Insects

  • Grasshoppers: Thresholds and 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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  • 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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  • Thresholds for major canola insects

    Insects

    This article provides a review of thresholds for major insect pests of canola, as well as background on how they were established and how following thresholds can improve profitability.

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  • Red insects: Turnip beetle and some Lygaeidae

    Insects

    Red turnip beetles are eating large patches in a few fields in central Alberta. Red turnip beetles eat plants from the brassica family only, and they are sometimes — though rarely — an economic pest in canola.

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  • Cabbage seedpod weevil: Scouting and spray timing

    Insects

    Cabbage seedpod weevils move to canola fields at the bud to early-flower stages. While they will feed on buds and destroy some of them, spraying is rarely recommended before 10% bloom.

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  • Canola Watch quiz: Worms

    Insects

    Can you go 4 for 4 on this worm-themed quiz?

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  • Insects: Diamondback moth, cutworms, flea beetle and more

    Insects

    Some fields are thinned by cutworm, diamondback moth larvae are at work but control is not usually required at this crop stage and swede midge are early in Ontario.

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  • Flea beetles and stressed crop

    Insects

    With hot, dry conditions, canola seedlings already under pressure from intense flea beetle feeding dried out and died.

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  • Cutworm scouting and spray decision factors

    Insects

    Why scout? Reason one: To confirm that cutworms are the cause. For example, fungal seedling diseases can cause seed and seedling decay that can lead to patches of missing plants Reason two: To identify the cutworm species present as this can influence management decisions. Underground-feeding cutworms are less likely to encounter spray, for one thing. And thresholds vary by species.

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  • Flea beetles: Temperature influences activity

    Insects

    Cool, windy, wet weather can delay flea beetle emergence. Peak emergence of the crucifer flea beetle occurs when ground temperatures reach 15°C, which is why perhaps it seems numbers are lower in many areas so far this year. They just haven’t come out yet in large numbers.

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