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A Cultural Variant of a Benomyl-tolerant Strain of Cercospora beticola. E. G. Ruppel, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, Crops Research Laboratory, Colorado State University, Fort Collins 80523; Phytopathology 65:734-735. DOI: 10.1094/Phyto-65-734.

A white variant (H1-12/W) developed from a benomyl-tolerant strain (H1-12) of Cercospora beticola on potato-dextrose agar containing 100 µg (active ingredient) benomyl/ml. The variant was stable through repeated subculturing and in passage through sugar beet. Benomyl tolerance of H1-12/W was similar to that of H1-12; however, the latter sporulated more prolifically in vitro and in vivo than the variant. H1-12/W was only slightly less virulent than H1-12 in sugar beet, but the incubation period for lesion formation was almost twice as long for H1-12/W as for H1-12. Reisolations from sugar beet infected with H1-12/W yielded cultures identical to H1-12/W, with no reversions to the parental strain.

Additional keywords: sugar beet, Beta vulgaris, strain virulence.