Reduced sensitivity of Uncinula necator to sterol demethylation inhibiting fungicides in southern Australian vineyards
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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 micro propagated 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.
Additional keywordsfungicide resistance grapevine powdery mildew
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- Köller W (1991) Fungicide resistance in plant pathogens. In ‘CRC handbook of pest management in agriculture. Vol. 2’. 2nd edn. (Ed. D Pimentel) pp. 679–720. (CRC Press Inc.: Boca Raton, Florida)Google Scholar
- Nass B (1991) The determination of baseline sensitivities of Uncinula necator (Schw.) Burr, to sterol demethylation inhibitors. Master Thesis, Lincoln University, New Zealand.Google Scholar
- Scheinpflug H (1988) Resistance management strategies for using DMI fungicides. In ‘Fungicide resistance in crop protection’. (Eds J Dekker, SG Georgopoulos) pp. 93–94. (PUDOC: Wageningen, The Netherlands)Google Scholar
- Steden C, Forster B, Steva H (1994) Sensitivity of Uncinula necator to penconazole in European countries. In ‘Fungicide resistance. BCPC monograph no. 60’. (Eds S Heaney, DW Slawson, DW Hollomon, M Smith, PE Russell, DW Parry) pp. 97–101. (British Crop Protection Council: Surrey, England)Google Scholar
- Steva H (1994) Evaluating anti-resistance strategies for control of Uncinula necator. In ‘Fungicide resistance. BCPC monograph no. 60’. (Eds S Heaney, DW Slawson, DW Hollomon, M Smith, PE Russell, DW Parry) pp. 59–66. (British Crop Protection Council: Surrey, England)Google Scholar
- Steva H, Cartolaro P, Clerjeau M, Lafon R, Gomes da Silva MT (1988) Une résistance de l′oidium au Portugal? Phytoma 402, 49–50.Google Scholar
- Wicks TJ, Emmett RW, Anderson CA (1997) Integration of DMI fungicides and sulfur for the control of powdery mildew. Australian and New Zealand Wine Industry Journal 12, 280–282.Google Scholar
- Wicks TJ, Emmett RW, Magarey PA, Fletcher GC (1984) Control of grapevine powdery mildew in southeastern Australia. I. Evaluation of protectant spray programmes. Agricultural Record 11, 12–15.Google Scholar
- Winter E, Anderson C (1998) A new approach to control grapevine powdery mildew. The Australian Grapegrower and Winemaker 417, 83–86.Google Scholar