Septoria in wheat crops can be well controlled by a standard azole and SDHI fungicide programme, although good management is becoming more important to keep the disease at bay.

While some growers have struggled to keep septoria out of their crops this year, trials by Bayer CropScience in Oxfordshire show a well-timed four-spray approach has given good control, even in this year’s high-pressure season.

Good disease control was achieved when only one SDHI fungicide was used in the programme at the site at Duxford Farm, near Hinton Waldrist, close to the River Thames and about 10 miles southwest of Oxford.

Tim Nicholson, Bayer’s commercial technical manager, says where the group’s standard recommendation of 0.55 litre/ha of Proline plus chlorothalonil at T1, followed by 1 litre/ha of Aviator at T2 was used this was visually not very different to where an SDHI was applied at T1.

“Even in Herefordshire at our site at Callow, where septoria pressure has been extremely high, the standard programme has given extremely good control,” he says.

However, the agrichemical group says using its SDHI-azole product Aviator at T1 as well as T2 in situations of high disease pressure has given a visual benefit in septoria control.

In both cases, the programmes began with a T0 spray of the azole Folicur plus chlorothalonil, applied in early April and completed with a standard overspray of at head spray at T3.

The need to pinpoint planned fungicide sprays was highlighted by Farmers Weekly’s trip to both sites as part of its Crop Doctor tour in early May .

Fungicide spray timing is crucial, especially with the curative power of azoles weaker than it was five years ago, Mr Nicholson points out.

“In some cases, T1s might have gone on a little early, and if they didn’t quite hit a fully emerged leaf three, that would have left part of leaf three and leaf two unprotected until the flag leaf sprays were applied,” he says.

In those situations, the gap between T1 and T2 would have been stretched past three to four weeks, and he adds it is perhaps unrealistic to expect clean plants when disease pressure has been so high.

It was too early to tell whether there had been any further shifts in sensitivity to azole fungicides, he says.

“Testing, as every year, will be carried out, but our trials suggest that where programmes have been timed effectively, control has been in line with what we would expect,” Mr Nicholson adds.

“But this year has highlighted that in high-pressure situations, it will be even more crucial to get your timings and doses spot on,” he adds.

See also: Septoria disease threat hangs over wheat crop