Monitor Bean Leaf Beetle Activity

Entomologists in the North Central region recommend including bean leaf beetle in the early season scouting schedule. Injury due to the beetle is easily recognized. See the article Recognizing bean leaf beetle injury in the Iowa Integrated Crop Management newsletter.

May 23, 2007

Kevin Steffey, University of Illinois, has noted that bean leaf beetles tend to "play dead" and drop from seedling soybeans to the ground when they are disturbed, and recommends to approach your sampling area quietly. Examining plants by hand is the easiest method for seedling soybeans. As the plants grow, use of a beat cloth may help assess numbers of bean leaf beetles per foot of row. Remember to scout in several areas of a given field to obtain a reasonable assessment of bean leaf beetle density for the field. A few high counts are offset when several areas of a field are not infested, lowering the average number of beetles per plant. There's no need to treat an entire field and spend more money than necessary if the field average of bean leaf beetles is lower than published thresholds.

University of Nebraska recommendations suggest a density of 16 adults per row foot in the early seedling stage before economic injury from physical feeding will occur. By the V2 stage, 39 beetles per row foot are required before economic injury will occur.

Bean leaf beetles are capable of transmitting a soybean virus called Bean pod mottle virus (BPMV) while feeding. While BPMV transmission can occur at any stage, early infection in the VC to V2 stage poses the greatest risk of yield loss. Field history of virus problems is the most important consideration in making the decision whether to spray for the bean leaf beetle to control virus diseases. Sprays must be carefully timed to be effective. Researchers at Iowa State University have constructed a flowchart to help growers with insect/virus management decisions. View the chart in the article Revisiting an Integrated Approach to Bean Leaf Beetle and Bean Pod Mottle Virus Management»

Information on these pages is from the cooperative effort of researchers throughout the North Central states. Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: NCSRP Plant Health Initiative at www.planthealth.info. Please do not use copyrighted photos without permission.