Submitted to: International Congress of Plant Pathology Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/16/1998
Publication Date: N/A
Technical Abstract: Sclerotinia blight, caused by Sclerotinia minor, is a devastating disease of peanut in Oklahoma and Texas, USA. The pathogen produces numerous sclerotia on culture media and on infected plant tissues as a mechanism of survival. Reaction of peanut germplasm and breeding lines to S. minor is performed under greenhouse conditions as well as in small field plots. A non-sclerotia-forming (NSF) isolate of S. minor was recovered from the field and was found to be non-pathogenic to peanut under greenhouse conditions. The objective of this research was to examine the degree of compatibility among sclerotia-forming (SF) and NSF isolates of S. minor. Thirteen isolates were initially paired, in a Latin Square design, in 9-cm diameter petri plates filled with 15 ml potato-dextrose-agar medium containing 100 mg streptomycin sulfate/L, to determine the macroscopic characteristics of reaction between the isolates. The microscopic examination of mycelial fusion among isolates was performed using the cellophane technique. The NSF isolate macroscopically exhibited incompatibility with all the SF isolates, where a distinct no-growth area separated the paired cultures on the petri plates. Also, two SF isolates were incompatible with the rest of the SF isolates in paired cultures. Mycelial fusion among compatible isolates ranged from 47 to 69%. Although macroscopically incompatible, a low degree of mycelial fusion (<20%) occurred between the two SF isolates and some of the SF isolates. No mycelial fusion occurred between the NSF isolate and any of the SF isolates. The pathological significance of these findings is being investigated.