Canola Watch

2006 Canola Watch Reports

Canola Watch Report No. 11 Western Canada – July 5, 2006

In this issue:
(click the bookmarked links below to move to specific sections of this report)

The Alberta Canola Producers Commission (ACPC) has developed an Alberta focused version of this report. Visit the ACPC website at: http://www.canola.ab.ca

Crop development continues to advance rapidly due to above normal temperatures across most regions. Development ranges from the late rosette-cabbage stage for late seeded fields up to 50-60% bloom for early seeded fields, and is largely a function of seeding date in most areas. Soil moisture in most areas continues to decline with the hot temperatures and lack of general rain. Only spotty thundershowers were received in most areas this past week. Areas of east-central and northern Saskatchewan remain well supplied with moisture, but conditions in central and eastern Manitoba are becoming quite dry, and much of the southern Peace and BC Peace regions are in need of moisture soon to avoid serious yield declines.

For current maps of moisture conditions from PFRA for western Canada, check the following links for precipitation from September 1 to July 2 and April 1 to July 2 respectively:
http://www.agr.gc.ca/pfra/drought/prpay06_e.htm
http://www.agr.gc.ca/pfra/drought/prpgs06_e.htm
http://www.agr.gc.ca/pfra/drought/pa_e.htm

The latest crop report from Manitoba Agriculture, Food and Rural Initiatives is available at:
http://web2.gov.mb.ca/agriculture/mwcr/

The latest crop report from Saskatchewan Agriculture, Food & Rural Revitalization is available at:
http://www.agr.gov.sk.ca/docs/reports/crop_report/crprpt060704.pdf

Additional moisture information for Alberta is available from Alberta Environment at:
http://www3.gov.ab.ca/env/water/WS/data/precipmaps/weekly.pdf

Fields in areas of northern and east-central Saskatchewan continue to exhibit stress from previous excess moisture. Excess moisture results in a lack of oxygen in the root zone that causes changes in plant colour such as yellowing or purpling, stunted growth, or premature bolting (small and spindly canola plants that are starting to bolt). The degree of damage will depend on several factors including crop stage, soil type and texture and time spent under water. For further information regarding the effects of excess moisture on canola growth, refer to the following link: http://www.canola-council.org/excessmoisture.aspx.

Areas with excess moisture may have also experienced substantial nitrogen losses in low-lying areas. Depending on conditions, growers may need to consider top dressing additional nitrogen to compensate. As well, growers who were conservative with their initial fertilizer applications for this crop and now find favorable to excellent growing conditions may also consider topping up their nitrogen and sulphur rates by top dressing. Refer to last week's Canola Watch report for more information on top dressing fertilizer: http://www.canola-council.org/seed/canola-watch/watch06-jun28.html

There are many reports of heat stress (plants wilting and sometimes taking on a bluish grey hue) and blossom blasting (flower or pod abortion) across western Canada. The most likely cause in these areas is probably drought and/or heat stress. While blossom blasting is normally associated with hot and dry weather, other stresses can also contribute to an increase in the number of aborted pods. For example, in soils at or near saturation warm weather will increase the plants' requirement for oxygen, causing increased stress and more pronounced symptoms. Other contributing factors could include heavy rain, hail or wind storms which cause flowers to drop prematurely. Insect feeding on buds, flowers and young pods can also cause blasting (buds turn white and fail to develop), flowers to fall without forming pods, or pods to drop without maturing. It is important to note that canola does have the potential to compensate right up to the end of flowering by increasing the number of branches, flowers and pods produced, provided conditions allow it to. For more information on heat stress check the following link: http://www.canola-council.org/temp_frost_hail.aspx

For a detailed discussion of how canola flowers, and its ability to compensate following a period of stress, check the following link: http://www.canola-council.org/gs_stage6.aspx

Although most of the heat stress symptoms described above are likely due to the warm temperatures, it is important to scout the affected areas to see if there may be some other underlying contributing factors such as root damage from root maggots or clubroot. As well, any late seeded fields that might still be candidates for a late herbicide application should be evaluated. Herbicide application at a time of stress may cause additional stress on the plant, resulting in a delay in development. Ensure that weed populations are large enough to warrant any late herbicide applications.

