So risky to relax with septoria
So risky to relax with septoria
DONT be tempted into false economies with T2 flag leaf sprays on apparently clean winter wheats, say specialists.
After Aprils unusually dry spell, conditions now favour the number one potential yield-sapper – Septoria tritici, warns Bayers Neil Waddingham.
"We are back to a more normal British summer, and I think the risk from septoria is still very high."
ADASs David Parish agrees. "We have had significant rainfall. With crops often wet all day septoria risk is enhanced. Remember, we are aiming to protect the two most critical leaves on the plant."
For best results and to guard against strobilurin-resistance both advocate triazole/strob mixes, with doses linked to perceived risk.
Varietal responses, based on treated and untreated yields from Recommended List trials, should drive decisions, Mr Parish advises.
Always apply mixtures
"Always use a mixture, formulated or otherwise," he stresses. His suggestions range from Landmark (epoxiconazole + kresoxim-methyl) for less responsive varieties like Claire and Malacca, through mixes of Opus (epoxiconazole) with Amistar (azoxystrobin) or Twist (azoxystrobin) for medium responders like Napier and Xi19, to Opera (pyraclostrobin + epoxiconazole) for the likes of Consort, Savannah and Tanker.
Outlay for an Opus/Twist treatment ranges from £23-31/ha (£9-£12.50/acre), notes Mr Waddingham.
"Opera fits in well if you are late with your T2, because of its excellent eradicant activity, which can buy back a few spray days," says Mr Parish.
It would also be the more appropriate product for gamblers tempted to postpone treatment to early ear-emergence. "But that is not a plan I would recommend. There is always a risk that the weather delays you even further and you cant keep disease out of leaf two." *
WHEAT T2 ADVICE
• Weather back to "normal".
• Renewed threat from S tritici.
• Main spur for flag leaf sprays.
• Strob/triazole mixes essential.