Farm Management

Blackleg defence options still available for canola growers

Fungicide efficacy studies by University of Melbourne researcher Dr Angela Van de Wouw (pictured) have produced positive news for canola growers. Photo: Emma Leonard

Canola growers in the southern cropping region 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 in 2017.

“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.

Source: GRDC

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