Media release: Season’s first stripe rust found in Mallee wheat

Thursday, August 6, 2009. 

Farmers are being urged to check wheat crops after reports of Victoria's first stripe rust outbreak for the season.

The Department of Primary Industries Senior Plant Pathologist Dr Grant Hollaway said these outbreaks, in the Mallee, were not unexpected and followed reports of the disease in Queensland and northern NSW.

"This season's early break and sowing of crops, coupled with wetter seasonal conditions have been favourable for rust development," Dr Hollaway said.

"Croppers need to begin checking their paddocks and be ready to spray if necessary because the disease is better managed by applying fungicides early in the epidemic rather than later.

 "Stripe rust is easiest to identify in the morning. Look for yellow stripes of pustules on the older leaves. The pustules are raised above the leaf surface and can be easily wiped off on to a white cloth or tissue leaving a yellow stain.

"Also watch for hot spots in the crop which develop just before the disease becomes widespread in the crop

 "If you don't find any stripe rust continue to monitor or a protective fungicide could be applied."

Dr Hollaway said after a fungicide application to crops, inspections should continue as fungicides only provide two to four weeks protection.

"There is often an apparent increase in stripe rust for a few days after spraying, which is caused by the development of symptoms of infections that occurred just before spraying. Control becomes apparent within a week of spraying," he said.

Last season, stripe rust was detected in regions at tillering and a fungicide spray was required in many varieties to protect green leaf area until the onset of adult plant resistance (APR) which starts around ear emergence. Varieties without effective APR may require sprays beyond ear emergence.

Stripe rust can cause considerable damage with losses of up to 50 per cent in susceptible varieties that are not treated with fungicide.

"In previous years dry springs have minimised the stripe rust development but with wetter conditions this season farmers will need to be vigilant to ensure their crops are protected," Dr Hollaway said.

For further information see the DPI Information Notes: Stripe Rust of Wheat (AG1167) and Cereal Disease Guide 2009 (AG1160) available from www.dpi.vic.gov.au/notes  

For more information contact Dr Grant Hollaway, Senior Plant Pathologist or Frank Henry, Extension Plant Pathologist, DPI Horsham, (03) 5362 2111.

MEDIA CONTACT: Simone Dalton (03) 5362 0762 or 0408 349 532