CLOVER PHYLLODY VIRUS IN CANADA AND ITS TRANSMISSION

Abstract

Phyllody in clovers, observed on rare occasions in Canada since 1902, is now common in Quebec, New Brunswick, Nova Scotia, and Prince Edward Island. Tests in the field indicated that natural spread of the disease could occur each month from June to September. A virus causing phyllody symptoms was transmitted by the leafhoppers Macrosteles fascifrons (Stal), Aphrodes bicinctus (Schrank), and Scaphytopius acutus (Say) from Trifolium repens L. to T. repens. M. fascifrons also transmitted the virus to and from Vinca rosea L. and Callistephus chinensis Nees. S. acutus transmitted the virus to V. rosea and Trifolium pratense L. The virus was also transmitted by dodder, Cuscuta gronovii Willd., from V. rosea to V. rosea. Clover phyllody virus (CPV) in Canada resembles CPV in England and Europe and both are transmitted by A. bicinctus. Although CPV in Canada is transmitted by M. fascifrons, which is a vector of aster-yellows virus (AYV), it differs from recognized strains of AYV in other vector–virus relationships, symptomatology, and geographic distribution.