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IV. Variation in fungicide tolerance: Comparisons between isolates of Erysiphe graminis f. sp. hordei tolerant and sensitive to the fungicide tridemorph
Author(s) -
WALMSLEYWOODWARD DIANNE J.,
LAWS F.,
WHITTINGTON W. J.
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.tb03939.x
Subject(s) - biology , fungicide , powdery mildew , mildew , horticulture , germination , pathogen , cultivar , botany , veterinary medicine , microbiology and biotechnology , medicine
Forty‐five single pustule isolates of barley powdery mildew taken at random from tridemorph treated and untreated plants were maintained in culture on leaf segments of barley cv. Golden Promise placed on agar containing benzimidazole. In repeated assays for tridemorph tolerance over a 10 month period, tolerance was found in 25 of 36 isolates from treated plants, and remained stable in all but four of the isolates wherein tolerance was lost after varying lengths of time. A negative correlation was found between pathogenicity and tolerance. The germination of tolerant isolates was less depressed than the sensitive on treated seedlings, but no differences between isolates were found on untreated seedlings. Colony growth of all isolates was slower on treated than untreated seedlings. On plants of several cultivars kept in growth rooms, mildew progressed more rapidly on treated barley when tolerant isolates were used as inoculum. Visible disease symptoms spread most rapidly on isolated, untreated plants, and most slowly on isolated treated plants, irrespective of the isolate. Disease on treated plants progressed more rapidly when untreated plants were adjacent, suggesting that interactions take place between pathogen populations on treated and untreated plants.