Insects

  • Late-season insects and pre-harvest intervals

    Insects

    We had reports this week of bertha armyworm at higher numbers (maybe not at thresholds) in some very localized areas, lygus (it’s getting late), flea beetles (don’t spray them, it won’t help for next spring) and aphids (probably don’t spray them either). While doing a pre-harvest scouting for disease, take a look at the insect […]

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  • Canola Watch quiz – Worm ID

    Insects

    How are your worm ID skills? Take the quiz and try to identify the four worms – two familiar, two not so much.

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  • Lygus: Scouting, thresholds and timing

    Insects

    Scout lygus at late flowering and podding stages using a standard insect net of 38 cm (15″) diameter. Take ten 180° sweeps, and aim to sweep the flowers and pods while moving forward. Count the number of lygus in the net.

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  • Late-season flea beetles

    Insects

    Flea beetles feeding on canola leaves and pods are unlikely to cause an economic loss. Entomologists have not set thresholds for late season flea beetle feeding, but it’s generally believed that numbers have to be very high — perhaps 100 per plant — before economic losses occur. You may also note that flea beetles can be highly variable at this time of year, with high numbers on some plants and next to none on others.

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  • Three insects to look for on canola pods

    Insects

    The three most common pod munchers are bertha armyworm, diamondback moth larvae and lygus bugs. Hot spots can sometimes be isolated to specific fields, so check each field. Before spraying, make sure insects counts are at or above economic thresholds. Applications made when insect numbers are below thresholds will not provide a positive return on investment and can do unnecessary harm to the many beneficial insects that help keep pest insect populations low.

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  • Canola Watch quiz – Insect thresholds

    Insects

    Scout for bertha armyworm, lygus bugs and diamondback moth larvae on pods, but only spray if insects counts are at or above economic thresholds. Try this quiz to brush up on thresholds.

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  • Grasshoppers thrive in hot, dry conditions

    Insects

    The nominal threshold for grasshoppers in canola is 8 to 12 per square metre. The challenge with the nominal threshold is counting the grasshoppers. As soon as you walk into an area, grasshoppers take off and do not cooperate with your attempts to count them. So entomologists have come up with more practical scouting techniques.

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  • Map of the Week – Bertha armyworm counts

    Insects

    A few hotspots with higher bertha armyworm moth counts are showing up in Alberta, Saskatchewan and Manitoba.

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  • Bertha armyworm: Thresholds

    Insects

    The economic threshold is the density of larvae where the economic value of the yield lost due to feeding equals the cost of control.

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  • Diamondback moth larvae observed

    Insects

    Diamondback moth larvae are at noticeable levels in many canola fields in the Eastern and southern Interlake areas of Manitoba. But levels are generally below the economic threshold.

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