Azole fungicide, prothioconazole, is now approved for use on cabbage and leeks, with the aim of the label being extended to include Brussels sprouts, broccoli and cauliflower in 2010 and carrots in 2011.

The vegetable crop formulation, Rudis, controls all four spotting diseases in cabbages and powdery mildew, and rust and purple blotch in leeks, manufacturer Bayer says.

Disease control in vegetable crops has become increasingly difficult with limited options, according to Nathan Whitehouse, Bayer’s product manager for fruit and vegetable crops. “Growers also need to combine curative and protectant activity in each spray, but resistance management guidelines restrict the use of strobilurins to two applications in a typical five-spray programme for cabbages or leeks.”

Rudis offers both protection and sustained curative activity, however, plus greening and physological yield effects, he claims.

In Dutch trials the product proved to be the best performer against ring spot in cabbages, reducing infection to 24% compared with 86% in the untreated.

UK trials, carried out by the Stockbridge Technology Centre in Yorkshire, showed a 12% yield improvement in leeks, similar to strobilurin products. However, by far the best result was achieved by programmes combining two applications of Rudis with two of Nativo 75WG (trifloxystrobin + tebuconazole), which boosted yields by 22%.