Is it soilborne disease?

Planting cereals early into warm, moist soil can enable crops to establish well, but from mid-winter to spring the growth of crops that initially appear healthy may look uneven, prompting questions about the cause.

Dr Alan McKay, principal scientist in soil biology and molecular diagnostics at the South Australian Research and Development Institute (SARDI), the research division of Primary Industries and Regions SA, says uneven crop growth may be caused by a number of factors including drought, soil structure issues, nutrient deficiencies or disease.

Look at roots

“If you suspect something might be wrong with your crop, dig up some plants and have a look at the roots,” he says.

Some of the common soilborne diseases in Western and North-Western Victoria are Rhizoctonia and Crown Rot.

“During the past couple of years, dry spring and summer conditions have allowed Rhizoctonia levels to build to the point that the pathogen is now infecting pulse and canola crops, not just cereals.”

Dr McKay says another dry spring disease is crown rot (Fusarium species). The pathogens responsible typically infect the outer leaf sheath during winter, turning it brown before moving into the lower stem and turning it a honey-brown colour around anthesis. If moisture stress is present during spring, white heads will develop.

PREDICTA® B

Making use of a PREDICTA® B test – a DNA-based soil test – before sowing will help confirm whether soil-borne pathogens pose a risk, in time to implement a strategy to reduce the risk of yield loss.

“At the end of the day, you’re going to be at the mercy of the season to some extent,” Dr McKay says.

In-crop diagnosis

Dr McKay is encouraging growers to examine crop roots during mid to late winter to see the impact of soilborne diseases.

BCG, with FarmLink and GRDC, will this year run 2 root disease workshops in the Wimmera Mallee, focusing on cereals. Demonstration trials will follow in 2021 to showcase a variety of potential management options.

Growers will be invited to bring plant samples from their crops. These will be examined by pathologists and the symptoms discussed.

Further details on these workshops will be released later in the year.

BCG is looking for paddocks with evidence of disease in which to run treatment demonstrations in 2021. If you have a paddock you would like us to consider, please contact James Murray 54922787.

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