Canola Watch Report No. 10

Western Canada July 10, 2008

In This Issue

Crops range from poor to excellent
Root maggots continue to chew
Watch for cabbage seedpod weevils
Diamondback moths
Revised insect thresholds in light of higher crop prices
Lots of questions about potential sclerotinia infection
Continue regular scouting
Questions & Contacts

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 and click the Alberta Canola Watch button.

Crops range from poor to excellent

Warm temperatures have helped many crops catch up in growth relative to the season. Crop development ranges from the rosette-bolting stage for late seeded and reseeded crops to the 60-70% flower stage for some earlier seeded fields.

Many areas received welcome showers, ranging from trace to over 50 mm. However, parts of northern Saskatchewan between Prince Albert and Nipawin and western areas of the Peace region including Grande Prairie, Rycroft, Dawson Creek and Fort St. John are critically dry with crop yield potential dropping.

For current maps of moisture conditions from the Prairie Farm Rehabilitation Administration (PFRA), check the following links: 

Since Sept. 1, 2007 - http://www.industrymailout.com/Industry/Redirect.aspx?u=113406&q=79822767&lm=11426940&r=101789&qz=4ac4a625ff922d2a156718bfe17e2f0c

Since April 1, 2008 - http://www.industrymailout.com/Industry/Redirect.aspx?u=113407&q=79822767&lm=11426940&r=101789&qz=02b71696ebfb22ce3b8a2d5ac5ce8a84

The latest crop report from Manitoba Agriculture, Food and Rural Initiatives (MAFRI) is available at: http://www.industrymailout.com/Industry/Redirect.aspx?u=113408&q=79822767&lm=11426940&r=101789&qz=6b57238e68b61936530dc469fa39bd5c

The latest crop report from Saskatchewan Agriculture is available at:

http://www.industrymailout.com/Industry/Redirect.aspx?u=117984&q=79822767&lm=11426940&r=101789&qz=d99415165b2f62c983284d836306b930

 

Additional moisture information for Alberta is available from Alberta Environment at: http://www.industrymailout.com/Industry/Redirect.aspx?u=113410&q=79822767&lm=11426940&r=101789&qz=cfaac4905a830603542a8b20e9c7e1e0

http://www.industrymailout.com/Industry/Redirect.aspx?u=113411&q=79822767&lm=11426940&r=101789&qz=020f288a0c81b39b81b66758ea5677f5

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Root maggots continue to chew

Root maggots continue to be found in the Peace region near La Crete, many parts of central Alberta and in central and north-central Saskatchewan near Watrous, Lanigan, Humboldt, Blaine Lake and Shellbrook. Root maggots will tend to be more prolific in areas that were wet this spring and prefer plants that are larger stemmed, which may explain why many of the Saskatchewan cases have occurred on previously manured fields. Saskatchewan reports have been as high as 5-10 maggots per plant, with plants having difficulty flowering as a result. Yield losses from the maggots occur as a result of the impaired moisture and nutrient uptake resulting from root damage caused by the feeding, as well as secondary root rot infections that can more easily invade throughout the feeding channels. Some people are asking about the possibility of insecticide application. There are currently no registered insecticides for root maggot control. Growers should not be applying any unregistered products due to the possibility of unacceptable crop residues. Although there are no effective methods of in-crop control, there are some agronomic practices such as increased seeding rates that can be used to try to reduce damage in future years. For further information on root maggots, refer to the following link from the Canola Growers Manual and then scroll down and click the section on root maggots: http://www.industrymailout.com/Industry/Redirect.aspx?u=114556&q=79822767&lm=11426940&r=101789&qz=8e5d6bbec4db0986565ecbe6d5be6a94 or to the following links from AARD and MAFRI: http://www.industrymailout.com/Industry/Redirect.aspx?u=117985&q=79822767&lm=11426940&r=101789&qz=3e310341b38697994e51d89bec962e19

http://www.industrymailout.com/Industry/Redirect.aspx?u=117986&q=79822767&lm=11426940&r=101789&qz=063260cc37f3be3f1f3f9596b577bedd

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Watch for cabbage seedpod weevils

Extensive spraying for cabbage seedpod weevils continues in southwestern Saskatchewan and throughout southern Alberta south of Hwy 1. Earlier sweep counts in many fields reported up to 4-10 weevils per sweep, but numbers have decreased to 1-3 per sweep in later seeded fields. Due to the higher price for canola, the threshold for spraying has been reduced from 3-4 per sweep to 2 per sweep.

