Rains bring wheat turnaround

Jo FulwoodThe West Australian

A prediction of potential wheat yields in individual Shires has shown a marked jump in productivity levels in the north-eastern Wheatbelt.

This forecast yield increase follows the deluge of rain received by the central and eastern Wheatbelt at the end of July.

Released by the Australian Export Grains Innovation Centre, the yield predictions map shows wheat yields in the Shire of Dalwallinu are now expected to be in the best 10 per cent when compared with all other years since 1916.

According to AEGIC crop forecaster David Stephens, late June yield rankings in much of the north-eastern Wheatbelt were on track to be in the lowest 10 to 30 per cent of years.

But he said the rain received at the end of July had given Dalwallinu growers a forecast half a tonne extra wheat yields.

"The maps have revealed one of the largest mid-season turnarounds in the State's expected wheat yields seen since the maps began 18 years ago," Mr Stephens said.

"The main reason for the yield improvement is that most of the rain fell slowly over a number of days and this enabled the moisture to move down into the plant rooting zone and replenish drying soils.

"This excellent reserve of soil moisture will now form a 'bank' that crops can draw on through to the end of the season."

When the AEGIC crop model STIN (moisture stress index) was run on July 27, and then on August 2, Shire yield predictions increased by more than 700kg per hectare in Koorda and Quairading, and between 600 and 680kg/ha in Bruce Rock, Dalwallinu, Goomalling, Mount Marshall, Trayning and Wongan Ballidu.

But Latham grower Brian McAlpine said despite the 80mm he received two weeks ago, he could not see wheat yields achieving record levels in Dalwallinu Shire this year.

Mr McAlpine says the rain received at the end of July would not compensate for the early sowing times, extended dry periods and high temperatures throughout autumn.

"We have had big dumps of rain throughout the growing season, but we've also had long stretches of dry periods, and this has affected the wheat yield potential here," he said.

"While the rain has been fantastic, we had very warm growing conditions in May, and a lot of the mace wheat had already bolted, meaning many of the plants haven't tillered.

"Much of the district is planted to Mace, and this variety is known for panicking in long dry periods, and the stage the plant is at now, we don't think it will fully utilise the moisture that we received two weeks ago."

Despite this, he said his business would be applying some nitrogen to capitalise on any new tillers on the plant.

"Powdery mildew is also a concern for this district, and this is a one in 10-year disease for us," Mr McAlpine said.

"While we aren't sure at this stage why exactly this has occurred this year, it's likely to be as a result of increased spore levels from autumn rains."

Mr McAlpine said in contrast the barley and canola crops throughout the district were looking outstanding.

Dr Stephens said the map was based on a midpoint of planting dates across each Shire, not early sowing dates, and the model assumed the recent rain would be 100 per cent effective for wheat crops, regardless of variety.

"This means the Shire rankings are probably overly optimistic given much of the Dalwallinu Shire is planted to mace and given that very early sown crops have bolted under warm temperatures and late July moisture stress," he said.

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