At Tamworth Agricultural Institute, Dr Steven Simpfendorfer has been determining the levels of crown rot inoculum present in stubble samples collected this year.

Key Points

• stripe rust, crown rot and yellow spot expected to pose a significant threat this year
• greater risk of crown rot and yellow spot
• dry 2007 growing conditions limited the decomposition of wheat stubble under break crops, hence the survival of stubble-borne fungal pathogens.

Optimism in the northern cropping zone for high prices from expected record wheat plantings is being tempered by concern that cereal diseases will make their presence felt.

With generally good stored soil moisture levels following the summer rains and the prospect of winter rain, hopes are high that the region will see one of its best seasons in years; and there is speculation that the prices now being paid will continue - at least until the world-wide wheat shortage is reversed.

However, NSW Department of Primary Industries plant pathologist at Tamworth, Steven Simpfendorfer, has cautioned that stripe rust, crown rot and yellow spot were expected to pose a significant threat this year.

"Stripe rust was certainly present in 2007, with the WA Yr17 pathotype found as far north as North Star," Dr Simpfendorfer said.

"While the dry spring conditions limited disease development, summer rain encouraged the growth of volunteer wheat on which the stripe rust pathogen survives, which will have been further favoured by milder summer temperatures.

"However, there’s an even greater risk of crown rot and yellow spot, simply because there will be more wheat sown back into wheat stubble to meet the larger predicted planting.

"The generally dry growing conditions in 2007 will have limited the decomposition of wheat stubble under break crops and hence the survival of these stubble-borne fungal pathogens.

"Consequently, wheat planted into break crops from 2007 may still have high disease levels."

As part of his research, Dr Simpfendorfer has collected stubble samples from around 200 paddocks in January to March 2008 to determine the levels of crown rot inoculum present.

He said while there were plenty of paddocks with low levels into which a winter cereal could be safely planted in 2008, some paddocks had stubble in which greater than 60 per cent was hosting the crown rot fungus.

"This is certainly a high risk situation for developing crown rot if sowing wheat or barley in 2008," he said.

"However, a significant number of these stubble samples also have good levels of fruiting structures of the yellow spot fungus on them.

"If predictions of a wetter than average season do eventuate, then yellow spot may be poised to cause a problem for growers."

Wheat prices and seasonal predictions certainly look encouraging, but growers need to take a balanced approach when considering their options for 2008.

Visit NSW DPI’s web site at www.dpi.nsw.gov.au/agriculture/field/field-crops/winter-cereals for further information on the management of cereal diseases.