and leaving them littered on the soil
surface. At an experimental site near Outram, we also
experienced a problem with magpies pulling up thousands
of seedlings, within 24 hrs of the area being planted. The
plants were re-planted, most survived and no further
damage occurred. Finch damage to flower heads is also
an issue where there are shelter belts or hedges nearby.
The birds will perch on the flower stem, cut open the
receptacle and pull out the individual florets. Damage
only occurs to mature flowers at the stage when the petals
have started to whether. This flower development stage
Arnica crown rot, A) Recovery of some infected plants, B) Shoot
wilting symptoms in two year old plants, C&D) Basal rot symptoms.
Finch damage to a mature arnica flower
Page 12 Crop & Food Research Report No
also corresponds to when the SL concentration in the flower is at its highest.
4 Flower Production
4.1 Time of flowering
The plants can produce some flowers in the autumn of the first season but the main
production would be expected to start in the spring of year two. The onset and rate of
flower development is dependent on the weather. In our experimental trials at
Invermay in a mild spring flowering has started at the end of September, but the first
flowers did not start to appear until the end of October in a cold spring. Currently
available seed lines are all highly variable in its flowering. The Arbo variety was slightly
less variable than seed sourced from the wild. Flowering can extend over more than a
two month period with the period of flowering much long in the first year and slightly
more compressed in subsequent years. In a first year crop, depending on the
environment, less than 50% of plants may flower, but this increases to over 80% in
subsequent years. At the highest and coldest site (Styx Creek) more than 95% of the
Arbo plants flowered in the first year.
4.2 Effect of flower maturity on quality
The timing of the flower harvest is critical to the concentration of the lactones in a flower
head. As shown earlier the lactone concentration progressively increases as the flower
matures from a bud to a pollinated flower with petals withered. The mass of the flower
head increases as the florets are pollinated and the seed starts to fill. The total lactone
content of New Zealand grown Arnica montana between 0.66% and 0.94%, is typical of
the quality found in Europe. Therefore harvesting more mature flowers will produce a
product with a high SL quality. An open flower can remain unpicked for 5-10 days and
the pick and re-pick of the flower crop is dependent on the seasonal growth conditions.
4.3 Flower harvesting and post harvest handling
Because of lack of uniformity of the flower stem architecture and poor synchrony of
flower maturity currently available seed lines are best suited to hand harvesting. The
cost of labour to pick flowers is quite a significant component of the production cost. To
pick only flowers at a set flower development stage is much more time consuming than
picking all flowers that are open at that time. We have found that if the first harvest is
delayed until a large proportion of the terminal flowers have all florets open and petals
withered (our flower development stage H) and this will optimise the quantity of flower
material available. Subsequent harvests can then be undertaken at 7 to 10 day
intervals depending on rate of flower development.
Flowers can be plucked from the flower stem using the thumb and index finger or
sliding a group of flowers between the index finger and the second finger and pulling
upwards in a sharp action. Collecting a quantity of plucked flowers in the palm of the
hand before transferring the flowers to the harvest bin, as opposed to transferring after
each plucking movement also speeds up the rate of picking. The rate of flower picking
is dependent on flower density but an average yield of 2 to 5 kg/hr of fresh flowers is
possible. In high flower densities picking two planted rows at a time, a picker will
harvest the equivalent of 0.8 to 1.0 kg of dried flowers per hour. We have also found,
using cheaply constructed inline two wheeled trolley with pneumatic tyres and an
adjustable seat which is pushed backwards down the lane way between the arnica
beds, also makes picking easier and reduces back strain. Picked flowers can be
Crop & Food Research Report No Page 13
dumped into large plastic bins with handles that can be pulled behind the trolley.
Disposable gloves should be warn when picking flowers to avoid skin reactions and
wearing long sleeves or arm guards will minimise brushing contact of the arms and
wrist areas against the flowers and flower stems. Pickers also need to be aware of
bees working the crop and the gloves can provide some protection against a bee string.
