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https://hdl.handle.net/2440/39
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Type: | Journal article |
Title: | Reduced sensitivity of Uncinula necator to sterol demethylation inhibiting fungicides in southern Australian vineyards |
Author: | Savocchia, S. Stummer, B. Wicks, T. Van Heeswijck, R. Scott, E. |
Citation: | Australasian Plant Pathology, 2004; 33(4):465-473 |
Publisher: | C S I R O Publishing |
Issue Date: | 2004 |
ISSN: | 0815-3191 |
Abstract: | Isolates of Uncinula necator with reduced sensitivity to triadimenol and, to a lesser extent, fenarimol have been detected in Australian vineyards. Grapevine leaves and berries affected by powdery mildew were collected from a home garden and 13 vineyards in nine viticultural regions in Australia between 1993 and 1998. Single-spore isolates of U. necator established from vines, either not exposed to DMIs (‘unexposed’ collection) or treated with DMIs (‘selected’ collection), were maintained on micropropagated grapevines in vitro. A bioassay for fungicide sensitivity was used to test 60 single-spore isolates of U. necator for sensitivity to triadimenol. Of these, 34 were tested for sensitivity to fenarimol. Mean EC₅₀ values for the 12 unexposed isolates were 0.07 and 0.08 mg/L for triadimenol and fenarimol, respectively. For the selected isolates, mean EC₅₀ values were 0.83 mg/L for triadimenol and 0.19 mg/L for fenarimol. In comparison with the unexposed population, there appeared to have been a shift in the selected population towards reduced sensitivity. Examination of more isolates from vineyards not exposed to DMIs may strengthen this conclusion. Cut-off EC₅₀ values, used to define individual isolates as having reduced sensitivity, were 0.42 mg/L (resistance factor, RF = 6) for triadimenol and 0.12 mg/L (RF = 1.5) for fenarimol. The findings were consistent with the existence of cross-resistance between triadimenol and fenarimol. |
Keywords: | Fungicide resistance grapevine powdery mildew |
DOI: | 10.1071/AP04066 |
Published version: | http://dx.doi.org/10.1071/ap04066 |
Appears in Collections: | Agriculture, Food and Wine publications Aurora harvest 6 |
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