September 5, 2003

Graingrowers are being advised to check their crops regularly, following the first report of stripe rust this season.

The Western Australia Department of Agriculture has confirmed the fungal disease in a crop of Carnamah wheat at Burracoppin, 25 kilometres east of Merredin.

Department cereal pathologist Rob Loughman said stripe rust had first been found as a single affected leaf during a routine crop inspection.  Subsequent inspection had also found stripe rust hot spots in the crop.

"Hot spots are areas of heavy infection, indicating the presence of the disease in the hot spot area for some time.  Affected plants showed typical stripes of the bright orange/yellow rust spores," Dr Loughman said.

"Stripe rust was first discovered in WA in August last year, and is one of a handful of leaf diseases farmers need to manage. Stripe rust became active in spring of last season, particularly in the Great Southern where the effects of the drought were less than in other areas.  But stripe rust had not been detected since December last year and despite intense interest, had not been detected in WA until now," he said.

"The find signifies the need to start checking crops for stripe rust by farmers, particularly in central and southern districts, where other rust carryover has been evident."

Dr Loughman said growers should check their crops for yellow-orange spore masses on leaves, generally in long stripes.

The next few weeks would determine whether the outbreak was localised or more widespread.  He said unless lower leaves of crops were inspected, early infections did not become apparent until yellow hot spots appear.

The disease is wind-borne and the pattern of infection in the Burracoppin crop indicates the disease may be reaching detectable levels in other areas if spores carried by wind had landed in crops earlier in the season.

Dr Loughman said that early detection of stripe rust was an important factor in the control of the disease.

"One of the lessons learnt from last year is to control the disease with fungicide when it is first detected.  Intermediate, moderately susceptible and susceptible wheat varieties should be sprayed when stripe rust is first detected in a crop," he said.

"Suspected samples of stripe rust should be sent to the Department of Agriculture for identification and further testing."

Dr Loughman said for many growers, 2003 might be their first experience with stripe rust.   He said correct identification was an important component of control strategies and it was always good to start off with the right diagnosis.

Growers can gather up to 20 leaves bearing the telltale signs of stripe rust and send them in a paper envelope to the Department. Contact details for growers should be included with the material and sent to AGWEST Plant Laboratories, Department of Agriculture, Locked Bag No. 4, Bentley Delivery Centre 6983.