VIEW ARTICLE

Resistance

Increased Value of Resistance to Infection if Used in Integrated Pest Management Control of Tomato Curly Top. M. W. Martin, Geneticist, Vegetable Crops Production, Agricultural Research Service, U.S. Department of Agriculture, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350; P. E. Thomas, plant pathologist, Vegetable Crops Production, Agricultural Research Service, U.S. Department of Agriculture, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350. Phytopathology 76:540-542. Accepted for publication 20 December 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-540.

Cultivars derived from the University of California tomato release VF145 have shown a tendency to escape the curly top disease caused by beet curly top virus. This resistance was much more effective under mild to moderate disease exposures, similar to those encountered in direct-seeded commercial fields, than under severe exposures in disease nurseries. Over a 13-yr period, in curly top nurseries at Prosser, WA, incidence of curly top in VF145 cultivars averaged 25% lower than in cultivars used to replace these VF145 cultivars in California. When considering only years of moderate exposure, however, the reduction in curly top by use of VF145 cultivars was 52%. The predominance of VF145 cultivars is suggested as an important component of the integrated pest management practices which greatly reduced curly top losses in California processing tomatoes during the last 30 yr. The disease-escaping ability of VF145 cultivars apparently was derived from cultivar Tiny Tim and is possessed by all VF145 cultivars tested. This disease-escaping ability of VF145 cultivars makes them particularly useful as parents in crosses with germ plasm having even higher levels of curly top resistance.