Evaluation of Foliar Clipping Treatments for Cultural Control of Sclerotinia Crown and Stem Rot in Crimson Clover. Robert G. Pratt, Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Forage Research Unit, Mississippi State 39762. Plant Dis. 75:59-62. Accepted for publication 25 June 1990. 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, 1991. DOI: 10.1094/PD-75-0059.

Foliar clipping treatments were applied to crimson clover at select points in the disease cycle of Sclerotinia crown and stem rot (SCSR), caused by Sclerotinia trifoliorum, to determine the potential of single and multiple clippings for cultural control of the disease. During each of 4 yr, crimson clover was seeded in September and grown until April. Foliage was cut in November and January of each year and in February during two of the years. Experiments were performed with and without sclerotia of S. trifoliorum added to plots. Estimates of SCSR severity and dry matter yields were obtained in April. During each of 3 yr in which environmental conditions favored SCSR, the November clipping was a significant (P ≥ 0.01) main effect for reduced disease severity and increased yield. The January clipping was a positive, negative, or nonsignificant main effect in different years. The February clipping was a negative main effect in 2 yr. Interactions between clipping treatments for disease severity or yield usually were not significant. Disease severity was inversely correlated (P ≥ 0.01) with clover yields in the 3 yr favorable for SCSR. These results indicate that cutting of foliage in November can provide significant cultural control of SCSR in crimson clover. Cutting in January may be beneficial but should not be attempted in locations subject to severe freezes. Cutting in February, and likely at other times after onset of mycelial spread of S. trifoliorum, should be avoided.