Determination of viral diseases and insect vectors on weeds adjacent to fields of vegetable crops.

Abstract

G. Apablaza, J. Apablaza, E. Moya and P. Reyes. Determination of viral diseases and insect vectors on weeds adjacent to fields of vegetable crops. Viral diseases and insect vectors from weedsgrowing adjacent to fields of tomato, pepper, melon, watermelon and squash -were determined in the V th and Metropolitan regions of Chile. Two hundred and eleven weed samples showing virus symptoms were analyzed for virus presence by DAS-ELISA and by mechanical inoculation to indicator plants. The relative importance of weeds, in decreasing order, was: Datura stramonium, Amaranthus spp., Raphanus sativus, Chenopodium album, Galega officinalis, Conium maculatum, Sonchus asper, Malva spp., Urtica urens, Bidens spp., Brassica campestris, Sorghum halepense and Solanum spp.. One to five of the following viruses were found infecting these weeds: alfalfa mosaic virus (AMV), cucumber mosaic virus (CMV), tomato spotted wilt virus (TSWV), potato virus Y (PVY), tomato mosaic tobamovirus (ToMV) and watermelon mosaic virus -2 (WMV 2). Syndromes of some of the viruses on weeds and on pepper plants are described. Aphids, thrips and some Lepidoptera species were also collected from the weeds under study and identified. Myzus persicae, a vector of CMV, WMV2, AMV, and PVY; and Thrips tabaci, a vector of TSWV, were commonly found. This information indicates that weeds growing, next to fields of crops, are inoculum sources of the viruses and hosts of their vectors.