Home / Canola Watch / Insects / Page 35
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Insects, heat stress, hail and sulphur deficiency can all cause bud discoloration and damage. Scouting closely for insects may be required to find out which might be the cause, especially if heat stress and hail can be ruled out…
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Check to see if lygus feeding is preventing crop from coming into flower. Bertha armyworm adults are mounting and larvae will start to hatch later this month. Leafhoppers are at higher than usual numbers in some locations…
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Insecticide control at the bud stage is rarely effective or economical even when counts are 15-20 per 10 sweeps. Under good growing conditions, canola can grow through this early damage without any yield loss. In some cases canola can actually yield more if some early bud feeding occurs. Lygus control at the bud stage may be warranted if all buds…
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Probably too early to spray cabbage seedpod weevil, diamondback continue feeding, bertha moth numbers are high in some regions, cutworms near the end but still active, and always think about those valuable beneficials — like those helpful killers, the lady bugs…
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Begin sweep netting for cabbage seedpod weevil when canola enters the flowering period. Select 10 locations within each field and at each location, count the number of weevils from ten 180° sweeps. At current prices, the threshold will be around 20-30 per 10 sweeps (2-3 per sweep). Anything below that and the canola plant will generally compensate for seedpod weevil…
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Leaf rollers probably aren't worth controlling. Wireworms will live up to 4 years as a larvae and will feed on canola. Bertha monitoring begins. Flea beetles numbers are falling for the season…
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Cutworms can leave canola fields with bare patches, clipped plants and large chunks out of stems and leaves. Flocks of birds — crows, gulls, etc. — can be a sign that cutworms are present in large numbers, but nothing beats digging to confirm your suspicions. Cutworm thresholds are based on stand reduction, not actual cutworm counts. The threshold for canola…
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Before spraying for diamondback moth larvae, make sure that: 1. Large areas within the field have reached the nominal threshold of 25% or more of the leaf area lost. 2. Diamondback larvae are still present. 3. They are actively feeding. (Many diamondback moth larvae may have started to cocoon (pupate) and are no longer a threat.) 4. Newest leaves are…
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Add diamondback moth larvae to your early season scouting list. Growers cannot expect insecticide seed treatment to protect canola from diamondback moth larvae, so spraying may be necessary in some fields or parts of fields. Before spraying, make sure that: 1. Large areas within the field have reached the nominal threshold of 25% or more of the leaf area lost…