With soybeans beginning to enter their flowering stages, we need to remind growers of the various defoliators that are starting to make their presence known. These defoliators include Japanese beetle adults, first generation bean leaf beetle adults, Mexican bean beetle adults, green cloverworm larvae, and grasshoppers, and all are now being found throughout the state. In terms of defoliation, it would be unusual for any of the above mentioned insects alone to cause significant defoliation throughout a field. However, a complex of two or more might cause defoliation levels to rise above threshold levels. Remember you need to sample from numerous locations in the field to get a good idea of what is happening across the entire field. For fields with large populations of Japanese beetles, remember that these beetles will congregate; finding one Japanese beetle means you will usually find a lot of them in the same area. Thus, at least for this insect, you need to make an extra effort to sample from numerous locations in the field to get a better idea of what is happening across the entire field. Growers are advised to initiate scouting procedures over the next few weeks to prevent defoliation from reaching the 15-20% defoliation threshold during the reproductive growth stages, R1-R5, which then rises to 20-25% during growth stage R6 late in the summer. When sampling, check numerous places within the field, avoiding the field edges which often tend to have higher levels than the rest of the field. A list of labeled insecticides for control of all these soybean defoliators is available at http://entomology.osu.edu/ag/545/soy545.pdf .
