GRDC manager for crop protection Dr Rohan Rainbow said recent dry seasons and reduced carbon inputs from crop residues had caused a decline in general biological activity, and this had favoured high levels of Rhizoctonia fungus.

"Data from testing of soil samples from 415 paddocks across southern Australia showed that levels of Rhizoctonia solani were generally high in most cropping regions in South Australia, as well as in western Victoria, the Geraldton and Esperance regions of Western Australia and Deniliquin in New South Wales," Dr Rainbow said.

"Sowing the crop early while the soil is still warm, and encouraging early seedling vigour, is the best short-term strategy.

"Other measures growers can take to reduce the impact of the disease include deep banding nitrogen, minimising stubble incorporation at seeding, ensuring adequate nutrition with nitrogen, phosphorus and zinc, and controlling autumn growth early."

* The GRDC’s Rhizoctonia fact sheet at www.grdc.com.au/factsheets provides additional details on managing Rhizoctonia for growers.