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Soybean bean leaf beetles (BLB) may be a threat to soybeans due to the potential for large, overwintered adult populations favored by the mild winter conditions. Early planted fields are at risk from BLB.
Adult bean leaf beetles overwinter on the edges of wooded areas, in fence-rows, and ditch banks near soybean fields. They become active and migrate to emerging soybean fields for feeding and propagating when springtime temperatures reach 50° F. The earliest-planted soybean fields have the greatest risk of economic feeding injury1.
Warm winters favor BLB adult survival in leaf litter in wooded areas or soybean debris. Entomologists from Iowa State have developed a predictive model for BLB survival. BLB adults are susceptible to low temperatures in winter. Typically, winter mortality ranges from 60-99% in Iowa. However, this year mortality is estimated at only 30-53% for various regions within Iowa2. This is the lowest mortality since the predictive model was first used in 2000. Early-planted fields should be monitored closely this year given the potential overwintering survival of BLB adult beetles is significant. Food-grade soybean and seed fields may be at significant risk for reductions in yield and seed quality.
BLB feed on infected plants and transmit the virus to the next plant on which it feeds. Virus transmission can occur at any growth stage, however early infection poses the greatest risk of reduced seed size and pod set resulting in potential yield loss. BPMV causes the discoloration of soybeans at harvest as well as the crinkling and mottling of leaves during the growing season. BPMV is also a cause of the “green stem” phenomenon, which can hinder harvesting operations. BPMV can be difficult to distinguish from soybean mosaic virus. Soybean varieties differ in susceptibility to BPMV.
Sources:1 Ratcliffe, S.T. et. al. 2004. Bean Leaf Beetle. University of Illinois Extension. Integrated Pest Management.2 Hodgson, E. and Sisson, A. March 28, 2012. Mild winter for bean leaf beetle. Iowa State University, Integrated Crop Management, www.extension.iastate.edu (verified 4/25/2012).3 Hunt, T. and K. Jarvi. April 22, 2011. Watch for Bean Leaf Beetles in Early Emerging Soybeans. University of Nebraska-Lincoln. Crop Watch. www.extension.iastate.edu (verified 4/25/2012). Photos by Brad Miller Monsanto Company. Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Acceleron and Design® is a registered trademark of Monsanto Technology LLC. Leaf Design℠ is a servicemark of Monsanto Company. ©2012 Monsanto Company. 04262012 JSC.