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Story Posted: July 21, 2010 Canola Watch 13: Diamondback spraying begins In This Issue: Diamondback moth larvae have arrived, Watch for blackleg, Impact of hail, Sclerotinia, Weedy fields, Scouting fields, Questions and contacts. Issues of the week Crop and weather update Alberta: Canola south of Lethbridge is stressed due to excess water, but canola looks good north of Vulcan and through the central region. Some areas northwest of Edmonton could use rain. A strip from Red Deer to north of Ponoka got up to 5" last week. Hail and high winds in the northeast damaged some fields. Staging ranges from 10% bloom to 90% bloom on some early seeded fields. Troy Prosofsky, CCC agronomy specialist for southern Alberta, notes that cabbage seedpod weevil numbers have dropped in that region in the past week. Read the Alberta crop report. Saskatchewan: Spotty showers across the province dropped next to nothing in some spots and up to 2" in others. Some fields are at the end of flowering, especially in the west. Most in the east are 50% to 70% flowering. Latest crops, which are not yet flowering, don't seem to be catching up. Read the Saskatchewan crop report. Manitoba: Heavy thunderstorms rolled through Tuesday night and earlier in the week, but it was generally dry the past seven days. Hail damage was reported in the central and Interlake regions. Earliest crops in the south are starting to show seed colour change. Many crops across the province are done flowering. Crops have been improving in many areas over the last week or so. Read the Manitoba crop report. Quick Hitters We've heard talk of spraying fungicide on hailed fields to keep blackleg from entering the plant through broken tissue. If growers are contemplating a fungicide application, they should also consider yield potential of the remaining crop and the risk of fall frost due to the delayed maturity, which could negate the benefits of the application. Products registered for blackleg suppression are normally applied prior to bolting, so check the product's pre-harvest interval if crops are at later growth stages. Impact of hail. Hail at flowering may not cause much yield loss but will delay maturity, increasing fall frost risk. When buds and flowers are lost due to injury, the plant recovers rapidly by developing additional flowers that normally would have been aborted. The plant also develops flowering branches from growth buds lower down on the plant, replacing to a degree, the lost buds, flowers and pods. Hail at podding means permanent loss. If hail strikes during pod filling or ripening, plant recovery is not possible. Sclerotinia. It has been a busy year for sclerotinia spraying. In fields at 20% to 30% flower with good yield potential and moist conditions, a spray to prevent sclerotinia stem rot may still be worthwhile. If fields are too wet for a ground sprayer, aerial application is an option. Weedy fields. Producers planning a pre-harvest application to control larger weeds and make harvest easier need to avoid off label applications. Higher rates could increase the risk of residues from the pesticides, which can become an export issue with canola customers. Scouting fields. When scouting at flowering, look for evidence of diamondback moth (read the article below) and if you see wilting plants, pull them and look for root maggots, root rot, blackleg and clubroot. For more tips on scouting at flowering, click here to hear Murray Hartman, Alberta provincial oilseeds specialist, on ACPC radio. Diamondback moth larvae have arrived You may find diamondback larvae when taking sweeps for lygus or cabbage seedpod weevil. If you find them in sweep nets, then it's worth doing a proper scout.
There is no established economic threshold for diamondback control at the flowering stages, but the threshold may be slightly lower at early flowering. Consider application at 10 to 15 larvae per 1/10 of a square metre at that stage. Click here for a PDF on diamondback ID, scouting tips and thresholds. Click here to read a summary of the recent AAFC survey of insects in the Peace region.
Questions and contacts If you have questions on regional issues, contact one of the following Canola Council of Canada regional agronomists or provincial oilseed specialists:
This report is supported by each of the provincial canola grower associations. For more information on some of their activities, check out the following links:
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