Treat fungicides as a precious resource

Photo of Fran Lopez Ruiz

Dr Fran Lopez-Ruiz, leader of the Centre for Crop and Disease Management Fungicide Resistance Group, says the best way to slow the development of fungicide resistance is to integrate multiple disease prevention strategies.


Fungicide resistance makes it more important than ever for growers to use a range of disease control strategies and use fungicides as a late, rather than first, option

Integrated disease management strategies

  1. Identify plant pathogens.
  2. Use fungicides correctly: always use recommended label dose and apply at the right time.
  3. Use fungicide mixtures with different MOA where possible.
  4. When possible, alternate fungicides with different MOA between spray routines.
  5. Implement stubble management and crop rotations. Manage the ‘green bridge’.
  6. Avoid susceptible crop varieties: check the annual crop variety guides.
  7. Know individual paddock risk. Plan ahead.
  8. Stay up to date on fungicide resistance developments – sign up for the CCDM newsletter.
  9. Participate in crop disease monitoring by sending in samples to the CCDM.

Fungicides are an important tool for controlling crop disease. However, growers need to make sure they treat fungicides as precious resources and use them as part of an integrated disease management (IDM) strategy that takes into account the risk of resistance development.

Researchers at the Centre for Crop and Disease Management (CCDM) are working on the development of readily adoptable tools to lessen the evolution of resistance. The CCDM, based at Curtin University, WA, was established in 2014 as the first of the bilateral research agreements that have been set up between the GRDC and specialist research institutions.

The centre’s Fungicide Resistance Group leader Dr Fran Lopez-Ruiz says the background to the research effort is the fact that fungal pathogens are notorious for developing resistance.

Resistance arises and takes hold when disease populations are repeatedly exposed to a single fungicide mode of action (MOA), without diversity. However, it is not until the population is resistant that growers notice fungicide failure.

“To put it simply, when we use a single fungicide mode of action, without diversity, susceptible strains are killed, while rare resistant individuals that contain rare genetic mutations are able to survive, in time taking over the population.”

With the growing threat of fungicide resistance across demethylation inhibitor fungicides, it is now more important than ever for growers to use integrated disease-control strategies. These strategies are summarised in a nine-point plan (see box) and include using fungicide mixtures and rotations with more than one MOA. The use of IDM has been shown to play a pivotal role in delaying the onset of fungicide resistance.

The Fungicide Resistance Group has been working with the CCDM’s newly appointed Improved Farming Systems program team to progress IDM strategies.

Improved Farming Systems program researcher Dr Mike Ashworth says reducing the severity of crop disease comes down to being prepared: “The more we know about crop diseases, the easier it is for us to help the industry avoid major outbreaks.

“Our research aims to refine techniques growers can use in the field and help them to incorporate additional disease-control diversity to avoid the development of fungicide resistance.”

Dr Ashworth encourages growers to use the limited number of effective fungicides available carefully.

More information:

Centre for Crop and Disease Management

Fungicide Resistance Group,

Dr Fran Lopez-Ruiz,

08 9266 306

Dr Michael Ashworth,

Useful resource:

Integrated Weed Management Manual


Seed destructor a model of R&D teamwork


Disease persistence requires diverse controls

GRDC Project Code CUR00022

Region West