Cropping

Soil-borne disease risk higher

By Country News

Grain growers in the southern cropping region who have experienced a dry growing season this year are being warned of a potential increase in the risk of some soil-borne diseases in 2019.

Rhizoctonia root rot and crown rot are two cereal diseases likely to pose a problem in parts of South Australia and Victoria where rainfall was below average this year.

A lack of rainfall has reduced the breakdown of cereal stubbles in pulse and oilseed break crops, promoting the risk of disease next season.

Soil-borne disease experts, supported by the Grains Research and Development Corporation, are advising growers to know their paddock’s disease risk profile well ahead of sowing in 2019 by having their soils tested through PREDICTA B — the DNA-based soil-testing service which enables identification of the pathogens posing the greatest threat to cereal crops.

Alan McKay, the leader of the South Australian Research and Development Institute’s Soil Biology and Molecular Diagnostics Group, said the risk of disease in 2019 would be heightened when growers decide to sow wheat back into this year’s failed wheat crops.

‘‘I expect rhizoctonia and crown rot will be the main issues as a result of low growing season rainfall, and growers should also keep an eye on cereal cyst nematode as levels have been trending higher over the past five years,’’ Dr McKay said.

‘‘Rhizoctonia, especially, has a competitive advantage in low-moisture situations and its levels have almost certainly increased this year.

‘‘It survives best when there is no summer rainfall and therefore reduced soil microbial activity.

‘‘If we do experience a dry summer and the break to the season is late, crop seedlings will be exposed to high levels of rhizoctonia next year.’’

Rhizoctonia root rot can reduce cereal yields by more than 50 per cent, with barley being the most susceptible.