Abstract Detail

Host/Plant Pathogen Interactions and Plant Health Management

Bisht, Vikram [1], Gudmestad, Neil [2], Desjardins, Mardi [3].

Occurrence of Boscalid and Azoxystrobin Resistance in Manitoba Isolates of Alternaria solani..

Early blight pathogen, Alternaria solani (Asol) has shown extensive resistance to boscalid and azoxystrobin fungicides in many potato growing regions of the US, including North Dakota. It was speculated that such resistance may also be present in Manitoba. Asol isolates were collected from all potato growing areas of Manitoba in 2012 and 2013 to determine the extent of boscalid (SDHI, FRAC #7) and azoxystrobin (QoI, FRAC #11) sensitivity. Over 120 isolates were tested in Manitoba lab using 50 ppm fungicide-amended PDA plates. Isolates (286) from 2012 and 2013 were sent to NDSU lab for molecular analysis for SDHI and F129 (QoI) mutations for fungicide resistances. SDHI mutations (H278Y, H278R, H134R, H133R and D123E) were identified in 57% of the isolates in 2013. This may be the first report of boscalid resistance from MB. SDHI mutations in AsSDHB gene (associated with moderate to very high boscalid resistance) were most prevalent- H278Y and H278R representing 17% and 22% of all isolates. AsSDHD gene mutations - H133R (2%) and D123E (4%) were least common. All isolates of 2012 and 43% of 2013 had no SDHI mutation, and were boscalid sensitive; while only 1% of North Dakota isolates were still sensitive. F129L mutation occurred in 98% of isolates, leading to reduced sensitivity to azoxystrobin. Dual fungicide resistance occurred in 40% of 2013 isolates, while 21% were sensitive to both. In general Manitoba isolates exhibited varying levels of SDHI reaction from highly sensitive to very insensitive, but against azoxystrobin there was a moderate level of insensitivity in most isolates.

1 - Manitoba Agriculture, Food and Rural Development, Crops Knowledge Center, 63, 3rd Ave. NE, PO Box 1149, Carman, MB, R0G 0J0, Canada
2 - North Dakota State University, Department of Plant Pathology , Walster Hall 306, Fargo, ND, 58102, USA
3 - Manitoba Agriculture, Food and Rural Development, Crops Diagnostic Center, 545 University Crescent, Winnipeg, MB, R3T 5S6, Canada

Keywords:
Early blight
Alternaria solani
Boscalid
Azoxystrobin
Fungicide resistance.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PPA023
Abstract ID:800
Candidate for Awards:None