AGRICULTURE

Français

Two-grooved Milk-Vetch (Astragalusbisulcatus)

CROP PRODUCTION NEWS #4 - JULY 23, 2015

Be on the look out for Two-grooved Milk-VetchAlso known as silver-leafed milk vetch or two grooved poison vetch, two-groovedmilk vetch is a member of the Fabaceae or Pea family and is a perennial nativeherb found throughout Alberta, Saskatchewan and Manitoba in rangelands androadside ditches.

This plant can accumulate quantities of selenium high enough to cause toxicity incattle, horses, sheep, and swine. High quantities of selenium cause acute toxicity,with symptoms including staggering, diarrhea, prostration, and abdominal pain.Plants that contain selenium content of less than 200 ppm cause chronic toxicity.Researchers used this plant (selenium content of 180 ppm) to conduct feedingexperiments on sheep. They found that the symptoms and microscopic lesions oftissues collected from the sheep were similar to those caused by locoweedpoisoning and not selenium poisoning. This finding suggests that other toxiccompounds in addition to selenium may be present.

Sheep can die in thirty minutes from eating a half a pound of Astragalusbisulcatus, and in 1907 and 1908, approximately 15,000 sheep in Wyoming diedwith symptoms of either alkali disease or the blind staggers; both of which wereoutcomes of digesting a large amount of selenium from Astragalus bisulcatus.Swainsonine is also found in this plant, which may explain why, in experiments,sheep exhibited symptoms more appropriate to locoism than to seleniumpoisoning.

For more information on weeds in your region, contact the Provincial Specialist,Weed Control or your Regional Crops Specialist.

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 - July 23, 2015 / Be on the look out for Two-groovedMilk-Vetch

© 2016 Government of Saskatchewan. All rights reserved.

AGRICULTURE

Français

CROP PRODUCTION NEWS #4 ­ JULY 23, 2015

Critical times for IrrigatingBy: Joel Peru, AAg, Irrigation Agrologist

Irrigation plays a vital role in providing crops with sufficientwater for their growing requirements. This becomes even moreevident during a dry growing season like we have experiencedin various areas of the province this year. When makingirrigation decisions it is important to know when to water, howmuch water to use and for what duration. Crops generallyrequire more water at their reproductive stages and less waterat their early growth stages. For example, a week after a wheatcrop emerges it uses approximately 1 mm of water a day. Fastforward 7 weeks and the same crop will be using over 7 mm aday if the temperature is around 30 degrees Celsius. It is alsoimportant to properly determine when to stop watering for theyear. Watering after a certain point in a crop’s lifecycle may

delay maturity and add to your input costs with no increase in return.

There can be negative impacts, like an increase in disease and lodging, if too much irrigating is done at certain growthstages. Moist, humid conditions create an ideal environment for diseases to flourish in most field crops, especially duringflowering. In order to prevent yield loss from disease it is best to not irrigate during flowering. Irrigating prior to floweringand resuming right after is a common strategy that allows the crop to have sufficient water while reducing the risk andseverity of diseases. Over irrigating can also cause lodging, especially when mixed with high soil fertility, causing plants tobecome too heavy to support themselves.

Table 1 is taken from the Ministry of Agriculture’s Irrigation Scheduling Manual. This table shows the growth stage for whena crop requires the most water, as well as when it is at the stage in which irrigating will provide no benefit.

Table 1: Critical water requirements periods and termination period for various crops

Crop Critical Water Requirement Period Irrigation Termination Period

Alfalfa All the time, especially after cutting Prior to killing frost

Grass All the time Prior to killing frost

Hard Spring Wheat Tillering and Flowering Soft dough

Barley Tillering and flowering Soft dough

Canola Late vegetation/spiking through flowering and pod development Initial seed ripening

Flax Flowering Prior to seed ripening

Grain Corn Tasseling and grain filling Dent stage

Grazing Corn Tasseling and grain filling Dent stage

Silage Corn Tasseling and grain filling Three weeks prior to harvest

Peas Beginning of flowering Pod filling

Potatoes Tuber initiation and tuber bulking Beginning of vine ripening

Dry Beans Late bud through pod formation Mid­August

Faba Beans Beginning of flowering When hald the pods are filled

For more information see the Saskatchewan Ministry of Agriculture’s Irrigation Scheduling Manual at or Contact anIrrigation Agrologist.

