Arable

Wet weather brings septoria pressure to yields

Friday 11 May 2012 17:02

Wheat growers should apply T2 sprays earlier to protect the flag leaf from septoria, warns Ryan Hudson, Agronomist for Strutt and Parker. Septoria is thriving in this year's wet conditions and if not curtailed has the potential to spread to later emerging flag leaves and damage wheat yields, he says: "The septoria pressure in the South East is the worst I have seen in at least two years."

Rain has been falling since mid-April across the South East and it is in these conditions that septoria is now showing the potential to affect the third and fourth stage leaves, even attacking the later, vital flag leaf.

There have been precious few spray windows due to rain and now crops are growing very fast after the dry spell, he warns.

"In these extraordinary conditions getting on top of septoria will be a challenge," says Mr Hudson.

Monitoring the growth stages of wheat closely and not working on calendar timings alone when spraying, especially in the wet conditions, is essential he advises.

He adds that growers should be prepared to make changes to spray plans if the crop growth stage has moved on and the flag leaf is going to emerge before they get the chance to spray a T1.

If the flag leaf has emerged then T1 spray plans should be reconsidered for the T2 timing, he advises. These fungicides will need to be significantly more robust to provide the best eradicant and protectant activity for the unprotected leaves.

Growers must ensure the dose of product is correct for the disease pressure; a 75% dose of a strong triazole which includes expoxiconazole or prothioconazole, with the levels of septoria present in crops is essential, he says.

At T2 growers might also consider the use of an SDHI such as Adexar (epoxiconazole and fluxapyroxad), which will provide some curative activity and good protection against septoria and rust.

However, says Mr Hudson should the weather improve and if growers can get a handle on septoria control then they could expect a high yielding year so the investment in a stronger fungicide programme is likely to pay off.

Key points in septoria control

  • Monitor crops and spray when necessary, do not rely on spray plans alone
  • T2s may need to be bought forward to protect the flag leaf
  • Increase dose rates
  • Make the most of every spray opportunity
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