Diseases caused by Alternaria species are very common worldwide. Host plants for this fungus family include: apples, broccoli, cauliflower, carrots, potatoes, Chinese cabbage, tomatoes, bok choy, citrus, many ornamentals and even some weeds.
This pathogen causes spots to develop in a target pattern of concentric rings. Many Alternaria species also produce toxins that travel into host tissues ahead of the fungus. Lesions can appear on leaves, roots, tubers, stems, and fruits.
UC ANR has a free downloadable publication to help you learn more about these diseases including:
- recognizing symptoms
- pathogen biology
- development of disease
- disease management.
Fruit with interior damage caused by
Alternaria citri.
Damaged foiage showing dark, circular lesions.
Blight lesions with concentric rings become angular
in shape when limited by leaf veins.
Damaged fruit showing large, sunken
black lesions caused by Alternaia alternata.
Carrot leaf tips discolored by Alternaria dauci.