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Earlier durum plantings better for crown rot, study finds

Broadacre
29.04.2022
A holistic approach to crown rot management could soon prompt farmers to sow durum earlier rather than later in the season, based on recent findings.

New research has challenged the traditional concept of sowing durum wheat towards the end of its sowing window, with trial results indicating that planting earlier could boost yield potential and minimise the impact of fusarium crown rot, which is tipped to be a big risk for northern growers this season.

Three trials in 2021 looked at the yield benefits of planting durum earlier in the recommended sowing window to avoid heat stress during grain fill and monitored how depth of sowing impacted crop emergence. The work was done as part of the Grain Research and Development Corporation (GRDC) and NSW Department of Primary Industry’s (DPI) five-year Grains Agronomy and Pathology Partnership (GAPP).

At sites in both southern and northern NSW, durum varieties recorded a hefty yield penalty when planted at the end of the sowing window (June) versus the start (early to mid-May), with later sown crops yielding between 5 to 31 per cent less.

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NSW DPI Senior Plant Pathologist Dr Steven Simpfendorfer said this could mean between a $125 per hectare to $1280 per hectare loss for growers (based on $500 per tonne grain price).

“There’s a general perception that durum goes well on a later plant, but the results we’ve recorded really make you question why you’d opt to plant late and expose the crop to potential increased risk of heat stress during grain filling,” he said.

“This has particular relevance this season in light of the high fusarium crown rot risk because anything that stresses the crop after flowering, such as high temperatures, will exacerbate the impact of this disease.

“If there’s fusarium crown rot infection in a paddock, timing the grain fill period to reduce heat stress can decrease potential yield loss by more than half.

“While this research shouldn’t encourage growers to sow durum in paddocks where they’ve identified high levels of fusarium crown rot inoculum, it does highlight how management decisions could reduce potential yield damage.”

Because durum can be sown into June, Dr Simpfendorfer said it was common for growers to wait until the end of the traditional window to potentially plant on better moisture.

However, results from the GAPP project showed that depth of sowing could facilitate an earlier plant, with trials indicating that it was more beneficial for durum to be sown deeper, earlier in the traditional window rather than later at 5 cm.

“The results showed sowing deeper into moisture at 10 cm allowed the crop to germinate and get up and away early,” Dr Simpfendorfer said.

“There was a yield penalty recorded going as deep as 15 cm, but it was still more beneficial to sow at this depth at the start of the recommended sowing window than planting later at 5 cm and having the crop fill grain in high temperatures.”

“If growers have moisture in the top layer of their soil early in the window, they could plant to that depth, but our preliminary results have shown that they shouldn’t be afraid to chase moisture and consider sowing a bit deeper with their durums.”

Dr Simpfendorfer said if growers were wanting to take advantage of an earlier durum plant, they need to be confident in their seed quality, as sowing deeper can reduce establishment and plant stand especially with lower vigour seed sources.

“Durum inherently has a decent coleoptile length compared to many bread wheat varieties, so growers can afford to plant deeper at 10 cm into moisture,” he said.

“Crop vigour is still extremely important for high emergence though, so growers should be getting their seed tested to know what they’re sowing.”

GRDC Crop Protection Manager North, Vicki Green, said this research was a great example of how growers can incorporate integrated management options into their regime to boost productivity.

“In a year where there’s high interest in durum but also a significant fusarium crown rot risk, it’s so important growers consider updated research to make more informed management decisions,” she said.

“GRDC has maintained a commitment to help growers manage disease risk but also maximise their profitability – this research and its outcomes reflect that.”

More information on this research will be published via the Northern Grains Research results by the middle of this year. Growers can find more information on durum via GRDC’s GrowNotes.

This story was originally published by the GRDC, a corporate Commonwealth entity responsible for planning, investing in and overseeing research, development and extension (RD&E) for grains.