July 13, 2022

QUIZ – Spray window + thresholds

This quick quiz is about pests on the scouting agenda this week. Check each field for crop stage and to see if risk exceeds threshold.

Diamondback moth larvae eating pods.
1. Diamondback moth larvae cause more yield damage at the podding stages, which is why thresholds are based on counts at this stage. The Canola Research Hub blog describes results from a recent study. Study results showed that yield loss was _________ in plants with ~2 larvae/plant at the podding stage (the current threshold) compared to the control, which had no larvae. (Fill in the blank.)
2. Good moisture increases the sclerotinia stem rot risk and good yield potential increases the return on investment from a spray. Based on the current situation, how many bushels per acre of yield protection would be the economic threshold for a fungicide application?
3. The most vulnerable crop stage for lygus feeding is after flowering, when seeds are enlarging on lower pods. That is why spray thresholds for lygus are based on sweep net counts at the podding stages. A threshold of ______ per 10 sweeps is suitable for good growing conditions. (Fill in the blank.)

 

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