Cercospora leaf blight (Cercospora carotae) and bacterial leaf blight (Xanthomonas hortorum) have been confirmed on UK carrot crops in the past three years.
The foliar diseases are well-documented in other European countries and are seed-borne. Symptoms of bacterial leaf blight include yellow, angular leaf spots that form irregular brown, water-soaked lesions with a yellow halo, eventually drying out and turning brittle, occasionally turning dark brown or black. Cercospora infection is shown as small, dark, angular specks on leaves that expand to grey/brown spots, sometimes with darker margins and yellow haloes.
After their first occurrence in the UK, the Plant Health & Seeds Inspectorate advised no statutory action as the pathogens are already established in Europe and generally cause minimal damage in typical UK weather conditions. This could change if temperatures rise, so growers have been advised to familiarise themselves with symptoms and control measures.
- For more details see www.hdc.org.uk.