VIEW ARTICLE

Ring Nematodes Increase Development of Bacterial Cankers in Plums. H. Mojtahedi, Department of Nematology, University of California, Davis 95616; B. F. Lownsbery(2), and E. H. Moody(3). (2)(3)Department of Nematology, University of California, Davis 95616. Phytopathology 65:556-559. Accepted for publication 5 December 1974. DOI: 10.1094/Phyto-65-556.

In a lathhouse experiment, cankers developed on branches of Marianna 2624 plum trees injected with an aqueous suspension of the bacterium, Pseudomonas syringae. Cankers did not develop on control trees injected with sterile water. More extensive cankers developed on trees whose roots were infected with the ring nematode. Criconemoides xenoplax, than on control trees not infected by nematodes. P. syringae was isolated from the infection site and from necrotic tissue associated with the injection, but not outside the necrotic tissue, or from sites injected with water. The nematode-infected trees, which were more susceptible to the bacteria, differed from the nematode-free control trees in other respects. Water stress was greater and nutrient levels lower in their leaves. They were smaller, lacked feeder roots, and suffered from waterlogging. Progression of cankers to death of tops, as often occurs in the field, occurred in our experiment in only two trees, both inoculated with C. xenoplax and P. syringae. This indicates that additional factors are essential to full development of this disease.