The pod stage is the critical time to watch for insect feeding in canola. When flowering is done, the crop cannot produce more flowers to compensate for insect losses. Thresholds for insects such as bertha armyworm, diamondback moth larvae (shown in the photo above) and lygus bugs are based on losses at pod feeding. However, take care with timing. Jumping…
July 17, 2013 - Issue 16
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Grasshopper numbers are at or near thresholds in some regions of the Prairies. The nominal threshold for grasshoppers in canola is 8-12 per metre square. How you go about counting them is the challenge. 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…
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Bertha armyworm moth counts continue to accumulate across the Prairies. Many areas are now at moderate to high risk, and adult numbers will continue to build this week. Adult counts can hint at the potential level of feeding by the larvae — the actual armyworms — starting about two weeks after the first wave of adults showed up in traps…
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—Go out in early morning or late evening when larvae are mostly active. —Mark out an area a quarter-metre square (50 cm by 50 cm) and beat the plants growing within that area to dislodge the larvae. Count the larvae that have fallen to the ground and multiply by 4 to get the number per metre square. Larvae will hide…
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