In line with previous years’ data, the latest HGCA research shows that two sprays of a triazole-based fungicide can achieve good phoma control at full and half dose. It is recommended that the first spray is applied when 10-20% of plants show phoma symptoms and the second when there are visible signs of reinfection.

“As some crops are well advanced with large plants while others have only 2 or 3 leaves, the plant growth regulator effect of the fungicide will be a key consideration this year,” says Dr Paul Gosling of HGCA. Products with PGR activity such as metconazole or tebuconazole may be favoured where plants are large and reach 4 – 6 leaves in October. On the other hand, on smaller plants where curative activity is needed, prothioconazole or flusiazole products may be more appropriate.

This season’s phoma risk forecast from Rothamsted Research predicts a mid to late October onset of the epidemic, meaning that small late-sown crops are most at risk. Getting the first spray timing correct will be crucial for these smaller plants which are at risk of up to 0.5t/ha yield loss if phoma is not controlled.

Fungicide performance information against light leaf spot will be available later this month and full results for wheat and barley will be presented at the HGCA Agronomists’ Conference on 10 December.

For full fungicide performance information go to hgca.com/disease control. The phoma risk forecast is available at rothamsted.ac.uk/phoma-leaf-spot-forecast