Top 3 diseases to watch for fungicide resistance

Three key fungicide resistance findings from the 2016 growing season remind Australian growers to stay vigilant when it comes to monitoring crop disease.

These are findings of the annual sampling report by the Fungicide Resistance Group, a program within the Centre for Crop and Disease Management, co-supported by Curtin University and the Grains Research and Development Corporation (GRDC).  

The three findings include wheat powdery mildew resistance (Figure 1C) to strobilurin fungicides from group 11, net-form of net blotch resistance (Figure 1A) to triazole fungicides from group 3, and the increasing spread of barley powdery mildew resistance (Figure 1B) to triazole fungicides from group 3.

Figure 1. A) Barley net form of net blotch, B) barley powdery mildew and C) Wheat powdery mildew have been highlighted in the 2016 Fungicide Resistance Group sampling report.

Figure 1. A) Barley net form of net blotch, B) barley powdery mildew and C) Wheat powdery mildew have been highlighted in the 2016 Fungicide Resistance Group sampling report.

Dr Fran Lopez-Ruiz is leading the research and said wheat powdery mildew resistance to strobilurin fungicides was probably the most concerning of the three cases highlighted in the report.

“This finding from Tasmania and Victoria will impact all areas affected by wheat powdery mildew, acting as an early warning to implement anti-resistance strategies against this disease, particularly as there are only two modes of action currently available to treat wheat powdery mildew,” he said.

“Net-form of net blotch resistance to triazole fungicides from group 3 was an interesting find in WA, as the pathogen’s target had changed shape and the number of targets had increased.

“And barley powdery mildew resistance is an old story for WA, but we are now seeing it spread to other states, as this pathogen gets the better of triazole fungicides from group 3.”

Figure 2. Detection of fungicide resistance in the grains industry from 2012 - 2016.

Figure 2. Detection of fungicide resistance in the grains industry from 2012 – 2016.

Dr Lopez said now, more than ever, growers should be using Integrated Disease Management (IDM) strategies to complement fungicide use in efforts to slow down the build-up of fungicide resistant disease.

He said responsible use of fungicides (such as rotations and mixtures), seeding resistant crop varieties and crop rotations are a great place to start.

“Also, if growers would like to test their crops for fungicide resistance, even before there are any obvious signs, they are more than welcome to send us a sample,” he said.

Dr Lopez-Ruiz says it is his team’s versatility and specialist knowledge which allowed them to find these cases of fungicide resistance.  

“Our team specialises in the detection of fungicide resistance and studying the mechanisms which allow resistance to occur,” he said.

“Our methodologies and the tools we produce can be applied to any fungal pathogen, so we find ourselves looking at many different pathogens across different crops and even across different industries.”

Dr Lopez-Ruiz said their resistance findings is thanks to the support of agronomists, crop advisers, industry and other research groups by sending in samples of crop disease and providing invaluable feedback.

“The detection of strobilurin resistance in wheat powdery mildew would not have occurred without field reports from local agronomists and researchers in Tasmania and Victoria. Monitoring the status of disease resistance is a really big job, and we can’t do this without support from the field.

“We hope to get more samples from the field in 2017 so we can continue to monitor disease for fungicide resistance.”

Download the full report here from the CCDM website. If you would like to send in samples of disease during 2017, email the team at frg@curtin.edu.au for more information.

Further information on sampling for and managing fungicide resistance is available on the CCDM website: http://ccdm.com.au/frg/

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