Resistance to Viruses in Trifolium Interspecific Hybrids Related to White Clover. G. A. Pederson, Research Geneticist, USDA-ARS-CSRL, Forage Research Unit, Mississippi State, MS 39762. M. R. McLaughlin, Research Plant Pathologist, USDA-ARS-CSRL, Forage Research Unit, Mississippi State, MS 39762. Plant Dis. 73:997-999. Accepted for publication 4 July 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-73-0997.

Six Trifolium interspecific hybrids, 24 F₂ plants from T. ambiguum × T. repens hybrid 435, and 48 T. ambiguum plant introductions and populations were evaluated for resistance to peanut stunt virus (PSV), clover yellow vein virus (CYVV), and alfalfa mosaic virus (AMV). One T. repens × T. occidentale, three T. ambiguum × T. hybridum, and two T. ambiguum × T. occidentale hybrids were resistant to PSV. Of these, only the T. repens × T. occidentale hybrid was fertile. Fifteen F₂ plants from T. ambiguum × T. repens hybrid 435 were resistant to PSV, CYVV, and AMV. The T. ambiguum plants had 99 and 100% resistance to PSV and CYVV, respectively. The T. repens × T. occidentale hybrid and T. ambiguum × T. repens F₂ plants may be valuable sources of virus resistance for incorporation into adapted white clover cultivars.