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Vector Relations

Effect of Temperature on Transmission, Translocation, and Persistence of the Lettuce Big-Vein Agent and Big-Vein Symptom Expression. F. V. Westerlund, Research Plant Pathologist, Moran Seeds Inc., Salinas, CA 93901; R. N. Campbell(2), and R. G. Grogan(3). (2)(3)Professors, Department of Plant Pathology, University of California, Davis, CA 95616. Phytopathology 68:921-926. Accepted for publication 11 November 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-921.

Lettuce big-vein agent (BVA) was transferred to lettuce soon after protoplasts of Olpidium brassicae zoospores infected lettuce root cells. The BVA was translocated to the top of plants 1 to 4 days prior to symptom expression; the most rapid translocation occurred at 18 and 22 C, and the slowest at 10 C. Translocation occurred at temperatures unfavorable for symptom expression (24 C), and BVA persisted in some shoot tips at this temperature for about 1 mo. Big-vein symptom expression was affected by the temperature of the tops of plants. It was severe if the tops were at 14 C regardless of whether roots were at 14 C or 24 C; virtually no symptoms developed in infected plants if tops were at 24 C and the roots were at 14 C or 24 C. Further attempts to characterize or mechanically transmit BVA were unsuccessful.

Additional keywords: Lactuca sativa, soil-borne vectors, soil-borne pathogens.