VIEW ARTICLE

Origin, Cause, Host Range and Spread of Cherry Rasp Leaf Disease in North America. A. Juergen Hansen, Research Scientist, Research Station, Agriculture Canada, Summerland, British Columbia; G. Nyland(2), F. D. McElroy(3), and R. Stace-Smith(4). (2)Professor, Department of Plant Pathology, University of California, Davis 95616; (3)(4)Research Scientists, Research Station, Agriculture Canada, Vancouver 8, British Columbia. Phytopathology 64:721-727. Accepted for publication 11 December 1973. DOI: 10.1094/Phyto-64-721.

Eleven virus isolates, serologically identical with cherry rasp leaf virus, were recovered from sweet cherry, peach, dandelion (Taraxacum officinale), plantain (Plantago major), native balsamroot (Balsamorhiza sagittata), apple trees inoculated with infected cherry buds, and from the nematode, Xiphinema americanum. Rasp leaf disease was induced in cherry cultivars by inoculation with buds from sap-inoculated seedlings of Prunus mahaleb, by inoculation of P. avium seedlings with infective nematodes, and by implant chips of infected Gomphrena globosa plants in California. Natural spread to peach occurred in an orchard and in an experimental plot in California. The herbaceous host ranges of five selected isolates were identical, and 22 of 24 test species became infected. The severity (but not the type) of symptoms varied between isolates and sources, but serological interactions in agar gels showed that all the isolates were closely related or identical, and that they were not related to the viruses which cause Eola rasp leaf and the rasp leaf diseases of Europe. The virus was seed-transmitted in Chenopodium quinoa and dandelion. It could be recovered readily from bait plants grown in infested field soil and from X. americanum in such soil. Local transmission by nematodes and presence of the virus in balsamroot or other native hosts probably explain the slow spread of the disease, and its occurrence over much of western North America.