Insects

  • Bertha armyworm: Hot pockets, scouting, rain

    Insects

    A heavily-infested field in western Manitoba (south of Riding Mountain National Park) generated a lot of interest on Twitter in the past week. It prompted a lot of scouting, which is good. But what this one field and the ensuing scouting demonstrated is that bertha armyworm population spikes can be highly localized.

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  • Canola Watch quiz: Diamondback moth

    Insects

    Test your diamondback management skills with these four questions…

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  • Diamondback moth larvae: Common questions

    Insects

    Diamondback moth larvae have been found in canola fields across the Prairies this year. Of those fields with the larvae, counts in many (perhaps most) are below and often well below thresholds. Some fields are at thresholds. Some fields seem to be well above thresholds. The key is to the check each field. Diamondback larvae can vary in number from field to field and even within areas of a field. (Photo credit: John Gavloski)

    Here are answers to common questions….

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  • Be on alert for bertha armyworms

    Insects

    Bertha armyworm adult moth counts were generally low across the Prairies in 2017. A few trap sites did enter the moderate risk level, but none was high. See provincial counts in the Prairie Pest Monitoring Network blog. However, as experienced with diamondback moth trap counts this year, egg survival could be higher in dry conditions and warm weather will promote rapid growth.

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  • Lygus thresholds: Dry vs Good conditions

    Insects

    Lygus. Credit: Dan Johnson

    In dry conditions, existing lygus threshold tables are still appropriate when making spray decisions. These tables indicate that if canola at the pod ripening stage is $12 per bushel and spray costs $12 per acre, the threshold is 11 lygus adults or late instar nymphs per 10 sweeps (~1 per sweep).

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  • Butterflies in canola

    Insects

    Butterflies have siphoning mouth parts, much like a straw. They are harmless to crops and may actually provide some pollination benefit. Butterfly larvae from these three species will feed on crops, but are not major pests of canola and rarely cause enough damage to warrant a spray.

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  • Keep watch for diamondback moth larvae

    Insects

    Diamondback moth larvae have been found in many fields this year. In most cases counts have been well below economic thresholds, but keep looking just in case. Some fields are at thresholds and a few have been sprayed.

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  • Grasshoppers thrive in hot, dry conditions

    Insects

    Grasshoppers can thrive in hot weather. The nominal threshold for grasshoppers in canola is 8-12 per square meter, although the higher end of that range may be more appropriate in a typical canola crop.

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  • Lygus bugs: Thresholds and scouting tips

    Insects

    Lygus. Credit: Dan Johnson

    In very dry conditions: 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 (0.5 per sweep).
    In moist and high-yield conditions: The economic threshold is quite a bit higher. At early pod stage, 50 lygus per 10 sweeps (5 per sweep) could cause a 2 bu./ac. reduction in yield.

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  • Insect update: What to look for right now?

    Insects

    While some areas are reporting higher numbers of diamondback moth larvae (shown above), it takes 100-150 larvae per square metre in immature to flowering plants or 200 to 300 larvae per square metre in plants with flowers and pods to cause enough damage to warrant a spray. Natural controls, including beneficial insects, tend to keep numbers below thresholds.

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