Stripe rust control starts now

Northern NSW cereal growers must remove volunteer wheat plants now if they are to be successful in managing stripe rust during the 2005 season.

The warning has come from NSW Department of Primary Industries plant pathologist at Tamworth, Steven Simpfendorfer, who said the ‘green bridge’ of self-sown wheat plants allowed the stripe rust fungus to survive between seasons.

“The biggest impact growers can have in controlling stripe rust is to remove volunteer wheat from their paddocks by the end of January,” Dr Simpfendorfer said.

“This will significantly delay the onset of infection, lessening its impact on yields and hence the frequency and amount of fungicides in-crop that may be required.”

DPI District Agronomist at Moree West, Nathan Ferguson, said many stubble paddocks in the Moree area had taken on a very green appearance following the rain that fell in November and December.

“Growers have already sprayed their paddocks to maximise water storage over summer, but many with volunteer wheat growth remain,” Mr Ferguson said.

“It’s difficult to say whether this has been oversight, or whether some farmers are trying to attain some grazing value. Because of the ever-present stripe rust risk, this volunteer wheat should be removed by the end of January at the latest.”

The 2004 stripe rust epidemic was the worst recorded in Australia in over 20 years and would be fresh in most cereal growers’ minds due to the anxiety it caused in deciding the need to spray, and limited access to chemicals.

A management strategy was developed by scientists across Australia, including NSW DPI, which calls for a collaborative effort to limit the disease’s inoculum loads and ability to spread across farm, shire and state boundaries.

Used on an area-wide basis, controlling the ‘green bridge’ dramatically delays the onset of stripe rust within an entire district, according to Dr Simpfendorfer.

“Stripe rust would then have to be blown in from a long distance to start infection, which means that stripe rust generally does not appear until later in the season when adult plant resistance genes in many varieties are already active,” he said.

The application of fungicides to the seed or fertiliser at sowing works in a similar way, in that it delays the onset of infection.

Dr Simpfendorfer said this should certainly be considered as an option for moderately susceptible varieties and early sown grazing wheat crops in 2005 as part of the integrated management of this disease.

Media contact: Dr Steven Simpfendorfer, NSW DPI Plant Pathologist at Tamworth Agricultural Institute, (02) 6763 1261.