Living with stripe rust isn’t going to be easy for northern New South Wales graingrowers, and they have a couple of serious issues to think about as they gear up for the 2004 harvest.

New South Wales Department of Primary Industries (NSWDPI) cereal pathologist Steven Simpfendorfer (photo) says industry alarm at the extent of the stripe rust outbreak this season could see growers make hasty decisions about what wheat varieties to keep as next year’s seed.

He says growers should resist the temptation to discard varieties that have had to be sprayed this year for stripe rust but which have other good resistances,  to the serious problem of crown rot for instance.

Dr Simpfendorfer says there are reports of northern New South Wales growers and even advisers talking about dumping valuable crown rot tolerant varieties like Lang, Baxter and Sunco, because they may need to be sprayed for stripe rust.

“Despite stripe rust being widespread this season, and many growers being forced into unusual programs of fungicide sprays on wheat, crown rot remains a challenge in itself,” Dr Simpfendorfer says.

“A wheat seed treatment that would provide eight weeks protection against stripe rust, and reduce pressure early in the season, would cost around $8 a hectare, and one spray of a cheaper fungicide another $7 or so a hectare.

“With wheat at $150 a tonne, a crown rot tolerant wheat variety would only have to yield an extra 100 kilograms (0.1 tonnes) a hectare to cover the cost of seed treatment and one in-crop fungicide spray, which might be all that was needed.”

Dr Simpfendorfer said it was well known that crown rot could cost growers well over 0.1 t/ha in susceptible wheat varieties in most seasons in the north, so it appeared to be false economics to consider dumping more resistant varieties for 2005.

Meanwhile, scientists working on the Australian Cereal Rust Control Program are emphasising the “social” side of stripe rust and the need for collaborative, communal action to limit the disease’s inoculum loads and ability to spread across farm, shire and state boundaries.

They admit a number of resistance genes in current commercial wheat varieties are struggling against the new, more virulent races of stripe rust, but say many new resistance genes are being developed and distributed to breeding agencies through the Australian Cereal Rust Control Program.

Until these new resistances find their way into new commercial lines, they say eastern states growers need to follow the example of the Western Australian industry, which ran  coordinated and collaborative campaign to break  the “green bridge” of self sown wheat plants that might have allowed rust pathotypes to survive between seasons.

The West Australians linked their campaign to St Patrick’s Day (March 17), with all self sown wheat to be sprayed or cultivated out by that date.

Growers needed to keep stripe rust in perspective and weigh up variety options based on resistance to all the major diseases in northern NSW and the yield potential in their individual systems.

There was a wealth of information about stripe rust available to growers and advisers on the Grains Research and Development Corporation (GRDC) GrainZone website, including all papers from the July round of cereal leaf disease workshops. Advice on a disease response scale used by the Australian Cereal Rust Control Program could be found at http://www.grdc.com.au/growers/as/stripe_rust2.htm