Masstock group field staff have identified high levels of seed-borne leaf and pod spot in winter bean seed samples and have issued advice, along with Processors and Growers Research Organisation (PGRO).

Winter bean growers must take steps to protect crops from higher levels of seed-borne leaf and pod spot (Ascochyta fabae), warns Masstock seed and crop manager David Neale. Test results from certified and farm-saved seed samples, taken by Masstock group field staff throughout the UK, have found levels of the disease as high as 20%.

"Given the current workload on farms and the desire to make the best of drilling opportunities, it is vital that farmers do not overlook the risks from this costly disease," advises Mr Neale. "Growers need to protect their seed investment.

Anthony Biddle, from the Processors and Growers Research Organisation, confirms that higher levels of Ascochyta have been identified this year. "We have seen levels as high as 10%, which is what you'd expect after the wet end to the summer," he points out. "We didn't find much early on in the year, but as the pods matured the disease got in and has infected seed."

Growers planting untreated seed with more than 1% infection can expect problems, he warns. "Ascochyta fabae is a seed-borne fungal disease that becomes apparent on leaves expanded by the end of November to December. Visual signs are circular, black-edged grey-brown lesions on the leaves. These produce spores which are spread by rainsplash."

A dry spell can kill off the disease, but a wet winter can produce an infection in the crop that is very difficult to control, explains Dr Biddle. "It's difficult to say what the effect on yield will be. It causes plant loss and the stems break, which can make harvesting very difficult."

Ascochyta can also be carried over on crop debris and volunteer beans, points out Mr Neale. "There will be a risk to bean crops in fields adjacent to those cropped with beans in 2004," he warns. "But by far the highest risk will be from infected seed."

The level of infection can be quickly gauged through testing. "The first line of defence against Ascochyta is to ensure seed is treated with a dressing that contains thiabendazole. Growers should certainly avoid using seed with an infection level above 3% in any case," he advises.

"We've built the Masterseeds brand on ensuring it maintains the highest standards in the business," points out Barry Barker, national seeds business manager for Dalgety. "Growers should be aware that test results on both certified and farm-saved seed samples do vary enormously. But they can be confident that Masterseeds' beans will still deliver the top performance - we would not supply untreated seed with an infection level above 0.2%."