By Blake Jackson
The University of Missouri Extension (MU Extension) is advising Missouri corn and soybean producers to heighten their vigilance against Japanese beetles.
State entomologist Ivair Valmorbida has observed a significant uptick in beetle populations throughout the state, particularly in northwestern and northeastern Missouri.
Japanese beetles are highly mobile insects that pose a threat to soybean crops by feeding on the upper canopy leaves. This feeding activity results in defoliation, leaving only the veins of the leaves intact.
Management decisions for soybean fields depend on the current growth stage and the severity of defoliation, including damage caused by other defoliating insects. Distinguishing between different types of feeding injury can be challenging.
MU Extension recommends the application of foliar insecticides in soybean fields when anticipated defoliation exceeds established thresholds.
These thresholds vary based on the growth stage, with 30% defoliation being the trigger point before bloom (V1-R2 stages), 10% during pod development (R3-R5 stages), and 15% at the full seed stage (R6 stage).
Corn crops are also vulnerable to Japanese beetle damage. These beetles target and clip corn silks, essential for successful pollination. Such damage can potentially lead to yield reductions.
Valmorbida recommends the use of foliar insecticides in cornfields if three specific conditions are met: an average of three or more beetles per ear, silk clipping exceeding half an inch in length, and less than 50% pollination completion.
By implementing a proactive approach of field monitoring and timely intervention strategies, Missouri farmers can effectively mitigate crop damage caused by Japanese beetles and safeguard a successful harvest season.
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Categories: Missouri, Crops, Corn, Soybeans