|Eastwell, K - WSU-IAREC, PROSSER|
|Grau, C - UNIV OF WISCONSIN|
|Mondjana, A - UNIV OF WISCONSIN|
Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Research Notes
Publication Acceptance Date: November 1, 2001
Publication Date: April 1, 2002
Citation: Larsen, R.C., Miklas, P.N., Eastwell, K.C., Grau, C.R., Mondjana, A. 2002. A virus disease complex devastating late season snap bean production in the midwest. Bean Improvement Cooperative Annual Report. 45:36-37. Interpretive Summary: During the 2000 and 2001 growing seasons, a virus epidemic infecting the snap bean industry caused severe yield losses. Affected states include Iowa, Illinois, Kentucky, Michigan, Minnesota, New York, Wisconsin, and Ontario, Canada. Symptoms on leaves of snap bean varieties included chlorosis, yellow mosaic, severe stunting, leaf roll, blistering, vein necrosis and malformation. Pods from infected plants exhibited necrotic areas externally and internally rendering them unmarketable. Severe twisting was also found on many other pods. At least seven different viruses were identified in the disease complex and include alfalfa mosaic virus (AMV), cucumber mosaic virus (CMV), tobacco streak virus, bean common mosaic virus (BCMV), white clover mosaic virus, clover yellow mosaic virus, and bean yellow mosaic virus. Plant samples evaluated rarely were infected with a single virus but rather more often with two or three viruses. The epidemic is attributed to population explosions of the soybean aphid, which was introduced into the US recently from Asia. The aphid has been shown to be a highly efficient vector of many viruses. A set of bean differentials used to evaluate strains of BCMV was inoculated in the greenhouse with AMV in attempt to identify resistant varieties. Results of those evaluations indicated that so far, no resistance is currently available to AMV. Resistance for other viruses including CMV are currently being evaluated. Based on the timing of mass movement of large populations of soybean aphids, a recommendation was made suggesting that devastating yield losses may be partially circumvented by early planting of snap bean crops.
Technical Abstract: A virus disease complex causing widespread stunting of snap bean (Phaseolus vugaris L. ) plants and severe pod necrosis was reported in Wisconsin during the 2000 growing season and was associated with the recent introduction of the soybean aphid (Aphis glycines) from Asia. In 2001, the disease was reported in Iowa, Illinois, Kentucky, Michigan, Minnesota, New York, Wisconsin, and Ontario, Canada. The complex has resulted in severe yield losses due to twisting of pods, pods exhibiting external and internal necrosis, and general plant decline. Many fields of late-season processing and fresh market snap beans suffered losses of up to 100%. The results of virus surveys conducted during the 2000 and 2001 growing seasons are presented.