Hail continues to be reported along with isolated scattered thundershowers. Potential canola yield losses will depend on stage of crop and the severity of the damage. Hail damage can also allow points of entry for diseases such as sclerotinia stem rot, alternaria black spot and blackleg to infect canola plants. Further information is available at the following link: http://www.canola-council.org/stress_hail.aspx.

Remember to keep scouting fields on a regular basis to detect problems early. Consider establishing a scouting tramline by driving an ATV in an 'X' or 'W' pattern in the field to establish pathways for crop scouting. This will allow for easier scouting once the crop is blooming.

Although the recent heat and drier weather have reduced the sclerotinia risk in many areas, growers need to evaluate each field for its relative risk. Temperatures above 25 degrees Celsius impair disease development. Producers should carefully consider all of the factors highlighted in the sclerotinia stem rot checklist before making this decision. These factors include how heavy their crop canopy currently is, the amount of moisture received in the two weeks prior to flowering and potential for future rainfall, years since last host crop, disease incidence in the past, and the presence of apothecia in neighboring fields where host crops were grown previously. Target yield, fertility program and expected value of the canola crop are also points to consider. Ensure that apothecia (mushrooms) that are found are properly identified as there can be other mushroom fungi present that do not contribute to sclerotinia risk.

A new publication called the Canola Disease Identification and Sclerotinia Risk Assessment Card is available to assist growers and crop scouts with these decisions. It includes the stem rot checklist as well as pictures to aid in accurately identifying the apothecia of the sclerotinia fungus. A PDF version can be found at http://www.canola-council.org/PDF/canola_plant_disease_risk.pdf#page=1 or contact your local Canola Council agronomist. Also, for more information and tips on late season scouting for both diseases and insects, view the latest Canola Advantage press release at http://www.canola-council.org/about-us/media-news/media-releases/media-jun1906.html. If a producer's risk assessment based on checklist results and/or petal testing suggests that spraying may be warranted but they are still unsure, splitting fungicide applications may be an option. Refer to last week's report for further discussion on split fungicide applications.

Root maggots continue to be reported in areas of north-central Alberta and northern Saskatchewan near Birch Hills. Any areas experiencing poor crop growth or poor rooting should be inspected for possible root maggot damage. Refer to the following link for more information on root maggot: http://www.canola-council.org/maggot.aspx

Bertha armyworm moth numbers continue to increase in traps placed in canola fields throughout western Canada. Cumulative counts for last week exceeded 1000 in areas of northwest Manitoba and 250 in areas of southwestern Manitoba. Increased numbers were also noted in north-central Saskatchewan near Shellbrook. Growers in these areas should be especially vigilant as the moth trapping continues. All growers should be aware of increasing moth numbers and watch for further information.

For more information on the bertha armyworm, refer to the following link:
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm2521
For interpreting bertha armyworm trap numbers, refer to the following link:
http://www.gov.mb.ca/agriculture/news/insect/bertha/interpret.html

Proper identification of bertha armyworm larvae is important as they can be confused with other larvae. As significant numbers of adult bertha moths have just started to appear over the last two weeks, it is unlikely that any large larvae found at this time will be bertha armyworm larvae. Mating begins within a week of moth emergence, and egg laying takes place on the underside of leaves shortly thereafter. Some eggs have been found in Alberta near Vermilion. With average temperatures, eggs will hatch within a week, but will likely take several weeks to reach the last two velvety black instars that cause most of the damage and are easiest to recognize. Typically the time from egg hatch to pupation is six weeks. For more information regarding bertha armyworm identification, please refer to the Canola Scouting and Sweep Net Insect ID Card and the following links:
http://www.canola-council.org/bertha.aspx
http://www.canola-council.org/PDF/sweepcard_pgs_04.pdf#page=1

Clover cutworms continue to be reported in the north Peace near Fort Vermilion and Lacrete. The larvae are very similar in size and color to the bertha armyworm larvae. The most distinctive way to tell them apart is that the wide stripe along each side of the clover cutworm is yellowish pink, while it is yellowish orange on bertha armyworm. Clover cutworms feed anywhere on the canola plant and can consume entire plants if populations are heavy. First generation larvae attack canola earlier than pests like bertha armyworm, but with light infestations the plants will generally recover. More research is needed to determine a definite economic threshold for clover cutworm, but many studies have shown that it may be similar to the economic threshold for bertha armyworm. However, clover cutworm infestations are often less uniformly distributed in a field than bertha armyworm. Therefore, while some areas of a field suffer heavy damage, others may be unaffected. For more information refer to the following link:
http://www.canola-council.org/clovercutwormid.aspx

