BARLEY researchers are warning growers of the growing problem of fungicide resistance in common barley diseases such as net form of net blotch (NFNB).
There have been confirmed cases of NFNB resistance to both succinate dehydrogenase inhibitor (SDHI) fungicides and demethylation inhibitor (DMI) fungicides.
South Australia's Yorke Peninsula has been a hotspot for resistance, while there have also been cases recorded on the Eyre Peninsula and Victoria.
Earlier in the year there were reports of a hybrid NFNB / spot form of net blotch (SFNB) disease resistant to fungicides in southern Western Australia.
The Centre for Crop and Disease Management (CCDM), and the South Australian Research and Development Institute (SARDI) has been investigating the issue of resistance and gathering samples from the Yorke Peninsula over recent months.
Analysing barley samples collected from 15 locations on the YP, the CCDM's fungicide resistance team has been able to paint a more detailed picture of the incidence of SDHI, DMI and dual resistance.
CCDM researcher Wesley Mair said the samples showed growers needed to be alert to the risk of resistance.
"Our previously released findings from 2019 showed that NFNB on YP was resistant to the SDHI seed dressing fungicide fluxapyroxad, and at the same time samples also showed resistance to the Group 3 DMI tebuconazole, which is a mixing partner in some DMI foliar fungicides," Mr Mair said.
"This latest testing now tells us that DMI resistance appears to be quite common, especially in the south of YP even though it hadn't been reported in SA previously."
According to the CCDM's fungicide resistance expert Fran Lopez-Ruiz, the testing of the more recent samples indicates that the SDHI resistance found on YP late last year is more widespread than first thought.
"The key now is to put in place steps to limit development and incidence of resistance as best growers can," Dr Lopez-Ruiz said.
SARDI plant pathologist Tara Garrard advised growers to be vigilant in watching for the disease and to put management strategies in place to help combat it.
"Anything we can help growers do to limit the amount of disease in the area is paramount and by taking the right steps they can help control resistance," Dr Garrard said.