Fungicide resistance in Australian viticulture

B.H. Hall, S.F. McKay, F. Lopez, Harper, Sandra Savocchia, A. Borneman, M. Herderich

Research output: Book chapter/Published conference paperConference paper

Abstract

Powdery mildew, Botrytis bunch rot and downy mildew are the three most economically important diseases in Australian vineyards. To determine the· incidence and severity of fungicide resistance in Australia, samples of all three diseases were collected from vineyards in the main viticultural regions of Australia and tested against a range of commonly used fungicides. Leaf disc bioassays were used to determine the EC511 values ofErysiphe necator (powdery mildew) for sensitivity to pyraclostrobin, pencona ole, myclobutanil and tetraconazole, and of Plasmopara viticola (downy mildew) to rnetalaxyl M, m,mdipropamid and pyraclastrobin. EC511 values, minimum inhibitory concentra­tions and discriminatory dose values were established for Botrytis cinerea isolates using a microtitre assay system and mycelial growth assay against fenhexamid, iprodione, pyrimethanil, boscalid, tebuconazole, azoxystrobin and jludioxonil. Representative isolates of each pathogen were genotyped for the presence of known mutations conferring resistance. The mutation linked with quinone outside inhibitor (Qol) fungicide resistance, G 143A, was found in isolates of powdery mildew from moist viticultural regions. Vt'hile phenotypic resistance of E. necator to the demethylation inhibitorfungiddes (DMis) was not widespread, the mutation linked with resistance, YI36F, was present in approximately 60% of the powdery mildew isolates. Populations of P. viticola resistant to metalaxyl have been confirmed in all states except South Australia, ,md the allele conferring resistance to Qol has been detected. B. cinerea resistant populations to fenhexamid, iprodione, boscalid and pyrimethanil were detected. While 54% of sites had 110 resistance deteded, two sites had populations resistant to all four fungicides. The results of the testing so far has confirmed the presence of resistant populations of these three pathogens to many fungicides throughout Australia. However, more work is needed to confirm how these results relate to the potential for field failure.
Original languageEnglish
Title of host publication16th Australian Wine Industry Technical Conference (AWITC 2016)
EditorsKate Beames, Ella Robinson, Peter Dry, Dan Johnson
PublisherThe Australian Wine Industry Technical Conference Inc
Pages87-90
Number of pages4
ISBN (Print)9780987048097
Publication statusPublished - 2016
Event16th Australian Wine Industry Technical Conference (AWITC 2016) - Adelaide Convention Centre, Adelaide, Australia
Duration: 24 Jul 201628 Jul 2016
https://awitc.com.au/program/proceedings/sixteenth/ (Proceedings)

Conference

Conference16th Australian Wine Industry Technical Conference (AWITC 2016)
CountryAustralia
CityAdelaide
Period24/07/1628/07/16
OtherThe 16th Australian Wine Industry Technical Conference and Trade Exhibition was conducted from 24-28 July 2016 at the Adelaide Convention Centre. Attendee numbers were the highest (>1,100) since the 2007 Conference in Adelaide, with the overwhelmingly positive feedback received to date indicating that all found the event to be a great success.
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