The prospect of early rust infections in 2006 is prompting Western Australia's wheat growers to increase the use of rust-targeted fungicides in the lead up to seeding.

Rust disease, particularly stripe rust of wheat, generally establishes earlier and spreads more in seasons like 2006 where summer and autumn rains have generated self-sown cereals, the ‘green bridge’.

Department of Agriculture, Western Australia plant pathologist Geoff Thomas (photo) said growers would benefit from delaying the onset of rust in crops by using fungicides that were active in the early part of the season.

Mr Thomas said fungicides used at seeding included long-acting seed treatments and in-furrow fertiliser treatment to provide protection to the crop from the day it emerged.

“Department research trials in 2004 and 2005 consistently showed that fungicides registered for stripe rust control at seeding provided 12-16 weeks protection,” Mr Thomas said.

“In these fungicide-protected crops, stripe rust was often not evident until the booting stage in spring, which means less requirements for fungicide sprays during the growing season.”

Mr Thomas said delaying the onset of stripe rust in crops slowed its development.  This mean’t there was more time to organise spraying of crops if required.

He said partially resistant varieties (rating 5-6) would also perform better when rust onset was delayed.  This was because their resistance began to express around head emergence to flowering.

Mr Thomas said in a high risk year like 2006, there was good reason to use seeding fungicide for any variety with a crop variety resistance rating of 6 or less.

“Seeding fungicides are suitable for a wide range of popular varieties as few mainstream varieties in Western Australia are fully resistant to stripe rust and some are quite susceptible,” he said.

“There is scope for growers finalising their arrangements for seeding to target seeding fungicide as an important component of integrated control of rust diseases, particularly stripe rust.

“For growers yet to adopt long acting seeding fungicides for rust risk management, 2006 would be a good season to try them out.”

Further information is available from the 'Plant disease forecast 2006' on the Department’s website at www.agric.wa.gov.au