Tolerance of Sclerotinia minor to Procymidone and Cross Tolerance to Other Dicarboximide Fungicides and Dicloran1

Abstract Procymidone-tolerant isolates of Sclerotinia minor Jagger were cross-tolerant to iprodione, vinclozolin and dicloran. Hyphal growth of procymidone-tolerant isolates an agar amended with 1 to 100 μg/mL procymidone, iprodione, vinclozolin or dicloran was similar. Procymidone-tolerant isolates were tolerant to all fungicides after 10 weekly hyphal tip transfers to nonamended agar. Subsequently, cross-tolerance persisted on agar amended with either 10 μg/mL procymidone, iprodione, vinclozolin or dicloran. Most procymidone-tolerant isolates of S. minor were pathogenic to peanuts (Arachis hypogaea L.) and caused symptoms similar to those initiated by sensitive isolates.