Canker Development on Plum Shoots Following Systemic Movement of Xanthomonas campestris pv. pruni from Inoculated Leaves. H. J. Du Plessis, Fruit and Fruit Technology Research Institute, Private Bag X5013, Stellenbosch 7600, South Africa. Plant Dis. 71:1078-1080. Accepted for publication 2 July 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-1078.

Leaves on Golden King plum trees in a greenhouse were inoculated with Xanthomonas campestris pv. pruni to determine if systemic movement of the pathogen leads to the development of summer and spring cankers. Summer cankers occurred only if the pathogen had been introduced into petioles and main veins within 5 wk of shoot emergence. Application of inoculum by spraying into intercellular spaces of unwounded leaf surfaces resulted in spring cankers during budbreak on trees previously chilled to dormancy at 4 C in the dark. Both types of cankers are apparently associated with systemic movement of the pathogen from infected leaf and shoot tissues.

Keyword(s): bacterial spot, Prunus salicina.