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Disease Detection and Losses

Sorghum Downy Mildew Loss Assessment with Near-Isogenic Sorghum Populations. J. Craig, Research plant pathologist, Agricultural Research Service, U.S. Department of Agriculture, College Station, TX 77841; G. N. Odvody(2), G. C. Wall(3), and D. H. Meckenstock(4). (2)Assistant professor, Texas Agricultural Experiment Station, Texas A&M University Agricultural Research and Extension Center, Corpus Christi 78410; (3)(4)Former graduate student, Plant Pathology and Microbiology Department, and visiting assistant professor, Soil and Crop Sciences Department, Texas A&M University, College Station 77843. Phytopathology 79:448-451. Accepted for publication 10 November 1988. 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, 1989. DOI: 10.1094/Phyto-79-448.

Three near-isogenic sorghum populations were used to determine the effect of sorghum downy mildew on sorghum grain yields. The near-isogenic populations were developed from the F₃ generation of a cross between the susceptible inbred T×412 and the resistant inbred SC 414-12. The near-isogenic populations were prepared by mixing equal quantities of seeds from F₃ full-sib families having the same disease reaction classification. The populations were used to evaluate the relationship between downy mildew incidence and grain yields and to provide data to test a previously proposed model of downy mildew yield loss. A significant linear relationship was found between grain yield and downy mildew incidence, and an acceptable level of agreement occurred between measured yields and yields predicted by the downy mildew loss model.