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IPM Crop Survey - Insect Update (08/05/21)

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Soybean aphid numbers continue to be low and were observed in about 19% of the soybean fields scouted last week, mainly in the eastern half of ND and central to northwestern MN. The percent of plants infested ranged from 3-42% with an average of 1-5 aphids per plant among the positive observations, and located mainly in eastern ND. All soybean fields were below the economic threshold (average of 250 aphids per plant and 80% incidence). Growth stages of soybeans ranged from R3 (beginning pod) to R5 (beginning seed). See maps on NDSU’s IPM website:

https://www.ag.ndsu.edu/ndipm/images/soybeans/2021/7-19-7.30/aphidincidence.jpg

https://www.ag.ndsu.edu/ndipm/images/soybeans/2021/7-19-7.30/aphidnumber.jpg

Spider mites increased slightly and were mainly present on field edges in about 14.5% of soybean fields surveyed last week, compared to only 3% last week. Field edge sprayings for spider mites in SE ND have been reported. See map on IPM website: https://www.ag.ndsu.edu/ndipm/images/soybeans/2021/7-19-7.30/mitesedge.jpg

Adult grasshoppers were detected in 89% of all the IPM fields (wheat, barley, soybean, sunflower) scouted last week and about 22% were at the economic threshold of >8-14 adult grasshoppers per square yard in the field. Here’s some of the photographs of the 2021 severe crop damage caused by adult grasshoppers. Thank you for sending them!

Frequent scouting is the key to early detection and timely pest management.

 

Adult Grasshopper Photos and Map July 19-30.2021.png
Photo Credit:
J. Stachler, V. Calles-Torrez, I. Dukart, T. Duchsherer

 

Janet J. Knodel

Extension Entomologist