MILLING oats may be a more profitable option than wheat in paddocks where there is a high level of fusarium crown rot, although it is unsuitable as a break crop to reduce the risk of the fungal disease.
Those were the key findings of a two-year Grain Flagship project, funded by the Western Australian Department of Primary Industries and Regional Development, opening the door to expanded oat production in WA.
Crown rot costs WA wheat and barley growers an estimated $7 million per annum, however, relatively little was known about its impact on milling oats.
The disease is widespread across the WA grainbelt, particularly in low to medium rainfall areas, where oats have not typically been grown.
With competitive prices for milling oats, growers in low rainfall areas have become more interested in sowing the crop, prompting the need to investigate variety susceptibility to crown rot.
DPIRD research officer Daniel Hüberli said all seven oat varieties tested were more tolerant to crown rot than the two benchmark wheat varieties, suggesting oats could be a cereal alternative for paddocks where there was a disease risk.
“In fact, average yield losses for milling oats to the predominant crown rot pathogen, Fusarium pseudograminearum, was four per cent, which is about four times lower than that measured in wheat,” he said.
The trials showed no oat varietal differences in yield responses to crown rot.
“These results are good news for growers, as it means there is a more tolerant cereal crop option that can be used in rotations where crown rot is a problem,” Dr Hüberli said.
“So, in paddocks where the crown rot risk is high and non-host options are limited, oats appear to be a better choice than wheat to limit the extent of yield loss.”
The field trials tested the milling oats varieties Bannister, Carrolup, Durack, Kojonup, Mitika, Williams and Yallara and two benchmark wheat varieties, Mace and Emu Rock, in inoculated versus uninoculated replicated plot trials at Merredin and Pingelly in 2016 and Merredin and Muresk in 2017.
At both sites, the pre-sowing inoculum levels in 2017 following the oat trials the previous year were not different among wheat and oats or between varieties sown in 2016.
Dr Hüberli said this meant oats could not be used as a break crop for wheat and barley crops, which are known to increase crown rot inoculum levels, as both trials had similar levels of inoculum in 2017.
“The trials showed there was no difference in disease levels in the 2017 Mace wheat crop following the different oat and wheat varieties,” he said.
“If the management strategy is to reduce the level of crown rot in a paddock, then a non-cereal crop, like canola or lupins, would be preferable to optimise profitability and provide good grass weed control.”
An economic analysis suggested milling oats was the most profitable crop for paddocks where crown rot was a problem, provided the price of oats was above $270 per tonne.
“The economics of oats compared with wheat becomes more attractive in the presence of high levels of crown rot,” Dr Hüberli said.
“In GRDC funded trials, wheat and barley varieties were found to vary significantly in relative yield losses due to crown rot, as documented in the current crop variety guides.
“It is important for growers with paddocks that have a high risk of crown rot to select the most appropriate cereal crop, based on the forecast for the season and yield potential.”