Canola Watch Reports

2007 Canola Watch Reports

#9 Western Canada – June 27, 2007

In this issue:
(click the bookmark 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: www.canola.ab.ca.

Crop development continues to vary widely based largely on when the crop was seeded. Earlier seeded crops in Manitoba, Saskatchewan and southern Alberta are well into bloom, whereas crops in other areas seeded in early June are at the seedling stage. Many areas of patchy emergence previously reported throughout north-central Alberta from Barrhead to Vegreville have been alleviated from recent rains, but the crop development within individual fields varies greatly, which will challenge crop management timing decisions for the remainder of the season. Although temperatures have been seasonal to warm in many southern areas, warmer temperatures are needed in more northern areas to enhance crop development, especially in areas affected by wet conditions.

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

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

Variable precipitation from trace amounts to over 125 mm was received across many parts of the west. For current maps of moisture conditions from PFRA for western Canada, check the following links for precipitation since September 1 and April 1 respectively:
www.agr.gc.ca/pfra/drought
www.agr.gc.ca/pfra/drought
Additional moisture information for Alberta is available from Alberta Environment at: www3.gov.ab.ca/env/water/WS/data

Excess moisture continues as the largest crop development issue across western Canada. Most of Manitoba, southeastern, north-central and northeastern Saskatchewan, central Alberta between Didsbury and Ponoka and the central Peace near Rycroft, Eaglesham and Fairview continue to suffer crop damage from wet conditions. Some areas report up to 20% of the seeded area lost from excess water damage. For more information on the effects of excess moisture, refer to last week's report at: www.canola-council.org/canola_watch_report_2007_08.html .

Hail continues to be reported across many areas, usually in conjunction with relatively localized thunderstorms. Manitoba was hit especially hard this past week with hail associated with tornados and intense thunderstorms. Hail damage at this stage of the crop usually results in a delay in development, as the plant channels its resources into rebuilding the damaged parts before advancing growth. If possible, herbicide applications should be avoided until signs of recovery are evident to help ensure good crop tolerance and adequate uptake by the weeds present. For more information on managing hail damaged canola, refer to the following Canola Watch press release: www.canola-council.org/media_jun2607.html.

Earlier seeded crops in most areas have completed herbicide application, but in many later seeded fields, growers are considering their second application of either glyphosate or Liberty. Prior to automatically applying the second herbicide pass, first consider whether or not the second pass is warranted given the remaining weed pressure. Also, if the canola canopy is starting to reach complete ground cover, the herbicide may not reach targeted weeds. Growers are cautioned when applying late first applications or the second applications of herbicides when the crop is in the bud stage, as late spraying could potentially lead to crop stress and blanks on the main stem. Refer to the following Canol@Fact ( www.canola-council.org/PDF/Jun13_Canola_Fact_Sheet.pdf) for more information on weed control timing including second applications and to the following Canol@Fact at www.canola-council.org/PDF/May24_How_Many_Weeds.pdf for more information regarding weed populations and economic thresholds.

Top dressing of nitrogen and/or sulphur continues to be considered by many growers especially in northern and eastern Saskatchewan. This practice should be considered by growers who were conservative with their initial fertilizer applications for this crop, unable to apply sufficient fertilizer at the time of seeding, or in areas with excess moisture that may have experienced substantial nitrogen losses from saturated soils. If the excess water recedes fairly quickly and the canola recovers, growers may need to consider top dressing additional nitrogen to compensate. Growers concerned about the nutrient status of their crop should consider tissue testing, but for recently flooded canola it is important to remember to allow for the plant to recover and growth to stabilize before tissue testing takes place. Some growers have tissue tested and their test reports indicate deficiency in sulphur. However, prior to applying fertilizer to recently flooded crops ensure that adequate plant recovery is underway or is likely, given the soil conditions and upcoming weather. Some of these nutrient deficiencies may be caused by leaching or denitrification, but in other cases, the plant roots are shut down because of the lack of oxygen and therefore the plant will be incapable of accessing applied nutrients from the soil unless conditions improve.

