July 29, 2015 – Issue 19

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  • July 29 Quiz — PHI

    Swathing

    Four questions to test your knowledge on pre-harvest intervals.

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  • Uneven crops and swath timing

    The swath timing decision becomes more difficult in crops with plants at multiple stages of growth. Here are some tips to help with the swath decision on these fields….

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  • Insect update: Check to be sure

    Grasshoppers stripped this canola bare in a field near Medstead, SK. But while this looks dramatic, just a few plants were damaged and spraying was not required. Photo credit: Amanda Wuchner

    Diamondback moth larvae and grasshoppers have been reported, but so far nothing of widespread significance. The photo shows what grasshoppers can do to a canola plant, but their damage is usually isolated to small patches. Bertha armyworm adult traps are coming down with very little in the way of hotspots.

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  • Long flowering and sclerotinia risk

    Fungicide applied late in the window can provide valuable protection from sclerotinia stem rot if flowering is extended or if conditions become more conducive to disease.

    Improved moisture in some regions has extended flowering. Some fields have been at “full flower” for what seems like weeks. Highly variable crops may also be at full flower or their “most yellow” — other terms for 50% flower — for longer than typically expected. This does extend the sclerotinia stem rot risk. But that “risk” may still not be high enough to warrant a fungicide spray — given the risk was so low before and that late applications tend to have a reduced benefit for yield.

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  • Crop protection products and international markets: What you need to know

    When it comes to maintaining Canada’s reputation as a high quality canola supplier, everyone in the canola value chain has an important role to play.

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  • Lygus thresholds — Economics

    lygus dan.johnson small

    Threshold tables for lygus suggest, for example, that if canola is $12 per bushel and spray costs $8 per acre, the threshold at the early pod stage is 5 lygus adults or late instar nymphs per 10 sweeps.

    Current thinking is that 5 lygus per 10 sweeps (0.5 per sweep) is too few to warrant a spray, and that the economic threshold is likely quite a bit higher.

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  • Swede midge: What to look for

    Swede midge larvae feeding at the bud can stop stem elongation and leave pods in a cluster. Source: Owen Olfert

    Swede midge females lay their eggs in canola apical meristems (growing points). Larvae hatching from those eggs feed within the meristems. Plant damage depends on the canola growth stage at which feeding occurs. The younger the canola plant, the greater the damage.
    Damage typically includes one or more of the following….

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  • Swede midge scouting and management

    Swede midge larvae inside floret. Source: Julie Soroka, AAFC

    Swede midge caused some yield loss in northeast Saskatchewan in 2013, and caused heavy yield losses in the major Ontario canola growing region. Swede midge’s flexible biology could make it well adapted to the Prairies, like wheat midge is today.

    Insecticides are registered for swede midge, but there are no viable recommendations for control at this point. There are no established economic thresholds or proven best timing for foliar sprays. The good news is that while their range seems to be expanding on the Prairies, swede midge numbers remain fairly low so far.

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  • Pre-harvest products for use in canola

    Glyphosate is registered for pre-harvest perennial weed control in canola. Glyphosate is to be applied when the majority of seeds are yellow to brown in colour and seed moisture is less than 30%. Heat fits between glyphosate and Reglone on the speed of dry down spectrum. Reglone is a contact herbicide (only kills what it contacts) and is registered in canola to dry immature green material to facilitate harvest. Reglone shuts the plant down quickly and basically STOPS it from maturing, which can lock in high green seed levels if applied prematurely.

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