A trial simulating mechanical harvesting of arnica flowers has been undertaken arnica
grown from an unselected seed line in New Zealand (Douglas et al 2004). The flower
stems were cut using electric hedge trimmers, the stems were dried and then the
flowers were mechanically separated from the low quality stem material to produce a
product of the same quality as the hand harvested material. The simulated mechanical
harvest treatment yielded over twice the total herbage as the hand-picked treatment,
but 34% of this material was the low quality stem material that was thrown away after
drying. Efficient mechanical harvesting of arnica flowers requires plants with more
uniformity in plant structure, time of flowering and flower development than currently
found in the unselected lines. Crop & food Research have a plant breeding programme
looking to increase the uniformity of these characters plus increase flower yield.
Once harvested the bulk flower material should be quickly dried or stored over night in
a cool room (1-3°C), if drier space is not immediately available. Large quantities of
picked flower material can rapidly heat to over 50°C, within 2-3hr when held at ambient
temperatures in midsummer. We have stored flowers in 40 litre stacker crates to avoid
heating. Heating can also occur in the chiller if the quantity of flower material in a bin or
container is too large or too tightly packed.
There are many types of commercial drying systems available and professional advice
should be obtained to identify the most suitable unit. Ideally the flowers should be dried
in the dark, in a forced air drier, at 40°C-45°C, to less than 10% moisture content and
within 24 hrs. Ideally the unit should have also humidity control. In a batch drying
system we have found galvanised sheet metal trays 70mm deep with a stainless steel
mesh with a small gap between each layer of trays works very well. If the trays are any
deeper than this or if the flowers are packed too tightly into the tray then the centre of
the layer dries very slowly and it may be necessary to remix the trays to get the product
dry. Slow drying can encourage the growth of yeast and moulds. Once dry the
individual florets in the flowers will have puffed up like a dandelion head and the
receptacle and stem will be brittle to the touch. The packing of the trays should be
done as uniformly as possible to ensure even air low throughout the whole drying stack.
An low cost in-line two wheeled adjustable seat trolley for flower harvesting.
Page 14 Crop & Food Research Report No
It is advised to wear gloves and have the arms covered when packing the fresh flowers
into the trays and in addition when emptying the dried trays a dust mask should also be
warn. The type of storage packing material is normal determined by the buyer. New
packaging rather than recycled materials should be used.
4.4 Flower Yield and returns
Flower yields are still quite variable most first year crops on lowland sites have yielded
between 150 and 300 kg/ha of dried flowers from unselected seed lines and the
German Arbo variety. At the Styx Creek site the average first year dried flower yield for
700kg/ha from the Arbo variety was. Data on flower yields Yield from second year
crops in New Zealand is still limited. Results from bulk plantings have ranged between
570 and 100 kg of dried flowers per ha. From the selected breeding material the flower
yields greater than 700 kg/ha have been obtained in the first year and over 1000 kg/ha
obtained in the second year from some of the better performing material. The current
price for dried arnica flowers is between $60 and $100/kg in New Zealand.
5 Acknowledgements
We thank the MAF sustainable farming fund, Weleda NZ Ltd., Crop & Food Research
and Venture Southland for their financial support of this project. We thank Ruth
Gardener, Pauline Seaton, Nancy and Bob Allen, Rob and Amy Markellie and Craig
Howard for information and images from the SFF arnica trial sites. Thanks to
Rosemary Anderson, Alison Evans and Tom Orchiston for information from the
Invermay trials and to Paul Verdonk for information on organic propagation of arnica in
cell transplant systems.
6 Sources of Information
Bisset, NG, Ed. (1994). Herbal Drugs and Phytopharmaceuticals. A handbook for practice on a scientific basis. Stuttgart, medpharm. pp.83-87.
Douglas JA, Smallfield BM, Burgess EJ, Perry NB, Anderson RE, Douglas MH Glennie, V. A. 2004. Sesquiterpene Lactones in Arnica montana: a Rapid Analytical Method and
Crop & Food Research Report No Page 15
the Effects of Flower Maturity and Simulated Mechanical Harvesting on Quality and Yield. Planta Med. 70: 166-170.
Dunlop, E 2003. The story of Dunedin Botanic Garden New Zealands first. Pub. Friends of Dunedin Botanic Gardens Inc. pp.284
Lange, D. (1998). Europe's medicinal and aromatic plants: their use, trade and conservation. Cambridge, TRAFFIC International. pp.73