Septoria and brown rust activity needed for T3 timing

With the recent combination of wet and windy weather across the country, growers need to be thinking through their T3 strategy with a view to keeping a lid on the spread of Septoria in winter wheat.

In addition, as crops begin to take up much of the nitrogen applied during a dry April, rapid plant growth could exacerbate the situation, warns one agronomist.

"Wind and rain is great for spreading Septoria," says UAP's technical manager Chris Bean, "and with some nitrogen only being taken up now, lush growth and bigger leaves in the wheat will compound the situation".

Mr Bean advises that in terms of a T3 application, growers should base their strategy around a good triazole with both Septoria and brown rust activity. He adds: "Where growers didn't use a strobilurin at T1, but did at T2, then another strobilurin at T3 would be suitable." For brown rust and Septoria situations he recommends Comet (pyraclostrobin) in a mix with a triazole. "There might have been a tendency in May for varieties that weren't affected by rust to be given a T2 spray that wasn't as robust as perhaps it could have been. A return of high temperatures will bring back the brown rust threat."

For Septoria situations with a lower brown rust threat Mr Bean suggests the ready-made triazole/strobilurin mix Mobius (prothioconazole + trifloxystrobin).

He also warns growers that nitrogen uptake at this time of year can be the driver for other key diseases. "We're now coming towards flowering and growers of quality wheats should keep an eye out for powdery mildew, alternaria and sooty mould for example. Cyflamid (cyflufenamid) is good on powdery mildew and has useful additional activity against ear Fusarium.

"We're getting to the point of the season where we need to protect the quality of Group 1 and 2 wheats. With damp soils and warm, still weather conditions, blossom midge could also begin to be a threat. Traps should now be out in areas where midge is a potential threat so that treatments can be made once thresholds are reached," concludes Mr Bean.