No resistance to the BASF fungicide boscalid (as in Tracker) has yet been found in septoria populations following further monitoring in 2007.

A total of 430 septoria isolates collected across northern Europe showed no difference in sensitivity to baseline measurements, the firm’s Gerd Stammler said at the British Crop Production Council congress in Glasgow.

However, some mutations in the binding site in Botrytis had been detected, which caused some resistance to the chemical.

“It is possible for those mutations to occur in septoria,” Dr Stammler told FWi.

But the combination of epoxiconazole and boscalid in Tracker was a good resistance management strategy, he maintained. “Epoxiconazole helps reduce the selection pressure on boscalid.”

If the mutations did occur, epoxiconazole’s full activity would still occur, although the contribution of the boscalid to disease control would be reduced, he pointed out.