New video puts the spotlight on wheat powdery mildew in WA

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The GRDC is investing in CCDM research to assess fungicide resistance for wheat powdery mildew.

PHOTO: Melissa Williams

Valuable research into fungicide resistance is taking place in Western Australia to maintain the long-term efficacy of control options for wheat powdery mildew (WPM).

There are only two fungicide active ingredients registered for control of WPM and growers rely on these heavily. These are Group 3 (demethylation inhibitors, DMI) and Group 11 (strobilurin/quinone outside inhibitors, QoI) that are already sold in mixtures with DMIs (such as azoxystrobin and epoxiconazole).

Another concern for industry is the recent discovery of the first cases of WPM resistance to strobilurin fungicides found in 2016 crop samples collected in Victoria and Tasmania. But researchers say that given this was an early finding there is more likelihood that the efficacy of this group of fungicides can be maintained for the longer term.

To achieve this, growers need to be mindful of what products they are using on wheat crops this year and in future seasons, says Dr Fran Lopez-Ruiz, Fungicide Resistance Group leader at the GRDC-supported Centre for Crop and Disease Management (CCDM).

Dr Lopez-Ruiz outlines tips for managing fungicide use for WPM in a new ‘Know More’ video by the GRDC. The short video guide covers the use of fungicides, how to report suspect samples and resistance issues, and the importance of research into preserving fungicide actives.

Dr Lopez-Ruiz advises in conducive seasons and susceptible areas it can be valuable to growers to monitor crops regularly and use a maximum of one strobilurin/QoI spray per year. He says if the crop requires extra fungicide treatments, it is advisable to use a DMI formulation that was not in the previous fungicide application, even if that DMI was in a DMI and strobilurin or QoI mixture. “To slow the evolution of resistance, we have to rotate within and between fungicide modes of action, and always check the registration label,” he says.

The Department of Agriculture and Food, WA (DAFWA), undertakes widespread crop disease surveillance across the WA grainbelt during the winter growing season. Results are available by subscribing to the department’s PestFax newsletter.

Growers are encouraged to report disease incidence through DAFWA’s mobile apps (MyPestGuide Reporter or MyCrop or PestFax).

Dr Lopez-Ruiz says leaf samples of disease – or suspected fungicide failure – can be mailed to CCDM for testing, along with stubble samples after harvest. More information is available on the CCDM website.

He says a better understanding of the resistance of diseases to a range of fungicides aids growers in either selecting appropriate varieties, or having a greater awareness of the major disease risks for crops and planning to address foliar diseases.

A full list of registered fungicide formulations can be found on the Australian Pesticides and Veterinary Medicines Authority website.

GRDC Research Code CUR00023

More information:

Dr Fran Lopez-Ruiz, CCDM,
08 9266 3061,

Useful resources:

Centre for Crop and Disease Management

GRDC Fact Sheet – ‘Wheat powdery mildew

Managing powdery mildew in wheat’, DAFWA

DAFWA mobile apps