Icy threat to WA crops

Widespread frost across the Wheatbelt early last week could wipe some of the cream off this year's expected 8.1 million tonne wheat crop.

With temperatures going as low as -2.3C at York, -1.2C at Southern Cross and -1.8C at Hyden last Wednesday morning, farmers are hoping it was too early in the season to have widespread implications.

Bureau of Meteorology and DAFWA weather stations show other areas hit hard included Narembeen, Bonnie Rock, Shackleton, Quairading, Tammin, Kellerberrin, Trayning, and Beverley.

York farmer Charlie Boyle said the weather station on his property showed the temperature stayed below zero for seven hours, reaching a minimum of -2.3C around 6 am.

But he said it would be days before he could assess the damage.

"It could have been massive, or it could be a non-event, we'll just have to wait and see," he said.

"There have also been a couple of mild frosts since then, so we won't know how much damage has been done for up to a week or 10 days."

"Most of the wheat was just out of the boot so it would have had to have been a stem frost to really do a lot of damage.

"There was a bit of moisture in the soil that generally allows the crop to handle the frost better."

The Boyles, who host a GRDC- funded frost trial on their property, will cut their wheat for export hay if the frost has been severe.

"Our whole farm is susceptible to frost, but we have strategies in place to handle this type of situation," Mr Boyle said.

"We don't grow much barley because you can't cut that for hay."

In Hyden, temperatures also stayed below 0C for seven hours, with the temperature bottoming out at -1.8C.

Landmark agronomist for the Hyden, Kondinin and Narembeen regions, Kirsty Smith, said many of the crops in the area were at the susceptible stage, and she expected some damage to be visible by the middle of this week.

Ms Smith said cloud cover over the district on the Wednesday morning could have saved some crops, particularly those to the east.

"It also didn't appear to go too far up into the landscape, so we are hoping the hill tops aren't as badly damaged," she said.

She said Hyden had been typically frost prone in the past, with one of the worst frosts in 2008 wiping out crops across the district.

"Many of the wheat and barley crops are flowering or are at grain fill stage so by mid-this-week we should start to see whether there has been any damage to the stem or we will be able to see the frosted grains in the head," she said.

According to Department of Agriculture and Food (DAFWA) research officer Ben Biddulph, growers should be alert but not alarmed about the impact of the frost.

"Frost symptoms may not be obvious for up to seven days after a frost event. The damage tends to be patchy and variable within a paddock," Mr Biddulph said.

"Low-lying areas and light-coloured soil types are usually most at risk and these areas should be checked first.

"Farmers need to be very confident about damage levels and consider all economic aspects before making decisions about managing their damaged crops."