Cabbage seedpod weevil populations continue to increase in southwestern Saskatchewan and throughout southern Alberta between Medicine Hat and Lethbridge. Sweep counts in some early seeded canola report up to 15-20 weevils per sweep and spraying is becoming general. Fields starting to flower are at most risk at this time of year and should be scouted frequently. For more tips on scouting and controlling cabbage seedpod weevil, refer to the following links:
www1.agric.gov.ab.ca/
www.directfocus.com/canolamanual

Diamondback moth larvae are being found in fields across eastern Manitoba, southern and eastern Saskatchewan, and southeastern Alberta. Feeding damage has been noted to be heavy in some fields, with some spraying occurring.

Spraying at early crop stages is unlikely to be warranted unless the larval populations and feeding damage are noticeably heavy and the crop is under stress and is having difficulty outgrowing the damage. In early crop stages, a proposed action threshold of 25-33% defoliation with continued larval feeding has been proposed by John Gavloski from MAFRI. However, in later vegetative stages prior to budding, it is likely that the action threshold can be higher, due to the fact that the crop vegetative growth is rapid at this stage, and in most cases, the crop will likely outgrow any appreciable damage. However, if larval feeding continues into the bud stage, with damage to early buds, then spraying is more likely warranted. If there are about 100 to 150 larvae per square metre feeding on buds, an insecticide application may be needed to minimize yield loss.

The following photo shows an example of bud damage from diamondback larval feeding (from Ward Toma, ACPC):
Diamondback moth larvae

If diamondback larvae are beginning to pupate, control measures may be ineffective. Once pupation is complete, these newly emerged moths will lay the eggs of the next generation. If there are larvae in cocoons on the underside of leaves, producers may want to postpone control measures until the new generation has emerged.

Growers should use caution before spraying for diamondbacks at this early stage because spraying is likely to destroy beneficial parasitoids, which help in reducing damage from subsequent generations. For a picture of a parasitoid wasp of diamondback, refer to the following link: www.canola-council.org/parasiticwaspsid.aspx

For more information on diamondback moth, refer to the following SAFRR link: www.agr.gov.sk.ca/docs/production/Diamond.asp

Grasshoppers have been reported in central and northern parts of the Peace region. Although most damage from grasshoppers usually occurs on cereals and forage grasses, damage to canola can occur if other food sources are not present. Scout carefully to determine whether the species noted are actually pest species and whether damage is occurring to canola. For more information regarding identification of grasshoppers, refer to the following web link from Dr. Dan Johnson at the University of Lethbridge: people.uleth.ca/~dan.johnson

Many early seeded fields in many regions are now well into bloom, with fungicide applications being considered . This is the time to scout individual fields to assess the risk for sclerotinia development and potential yield loss. The high levels of soil moisture in many areas combined with warm temperatures and crops at full ground cover, creates conditions that are conducive to sclerotinia 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.

A publication called the Canola Disease Identification and Sclerotinia Risk Assessment Card is available to assist growers and crop scouts with this decision. 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 www.canola-council.org/PDF/canola_plant_disease_risk.pdf or contact your local Canola Council Agronomy Specialist.

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. An initial reduced fungicide application at 20 to 30% bloom will help control early onset of the disease. If conditions become drier, a second application may not be needed. However, if this approach is taken and conditions remain wet and humid, a second application will be needed to maximize the benefits of spraying the fungicide. Producers should assess these factors and consult their local agronomist or chemical representative to determine if a single or a split fungicide application is best for their particular situation.

For growers that have decided to apply a fungicide to control sclerotinia, determining the bloom stage of the crop is important. The optimum stage for a single fungicide application is when the maximum number of flowers is open but little if any petal drop has taken place, usually at or slightly above 30% bloom. Typically at this stage in B. napus canola there is an average of about 20 flowers open on the main stem, with some flowers open on secondary branches but little or no pod formation. For more information on bloom stage identification check the following link: www.canola-council.org/sclerotiniachemical.aspx .

Producers and dealers who are interested in using the Canola Petal Test kits to assist in gauging the level of sclerotinia in individual fields should order their kits from the distributor, Discovery Seed Labs, (450 Melville Street in Saskatoon ph.306-249-4484) ( www.seedtesting.com/contact.html), as soon as possible so that their kits can be sent out and ready when required.

Remember to keep scouting fields on a regular basis to detect crop development 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 with minimal trampling at later crop stages, especially once the crop is blooming.

Direct questions regarding this report to John Mayko, Senior Agronomy Specialist, Parkland West (West Central AB), 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:

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.