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Resistance

Aspects of the Protection of Cucumber Against Colletotrichum lagenarium by Colletotrichum lagenarium. J. Kuć, Professor, Department of Plant Pathology, University of Kentucky, Lexington, KY 40506; Susan Richmond, Graduate Student, Department of Plant Pathology, University of Kentucky, Lexington, KY 40506. Phytopathology 67:533-536. Accepted for publication 6 October 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-533.

Inoculation of a cotyledon or first true leaf (leaf 1) of cucumber with Colletotrichum lagenarium systemically protected cucumber plants against disease caused by subsequent challenge inoculations by this pathogen. Protection was evident as a reduction in the number and size of lesions. Inoculation of leaf 1 when the second true leaf (leaf 2) was one-fourth to one-third expanded, systemically protected plants for 4-5 wk. A second or booster inoculation, 3 wk after the first inoculation, extended the time of protection into the fruiting period. Protection was elicited by and effective against two races of the fungus and was evident, not only with susceptible cultivars, but also with two cultivars which have resistance to anthracnose. A direct relationship existed between the number of spores used for protection and the extent and duration of protection. A single lesion produced significant protection. Protection of leaf 2 was evident 96 hr after leaf 1 was inoculated. Excising leaf 196 hr after inoculation did not reduce protection of leaf 2. Leaf 2 was protected if excised 120 hr after leaf 1 was inoculated.