Biology of Triphenyltin-Resistant Strains of Cercospora beticola from Sugar Beet. C. N. Giannopolitis, Benaki Phytopathological Institute, Kiphissia, Athens, Greece. M. Chrysayi-Tokousbalides, Benaki Phytopathological Institute, Kiphissia, Athens, Greece. Plant Dis. 64:940-942. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-940.

Strains of Cercospora beticola resistant to triphenyltins in vitro isolated from sugar beets in northern Greece caused leaf spot disease that was not controlled in growth chamber studies by recommended rates of triphenyltin acetate. Resistant strains do not differ from sensitive strains in in vitro growth rate or colony characteristics. No relationship exists between triphenyltin resistance and benzimidazole resistance in the pathogen. Virulence varies among both triphenyltin-resistant and -sensitive strains. Triphenyltin-resistant strains, however, seem to have less competitive ability than triphenyltin-sensitive strains, which could account for the delayed appearance of resistance to this fungicide. Because of their reduced competitive ability, resistant populations in the field may decline after the selective agent (triphenyltins) has been removed.

Keyword(s): maneb.