Bacterial canker of sweet cherry - infection of horticultural and natural wounds, wound healing, and spread with contaminated pruning tools

• Published in: Phytopathology 2009-06, Vol.99 (6), p.S123-S123
• Main Authors: Spotts, R A, Wallis, K, Serdani, M
• Format: Article
• Language: English
• Subjects: Bacteria; Prunus; Pseudomonas syringae
• ISSN: 0031-949X

Bacterial canker, caused by Pseudomonas syringae pv. syringae (Pss), is a major disease of sweet cherry trees and is particularly serious in many parts of Oregon. A sweet cherry orchard, cv. Sunset Bing on Gisela 6 rootstock, was planted in 2006. Trees were inoculated with a suspension of 3 x 10 super(8) cfu/ml of Pss isolate KM406 throughout the 2006 and 2007 seasons at 7 times that corresponded to cultural operations that cause potential sites for infection. These sites included heading cuts, scoring cuts, dormant and summer pruning, leaf scars, and early and mid-winter low temperature injury. Studies also were conducted on the length of time needed for pruning wounds to heal and the potential spread of bacterial canker with pruning tools contaminated by cutting through active cankers. Infection occurred in all wound site types, and incidence ranged from 32 to 100%. Inoculation of heading cuts and leaf scars each resulted in 50% tree mortality. Canker length and tree mortality were least for freeze injury in early winter and dormant pruning wounds. Pruning wounds made in summer healed within 1 to 2 weeks. Pruning wounds made in winter required about 2 to 3 weeks for healing to occur. Pss was not spread by contaminated loppers when cutting was done in January or August.