First Report of Sclerotium rolfsii and Rhizoctonia solani on Sainfoin. K. E. Woodard, Texas Agricultural Experiment Station, Stephenville 76401. R. M. Jones, Texas Agricultural Experiment Station, Stephenville 76401. Plant Dis. 69:905. Accepted for publication 11 June 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-905f.
Sainfoin (Onobrychis viciaefolia Scop.) was planted in test plots at Stephenville in the spring of 1983 for evaluation as a potential forage crop in north central Texas. Plants began showing disease symptoms in June 1984 and 85% were dead or dying by 23 July. Sclerotium rolfsii Sacc. was isolated from crown tissue of all diseased plants, and Rhizoctonia solani Kühn was isolated from roots of about 25% of diseased plants. Koch’s postulates were completed for both S. rolfsii and R. solani. Symptoms on 2- to 3-mo-old plants inoculated with S. rolfsii included sudden wilting and browning, dry rot of the crown, and death of the plant within a few days. Abundant white mycelial growth and brown sclerotia developed on plant tissue at the soil line. Symptoms matched the disease progress observed in field plots. The R. solani AG-4 isolate caused preemergence and postemergence damping-off of 100% of the sainfoin seedlings at an inoculum density of 24 propagules per 100 g of sterilized soil. We believe this to be the first report of S. rolfsii and R. solani on sainfoin in the United States.