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Vector Preference, a Factor of Resistance to Curly Top Virus in Certain Tomato Cultivars. Peter E. Thomas, Plant Pathologist, Plant Science Research Division, ARS, USDA, Prosser, Washington 99350; Mark W. Martin, Geneticist, Plant Science Research Division, ARS, USDA, Prosser, Washington 99350. Phytopathology 61:1257-1260. Accepted for publication 26 May 1971. DOI: 10.1094/Phyto-61-1257.

A portion of the resistance of certain tomato cultivars to infection by curly top virus appears to be the result of nonpreference by the vector, Circulifer tenellus. Leafhoppers released on plants of six susceptible and six resistant cultivars spent less time on certain of the resistant than on the remaining resistant and susceptible cultivars. We developed a method to remove any resistance attributable to nonpreference from results of susceptibility assays. Those cultivars upon which leafhoppers spent the least time were 21 to 23% more susceptible to virus infection when resistance attributable to nonpreference by the vector was removed; but the susceptibility of the other cultivars was not affected. The major portion of resistance could not be attributed to vector preference and, therefore, must be the result of mechanisms operative after introduction of virus into the plant by the vector.

Additional keywords: Lycopersicon, incidence of infection, relative resistance, susceptibility tests.