Status of Virus and Virus-like Problems on Processing Beans in Wisconsin During 2000 Craig R. Grau Ana Mondjana Walter R. Stevenson University of WI- Plant Pathology Description of Field Situation in 2000 • Problematic fields near Belgium and Cambria, Wisconsin • High incidence of plants with virus-like symptoms • Randomly distributed symptoms in the field • Many fields exhibiting these symptoms were destroyed prior to harvest Description of Field Situation in 2000 • Symptoms observed in the field: – Pod distortion – Affected pods had a dark brown discoloration internally – Leaf distortion – Mottling and mosaic patterns Symptoms observed at Cambria • Leaf mottling and mosaic • Internal pod discoloration • Pod necrosis Leaf mosaic and necrosis, Cambria Leaf mosaic at Cambria Rugosity at Cambria Leaf mosaic at Cambria Pod necrosis at Cambria Deformed pods from Cambria Symptoms observed at Belgium • Leaf mottling and mosaic • Internal pod discoloration • Pod necrosis Mottling on leaves at Belgium Leaf mottling at Belgium Rugosity and mottling at Belgium Leaf rugosity at Belgium Pod necrosis at Belgium Pod necrosis at Belgium Virus Assays Conducted for Belgium samples • Soybean mosaic virus • Bean yellow mosaic (SMV) (BYMV) • Alfalfa mosaic virus • Tobacco streak virus (AMV) (TSV) • Clover yellow vein virus • Bean common mosaic (CYVV)-conducted by Dr. virus (BCMV) Robert Gilbertson, Univ. of CA- Davis • Bean pod mottle virus (BPMV) Virus Assays Conducted for Cambria samples • Alfalfa mosaic virus Node discoloration at (AMV) Cambria • Bean yellow mosaic virus (BYMV) • Tobacco streak virus (TSV) Viruses Detected in Symptomatic Snap Beans Viruses Assayed AMV BCMV BYVV CYVV TSV % samples positive Belgium 85 15 8 100 15 Cambria 67 NA 0 NA 0 Greenhouse Experiments • Inoculum from field infected snap beans caused similar symptoms on inoculated plants • Pods provided the best source for virus detection and transmission • Symptoms expressed confirmed by ELISA assay for AMV Transmission of Stylet-Borne Snap Bean Viruses Clover yellow vein virus (CYVV) Bean yellow mosaic virus (BYMV) Aphid transmitted Center for IPM; NC State Aphid transmitted Alfalfa mosaic virus (AMV) Center for IPM; NC State Aphid and seed transmitted Transmission of Stylet-Borne Snap Bean Viruses Seed and pollen Bean common transmitted Center for IPM; NC State mosaic virus Aphid transmitted (BCMV) Tobacco streak virus http://newcrop.hort.purdue.edu/rhodcv/ hort410/peas/beanfl.jpg (TSV) Thrips transmitted Snap Bean Virus Inoculum Sources and Insect Transmission Aphid AMV, BCMV, CYVV, BYMV AMV, CYVV Other BYMV, TSV Legumes Seed AMV, BCMV, TSV Typical Symptoms for Detected Viruses Virus Leaf Necrosis Pod AMV Deformed Mild Malformed CYVV Yellow mosaic Apical Severe malformation; wall discoloration? BYMV Yellow mosaic Apical Slight malformation BCMV Green mosaic Severe Wall discoloration TSV Dark veins Red nodes Malformed , lesions Conclusions • Alfalfa mosaic virus (AMV), clover yellow vein (CYVV), bean common mosaic virus (BCMV), and tobacco streak virus (TSV) are associated with symptoms observed in 2000. • Although AMV was commonly detected, field symptoms were more closely associated with symptoms characteristic of clover yellow vein (CYVV) and bean common mosaic virus (BCMV). • An aphid transmitted complex of viruses are present and merit further investigation. Proposed Further Research • Field survey of snap beans and other legumes for types and frequency of viruses. • Determine whether viruses in snap beans are common to other legumes. Proposed Further Research • Evaluate snap beans cultivars and germplasm for reaction to AMV and CYVV. • Determine seed transmission of detected viruses. • Determine if viruses are a component of the Disease X symptoms in snap beans.