For more information on the cabbage seedpod weevil, refer to the following links:

http://www.industrymailout.com/Industry/Redirect.aspx?u=114560&q=79822767&lm=11426940&r=101789&qz=317110cfc8ed60494d5b1e1b3c23eea6

http://www.industrymailout.com/Industry/Redirect.aspx?u=117987&q=79822767&lm=11426940&r=101789&qz=79b4f746ac95336ed676dd3a590b3e53

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Diamondback moths

Damage from diamondback moth larvae ("window-paneing") has been noted in parts of Manitoba, despite extremely low numbers in local diamondback moth traps. In many cases this first generation is now pupating in the silken cocoons formed on the plants, so it will be the next generation that growers will need to watch for as we reach the early podding stage. Growers should be on the lookout for diamondback as the diamondback traps are not foolproof as an early warning tool. For more information on diamondback moths refer to the following link: http://www.industrymailout.com/Industry/Redirect.aspx?u=114557&q=79822767&lm=11426940&r=101789&qz=2aed109080bd3808ac036926f11bab2f

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Revised insect thresholds in light of higher crop prices

Due to higher commodity prices, a committee of provincial entomologists has put together some revised thresholds for several insects. A link outlining those revisions is available at: http://www.industrymailout.com/Industry/Redirect.aspx?u=117988&q=79822767&lm=11426940&r=101789&qz=3a17cde200b3b84aae1bb1349eaec7ad

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Lots of questions about potential sclerotinia infection

Producers should carefully consider all of the factors highlighted in the sclerotinia stem rot checklist before making the decision to apply a fungicide. 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 http://www.industrymailout.com/Industry/Redirect.aspx?u=114561&q=79822767&lm=11426940&r=101789&qz=31712a700122e1e26ce16e70e3a64b26 or contact your local Canola Council agronomist.

If a producer’s risk assessment based on checklist results and/or petal testing suggests that spraying may be borderline, 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 who 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. Decaying petals provide the initial food source for spores, and carry those spores down into the crop canopy. 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 the first secondary branch below the main stem but little or no pod formation. Some early seeded fields are past the 50% bloom stage and into pod formation, and are now too advanced for effective fungicide application.  For more information on bloom stage identification, click the following link from Bayer, choose canola and then click "Why Proline?" Follow the prompts for tips and pictures on identifying bloom stage: http://www.industrymailout.com/Industry/Redirect.aspx?u=117989&q=79822767&lm=11426940&r=101789&qz=c7621e0c9c23bcf364c9ea072995c05a

If you choose to apply a fungicide for sclerotinia protection, follow these steps to maximize the efficacy of the product applied:

  • Use higher water volumes and appropriate nozzles to ensure good spray coverage. This is especially important in crops with very dense canopies.
  • Don’t overestimate bloom stage in stands with uneven maturity, as a significant number of plants hidden in the canopy may not have completed bolting. If more mature plants are starting to drop petals, take into consideration the weather conditions. If conditions have been drier and less conducive to infection, it may be all right to delay a single fungicide application to target an average of 30% bloom. However, if conditions have been wet and odds of significant infection are high, it will be those early infections from the initial petal drop that are likely to do the most damage. Spraying a little early is probably wise.
  • Consider split applications, especially in fields with uneven maturity, which will lengthen out the bloom period substantially. For most products registered for split application it is recommended to make the initial application at about 20% bloom, followed by the second application at around 50% bloom if conditions are still conducive to sclerotinia infection.

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Continue regular scouting

Scout fields on a regular basis to detect crop development problems early. Consider establishing a 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.

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Questions & Contacts

Direct questions regarding this report to John Mayko, Senior Agronomy Specialist with the Canola Council of Canada at maykoj@canolacouncil.org ph/fax: 780-764-2593.

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

Derwyn Hammond, Agronomy Specialist, Manitoba, hammondd@canolacouncil.org,
204-729-9011
Ingrid Kristjanson, Manitoba Agriculture, Food and Rural Initiatives, Ingrid.Kristjanson@gov.mb.ca,
204-746-7504
David Vanthuyne, Agronomy Specialist, Eastern Saskatchewan, vanthuyned@canolacouncil.org,  
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