David Owens, Extension Entomologist, owensd@udel.edu and Bill Cissel, Extension Agent – Integrated Pest Management; bcissel@udel.edu
We continue to see low numbers of Japanese beetles, green cloverworms, and thrips in fields. There has been an uptick in the number of pirate bugs, feeding on thrips and early instar worms. Dectes is showing up in fields. Fields with the greatest number of Dectes should be prioritized at harvest, as much as possible. Defoliation in general has been pretty light. Two spotted spider mite hotspots can be found in several fields. Pay attention to field edges when scouting for them.
An Extension bulletin produced by Virginia Tech may be of interest. There is a relationship between defoliation, leaf area index, and yield. If the canopy closes by R3, and there are more than 3.5 acres worth of leaves for every ground acre, leaf feeding will not have as great an impact on yield, whereas thinner canopies are more sensitive. The bulletin and some useful photos can be found here: http://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/444/444-203/444-203_pdf.pdf.