Phoma Risk For All                                                              

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Mr Sparling warns that all crops are equally vulnerable. “The disease can spread from leaf and petiole to stem very quickly, especially in small plants. Backward crops carry the same risk as those that got up and away early,” he warns.

And despite drilling pressure Mr Sparling says growers shouldn’t see disease control as less of a priority. “For many regions Phoma is the greatest disease threat and few varieties have good resistance scores. It is a disease that cannot be treated retrospectively.

“The weather has been favourable with several rain events during August and September. We’re already seeing it in crops, and in volunteers it is very noticeable,” he notes.

Mr Sparling will base this autumn’s treatments around prothioconazole. “I always try and target a well timed single spray when symptoms appear and prothioconazole is the most active product we have. However, in severe situations a second spray is advisable.

“Prothioconazole also has the advantage that it is a good LLS treatment. With LLS now a concern in many areas it makes sense to tackle both,” he suggests.

Bayer’s product agronomy manager James Taylor-Alford says that for Light Leaf Spot control prothioconazole is by far the most robust choice this autumn. “There are product options for Phoma control but I would argue that for acceptable Light Leaf Spot control there is little choice apart from robust doses of prothioconazole’.

“In crops that established well this autumn, some growers will want to build in some plant growth regulation ahead of spring, however, the most effective growth regulation sprays year in year out are at the stem extension stage not during the autumn.  Get the disease control strategy right in the autumn first.

Apply Proline275 at 0.32 l/ha at first signs of Phoma infection and be prepared to repeat four weeks later.  If you are planning only one autumn fungicide application then use 0.46 l/ha” concludes Dr Taylor-Alford.