Bean Leaf Beetle Populations Reach Impressive Levels in Early-Planted Soybeans

May 19, 2000
In last week's Bulletin, we presented some life cycle information and management tips for bean leaf beetles. During the past week, we've received calls from many producers concerning soybean seedling injury caused by bean leaf beetle feeding. Most severe injury is being reported by growers who were the first in their local areas to plant soybeans. With the very mild winter, great overwintering survival, and early planting--well, you have the perfect combination for troubles with bean leaf beetles. Although some fields have very large densities of bean leaf beetle adults, don't panic. Fortunately, very impressive densities of adults are required to deliver an economic punch (16 per foot of row in the early seedling stage, 39 per foot of row at stage V2+). Rescue treatments for the great majority of soybean fields are never required. Research conducted by Larry P. Pedigo, an entomologist with Iowa State University, allows producers to effectively evaluate the wisdom of applying a rescue treatment based on bean leaf beetle adult densities, projected market value of soybeans, and the cost of a rescue treatment (Table 1). Before any treatment decision is made for bean leaf beetles, please consult Table 1.--Mike Gray

Author: Mike Gray