Abstract
The author carried out indexing experiments of grape viruses using four indicator plants, Mission, Baco 22A, LN-33, and Rupestris St. George, during the period, 1965 to 1970. Eleven varieties grown in Japan were proved to carry leafroll virus and five varieties to carry corky bark virus. Two varieties appeared to be infected by both viruses simultaneously. Fanleaf virus was not detected in the experimental indexing.
