Now is Critical Time for Soybean Defoliation
Bean leaf beetle numbers are high in some soybean fields, according to Purdue entomologists Rich Edwards, John Obermeyer, and Larry Bledsoe.
These leaf-eaters and others, such as Japanese beetles and green cloverworm, mean leaf removal and possibly significant damage.
"The impact of defoliation is greatest during pod fill because of the importance of leaf area to photosynthesis and, ultimately, yields," Edwards says. "The best management guidelines for soybean defoliators involve identifying the insect pests and then characterizing the level of defoliation and growth stage of the beans."
Management decisions, he says, will depend on expected market price of the soybeans, treatment cost, damage level, growth stage, and potential yield.
"At mid pod fill, consider treatment when defoliation exceeds approximately 15 to 20 percent and the defoliators are still present and actively feeding," he says.
For more guidelines and suggested insecticides refer to Purdue Extension Publication E-77, Soybean Insect Control Recommendations. For a PDF copy, click on the E-77 link at the following Web site: http://www.entm.purdue.edu/entomology/ext/targets/e-series/e-list.htm.