Curative Septoria situations driven by the perfect storm

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Agronomists and growers across the UK are reporting continuing high disease pressure following interrupted spray programmes, making it even more important to protect wheat crops with robust and timely T2 fungicide sprays.

In many areas, wet weather caused havoc with T0 sprays, with many missed or going on late, and most T1 sprays were delayed.

The aim must be to apply T2 sprays when the flag leaf is three-quarters to fully emerged, even if that means shortening the T1-T2 interval, says BASF business development manager Ben Freer.

“Continuing warm temperatures will result in a rapid explosion of disease,” he adds. “A robust dose of Adexar or Librax with CTL is the best approach, even if the T1 has only just recently been applied.”

AICC member Ben Boothman, who is based in North Yorkshire, says Septoria is the biggest concern, with disease at the plant base ready to be spread by rain splash.

“I would say we are at medium to high risk of Septoria this year, with the weather being the key to its development.”
Some of his T1 programme was based on Tracker to get a low cost SDHI plus rust active epoxiconazole onto crops early. Other clients have used epoxiconazole/CTL or azole and strob mixtures, depending on risk.

Mr Boothman hopes he can keep to a three-week T1-T2 interval, but will consider a T1.5 treatment if this is stretched.

Librax is his T2 choice, with AHDB trials in 2015 showing how effective it is both on Septoria and yields. “It is the standout performer,” he says.
NIAB TAG agronomist Julian Thirsk, who looks after crops from South Yorkshire to Northumberland, will also use Librax, as well as Adexar, at T2.

“Yellow rust has been bubbling up in the south of my area,” says Mr Thirsk. “It appears to be mutating so will need watching.”

Septoria pressure is high everywhere, but especially so further north, he adds. “It is present high up in the leaf canopy on many crops – even a heavy dew can spread it upwards.”

Robust T1s with good curative activity, for example Adexar plus Chord plus chlorothalonil, have been employed, but he expects to follow relatively soon with a strong T2, hopefully no more than 18 days after T1, to keep things under control.

Adexar will be first choice on more rust-prone crops, together with chlorothalonil. “Xemium is the strongest SDHI on rusts and I’m backing that up with epoxiconozole, the best azole against that disease.”

Mr Thirsk will use Librax plus epoxiconazole where septoria is the main target. “BASF suggests Librax has slightly better curative action, and its advanced formulation appears to boost metconazole’s activity.

“I think there was a shift in Septoria populations last year in this area, so mixing up azoles within a fungicide programme makes sense.”

Andrew Hunt, who grows Revolution, Reflection, KWS Lili and JB Diego at Great Melton Estate, near Norwich, used Adexar T1 on early-drilled first wheats whose lower leaves were defoliating with Septoria.

He’ll be using it again at T2, to make sure leaves 1, 2 and 3 are kept clean. “I consider Adexar to be the best product as it does the best job on disease and keeps the rest of the plant greener for longer.”

Conor Colgan, of Lowick Farm, near Berwick-upon-Tweed, is also opting for a second Xemium application at T2.

Disease prevention is key when it comes to planning fungicide programmes. “My fungicide spend is usually at least £10/ha more than most farmers because I’m cautious and I know I’ll benefit given the productivity of our soils,” he says.

At T1 he used Imtrex + Bravo + Kestrel, the latter to supply two different azoles. At T2, he plans to apply Librax + Bravo + Ignite + Comet 200, providing a second application of Xemium and Bravo for the season, plus epoxiconazole and metconazole.

“It’s a high disease pressure year, so I’ve chosen Librax because of the formulation quality, the complementary active ingredients and the interesting work BASF has communicated on effective leaf penetration and uptake. I’ve added Comet 200 for its rust control and greening boost to drive yield.”

Keith Challen, farm manager for Belvoir Fruit Farms, Leicestershire is another grower using Xemium twice this year.

“It’s been the perfect storm, wet and warm all winter, coupled with high biomass crops and the presence of lots of disease. It’s a year that you can’t take your foot off the gas.
“No other product offers the protectant and curative disease control that Xemium does. I’ve used it at T1 and I’ll use it again at T2.”

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