In soybean, insecticide treatment decisions are based on growth stage and amount of defoliation, including injury from other defoliators because it is difficult to distinguish among the types of feeding injury.
Foliar insecticide treatment is recommended when defoliation is expected to exceed 30% before bloom (V1-R2 growth stages), 10% from pod development to pod fill (R3-R5) and 15% at the R6 (full seed) growth stage.
Japanese beetles are also considered a pest in corn crops. They focus on clipping corn silks necessary for pollination, which can lead to some yield reductions, says Valmorbida.
Valmorbida says foliar insecticide application is warranted in corn crops if the three following conditions are met:
- There are an average of three or more beetles per ear.
- Silks have been clipped to less than 0.5 inch.
- Pollination is less than 50% complete.
MU Extension’s pest monitoring website offers an alert system for Japanese beetles and other pests. Subscribe to alerts at https://ipm.missouri.edu/pestMonitoring or email ipm@missouri.edu.
Valmorbida also recommends the following publications:
Source : missouri.edu