A SPECIFIC OFF-LABEL approval (SOLA) is being sought for the control of potato disease powdery scab with Shirlan (fluazinam) by the Scottish Agricultural Colleges.

“Powdery scab has been the bane of many seed and ware potato growers lives,” says SAC”s Stuart Wale. Losses to the disease average about 6m a year for seed potato growers, and 1m for ware growers.

In trials, Shirlan has given between a 20% and 40% reduction in incidence of powdery scab on tubers, and 40-80% reduction in severity of symptoms, he says.

“It doesn”t control the disease completely, but we”re sufficiently confident in its efficacy to apply for a SOLA.

” But off-label approval, if granted by the Pesticides Safety Directorate, will only cover seed crops initially, admits Dr Wale.

“That”s to avoid consumer residue issues.” Ultimately, he hopes the product will gain full approval.

Under the terms of the approval, 3 litres/ha of Shirlan will be applied to soil and incorporated just before planting. Application methods suggested include using a spray rig fitted on to de-stoning machines. “That has given the best results in trials.

” Growers using Shirlan for powdery scab control will be prevented from also using the product for blight control. “That shouldn”t be a problem. There are plenty of other options.

” Dr Wale expects approval, if granted, to come in time for this season”s cropping.