Dr Noel Knight. Photo: UniSQ

BARLEY seed could be carrying more than the potential for a new crop, with emerging research from the University of Southern Queensland finding that fungicide-resistant net blotch can be carried on seed and transferred to seedlings.

The research provides important evidence of this seed-to-seedling transmission, revealing a previously unrecognised pathway for fungicide resistance to move between crops and seasons.

The finding highlights the role of seed source when managing a net blotch, one can severely impact Qld barley.

The researchers tested 16 barley seedlots sourced from grower fields across the Darling Downs and detected net blotch pathogen DNA in 13 of them.

The team then investigated whether the seed was also carrying markers associated with decreased sensitivity to fungicides, an emerging concern for Qld barley growers.

Importantly, researchers planted one of the higher-risk seedlots and monitored the resulting seedlings.

The same reduced fungicide-sensitivity types detected on the seed were subsequently found in net blotch lesions on the seedlings, providing evidence that fungicide-resistant net blotch can move from seed into the next crop.

Net blotch can do significant damage to barley crops. Photo: UniSQ

Lead researcher Noel Knight said the finding added an important new consideration to how growers manage the disease.

“Seed isn’t just planting material. It can be a disease-management decision,” Dr Knight said.

“Growers rely on a combination of varietal resistance, inoculum management and fungicides to manage net blotch, but our research suggests seed source should also be considered when managing disease risk.”

Net blotch can reduce barley grain yields by 10 to 40 per cent, with losses exceeding 40 per cent reported during severe outbreaks.

The disease poses a significant threat to an industry that contributes approximately $190 million annually to the Qld economy.

Dr Knight said fungicide resistance was a growing concern as reduced sensitivity to important fungicide groups emerged in net blotch populations.

“If growers are doing everything recommended to manage disease but unknowingly plant seed carrying both the pathogen and reduced fungicide sensitivity, they could be introducing additional disease risk at the start of the season.”

The research does not change existing recommendations to choose less-susceptible barley varieties, reduce disease inoculum and rotate or mix fungicides, but suggests seed source may be another factor growers should consider.

The researchers found three of the 16 seedlots had no detectable net blotch, suggesting lower-risk seed may be identifiable, and that seed testing, which is unavailable for net blotch and fungicide resistance on seed, could help growers make more informed disease-management decisions.

However, Dr Knight stressed that further research and testing were needed to determine how widespread the issue is, how often it occurs across seasons and how environmental conditions influence seed-to-seedling transmission.

“There is more work to do before we might fully understand the significance and impact of seedborne fungicide resistance.”

“Rather than sounding the alarm, we’re adding another piece to the puzzle and giving growers another consideration to manage disease risk.”

The research is being prepared for publication.

It was conducted by Dr Noel Knight, Dr Barsha Poudel and Professor Levente Kiss at UniSQ’s Centre for Crop Health through the Broadacre Cropping Initiative, a joint investment by UniSQ and the Queensland Department of Primary Industries.

Source: UniSQ