Crop Watch: cold weather halts spraying

The Easter cold snap has forced many growers to delay planned T0 fungicides and outstanding Atlantis (iodosulfuron + mesosulfuron) applications, according to FWi’s team of agronomists this week.

Lincolnshire-based Ruth East said spraying had been put on hold until day temperatures of at least seven degrees, along with warmer nights, returned for at least seven days.

“Crops need to be actively growing, and not frost or wind damaged in order for fungicides and growth regulators to be taken up by the plant and to work effectively,” she said.

Warmer conditions needed

Dan Dines was also waiting for warmer weather to return before applying T0s and growth regulators. “Warmer conditions are needed if chlormequat is to be effective,” he advised.

The most forward wheats around the Wiltshire/ Dorset border were at growth stage 31, with leaf four fully-emerged, and the bulk were at, or nearing GS 30, he said.

“They can remain at this growth stage [30] for several weeks, and will only change to sexual development when the day length and light intensity changes,” Ms East added.

Agrovista’s Swaran Bachoo said where growers were planning to mix outstanding Atlantis with T0 fungicides, care should be taken. “Chlorothalonil mixtures with Atlantis are to be avoided, as it will give reduced blackgrass control.”

Cold weather

He also warned that the cold weather was unlikely to dramatically reduce diseases such as septoria or brown rust. “At best the disease will be set back by a few days.”

But, Robert Sullivan said that cold, dry weather in Northumberland meant levels of disease were “very low”. He still planned to apply a T0 fungicide though, the decision made easier by high grain prices.

“Certainly the most forward crops are likely to get a T0/ PGR around the end of the month.”

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