TY - JOUR T1 - Mechanical Transmission and Rootstock Reservoirs as Factors in the Widespread Distribution of Viroids in Grapevines JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 213 LP - 216 DO - 10.5344/ajev.1988.39.3.213 VL - 39 IS - 3 AU - J. A. Szychowski AU - A. C. Goheen AU - J. S. Semancik Y1 - 1988/01/01 UR - http://www.ajevonline.org/content/39/3/213.abstract N2 - With the recent evidence of the almost ubiquitous occurrence of grapevine viroids in California, intriguing questions have arisen concerning the significance of viroids to vine growth and productivity. Of fundamental importance in addressing these considerations is an understanding of the manner in which such a general distribution of grapevine viroids has been accomplished. GV1, GV2, and GV3 were demonstrated to be transmissible agents in Emperor seedlings and viroid-free, shoot tip cultured Cabernet Sauvignon grapevines. Analyses of multiple selections of these varieties have never detected the presence of GV2. Therefore, the transmission of GV2 in these tests suggests that these varieties are not resistant to GV2, but probably have never been exposed to this viroid. A survey of samples taken from the rootstock collection at the University of California, Davis, detected at least one grapevine viroid in all varieties tested. Two of the newly released rootstock varieties tested contained an unusually high concentration of the less commonly found GV2. Therefore, two possible sources for the spread of grapevine viroids have been identified: (1) mechanical inoculation among vines, which might be accomplished during routine cultural practices; and (2) systemic transmission between grafted rootstocks and scion varieties containing grapevine viroids. ER -