Spatial and Temporal Distribution of North American Grapevine Yellows Disease and of Potential Vectors of the Causal Phytoplasmas in Virginia

Abstract

Abstract North American grapevine yellows is a destructive, phloem-limited disease of winegrapes in the mid-Atlantic and northeastern regions of the United States caused by at least two phytoplasmas (aster yellows and X-disease Candidatus phytoplasma spp.). Because insects have been identified as vectors of grapevine yellows in several countries, one or more insect vectors are suspected of transmitting the phytoplasmas in North American vineyards. Adding to evidence in support of insect transmission of North American grapevine yellows were observations that diseased vines often occurred in clusters frequently near vineyard edges that bordered woodland vegetation, suggesting movement of insect vectors into vineyards. The spatial distribution of North American grapevine yellows-affected vines was annually assessed in two northern Virginia vineyards over an 8-yr period. Spatial analysis indicated that diseased vines were significantly clustered, or their distribution was nonrandom, in both vineyards. Cluster...