Carrot leaf bligh

Alternaria Leaf Blight is a foliar disease of carrots caused by the fungus Alternaria dauci. Alternaria dauci is included in the porri species group of Alternaria, which is classified for having large conidium and a long, slender filiform beak. Because many of the members of this group have similar morphology, Alternaria dauci has also been classified as formae specialis of carrots, or A. porri f. sp. dauci.

Symptoms of A. dauci appear first as greenish-brown, then water-soaked, and finally necrotic lesions 8–10 days following an infection event. These lesions will appear on carrot leaflets and petioles, and have a characteristic chlorotic, yellow halo. The lesions can be irregularly shaped, and will often appear on older leaves first.