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United States Department of Agriculture

Agricultural Research Service

Title: Snap bean virus identification and management strategies

Author
item Larsen, Richard

Submitted to: National Food Processors Association Meeting
Publication Type: Proceedings
Publication Acceptance Date: November 14, 2006
Publication Date: November 15, 2006
Citation: Larsen, R.C. 2006. Snap bean virus identification and management strategies. Proceedings of the National Food Processors Association Meeting.

Interpretive Summary: In 2000, a severe virus outbreak occurred in snap beans in Wisconsin and other neighboring snap bean production states. The epidemics have continued through 2005 and are the result of high populations of the soybean aphid (Aphis glycines). The most frequently detected viruses included Cucumber mosaic virus (CMV) and many different biological strains of Alfalfa mosaic virus (AMV), When CMV and AMV occur as mixed infections, necrotic lesions or line patterns were evident on pods. Two other important viruses detected included Clover yellow vein virus (ClYVV) and Bean yellow mosaic virus (BYMV). Methods used to identify these viruses include biological assays, serology using ELISA an inexpensive, fast and reliable standard for detection of most of the snap bean viruses an inexpensive, fast and reliable standard for detection of most of the snap bean viruses, and reverse-transcriptase polymerase chain reaction, a molecular technique by which the results are similar to DNA fingerprinting. The latter was used exclusively for identification of ClYVV, as the virus could not be detected by the standard ELISA tests. The common viruses listed above are transmitted in a matter of seconds by the soybean aphid, as well as other aphid species. Hence, application of such chemicals including seed treatments may actually increase virus spread rather than control it. Control of the soybean aphid on a large scale basis is not practical or economically feasible. Some late season planting strategies have been shown to reduce losses in snap bean due to virus infection in the upper Midwest. The most effective management strategy is to develop and plant cultivars with resistance or tolerance.

Technical Abstract: In 2000, a severe virus outbreak occurred in snap beans in Wisconsin and other neighboring snap bean production states. The epidemics have continued through 2005 and are the result of high populations of the soybean aphid (Aphis glycines) The most frequently detected viruses included Cucumber mosaic virus (CMV) and many different biological strains of Alfalfa mosaic virus (AMV). A high incidence of CMV and AMV occurring as mixed infections was associated with necrotic lesions or line patterns on pods. Two other important viruses detected included Clover yellow vein virus (ClYVV) and Bean yellow mosaic virus (BYMV). The viruses in this complex resulted in severe yield losses where many fields of late-season processing and fresh market snap beans suffered losses of up to 100%. The characteristic symptoms and methods for identification of each virus are discussed. The use of pesticides in attempt to control the spread of snap bean viruses is generally ineffective. Use of resistant or tolerant varieties and early-season planting strategies are currently the only effective methods of virus control in snap beans in these regions.

Last Modified: 4/19/2014
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