The need to be diligent in treating barley planting seed for seed-borne diseases has been brought home to some growers who last season faced serious marketing problems as a result of covered smut in their crops.

Queensland Department of Primary Industries principal plant pathologist Graham Wildermuth said covered smut could be effectively controlled with seed dressings, with the cost of seed treatment being minimal compared with production and marketing losses.

Dr Wildermuth said end users did not accept covered smut-contaminated grain unless it was heavily discounted.
He said covered smut was recognised by the appearance of masses of spores enclosed in a semi-persistent membrane that covered the smutted spikelets.

It survived as teliospores on seed or in infested soil. Spores geminated when the soil temperature range was 14-25deg and soil moisture was low.

"Infection occurs as the seedlings emerge from the sprouting seed. The fungus enters the young seedling and grows within the growing point of the developing barley plant.

"A smutted head emerges rather than a flowering barley head. The membrane covering the smutted tissues keeps the smut spores from being dispersed until harvest. "At harvest spores are released and mix with healthy seed or fall to the ground," Dr Wildermuth said.

If growers had concerns about seed infection they should look at accessing seed from a clean source.
As the disease could be soil as well as seed-borne planting seed should be treated every year regardless of the cleanliness of its source.

More information on covered smut, including chemicals and application rates for seed treatment, is available at www.dpi.qld.gov.au/fieldcrops or by contacting the DPI Call Centre 13 25 23.