Resistance to Meloidogyne incognita in Trifolium Interspecific Hybrids and Species Related to White Clover. G. A. Pederson, Research Geneticist, USDA-ARS-CSRL, Forage Research Unit, Mississippi State, MS 39762. G. L. Windham, Research Plant Pathologist, USDA-ARS-CSRL, Forage Research Unit, Mississippi State, MS 39762. Plant Dis. 73:567-569. Accepted for publication 21 January 1989. 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/PD-73-0567.

Eight species of Trifolium and seven interspecific hybrids of Trifolium related to white clover (T. repens L.) were evaluated for resistance to the southern root-knot nematode, Meloidogyne incognita. The highest percentages of resistant plants (gall index <2 on a scale of 0–5) were found in MS-2x of T. ambiguum (38%) and T. nigrescens (32%). No resistant plants were observed for T. argutum, T. hybridum, PI 368173 of T. occidentale, T. repens, or PI 341939 of T. uniflorum. Fertile interspecific hybrids with mean gall indices <2 were (T. repens × T. nigrescens) × T. repens, T. isthmocarpum × T. repens, and T. repens × T. uniflorum. Due to its cross-fertility and high level of resistance, T. nigrescens may be a valuable source of resistance to M. incognita for white clover.