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IV. Variation in fungicide tolerance: Variation in Erysiphe graminis f. sp. hordei in response to the fungicide ethirimol
Author(s) -
HOLLOMON D. W.
Publication year - 1980
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1980.tb03938.x
Subject(s) - biology , powdery mildew , fungicide , heritability , erysiphe graminis , mildew , genetic variation , genotype , botany , bioassay , poaceae , horticulture , veterinary medicine , hordeum vulgare , genetics , gene , medicine
The genotypic variation of Erysiphe graminis f. sp. hordei was examined using ethirimol in an in vitro bioassay. ED 50 values of 45 isolates from untreated crops ranged from 0·002 μg/ml ‐1 to 20μg/ml 1 . Less variation was encountered in isolates from ethirimol treated crops, where ED 50 values ranged from 0·02 μg/ml ‐1 to 20μg/ml ‐1 . Crosses between isolates with intermediate levels of ethirimol sensitivity increased variation, and many progeny exceeded the sensitivity of either parent. The response of barley powdery mildew to ethirimol seems to be controlled by a complex genetic system, rather than by one or two major genes. Nevertheless, heritability was surprisingly high in two crosses analysed (0·596). Progeny virulent on the varieties Julia (v g ) or Sultan (v as ) were possibly more resistant to ethirimol than those with the alternative avirulent allele, but the differences were not significant ( P = 0·05).