Some Early Planted Soybean Fields Sprayed For Bean Leaf Beetle Control

Published: May 30, 2008

High numbers of bean leaf beetle adults have required insecticide applications to reduce numbers below economic threshold levels in some early planted soybean fields. Adult bean leaf beetles migrating from overwintering sites to early planted soybean fields have resulted in heavy leaf feeding and some plant mortality. In many areas wet weather has limited soybean planting and accumulated high numbers of beetles in seedling soybean fields that are available. The bean leaf beetle produces two generation annually in Missouri with larvae feeding on soybean roots. The economic threshold for bean leaf beetle adult feeding on seedling soybean is 5 or more beetles present per row foot or 1 or more plants destroyed per row foot. In most years control of beetles causing early season defoliation of soybean seedling is not needed. However the limited number of soybean available early season has forced high numbers of beetles into fields with seedling soybeans. Economic damage from bean leaf beetle is more common later in the season when beetles of the second generation feed on soybean pods.