Resistance to Colletotrichum fragariae in Strawberry Affected by Seedling Age and Inoculation Method. Barbara J. Smith, Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Small Fruit Research Station, Poplarville, MS 39470. L. L. Black, and G. J. Galletta. Professor, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803; and Research Geneticist, U.S. Department of Agriculture, Agricultural Research Service, Fruit Laboratory, Beltsville, MD 20705. Plant Dis. 74:1016-1021. Accepted for publication 18 June 1990. 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, 1990. DOI: 10.1094/PD-74-1016.

Two- to 4-wk-old strawberry seedlings (age after transplanting at the first true-leaf stage) were more susceptible to Colletotrichum fragariae than 14- to 18-wk-old seedlings when spray-inoculated with a conidial suspension. Comparisons were made among inoculation methods used to evaluate strawberry resistance to anthracnose crown rot caused by C. fragariae. Spray inoculation was the best method to determine the overall host reaction (i.e., the foliar and crown reaction of large populations of plants), but crown injection was more reliable to assess the crown response. In crown injection tests, more than half of 14- to 18-wk-old seedlings from crosses of anthracnose crown rot-resistant clones were resistant to the crown rot phase of this disease, while most cultivars and progenies of susceptible parents were very susceptible. Thus, it seems possible to screen for foliar and crown rot resistance.