Source: GRDC

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Technical reference links for advisers Stripe rust management in wheat

Graingrowers need to be on the lookout for stripe rust, after several cases of the fungal disease were found in northern New South Wales and South Australia late last week.

But with continuing dry conditions and low yield expectations for most cropping regions across Australia, growers need to carefully consider what - if any - management decisions need to be made if stripe rust is found on their property.

Dr Gordon Murray, principal research scientist (plant pathology) with the New South Wales Department of Primary Industries, says he expects stripe rust to emerge across the entire eastern wheatbelt within the next two weeks.

"And when that occurs I would ask people to very carefully consider their yield potential before they consider spraying fungicide on their crops," Dr Murray said.

Trial results from the New South Wales Central West Farming Systems group for the past two years show that economic responses to the application of fungicide treatment for stripe rust were non-existent in poorer yielding crops, even if those crops were highly susceptible to the disease. Ken Motley, district agronomist at Forbes, NSW, said responses in wheat crops like H45 (very susceptible) did not occur until the potential yield was above 2.3-2.5 tonnes a hectare, while for moderately susceptible wheats (Chara, Diamondbird), the potential needed to exceed 3.5 t/ha.

"There are obviously exceptions to this rule, and for those with irrigated crops or the few that have been receiving good rainfall, it still might be economically beneficial to spray for stripe rust," Dr Murray said.

"The important thing for all farmers will be to ensure they properly assess both the yield potential and cost of applying a fungicide treatment now," he said.

In the event that most farmers will elect not to spray this year, very high levels of inoculum could be present for next season. Therefore thought needs to be given now to planting resistant crops, and applying fungicide treatments to seed for the 2007-08 season.

Last week's stripe rust outbreaks were recorded near the NSW towns of Moree, Narrabri, Gurley, Mungindi, and Croppa Creek, while the South Australian outbreak was recorded on the Yorke Peninsula. Dr Murray said he expected outbreaks would be recorded throughout SA, Victoria and NSW in the next two weeks.