ISHS Acta Horticulturae 169: International Workshop on Improvement of Sweet and Sour Cherry Varieties and Rootstocks
ROOT AND CROWN ROT OF CHERRY IN NEW YORK CAUSED BY PHYTOPHTHORA MEGASPERMA AND PHYTOPHTHORA CRYPTOGEA |
| Authors: | J.E. Hayes, H.S. Aldwinckle, S.N. Jeffers |
| Abstract:
Increasing losses of cherry trees in New York orchards were found to be frequently associated with root and crown rot. This study was undertaken to determine whether Phytophthora species were associated with the problem, to identify the species involved, and to demonstrate their pathogenicity to cherry. During the summers of 1980, 1981, and 1982, isolations were made from diseased root and crown tissues of 23 cherry trees in six orchards in western New York. Phytophthora megasperma and Ph. drechsleri were isolated from six trees in three orchards and five trees in two orchards, respectively. Two species of Pythium were also isolated. One isolate of each of these fungi, as well as other isolates of Ph. megasperma from apple, alfalfa, soybean, and cherry were each tested for pathogenicity on 4-mo-old Mahaleb cherry and Grimes Golden apple seedlings in artificially infested, pasteurized orchard soil. The same isolates were also tested for pathogenicity on 6-wk-old alfalfa plants growing in artificially infested vermiculite and on 15-day-old soybean plants using a hypocotyl inoculation technique. The New York isolate of Ph. drechsleri from cherry killed all of six cherry seedlings and Ph. megasperma from cherry in New York killed four of six. Ph. megasperma from cherry in California, apple, alfalfa, and soybean each killed one of six seedlings. One cherry seedling grown in Pythium-infested soil died. Phytophthora drechsleri from cherry in New York was most virulent on the apple seedlings, also. All other isolates except Ph. megasperma var. sojae caused some symptom development. Only isolates of Ph. megasperma originally from alfalfa and soybean caused necrosis on those plants. In 1982, 12-yr-old cherry trees were wound-inoculated at the root crown with Phytophthora drechsleri from cherry in New York, Ph. megasperma from cherry in New York and California, and Pythium sp. #1. The trees were inoculated at bloom, during shot expansion, and after bud set. No definite conclusions were drawn pertaining to rootstock susceptibility or time of greatest host susceptibility. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
