August 4, 2022

QUIZ – Sweep netting

Four questions on timely scouting based on major insects observed in canola fields this week: lygus bugs, diamondback moth larvae and grasshoppers.

1. Here is 10 sweeps' worth of lygus bugs captured this week around Fairview, Alberta. Do you think the count is over threshold?

2. A CCC agronomy specialist found these two green diamondback moth larvae in a sweep net. Are diamondback thresholds based on sweep net counts?

3. Sweep netting can show the biodiversity of insects in the flowering canopy of a canola field. The bottom arrow points to a lygus nymph with developing wings. You include these in your threshold counts along with adults. The top arrow points to a beneficial insect looking like its about to eat a diamondback moth larva (middle arrow). What is that beneficial insect?

4. Grasshoppers might show up in your sweep net, but grasshopper thresholds are not sweep-net based. They are based on counts per square metre. The nominal threshold for grasshoppers in canola is ______ per square metre. (Fill in the blank.)

 

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