Bean virus predicted to have a down year

    Soybeans in Iowa stand a lesser chance of contracting a pesky virus called bean pod mottle virus compared to previous years, according to agronomists and plant pathologists at Iowa State University (ISU). Iowa State University plant pathologists Emmanuel Byamukama, Alison Robertson and Forrest W. Nutter Jr. released a report earlier this month that indicated that 83 of the 99 counties in Iowa are at low risk of encountering the bean pod mottle virus. Of the 16 counties listed as moderate risks for the virus, 15 were in southeast Iowa, although Washington County was not one of them. Five of the six counties that border Washington were rated as moderate risks, the only exception being Iowa County, which is at low risk.

    Iowa State University agronomist Jim Fawcett said that the bean pod mottle virus can cause reduced yields. Once a soybean plant has become infected with the virus, the symptoms of the virus may not be visible until late July or early August. Fawcett said that an infected plant will have noticeably crinkled leaves by that time, and that its stem will stay green for a longer period of time than normal.

    Jim Jensen, an Iowa State University farm management specialist, remarked that if a bean?s only infection is the bean pod mottle virus, it can expect a yield reduction of 10 to 17 percent. However, if the plant is infected with the virus, it becomes more susceptible to other diseases. Jensen said that if a bean plant contracts an additional virus, its yield could decline by 50 percent. 

    The virus is transmitted by bean leaf beetles that feed on soybeans. The ISU plant pathologists based their risk assessment of the virus on the likely number of bean leaf beetles in each county, as determined by the number of days below freezing the county experienced over the winter. Jensen explained that the beetles were able to survive better in southeast Iowa because the winter temperatures were warmer here than in other parts of the state, and therefore killed fewer beetles.

For the full story, see the April 23 edition of The Washington Evening Journal