It is highly likely that soybean producers in the Midwest will see higher bean leaf beetle populations in 2016. An overwinter survival model from Iowa State University (ISU) Extension indicates bean leaf beetle mortality rates of just 35 to 68 percent compared to a 25-year average of 72 percent. In light of those figures, agronomists, crop consultants and growers are being warned to monitor fields closely.
Higher populations of bean leaf beetles pose several concerns for soybean yield potential. Early- and mid-season feeding from the overwintered population and first-generation bean leaf beetles can cause foliar and stem damage. In addition, bean leaf beetles can transmit bean pod mottle virus, a widespread infection that can result in mottling, green stem symptoms and yield losses as high as 52 percent, according to research from the University of Nebraska-Lincoln.
Even if the first generation of bean leaf beetles don’t reach an economic threshold, researchers recommend growers keep their guard up for second-generation damage. Appearing in late-summer months, the second generation poses a greater risk for economic loss through pod feeding and leaf defoliation. To keep bean leaf beetle populations in check, it’s recommended that growers scout until seed set and use a bean leaf beetle threshold calculator tool such as that of ISU Extension.
As one insecticide manufacturer agronomist noted, “Bean leaf beetles can be erratic. Timely scouting is extremely important if you’re going to treat for bean leaf beetles. If you see pod feeding later in the summer, you should pull the trigger on an insecticide—you wouldn’t want pod loss on your soybeans.”
Rich Lee, product development agronomist at Syngenta, in pointing out the dangers of bean leaf beetle damage suggested that Endigo ZC insecticide effectively prevents yield loss from damaging insects like bean leaf beetles.
Taking action when bean leaf beetles reach an economic threshold can significantly reduce soybean injury and the incidence of bean pod mottle virus, ultimately saving yield and profit.