Barley disease warning

This NFNB mutant may have existed for several years prior to its detection.

“This mutant form of NFNB is resistant to several active ingredients within three different kinds of fungicide: Group 3, Group 7 and Group 11,” Dr Dadu said.

“NFNB has the potential to reduce barley yield by up to 40 per cent and grain quality, so resistance to key active ingredients within the three main fungicide groups used to control the disease is very concerning for growers.”

He said the net form net blotch starts as pinpoint brown lesions, which elongate and produce fine, dark brown streaks along and across the leaf blades, creating a distinctive net-like pattern.

Older lesions continue to elongate along leaf veins and often are surrounded by a yellow margin.

Dr Dadu warned growers that this new mutant form of NFNB might be more widespread than first thought.

“Fungicide resistance to Group 3 and 7 fungicides has been around for several years and was again confirmed during 2024 in barley samples collected from Inverleigh, Hamilton, Horsham and Kaniva.”

He said growers of susceptible barley varieties and in particular RGT Planet and Zena CL should monitor crops closely and if they suspect new forms of resistance contact crop-safe@agriculture.vic.gov.au

AgVic said growers should review their Integrated Disease Management processes and take the following proactive steps to reduce the spread of the NFNB mutant: