Rapid Detection of Agrobacterium tumefaciens in Grapevine Propagating Material and the Basis for an Efficient Indexing System. F. A. Tarbah, Department of Plant Pathology, University of Missouri, Columbia 65211. R. N. Goodman, Department of Plant Pathology, University of Missouri, Columbia 65211. Plant Dis. 70:566-568. Accepted for publication 26 November 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-566.

Sap from hardwood stem pieces of five grape cultivars and 10 rootstock selections was collected by a water-displacement procedure and plated on a medium selective for the Agrobacterium tumefaciens biovar 3. Of 36 strains of A. tumefaciens recovered, 86% were identified as biovar 3 according to their physiological and virulence characteristics; 90% of the apical portions of grape canes sampled were free of A. tumefaciens. Our data provide the basis for a simple, yet rapid indexing system for the detection of low populations of unevenly distributed A. tumefaciens cells in grape wood. With this procedure, it should be possible to obtain A. tumefaciens-free propagating material.