Prolonged dry periods could heighten the risk of powdery mildew in carrots this season, Syngenta Crop Protection UK has warned.

According to the company, the disease is particularly prevalent in dense crops where the leaf canopy has closed over and humidity levels are high, and where crops at the end of their fungicide programmes ready for harvest.

Global warming weather patterns of hot, dry summers, with intermittent heavy rain, could make this the typical season of the future, the company warned.

David Martin of Plantsystems said there was a significantly increased Powdery Mildew risk factor after monitoring in-field weather conditions and predictive models of disease development, designed to optimise growers’ spray timing.

“Weather conditions through July have been ideal for Powdery Mildew. Growers might expect to find patches of white powdery colonies developing on leaves. If they don’t control early infection quickly, it will rapidly spread across the crop,” he said, adding that growers spraying for Carrot Fly on a 10-14 day cycle, and including a prophylactic fungicide, could be suppressing the disease symptoms.

However, the company announced that conditions have reduced the risk of Sclerotinia and Alternaria.