3. Wheats still unsprayed
Again the high levels of disease already present rule out any thoughts of strobilurin fungicides, says Mr Metcalfe. Even with the addition of a clean-up triazole the full benefits would not be forthcoming, he explains.
"Crops have got to be clean right the way through the season to get full advantage from them. It would also be too costly to go through with a full-rate triazole at £12/acre and a strob at £15.
The only sensible tactics for untreated fields is to get on as soon as possible with a full-rate triazole in a water volume high enough to get good crop penetration, he says. "But I am worried about the amount of disease and whether we shall be able to contain it if we get a wet summer."
In second wheats Opus, rather than Folicur, is his preferred option, mainly for its effect on eyespot. Even at this late stage he believes it provides some useful protection against the disease.
NO PREVIOUS FUNGICIDE
• Full-rate triazole asap.
• High water volume.
• Strob benefits limited & too costly.
Do not delay the flag leaf spray this season even if T1 sprays were delayed, urges BASF.
Septoria pressure is the highest BASF business development manager John Peck says he has ever known. "Yield potential is good, but the problem is what is conducive to high yield is also conducive to high disease," he says. "You cannot afford to take risks with the flag-leaf."
Septoria is present on leaves but may not be visible yet as the latent period of the disease was extended by the cold weather, believes trials manager Stuart Godding.
They advise a full-rate flag-leaf spray as soon as the leaf is out. "You cannot assume a three-quarter rate triazole applied at GS 33 will last to ear emergence."