The Department of Agriculture of Western Australia and the grains industry are refining a management plan following the detection of Fusarium head blight fungus on a wheat grain sample from last season's crop on the south coast. Department plant industries executive director David Bowran said the disease had been detected in a sample collected as part of a routine pre-delivery quality assurance test by Cooperative Bulk Handling (CBH). “The fungus, Fusarium graminearum, has not been recorded in Western Australia since 1959 when it occurred as a stalk rot in sorghum," Dr Bowran said. “Most experience with the disease in Australia is in areas of New South Wales and Queensland, where Fusarium Head Blight has occurred sporadically for many years.” Fusarium head blight of small grain cereals is a destructive disease in the humid and semi-humid wheat and barley growing areas of the world including the United States, China, South America and Europe. The disease is most prevalent in warm moist climates where wheat follows a summer crop of corn, maize or sorghum, which are alternative hosts for the pathogen. It causes affected heads to ripen prematurely. The quality effects include discoloured and shrivelled kernels, depressed seed weights and reduced seed quality and vigour. Dr Bowran said there was an extraordinary rainy period last spring that coincided with the flowering of the suspected wheat crop and this was known to favour infection.

Growers are asked to look out for Fusarium head blight this spring.  Bleached spikelets appear after flowering and spikelet death spreads along the head causing discoloured and shrivelled kernels.

“The recent find in wheat has been linked to a situation where the causal fungus grew on summer crop residues grown in the wheat rotation,” he said.

“The wheat harvest that followed was interrupted by significant rains in early January, which is also thought to have increased the disease on grain.”

The fungus infects a range of winter and summer cereals and grasses and can survive on the residues of these for a number of seasons, particularly under no-tillage. Spores are produced on the crop residues during warm moist weather and are dispersed by wind and rain splash.

The isolated nature of the find has prompted Department GrainGuard team to resume surveying for this disease, which has not been detected previously on wheat.

At this stage, despite extensive testing of samples of both wheat and barley from receival points across the south coast, Fusarium head blight has only been found on wheat and only on samples from grain associated with one farm enterprise.

Farmers are being asked to lookout for the disease during grain filling this spring.  The first symptoms are individual brown spikelets and glumes which appear after flowering and can spread up and down the head. In humid conditions, a salmon pink to orange fungal growth can appear.

Under the right conditions, Fusarium graminearum can produce mycotoxins in the affected grain. Mycotoxins can be harmful to animals and humans if ingested in large quantities.

Some affected grain from the recent find has shown detectable toxin, however AWB has sensitive testing procedures which are used to ensure grain for export and domestic use meets internationally recognised benchmarks for safety before it can be traded.

Dr Bowran said the Department would be working with south coast growers this spring to monitor cropping rotation and management practices to limit opportunities for the fungus to spread and damage crops.

More information about the disease and how to look for it will be made available to growers at field walks this spring.