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 ­ July 23, 2015 / Critical times for Irrigating

© 2016 Government of Saskatchewan. All rights reserved.

AGRICULTURE

Français

Ladybug larva in a lentil crop

CROP PRODUCTION NEWS #4 - JULY 23, 2015

Insect Update – to July 20, 2015Reports of aphid infestations have been common during the past couple weeks with areasaffected throughout the Province. Many of the reports have been from southwestSaskatchewan in lentil crops. Both pea and lentil appear to be the most affected.

Aphids have slender mouthparts that they use to pierce plant tissue to suck plant sap. Thesap has to be actively flowing for the purpose of filling seeds. If seed filling is complete andthe crop ceases to be lush and actively growing, the next generation of aphids may emergein a winged form and migrate to other greener crops.

Being soft-bodied, aphids are very sensitive to physical disturbance. A heavy rain or severewind can dislodge aphids and reduce their numbers in a crop but generally notsignificantly. Regular monitoring is essential in identifying changes in population densities.

Timing and necessity of insecticide applications should be treated on a case by case basis.Early application of insecticide likely won’t provide a yield response but will affectbeneficial predators (e.g. lady beetle larvae and adults) and wasp parasites. Lateapplication would have no beneficial result and will be an unnecessary expense as the aphids cannot damage crops thathave completed seed filling. Research has shown that the best result from insecticide application for economicinfestations of aphids on peas is at late flowering to early pod. From this stage until soft dough there will be a graduallydiminishing yield response by the plants as a result of insecticide application.

Beneficial insects and disease can play a major role in managing aphid populations. Aphids have many predators asidefrom lady beetles including, ambush bugs, minute pirate bugs, and hover fly larvae. Several species of tiny wasps lay theireggs in aphid nymphs, killing the nymph. The result is gray or tan “bloated” but empty aphid bodies referred to as“mummies”. There is a larger exit hole in the mummy, from which the adult wasp has emerged. In humid conditions anentomophthoran disease can kill large numbers of aphids. These natural control agents may not be effective in reducinglarge infestations, but when aphid numbers are around threshold levels, bio-control may be a better alternative thaninsecticides. Because of their rapid ability to increase in numbers, aphids have been known to rebound to high levelsseveral weeks after insecticide application. Regular monitoring for these beneficial insects, as well as for the aphids, isimportant and can save considerable expense and labour.

Aphids have specific host crop preferences. Although some may feed on more than one crop, not all aphids will attack allcrops. Aphids noted in pea and lentil will be predominantly the pea aphid. However in canola there are two or threespecies that could be encountered. The species feeding on canola leaves are generally not a concern. However the turnipaphid tends to cluster on stems, often near pods and flowers and can affect pod filling.

Recommended economic thresholds (ET) for aphids: Keep in mind that there are several factors affecting the economicthresholds and control decisions - market value of the crop, cost of control, moisture conditions, and crop stage. These ETsshould be used as a guideline. As a general rule of thumb, as the commodity value rises use the lower end of theeconomic threshold.

1) Field Peas – Currently the ET recommended is 2 to 3 per 20 cm plant tip at late flowering – early pod. This economicthreshold was developed based on counts on the plant tip for an older variety (Century pea). Newer varieties may be ableto tolerate more aphid feeding and there are also likely more aphids on the rest of the plant. The chart below is fromresearch on aphids on peas from Dr. Bob Lamb (A.A.F.C., Winnipeg) and provides an estimate of yield loss related toaphid numbers.

Aphids per tip % yield loss

1 3.4

2 4.9

3 6.1

4 7.1

5 8.0

6 8.8

7 9.6

8 10.3

2) Lentil - Information on aphids in lentil from North Dakota suggest an ET with 3 qualifiers:30 to 40 aphids per 180 degree sweep and few natural enemies are present and aphid numbers do not decline over a 2day period.

