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Etiology

Identification, Seed Transmission, and Host Range Pathogenicity of a California Isolate of Melon Necrotic Spot Virus. R. Gonzalez -Garza, Former graduate student, Department of Plant Pathology, University of California, Riverside, CA 92521, Present address of senior author: Instituto Nacional de Investigaciones Agricolas, Centro de Investigaciones Agricolas del Golfo Norte, Campo Agricola Experimental General Terán, Nuevo León, México; D. J. Gumpf(2), A. N. Kishaba(3), and G. W. Bohn(4). (2)Associate professor, Department of Plant Pathology, University of California, Riverside, CA 92521; (3)Research entomologist, U.S. Department of Agriculture (USDA), Federal Research, Science and Education Administration (FR/SEA), Riverside, CA 92521; (4)Research geneticist, USDA, FR/SEA, Brawley, CA 92227. Phytopathology 69:340-345. Accepted for publication 21 September 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-340.

A 30-nm diameter isometric virus with host range restricted to the Cucurbitaceae was isolated from declining muskmelons. Systemic infections were produced only in Cucumis melo and C. anguria var. longipes. The virus had a dilution end point of 10^–4, a thermal inactivation point of 60 C and its longevity in vitro was 32 days. The virus was seed transmitted in commercial melon seeds and in an aphid-resistant melon inbred line. No symptoms were produced and virus could not be recovered from the top leaves in 8.8% of 78 melon lines, and hypersensitive reaction without systemic spread of virus was observed on 53.2% of those lines. The remaining 38% were systemically infected by the virus. Studies of host range, symptomatology, physical properties, transmission, and serology indicated that the virus is a strain of muskmelon necrotic spot virus.