Potato Blight

Potato blight is one of the most dangerous diseases affecting tomatoes and potatoes. It is caused by Phytophthora infestans—a fungus-like organism belonging to the oomycetes, rather than a true fungus. The disease causes rapidly expanding brown spots on leaves, stems, and fruit, especially during cool and damp weather. Prevention includes ensuring good air circulation, avoiding prolonged leaf wetness, and removing volunteer tomato and potato plants. Heavily infected plants should be removed entirely, and in the case of isolated lesions, all infected tissue should be cut out without spreading spores. Infected material should not be placed in a regular compost pile, and used tools must be cleaned. Pesticides can prevent infection or limit the spread of the disease, but only products currently approved for use on tomatoes and for the specific user should be applied, in accordance with the label instructions.