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Identification, Disease Incidence, and Distribution of Viruses Infecting Peppers in California. O. A. Abdalla, Former Graduate Research Associate, Department of Plant Protection, College of Agriculture, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia. P. R. Desjardins, and J. A. Dodds. Professor, and Professor, Department of Plant Pathology, University of California, Riverside 92521. Plant Dis. 75:1019-1023. Accepted for publication 3 April 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1019.

In a 2-yr survey during 1984 and 1985, a total of 1,195 pepper (Capsicum annuum) samples were collected from Ventura, Tulare, and Imperial counties in California. An indirect enzyme-linked immunosorbent assay (ELISA) technique was used to test all samples for the presence of one or more of the following viruses: potato virus Y (PVY), tobacco etch virus (TEV), pepper mottle virus (PeMV), cucumber mosaic virus (CMV), potato virus X (PVX), alfalfa mosaic virus (AMV), and tobacco mosaic virus (TMV). Eight hundred and sixty samples were collected at random, and the rest of the samples were collected in a nonrandom manner based on selection of plants expressing symptoms. The percent virus incidence in the 486 random samples collected during the 1984 season was as follows for Ventura County: CMV, 39.1; TEV, 36.1; PVY, 31.5; PeMV, 28.2; AMV, 11.5; PVX, 9.7; and TMV, 7.6%. For Tulare County, the incidence was as follows: TEV, 98.8; PVY, 85.2; PeMV, 70.4; CMV, 67.9; AMV, 64.2; PVX, 60.5; and TMV, 22.2%. Incidence in Imperial County was as follows: TEV, 88; PVY, 82.7; PeMV, 76; TMV, 60; AMV, 54.7; PVX, 50.7; and CMV, 49.3%. The percent virus incidence in the 374 random samples collected during the 1985 season were as follows for Ventura County: TEV, 58.4; PVY, 51.7; PeMV, 40.4; CMV, 39.2; AMV, 39.2; TMV, 29.4; and PVX, 18.8%. For Tulare County, incidence was as follows: CMV, 97.5; TEV, 90; AMV, 50; PVX, 37.5; PeMV, 17.5; PVY, 10; and TMV, 0%. Incidence was as follows for Imperial County: PeMV, 87.3; PVY, 86.1; TEV, 82.3; AMV, 7.6; TMV, 2.5; CMV, 0; and PVX, 0%. In the 335 nonrandom, symptomatic samples gathered in 1985, the seven viruses were found in the following frequencies: TEV, 84; CMV, 67; PVY, 60; PeMV, 58; AMV, 51; PVX, 38; and TMV, 19%. Ten percent of the samples with viruslike symptoms were negative for the seven viruses for which tests were carried out. Mixed virus infections were dominant over single infections in the field and accounted for 64% of infected samples during the 1984 season and 90% during the 1985 season. The importance of PeMV in California has not been emphasized before this survey.