Phytophthora Seed Rot and Seedling Blight of Sainfoin (Onobrychis viciifolia). F. A. Gray, Associate Professor, Plant Science Department, University of Wyoming, Laramie 82071. D. S. Wofford, Assistant Professor, Plant Science Department, University of Wyoming, Laramie 82071. Plant Dis. 71:74-78. Accepted for publication 3 June 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0074.

Phytophthora megasperma was recovered from damped-off seedlings of sainfoin (Onobrychis viciifolia) grown in field soil naturally infested with P. megasperma. In tests conducted in the greenhouse with several sterile growing media, seed and very young seedlings were readily colonized and killed by P. megasperma, whereas older plants were unaffected. The Canadian cultivar Nova and the Montana State University experimental line Bozeman showed a moderate level of seedling resistance. Seedling resistance was also shown in several O. viciifolia plant introductions. The highest resistance (85% seedling survival) occurred in PI 229613 from Iran. Treating seed with the fungicide metalaxyl increased seedling survival by 47% in field soil naturally infested with P. megasperma.