STROBILURINS ARE not a cost-effective form of disease control and generally do not boost yields any more than triazoles, new TAG trials suggest.

Tests in most regions had little impact on yield when compared with triazole use, says agronomist Tim Mayhew. “Strobilurins gave very variable responses. But we didn’t see much evidence for yield enhancement.”

Cornish work found winter wheat output similar whether TAG used Opus by itself or added the strobilurins Twist (trifloxystrobin) or Opera (pyraclostrobin + epoxiconazole). Any variation was in line with the level of septoria infection, showing that any lift in yield was through disease control, says Mr Mayhew.

“Use a high rate of fungicide and a low rate of strobilurin to capture the best yield enhancement,” he advises. “At the end of the day, very few strobilurins were cost-effective.”