The Department of Agriculture, Western Australia has revised its risk assessment for rust in some parts of the State following heavy rains at the beginning of the month.

Following a very dry summer the rust risk across much of the wheatbelt remains at normal levels, which is expected to be less than that of the 2004 season.

However, Department plant pathologist Geoff Thomas said in some areas of the wheatbelt, particularly in parts of the central, great southern and southern regions, recent heavy rains had built up soil moisture which could see volunteer wheat germinate and survive through to after seeding.

Mr Thomas said volunteer regrowth in autumn, prior to cropping could lead to the early re-establishment of rust infection, as existing very low levels of rust would have opportunities to start building-up.

“While the potential for rust outbreaks exist every season, a dry summer, such as we have just had, normally results in them being fewer and later.  However where there were significant early rains, the potential for an early build-up of rust has increased marginally.

“Growers in those areas should be aware of this potential and remove volunteer cereals that may act as a green bridge ahead of emergence this year. They should also be aware of the importance of early monitoring of crops for rust diseases during the season. 

More information about plant disease potential is in the plant disease forecast for 2005 on the Department website at www.agric.wa.gov.au.