The latest results from fungicide performance trials against phoma leaf spot show that good control can be achieved with a two-spray programme.

Treatment timing is important to get the best control, the first application should be made when 10–20% of plants have phoma leaf spot and the second application when reinfection is evident – 4 to 10 weeks later. In trials, half rates were sufficient to get good control and a significant yield benefit.

The phoma forecast can help with spray decisions by providing an overview of phoma levels at a number of trial sites across the UK. However, the dry weather in September has led to patchy development with no consistent regional pattern, so walking and monitoring crops is essential.

“We are seeing the first symptoms of phoma leaf spot in crops now and, with recent rain, are likely to see threshold levels in some crops in the next few weeks,” says Dr Faye Ritchie of ADAS. “All triazoles are good as protectants so, for many growers, product choice will depend on other features.

"Curative activity, for example, with prothioconazole products, is important when small plants are infected. Products with plant growth regulatory activity, such as metconazole or tebuconazole may be favoured as protectants where plants are large and reach six leaves by mid-October."

This autumn, an SDHI + strobilurin co-formulation, known as Refinzar, is available for the first time, full details about how it performed, as well as an update on currently available products, is available in the full report.

Fungicide performance results for light leaf spot are also available, full results for wheat and barley will be presented at the HGCA Agronomists’ Conference on 9 December.