Seesawing temperatures cause issues for Mid West crops

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Frost on wheat.
Camera IconFrost on wheat. Credit: GRDC

Seesawing temperatures are causing headaches for farmers in the Geraldton Port Zone as thirsty crops battered by freezing temperatures contend with days above 30C.

Growers inland from Geraldton shivered through temperatures between 0.9C and 4C during September 3 and 5, with widespread frosts recorded across the Mid West.

The lowest temperatures were recorded on September 3, hitting a near-freezing 0.9C at Canna, Perenjori, Morawa and Mingenew.

Yuna, Eradu, Wongoondy, Allanooka, Tenindewa and Mullewa hit 2.4C that morning, while Northampton and Allanooka dipped to 3.1C.

While the maximum temperature in those areas hovered between 17C and 25C on those frost-inducing days, the temperature took an upwards turn last week.

The mercury hit 31C at Yuna, Mullewa on September 8, and 32C at Northampton and Allanooka on September 7.

Eradu, Wongoondy and Tenindewa had two days of 30C and 31C weather on September 7 and 8, with the temperature hovering at 28C for a day on either side.

Elders agronomist Belinda Eastough, who also farms at Yuna, said the “extreme” turn in the weather and a lack of rain was “knocking off more yield” than the frost itself.

“The extreme temperatures are starting to take the cream off the top,” she said.

“The heat means the plant cannot pull enough moisture in, so they shut down and stop filling with grain.

“The heat sterilises the pollen if it is flowering. Wheat is pretty tough, but it is a shock for the crops to go from being very comfortable to dealing with extreme temperature.”

She said head frost — where cold air or water is caught next to the flag leaf — had been more prevalent than the stem frost, where water settles inside the leaf sheath.

“When we get a severe frost the crops will change colour within days. There were no major immediate changes,” Ms Eastough said.

The extreme temperatures are starting to take the cream off the top.

Belinda Eastough

She said it was not unusual for the Mid West to record patches of frost, with the worst events before this year recorded in 2015 and 2016.

The frost event earlier this month was the second for this growing season, Ms Eastough said, with crops in low-lying sand plain areas near Yuna hit by frost about a month ago.

She said with little rain recorded in the Mid West during the past month, growers were “looking for a rain”.

“A rain would be worth a lot of money right now; I would say that if we don’t get much rain in September and it stays very warm, we would be looking at an average season,” she said. “We have all farmed for a very good season, input-wise and attitude-wise ... everything has been geared towards an excellent season.”

Planfarm agronomist Nick McKenna, based in Geraldton, said the lack of rain in August had been a “killer for crop potential”.

Planfarm agronomist Nick McKenna.
Camera IconPlanfarm agronomist Nick McKenna. Credit: Planfarm

“Normally August is a reliable month for rainfall,” he said.

“Some people have recorded 30mm but many have had around 7mm. It is well down on the long-term average, and lower than what growers hoped for.

“That lack of rain has been the main contributor to a decline in potential yield.”

Mr McKenna, pictured, said some farmers would start desiccating early-sown canola — put in around the time cyclone Seroja hit on April 11 — as early as next week after a dry six weeks.

“Most of the wheat sown after the middle of May is still looking for a rain,” he said

.“Most of the crops got their flowering done before the hot (30c-plus) days, but some later-sown crops will have some yield potential taken away.

“It is a bit of a shame that some of that yield has fizzled due to the warm weather and dry conditions. The last big rain was about six weeks ago.”

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