Studies on virus diseases of the grapevine in California

The principal symptoms that characterize the virus diseases of grapevines found in vineyards of California are described. The diseases are: PIERCE's disease, fanleaf, yellow mosaic, vein banding, leafroll, yellow vein, asteroid mosaic, and corky bark. It is the first report of the graft transmission of corky bark and an unidentified virus that produces fleck in Vitis ruprestris var. St. George.All of the grape viruses can be transmitted by one or more grafting methods, but chip-bud grafting has proved to be simple and effective. The soilborne viruses that cause fanleaf, yellow mosaic, and vein banding all mechanically sap-transmit to, and produce very similar, mostly indistinguishable symptoms in different herbaceous hosts. The GYVV (grape yellow vein virus) will also sap-transmit to several different herbs, yet the symptoms differ from those induced by the soil-borne viruses.Xiphinema index transmitted the GFV (grape fanleaf virus) from roots of sap-inoculated Chenopodium amaranticolor to roots of V. rupestris var. St. George. Evidence shows that X. index will also transmit the GYMV (grape yellow mosaic virus) from vine to vine. Evidence indicates that fanleaf, yellow mosaic, and vein banding are distinct diseases with definite and consistent symptoms, although apparently caused by strains of the same virus.Results of these tests to control the soil-borne grape viruses by injection of chemicals into the soil show that carbon bisulfide and methyl bromide are the most effective, though none of the chemicals used give complete control