New South Wales, Australia
May 31, 2017

Canola growers in New South Wales still have options for control of blackleg this season despite reduced efficacy to fluquinconazole (a fungicide for seed treatment) observed in some paddocks.

A Grains Research and Development Corporation (GRDC) investment undertaken by Marcroft Grains Pathology and the University of Melbourne has shown that whilst fluquinconazole seed treatment (the active ingredient in products including Jockey®Stayer®) is no longer 100 per cent effective in approximately one in seven paddocks tested, several other fungicides from the same mode of action group remain unaffected.

All seed-applied fungicides currently registered for blackleg control in canola are from the same mode of action group, the Demethylation Inhibitors or DMI-fungicides.

Two years ago, canola stubble samples tested by researchers found that 15 per cent of 200 paddocks surveyed across Australia contained fungal isolates with tolerance to the active ingredient fluquinconazole.

“Tolerance means that the fungicide has reduced efficacy against the blackleg fungus compared to known susceptible isolates,” said University of Melbourne researcher, Dr Angela Van de Wouw.

“Because fluquinconazole is from the same mode of action group as some other fungicides used on canola, we were concerned there may be reduced effectiveness across the different active ingredients.

 “But our research to date shows positive news for growers – fluquinconazole-tolerant blackleg isolates showed no change in susceptibility to either prothioconazole plus tebuconazole applied as a foliar application or flutriafol applied in-furrow.

“Put simply, prothioconazole plus tebuconazole and flutriafol still remain effective against blackleg in situations where fluquinconazole has shown reduced efficacy.”

The research outcome is positive news for growers, given that a 30 per cent increase in canola plantings is expected this year.

“There will be a significant area of canola planted in 2017 and some growers may be concerned regarding the expected efficacy of fluquinconazole applied as a seed treatment on their property,” Dr Van de Wouw said.

“But for those growers, blackleg can likely still be managed through appropriate choice of fungicide chemistry – as just one part of an integrated disease management strategy based upon careful varietal selection, as highlighted in the GRDC’s Blackleg Management Guide.

The key pillars of management of blackleg, as detailed in the guide, include:

• Never sow a canola crop into last year’s canola stubble;
• Monitor crops in spring to determine yield losses in the current crop;
• Choose a cultivar with adequate blackleg resistance for your region (the updated Blackleg Management Guide includes the latest resistance ratings);
• Relying only on fungicides to control blackleg poses a high risk of fungicide resistance development;

If monitoring has identified yield loss and the same cultivar has been grown for three years or more, choose a cultivar from a different resistance group.

Website: http://www.grdc.com.au

Published: May 31, 2017