pnut pnut Peanut Science 0095-3679 0095-3679 American Peanut Research and Education Society 10.3146/i0095-3679-24-1-5 Effect of Soil pH on Sclerotial Germination and Pathogenicity of Sclerotium rolfsii1 M-Y. Shim and J. L. Starr 2, * Dept. Plant Pathology and Microbiology, Texas A&M Univ., College Station, TX 77843

1 This study was partial fulfillment of the requirements for the first author's Ph.D. degree. Supported by the Texas Peanut Producers Board and USDA IPM grant no. 92-34103-6937.

 *Corresponding author. 1 1997 24 1 17 19 American Peanut Research and Education Society 1997 American Peanut Research and Education Society Abstract

The effect of soil pH on sclerotial germination and pathogenicity of two isolates of Sclerotium rolfsii on peanut was examined. Sclerotial germination for both isolates was greater (P ≤ 0.05) in acidic soil than at alkaline pHs. Similarly, percentage of peanut stems infected by S. rolfsii in greenhouse tests was greater at soil pH 5.6 than at alkaline soil pHs (P ≤ 0.05), but disease did develop at soil pH 8.7 and 9.8. In contrast to a previous in vitro study, these data confirm that sclerotia of S. rolfsii will germinate and initiate disease at soil pH > 7.0.

 Key Words Arachis hypogaea; , groundnut; , peanut; , stem rot; , sclerotia