Mike Lamond of the Grain Industry Association of Western Australia (GIWA) said factoring in frost and dry the WA crop could drop to 14m tonnes.
“We don’t know just how much the frost will hit the crop, but the dry is a big problem, the headlines have been on the frost but we could easily see the dry being the major factor in yield losses,” Mr Lamond said.
It comes the same week as Victorian crops were also smashed by heavy frost.
Following the bitter frost, which saw temperatures drop to -4 in parts of the upper Great Southern, Mr Lamond said he expected barley to be the crop hardest hit by frost.
“We could easily lose 500,000 tonnes of barley, it is more advanced than wheat and at a more susceptible stage,” he said.
In terms of wheat damage, Mr Lamond said it was not likely there would be much head damage as most of the crop was yet to come out in ear.
“We have some concerns about stem frost, but that is something we are not that familiar with in WA so we will have to wait to see whether there are any problems on that front.”
Mr Lamond said the worst impacted area was the upper Great Southern and parts of the south-eastern Wheatbelt.
“We saw very cold temperatures in places like the Lakes District, from Hyden down to Lake King.”
Scott Crosby farms at Nyabing in the upper Great Southern, east of Katanning.
He said it had got down to close to -5 for a period of time on his farm.
“It is a bit early to tell the complete damage but it is safe to say it is a major event,” Mr Crosby said.
“We’ll see a variety of different damage from the frost, stem, head and flower frost,” he said.
“I’ll definitely be cutting some hay for my own use and maybe even potentially selling some, but we’ll just have to assess the damage properly.”
He said further east, where crops were under more moisture stress, the impact of the frost could be larger.
Mr Lamond said barley growers in the frost hit areas mainly grew feed lines.
“Malt production in WA is concentrated further to the north.”
He said barley could be more tolerant of frost than wheat due to its staggered flowering so there was still hope for frost hit crops.
“In other frost-hit years people have swathed (windrowed) the crop, harvested the little bit of grain that was still there then baled the straw and mitigated losses that way.
“Given straw is relatively valuable this year that could be in some people’s minds once again.”
While he does not expect wheat frost damage to be as severe he said GIWA’s wheat production number of 10.2m tonnes for WA would definitely be under fire.
“There definitely is risk to the downside on that figure, more so from the dry than the frost.”
“Big areas in the eastern Kwinana port zone from Merredin up to Koorda, the crops there were looking sensational but have gone backwards with the dry September, we could easily lose a million tonnes of total grain production in that area alone from earlier estimates.”
In terms of positive crop prospects, Mr Lamond said the mid-north of the state, around Moora and Miling remained in top condition.