Timing is key against frost attacks

 Dr Ben Biddulph presents the finding from DPIRD's frost risk management trials at the Grains Research Update, Perth.
Dr Ben Biddulph presents the finding from DPIRD's frost risk management trials at the Grains Research Update, Perth.

CROP species and sowing dates are the greatest drivers of yield in frost-prone areas, according to cereal trials conducted by the Department of Primary Industries and Regional Development (DPIRD).

The results of the frost trials, which spanned six seasons, were presented by research scientist Ben Biddulph on day two of the Grains Research Update, Perth, early last week.

Dr Biddulph said the study found zoning frost-prone areas and managing them by sowing the appropriate crop and maturity types were the best agronomic options for managing frost risk.

"We've re-evaluated what are the biggest tools in the toolbox when it comes to frost management in cereals, and how to get the most out of these," Dr Biddulph said.

"The interaction of crop species with sowing date is still the greatest driver of yield in both frost prone and non-frost-prone environments."

The frosted trials showed that delaying head emergence or flowering through maturity and sowing time had a bigger impact on yield and quality than what genetic yield potential did.

"With April sowing in both frost-prone and non-frost-prone areas, sowing longer season maturity types is a stronger driver of yield and quality," Dr Biddulph said.

"There is no practical way to 'beat the frost' in frost-prone areas by sowing mid-season maturity types of wheat, barley or oats in April.

"There is a real risk that grain yield and quality will be compromised."

In more recent trials, DPIRD compared nitrogen application and seeding rates with the impact of frost severity and duration, and damage from subsequent frost events.

Dr Biddulph said the results of the study, which consisted of small plot and farmer scale trials in frost-prone landscapes across the central and southern Wheatbelt, found reducing nitrogen and seeding rates to half of usual farmer practice could reduce the severity and duration of a frost event.

"However, frost damage is not consistently reduced to justify this management strategy as an economic option," he said.

"Reducing nitrogen and seeding rates can cause the canopy to flower several days later and over a wider window, but the crop is not able to consistently avoid frost damage, because a shift in the flowering window of about two weeks is required.

"Variety choice, based on maturity, is a more reliable tool for growers to use to delay flowering and avoid high frost risk periods."

In terms of practical recommendations, Dr Biddulph suggested growers continue to sow longer maturity varieties of all crop types and maintain high seeding rates and standard nitrogen input.