Rust outbreak requires immediate treatment

Yellow rust is now widespread in many susceptible crops, particularly in northern and eastern England, and five sprays may be required to protect yield, agronomists warn.

With the cool, moist conditions experienced recently being ideal for rust, reports of the disease are increasing.

“On 9 March I could see some yellow rust in Oakley, but by 12 March it was in every field of the 4,000-5,000 acres of the variety that I have,” says Sean Sparling, AICC agronomist in Lincolnshire and the North.

Despite Oakley being the worst affected variety, there have also been some cases seen in Warrior, which has a good resistance score to yellow rust, so vigilance is required to protect infected crops.

There is the possibility of changing fungicide strategy to a five-spray programme in areas where yellow rust is taking hold, according to Andrew Wells of the Arable Alliance in Nottinghamshire and Lincolnshire.

“I warned growers with Oakley in the ground of the possibility that we may need an extra spray, as we were seeing yellow rust present coming out of the winter, so they are prepared to be flexible,” says Mr Wells.

“I’m concerned it’s a long time to wait until the traditional T0 timing, and I’m not prepared to leave crops unprotected for three weeks.”

Yellow rust is an extremely active disease, so dampening it now is a priority, says Bob Simons, KWS agronomy consultant.

“The trickiest period is now until flag leaf, and it’s critical to keep new growth clean. Where yellow rust has broken out in a big way, a low-cost triazole-based treatment now will see crops through until the traditional T0 timing,” say Mr Simons.

“People that are growing Oakley should be planning a very robust T1, as the variety still performs well with the correct management,” he explains.

Present reports suggest that the yellow rust problem is generally confined to the eastern and northern regions of England, with Stephen Harrison, independent agronomist in the South West, not seeing any yellow rust, even in Oakley.

“Where winter wheat had a fluquinconozole seed treatment I have seen no rust whatsoever, but now growers have their T0 sprays in stock, the application can be bought forward in the worst situations,” says Mr Harrison.

Brown rust is also providing cause for concern, with infected crops of Stigg reported in Norfolk, prompting fears that brown rust could also prove to be a big threat this season.

Andrew Cotton, of Cotton Consultancy, is seeing considerable infection in his area of Buckinghamshire, Oxfordshire, Northamptonshire and Berkshire.

“Some crops that are already at growth stage 30 have received a T0 treatment based on triazoles with chlorothalonil, dependant on herbicide requirements, and all other wheat crops will be having the same in due course,” says Mr Cotton.

“If brown rust is not controlled at this stage it can be a big problem to control later in the programme,” he adds.

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