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Resistance

Graft Transmission of Systemic Resistance of Cucumber to Anthracnose Induced by Colletotrichum lagenarium and Tobacco Necrosis Virus. A. E. Jenns, Graduate student, Department of Plant Pathology, University of Kentucky, Lexington, 40546; J. Kuc, professor, Department of Plant Pathology, University of Kentucky, Lexington, 40546. Phytopathology 69:753-756. Accepted for publication 31 January 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-753.

Resistance to anthracnose, which was induced by infection of the first true leaf of cucumber cultivar SMR-58 with Colletotrichum lagenarium or tobacco necrosis virus (TNV), was transmitted to a scion of the same cultivar grafted onto the infected plant above the first true leaf. Resistance also was transmitted if grafting preceded the inducing inoculation. Resistance to anthracnose in susceptible cucumber was not transmitted by grafting onto uninoculated resistant cultivars but it was transmitted if the resistant rootstocks were inoculated with C. lagenarium. Susceptible cucumbers remained susceptible to anthracnose when grafted onto rootstocks of pumpkin and squash which were uninoculated or inoculated with C. lagenarium or TNV. C. lagenarium did not produce visible lesions on pumpkin or squash leaves, but TNV did so. Watermelons and muskmelons grafted onto susceptible cucumber rootstocks were protected against anthracnose by inoculating the rootstocks with C. lagenarium. The “signal” for induced systemic resistance is not cultivar-, genus-, or species-specific.