Symptoms: Generally found in the eastern part of the United States, anthracnose is caused by fungi in the genus Colletotrichum, a common group of plant pathogens that are responsible for diseases on many plant species. Infected plants develop dark, water soaked lesions on stems, leaves or fruit. The centers of these lesions often become covered with pink, gelatinous masses of spores, especially during moist, warm weather. Anthracnose can reduce a beautiful harvest into rotted waste in just a few days.
The fungal disease overwinters in and on seeds, soil and garden debris. Cool wet weather promotes its development, and the optimum temperature for continued growth of the spores is between 75-85 degrees F. Moisture is required for development and germination of the fungus as well as for infection of the plant. It is spread by wind, rain, insects and garden tools.
Control: Choose resistant plant varieties when possible and use western grown seeds, which have not been exposed to the disease. If anthracnose is a common problem, do not save your own seed from plantings. To avoid spreading the disease, keep out of gardens when plants are wet and make sure to disinfect all garden tools (one part bleach to 4 parts water) after use. Do not compost infected leaves, fruit or stems and thoroughly clean up garden areas in the fall, after harvest, to reduce over wintering sites for the fungal spores.
Sulfur or copper powders/ sprays should be applied weekly to infected plants starting when the disease is first noticed and continuing throughout the growing season. These organic fungicides will not kill the disease, but prevent the spores from germinating. Seeds may also be treated prior to planting.
Photo Credit: Pacific Northwest Handbooks