Sclerotia of Sclerotinia minor were soaked in a conidial suspension (1.3 × 107 conidia/mL) of Penicillium citrinum at 25 ± 2 C for 1 h. This resulted in coating each sclerotium with about 3.7 × 104 conidia. Treated sclerotia were incubated either in the dark on dry or damp Whatman No. 1 filter paper or in pasteurized and nonpasteurized soil at 25 ± 2 C, for up to eight weeks. Colonization by P. citrinum of sclerotia incubated on damp or dry filter paper was 70 and 25%, respectively. Seventy four percent of sclerotia incubated in pasteurized soil were colonized and destroyed by P. citrinum, whereas 55% colonization and destruction occurred in sclerotia incubated in a nonpasteurized soil. Similarly treated sclerotia of Sclerotinia sclerotiorum variety major and Sclerotium rolfsii were incubated in pasteurized soil and colonized by P. citrinum at 45 and 5%, respectively, over the same period of time. Up to 50% colonization and destruction by P. citrinum has been observed on sclerotia of S. minor recovered from soil in a peanut field in Oklahoma. These findings suggest a potential use of P. citrinum as a biocontrol agent for S. minor.

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Author notes

1Cooperative investigation of U.S. Department of Agriculture, Agricultural Research Service and Oklahoma State University. Journal Article No. 5162, Oklahoma Agricultural Experiment Station, Oklahoma State University, Stillwater. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the USDA or by Oklahoma State University, or imply their approval to the exclusion of other products or vendors that may also be suitable.