“Unprecedented” brown rust infections may require a further top-up spray to see wheat crops through to harvest, growers are being told at Cereals 2007.

“Around half the growers have told me they applied ear sprays more than ten days ago,” Bill Clark, who was manning the HGCA Appropriate Fungicide dose demonstration, said.

“The low dose triazole / strobilurin fungicides they applied are likely to be running out of steam (against brown rust) now.”

Even if crops senesced earlier than usual this season, they would still have another four weeks left of grain filling, he suggested. “They need more protection. Growers have already spent £50-60/ha, but they are risking yield to save £5-6/ha.”

Yield losses from late season brown rust attacks could cost up to 20% in yield, he said.