Grasshoppers continue to hatch in areas of the Peace including Dawson Creek, Beaverlodge and Grande Prairie. Since there are many species of grasshoppers in western Canada, growers need to be sure that the grasshoppers found during scouting are indeed pest species. Refer to the following AAFRD and SAFRR links for further information on identification and management of pest grasshoppers:
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/for8648
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex6463
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3497
http://www.agr.gov.sk.ca/DOCS/crops/integrated_pest_management/insects/grasshopperff.asp?firstPick=Crops&secondpick=Integrated%20Pest%20Management&thirdpick=Insects

Cabbage seedpod weevil adults continue to be reported throughout southern Alberta and southwest Saskatchewan. However, numbers appear to be dispersed as more fields come into flower, attracting the adults. The economic threshold for the weevil is 3 to 4 per sweep, or 30 to 40 in 10 sweeps. Research conducted by Dr. Lloyd Dosdall and Doug Moisey has shown that weevil migration into canola doesn't peak until early to mid flowering, as the weevil is attracted to the yellow color of the canola flower. It is important not to spray too soon, as the weevil will continue to invade for at least a week to 10 days beyond first flower. The optimum time to spray is at early flowering, or more specifically 10% bloom, if possible. Spraying at 10% bloom will allow the weevils more time to move into the field, while preventing significant egg laying in newly forming pods.

For more information on identification and control of cabbage seedpod weevil refer to the following AAFRD link: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex2538

Check the following link for the 2006 cabbage seedpod weevil forecast map: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm10585

Some spraying for lygus bugs continued in the northern and central areas of the Peace region. In particular, there may be an opportunity for some migration of lygus bugs into canola from alfalfa crops now being cut for hay. However, the threshold for lygus bugs can vary greatly, depending on the crop stage and commodity prices. For more information on lygus bugs check the following links: http://www.canola-council.org/lygusmonitoring.aspx Ensure that appropriate thresholds are reached before considering insecticide application.

Direct questions regarding this report to John Mayko, Agronomic Research & Extension Manager with the Canola Council of Canada at maykoj@canola-council.org ph/fax: 780-764-2593.

Direct specific questions regarding regional issues to one of the following Canola Council of Canada agronomists or provincial oilseed specialists:

Derwyn Hammond, Agronomist, Manitoba,
hammondd@canola-council.org, 204-729-9011

David Vanthuyne, Agronomist, Eastern Saskatchewan,
vanthuyd@canola-council.org, 306-782-7799

David Blais, Agronomist, Western Saskatchewan,
blaisd@canola-council.org, 306-895-2122

Jim Bessel, Senior Agronomist, Northeastern Saskatchewan,
besselj@canola-council.org, 306-373-6771

Penny Pearse/Scott Hartley, Saskatchewan Agriculture, Food & Rural Revitalization,
ppearse@agr.gov.sk.ca / shartley@agr.gov.sk.ca , 306-787-4671 / 306-787-4669

Doug Moisey, Agronomist, Central Alberta,
moiseyd@canola-council.org, 780-645-3624

Jackie Heck, Agronomist, Peace River Region,
heckj@canola-council.org, 780-853-5261

Matthew Stanford, Agronomist, Southern Alberta,
stanfordm@canola-council.org, 403-758-6660

Murray Hartman, Alberta Agriculture, Food & Rural Development,
murray.hartman@gov.ab.ca, 403-782-8024

Kerry Clark, BC Ministry of Agriculture, Food & Fisheries,
Kerry.Clark@gov.bc.ca,  250-787-3213

The Canola Watch Report provides just-in-time information on canola production to growers and industry. Contributors to the Canola Agronomy Network are:

Manitoba Agriculture & Food; Manitoba Canola Growers Association; Agricore United; Saskatchewan Wheat Pool; United Farmers of Alberta; Saskatchewan Agriculture, Food & Rural Revitalization; Saskatchewan Canola Growers Association; Saskatchewan Canola Development Commission; Alberta Agriculture, Food & Rural Development; Alberta Canola Producers Commission; BC Ministry of Agriculture; Food & Fisheries; and the Canola Council of Canada.

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