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Resistance

Inheritance of Collar Rot Resistance in the Tomato Breeding Lines C1943 and NC EBR-2. Marisa Maiero, Former graduate student, Department of Horticulture, University of Maryland, College Park, MD 20742, Present address: Department of Agronomy and Horticulture, Box 30003, New Mexico State University, Las Cruces, NM 88003; Timothy J Ng(2), and Thomas H. Barksdale(3). (2)Professor, Department of Horticulture, University of Maryland, College Park, MD 20742; (3)Former plant pathologist, Vegetable Laboratory, USDA-ARS, Beltsville, MD 20705. Phytopathology 80:1365-1368. Accepted for publication 10 July 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-1365.

Collar rot is a tomato seedling disease caused by the fungus Alternaria solani. Resistant and susceptible parents, F₁, F₂, and backcross generations were evaluated for collar rot resistance in a greenhouse. Genetic analyses included midparent-hybrid comparisons, diallel analysis, and generation mean analysis. The genotypes C1943 and NC EBR-2 were most resistant to collar rot. Additive and dominant effects were important in controlling the trait, and collar rot resistance was incompletely recessive to susceptibility.