3) Canaryseed – based on U.S. and Australian research the current recommendation for considering insecticideapplication for aphids on lentil is:10 to 20 aphids on 50% of the stems

4) Cereals (e.g. wheat barley) - 12 to 15 aphids per stem prior to soft dough

5) Canola – As a guideline, researchers have suggested that if 10 to 20 per cent of the stems have clusters of the turnipaphids, control is likely warranted.

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 - July 23, 2015 / Insect Update – to July 20, 2015

© 2016 Government of Saskatchewan. All rights reserved.

AGRICULTURE

Français

CROP PRODUCTION NEWS #4 - JULY 23, 2015

Plant Industry Who's WhoGetting to the root of it in the Plant Industry section of the Crops and Irr igation Branch

The Crops and Irrigation Branch of the Saskatchewan Ministry of Agriculture is committed to providing strategicdevelopment, production and regulatory services to a thriving crop sector. To that end, the majority of branch staff aretechnical experts who serve as a subject matter resource for problem solving, diagnostics, inspections and the preparationof technical materials, as well as provide sector development and program or policy development.

Doug Pchajek, PAg – Manager, Plant Industry Section, Reginadoug.pchajek@gov.sk.ca / (306) 787-4661

Chantal Jacobs, PAg – Provincial Specialist, Alternative Cropping Systems, ReginaChantal has been with the Ministry since 2005 and enjoys the diversity of her role working withproducers, researchers and Ministry programs.chantal.jacobs@gov.sk.ca (306) 798-0945

Glen Sweetman, PAg – Provincial Specialist, Greenhouse and Nursery Crops, ReginaGlen has a diverse background: managing a nursery and a garden centre, working as an urbanforester, a consultant in Australia and a greenhouse grower. He has also done volunteer work inTibet and China. glen.sweetman@gov.sk.ca (306) 787-6606

Forrest Scharf, PAg – Provincial Specialist, Fruit Crops, ReginaPrior to joining the Ministry in 2007, Forrest was the Special Crops Technologist for AlbertaAgriculture, and had previously been a research assistant for the University of Saskatchewan FruitProgram.forrest.scharf@gov.sk.ca (306) 787-4666

Connie Achtymichuk, PAg – Provincial Specialist, Vegetable Crops, Outlook/ReginaConnie has been with the Ministry since 2005. She works in Outlook and Regina in close contactwith vegetable growers in the province.connie.achtymichuk@gov.sk.ca / (306) 787-2755

Dale Risula, PAg – Provincial Specialist, Special Crops, ReginaDale has worked with the Ministry for 28 years in six different branches, including Extension, Research and the AgricultureKnowledge Centre, and came to this branch in 2008.

dale.risula@gov.sk.ca / (306) 787-4665

Geoff Wilson, PAg – Provincial Specialist, Apiculture, Prince AlbertPrior to moving to Saskatchewan for this job in 2009, Geoff was the owner and operator of a 500-colony beekeeping business near Kingston, Ontario.geoff.wilson@gov.sk.ca / (306) 953-2304

Mitchell Japp, M.Sc., PAg - Provincial Specialist, Cereal Crops, ReginaMitchell enjoys the challenge of researching a new problem – something he’s effectively done in hisrole the last 7 years.mitchell.japp@gov.sk.ca / (306) 787-4664

Terry Kowalchuk, M.Sc., PAg - Provincial Specialist, Forage Crops, ReginaTerry loves working in the agriculture industry. Each of his 25 years in the sector have presented aunique set of circumstances along with a fresh set of challenges and opportunities.terry.kowalchuk@gov.sk.ca / (306) 787-7712

Barbara Ziesman, AAg, PhD candidate - Provincial Specialist, Oilseed Crops, ReginaBarb joined the Ministry earlier this year and has since enjoyed meeting new people and receivingcalls related to oilseed agronomy.barbara.ziesman@gov.sk.ca / (306) 787-4668

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 - July 23, 2015 / Plant Industry Who's Who

© 2016 Government of Saskatchewan. All rights reserved.

AGRICULTURE

Français

Worn chopper parts can result in poor performance andincreased fuel consumption.

