Bean pod mottle virus (BPMV) is a virus disease found throughout Iowa in soybeans and other legumes. There are two potential problems with bean pod mottle virus: reduction in soybean quality and yield loss.
Symptoms of infection by bean pod mottle virus are most apparent during periods of cool weather and when the plant is actively growing. Infected soybean plants may have mottled or crinkled leaves and plants may be stunted.
Symptoms may resemble injury from herbicide drift or symptoms of other soybean viruses. As soybeans mature, foliar symptoms are less apparent. Infected plants may have mottled or discolored seed at harvest (Figure 1). Delayed maturity of stems and leaves ("green stem") may also occur in BPMV-infected plants.
There are two potential problems with bean pod mottle virus: reductions in soybean quality and reductions in yield. The effect of bean pod mottle virus on yield has been shown to vary by soybean variety and growing conditions. Over a broad geographic range, yield reductions between 10% and 40% have been reported.The impact of BPMV on yield depends upon the time of virus infection; the earlier the soybean is infected with virus, the greater the effect on yield and seed quality.
Another problem with BPMV is that a synergistic reaction occurs when plants are infected with both BPMV and soybean mosaic virus. Reduction in yield is much greater in mixed infections than either virus alone.
Most plant viruses are spread from plant to plant by specific insect vectors. In the case of BPMV, the bean leaf beetle, spreads the virus from plant to plant as it feeds. In addition to soybean, showy tick trefoil, a native host for bean leaf beetles, can carry the virus. BPMV can also be seedborne.
Management of Bean Pod Mottle Virus
It's important to establish a field history of BPMV before deciding on management options. Factors that indicate a field history of BPMV are:
• a significant yield reduction in the previous year
• mottled or discolored seed and/or seed test indicated presence of BPMV
• delayed maturity in some plants - "green stem syndrome"
• large bean leaf beetle populations in the fall
There are no known commercial soybean varieties with resistance to bean leaf beetles or bean pod mottle virus. The short-term management options available for growers at this time are carefully-timed soybean planting and insecticide application for early-season bean leaf beetle control. Do not plant mottled or discolored seed from fields which had a high level infestation of bean leaf beetle.
Bean pod mottle virus is back in Iowa in 2006 and the populations of bean leaf beetles seems to be the worst we have seen since 2002. See the recent update on bean pod mottle virus and what we can expect during the harvest of 2006.
A good summary of management of BPMV in Iowa can be found in this article in the Integrated Crop Management newsletter: Management decisions for bean leaf beetles and bean pod mottle virus (May 2005).
Bean pod mottle virus. A threat to U.S. soybean production. Giesler, L. J., Ghabrial, S. A., Hunt, T. E., and Hill, J. H. 2002. Plant Disease 86:1280-1289. (link to PDF file).