Windrow burn could curb sclerotinia

In addition to being an effective harvest weed-seed-control (HWSC) strategy, preliminary research suggests narrow windrow burning of canola stubble may also help manage sclerotinia stem rot. The preliminary findings come from trials conducted in Western Australia by the Centre for Crop and Disease Management (CCDM), jointly supported by Curtin University and the GRDC, and in collaboration with the Australian Herbicide Resistance Initiative (AHRI).

The trials show temperatures achieved when burning narrow canola windrows kills sclerotia – sclerotinia stem rot’s primary source of inoculum – within the windrow.

Canola is a profitable break crop in WA, but increased plantings have seen a rise in the incidence and severity of sclerotinia outbreaks, which significantly reduce canola yields.

With no genetic resistance among current varieties to the fungal pathogen that causes sclerotinia, there is a management reliance on fungicides and crop rotations.

Kyran Brooks conducted the research as an honours student at CCDM, with supervision from AHRI research agronomist Dr Mike Ashworth and CCDM senior research agronomist Dr Sarita Bennett: “In our trials, temperatures greater than 500°C were consistently maintained in the centre of the windrow for more than eight minutes, with temperatures exceeding 350°C achieved at the edges of the windrow for the same amount of time,” Mr Brooks says.

“These temperatures and durations well exceeded the minimum requirement to kill sclerotia of all sizes – which is 350°C maintained for 10 seconds.”

Mr Brooks, now an agronomist with Landmark, says narrow windrow burning, which has already been proven to kill weed seeds after harvest, provides an effective technique to kill sclerotia as part of a wider integrated disease management strategy.

Dr Ashworth says narrow windrow burning of canola stubble represents an important and cheap non-fungicidal tool to control sclerotinia.

“The findings from the sclerotinia trials suggest growers might benefit from taking some of the learnings from weed research and applying them to disease management,” he says.

“Killing sclerotia using heat before it enters the soil is a good example of this.”

GRDC Research Code CUR00023

More information:

Mike Ashworth, AHRI
0428 053 404
mike.ashworth@uwa.edu.au

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