Finely chopping and uniformly spreading the straw and chaffprovides the best conditions for seeding the next crop. (Photocourtesy of Redekop)

CROP PRODUCTION NEWS #4 - JULY 23, 2015

Service the combine straw chopper too!By: Ken Panchuk, PAg. Provincial Specialist, Soils

Harvest is going to be different this year with most crops beingshorter than previous years. When determining your feedoptions, consider lentil and pea residue. Both make excellentlivestock feed and can be baled, collected or swath grazed.Pulse residues need to be channeled into narrow windrows tooptimize recovery or use.

Chopper parts do wear more quickly after big crops and/or wetharvest conditions. These parts need to be checked andreplaced if worn to keep the machine operating at peak

efficiency.

With the flax crop being short it may be much easier to fine-chop and spread. The cereal residue volume will also bereduced so less horsepower and fuel will be used for fine-chopping and spreading.

For more information contact your local machinery dealer.

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 - July 23, 2015 / Service the combine straw choppertoo!

© 2016 Government of Saskatchewan. All rights reserved.

AGRICULTURE

Français

CROP PRODUCTION NEWS #4 ­ JULY 23, 2015

Understanding the Saskatchewan and Manitoba FHB Risk Maps

Map on left shows FHB risk based on relative humidity in previous 5 days plus 2 days forecast for Saskatchewan spring wheatcrops heading on July 22; map on right shows FHB risk based on temperature and precipitation in previous 7 days for Manitobawheat crops flowering on July 22.

By: Faye Dokken­Bouchard (Plant Disease) and Mitchell Japp (Cereal Crops), Provincial Specialists, Saskatchewanand Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba

For the first time, FHB risk maps were available in both Saskatchewan and Manitoba. At times the maps appeared toindicate a different risk for growers in each province, which can be concerning for farms along the Manitoba­Saskatchewan border. However, closer examination reveals minor differences in the models and maps, which are usefulfor considering FHB risk.

In Saskatchewan, maps are created with models (depending on spring or winter wheat) using temperature and/or relativehumidity in the previous 5 days, plus 2 days forecast. While in Manitoba, maps are created with a model that uses thehours of precipitation and the hours with temperatures between 15 C and 30 C during the previous 7 days. Each provincethen has its own categorization based on slightly differing threshold values ­ low, moderate, high (and extreme inManitoba) to illustrate the output from their respective models.

Models are also constantly validated and fine­tuned for the region where it is relevant. The model that is best for theFusarium population and conditions in individual provinces in western Canada, or even across the border in the U.S.,might not be the same. However, crop scientists and pathologists continue to work together to determine how FHB riskmaps can be most valuable to all farmers, including those along the border! Producers along the border may have apotential advantage in assessing risk, by using both maps to determine which is most relevant to their farm. Risk maps aredesigned to be as accurate as possible but they may not represent a producer’s individual field(s).

Regardless of the model used, no FHB risk map can be taken as a stand­alone tool to make management decisions aboutFHB as it only takes the environment into account. The existence of disease requires 3 factors: the interaction of asusceptible host, a virulent pathogen, and an environment favourable for disease development. Although a risk map inSaskatchewan or Manitoba may show high risk due to environment, disease risk may actually be low if the wheat crop isnot at the proper stage for infection.

We strongly encourage referring to additional information and consulting with local extension specialists and agrologiststo determine if fungicide application is needed to suppress FHB in your area.

If you have any questions on the FHB Risk maps or FHB management, please contact Manitoba Agriculture Food andRural Development, or the Saskatchewan Ministry of Agriculture.

RELATED LINKSWhere to find Saskatchewan’s FHB Risk MapsWhere to find Manitoba’s FHB Risk MapsScouting and Control of FHBAdditional information on FHB

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 ­ July 23, 2015 / Understanding the Saskatchewanand Manitoba FHB Risk Maps

© 2016 Government of Saskatchewan. All rights reserved.

AGRICULTURE

Français

Yellow streaking cause by WSMV in durum wheat.

CROP PRODUCTION NEWS #4 - JULY 23, 2015

Wheat Streak Mosaic Virus and the Green BridgeBy: Faye Dokken-Bouchard, Provincial Specialist, PlantDisease

Thanks to the keen eye of growers and agronomists thisseason, as well as lab confirmation, a few wheat fields havebeen diagnosed with Wheat Streak Mosaic Virus (WSMV).

