Levels, Dependability, and Usefulness of Resistance to Tomato Curly Top Disease. 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. Plant Dis. 70:136-141. Accepted for publication 31 July 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-136.

Disease losses caused by beet curly top virus (BCTV) in lines of tomato (Lycopersicon esculentum) derived from interspecific hybridization with wild Lycopersicon species ranged from essentially none to almost complete destruction over a 3-yr period. Exposure to large populations of viruliferous leafhoppers in transplanted field disease nurseries caused disease incidence ranging from a low of 2–14% in the most resistant group through several intermediate levels to 70–100% in the most susceptible commercial cultivars. The various levels of resistance were consistent from year to year and were accurately determined throughout the season when the disease was prevalent. Disease incidence was more strongly influenced in some lines than others by plant age at time of disease exposure. Fields transplanted in May and interplanted with sugar beets provided the severe disease exposure needed to screen and compare hybrid progenies with standard reference lines from representative types. Resistance potentially useful in commercial production was not accurately measured when transplanting was delayed until midsummer, when vector populations were very large.

Keyword(s): integrated pest management.