Alternaria leaf blight, caused by Alternaria dauci (Kohn) Groves & Skolko, is one of the most devastating foliar pathogens of carrots (Daucus carota L.). Lesions appear as minute, necrotic, dark brown spots often initiated on the edge of the leaflet blade. They later enlarge in size and may merge into a large necrotic area, causing shriveling of the entire leaflet (1). In summer 2000, observations made in several carrot fields in the northwestern part of the Negev Region in Israel revealed infections that were atypical for A. dauci because they were initiated primarily in the middle section of the leaflet blade and were surrounded by a large yellowish area. A. longipes (Ellis & Everh.) E. Mason was consistently isolated from the lesions. Occasionally both A. longipes and A. dauci developed on the same leaves. The two pathogens differed in conidial morphology (size and shape of spore and beak) when cultured on potato dextrose agar medium. One hundred conidia of each species were measured.
Alternaria leaf blight, caused by Alternaria dauci (Kohn) Groves & Skolko, is one of the most devastating foliar pathogens of carrots (Daucus carota L.). Lesions appear as minute, necrotic, dark brown spots often initiated on the edge of the leaflet blade. They later enlarge in size and may merge into a large necrotic area, causing shriveling of the entire leaflet (1). In summer 2000, observations made in several carrot fields in the northwestern part of the Negev Region in Israel revealed infections that were atypical for A. dauci because they were initiated primarily in the middle section of the leaflet blade and were surrounded by a large yellowish area. A. longipes (Ellis & Everh.) E. Mason was consistently isolated from the lesions. Occasionally both A. longipes and A. dauci developed on the same leaves. The two pathogens differed in conidial morphology (size and shape of spore and beak) when cultured on potato dextrose agar medium. One hundred conidia of each species were measured.