Most plant diseases can survive as resting structures in soil oron decaying plant material. They overwinter on crop residueand produce spores when conditions are right for diseasedevelopment. Many diseases waiting for a host can survivelike this for years. However, diseases like WSMV, Aster Yellows,and even rusts require a living host at all times to survive.These plant diseases are considered “biotrophic” and a “greenbridge” of living susceptible hosts is required to keep thedisease cycle going. For fungal diseases like rusts that can

infect one or two plant species, the green bridge must be 2 plants that are both green. For viruses and phytoplasmas thatare transmitted via an insect vector, the green bridge involves a combination of susceptible plants and/or insect hosts.

Wheat streak Mosaic Virus (WSMV) is carried and transmitted by the wheat curl mite (Aceria tosichella), and usuallyoccurs in areas where both winter wheat and spring wheat are grown. The mite requires green plants for feeding andreproduction. Grasses and other cereals can be infected, but are not important for perpetuating the disease.

Yellow, stunted plants often appear first at the edge of the field or in patches. Infection may occur on winter wheat in thefall, but symptoms are not noticed until the spring. The leaf curl mite is not visible to the naked eye, but may cause leafcurling, another symptom to watch for.

Varieties, such as Radiant winter wheat, have resistance to the wheat curl mite. Mites may transfer WSMV from greenspring wheat crops to emerging winter wheat crops if the latter is seeded too early. Wait until the spring wheat crops havematured – the rule of thumb is “green free” for at least one week – before planting winter wheat. There are no pesticides orbiological agents available to manage the mite or virus directly.

There can be a number of reasons for yellowing and because WSMV can cause yield damage (although not alwayssignificant), it is important to properly diagnose this disease. The Crop Protection Laboratory in Regina can confirm WSMVusing an Enzyme-linked Immunosorbent Assay (ELISA) test.

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 - July 23, 2015 / Wheat Streak Mosaic Virus and theGreen Bridge

© 2016 Government of Saskatchewan. All rights reserved.

AGRICULTURE

Français

CROP PRODUCTION NEWS #4 - JULY 23, 2015

White Heads in Wheat?Fusarium Head Blight and Other Disease IssuesWheat that survives the seedling blight and root rotting complex (Cochliobolus sativus and Fusarium spp) at the seedlingstage but succumbs after heading may suffer from prematurity blight. Infected plants are often scattered in the field and pulleasily from the soil and exhibit poorly developed and discoloured roots and crowns along with white heads that producelittle or no kernels.

Take all (Gaeumannomyces graminis) can cause stunting, reduced tillering, empty white heads, and premature ripening ordeath. The disease often occurs in patches and similar to root rots, plants with rotten roots pull easily from the ground.Unlike root rots, fungal growth may be visible on the lower stem of plants infected with take all and roots and culms mayexhibit a shiny black appearance.

In older forage grass crops, white heads are common, and are also referred to as silvertop. Flowering heads becomebleached and empty, while the stems remain green but pull easily from the leaf sheath. Where the stem detaches whenpulled, tissue may be rotten with evidence of stem-feeding insects and/or Fusarium poae, but the cause has not beenidentified.

Silvertop in crested wheat grass: bleached mouldy heads andpinched rotten stems.

Most of the Fusarium species involved in root rots may also cause fusarium head blight (FHB) if spores come in contactwith the heads, spreading through rain or wind during anthesis (flowering). Premature bleaching will be apparent in one ormore of the spikelets in a head, sometimes including the rest of the spike above the point of infection. These spikelets maynot produce seed, or result in light, chalky kernels. Pink or orange Fusarium spores are sometimes visible on the glumesof infected plants, particularly when conditions remain wet after infection.

Fusarium Head Blight in wheat: bleaching of spikelets

Barley yellow dwarf infections may cause premature death of infected plants, which are stunted with yellow leaves and fewtillers. Spikelets may be sterile on the top and bottom of the spike, which is also reduced in size.

Under high disease pressure from leaf spots, glumes and awns may become spotted. Plants that have died or ripened

prematurely for any reason may also exhibit “sooty moulds” which turn the heads brown or black due to growth ofsaprophytic fungi. By the time any of the above disease issues appear, control with a fungicide is not beneficial.

Aster Yellows (AY) was widespread in other crops in 2012, which raised the concern that white wheat heads were causedby the same phytoplasma. AY distort and discolour infected plants in a way that tends to make them more appealing toleafhoppers, which facilitates feeding and spread the disease. Documented symptoms in wheat include yellowing leaves,shriveled heads with distorted awns or production of floral parts that look like leaves, but not white heads. While somesamples collected in 2012 tested positive for AY, it is not conclusive that white heads are a symptom of infection, becausewheat is commonly infected with AY without any symptoms. As a precaution, samples can be submitted to researchers forAster Yellows diagnosis, but there is nothing that can be done to control the phytoplasma and leaf hopper control is noteconomical.

InsectsThere are insects that can cause white heads in wheat. Most commonly it is the wheat stem maggot (MeromyzaAmericana), which is the larva of a fly. Eggs are laid by the adult fly in the upper part of the plant and the larva burrows toconsume the interior parts of the stem. The upper part of the stem dies and the result is a bleached or white head.Although the white heads are obvious in a green field, the actual infestation of wheat stem maggot is usually only aboutone per cent. To determine if it is a maggot, pull the wheat head and stem from the sheath. If the stem pulls out easily, amaggot can often be found. If the stem does not detach easily it is usually indication of another problem.

Wheat stem sawflies do not generally cause white heads in wheat. The feeding of a sawfly larva can result in reducedseed set or shriveled seed but not mortality of a complete head.

Herbicide DamageIt is very unlikely that herbicide exposure would result in the production of white heads in cereal plants without othersymptoms of that herbicide also being apparent. Herbicides in Groups 1, 2, 5, 6, 7, 9, 10, 11, 14 and 27/28 have thepotential to produce bleaching symptoms. Exposure to these herbicides would have to occur very late in the developmentstages of the plants to produce white tissues in the head; in most cases well beyond their recommended applicationwindows.

Group 4 herbicides can also result in the formation of white heads, either directly as a result of applications outside of therecommended application window, or indirectly as an additional stress on a plant already predisposed to the formation ofwhite heads as a result of other stresses indicated in this article. The risk of Group 4 herbicides being an indirectcontributor to the formation of white heads increases greatly when applied outside of the recommended plant stage.

Environmental StressEffects of environmental stress related to white heads include destruction of chlorophyll, floret sterility (empty heads), andprematurity blight. High temperatures along with bright sunlight and hot winds may cause heat sterility or stress of entireplants or portions of the head, depending on how much of the head is exposed when it gets hot. Heat during filling canalso cause a number of issues with kernel conditions as well. On the other hand, low temperatures can also stress plantsand damage immature heads.

Stress in wheat: heads or parts of heads that were not affectedwere likely in the leaf sheath when the stress (likely hightemperatures) occurred (Courtesy of Richardson Pioneer)

In 2012, plants were often stressed due to excess moisture earlier in the season, which resulted in shallow rooting depthand plants that were particularly sensitive to heat stress later in development. In 2015, insufficient moisture is a moreprobable cause of plant stress. When plants run out of water, they will respond by making physiological sacrifices inattempt to set some seed. Depending on the stage, this may mean premature senescence of leaves, heads or the entireplant. High salinity can also play a role, particularly during drought stress.

Prematurity blight in wheat: likely caused by environmental stress(Courtesy of Saskatoon Co-op)

Hail damage can cause white heads, when death occurs above the point of injury. In this case wheat heads will beaccompanied by signs of physical damage (broken stems, missing glumes, etc), and injury to other plants (includingweeds) in the vicinity.

Unfortunately, no matter what the cause of white heads in wheat this season, nothing can be done at this stage to resolvethe issue. There may be more than one factor at play in a given field, and while the appearance may be alarming, thesymptoms will likely appear worse than the actual damage.

Home / About Agriculture / Information Services / Crop Production News / Crop Production News #4 - July 23, 2015 / White Heads in Wheat?

© 2016 Government of Saskatchewan. All rights reserved.