The most destructive disease of potato is Late Blight, which can also infect tomato, egg plant, peppers and petunia. Late blight is favored by cool, wet temperatures. The late blight fungus survives and can be carried in infected potato tubers and can serve as the source of an epidemic. Spores from the fungus may be wind borne and carried 50 miles or more. Therefore, all infected cull potatoes and volunteer potatoes should be destroyed. Please call your County Extension office if you suspect you might have this disease.
Late blight lesions are light brown surrounded with a light halo. Lesions can advance to decay entire stem. Tubers can also be infected.
Blackleg appears dark and inky. May affect stems and rot tubers
Potato scab appears as raised or sunken lesions on potato skin
Potato mosaic is spread by aphids, infected tubers, and mechanically. Leaves appear mottled and crinkled and may be dwarfed. This disease is transmitted to the tuber and will cause disease in next years crop.
Potato Flea Beetle causes holes in leaves and larvae burrow into tubers
All Insect Photos - W. Cranshaw, CSU, Bugwood.org
Tri-fold with potato culture and disease information available by request
Questions? MSU Potato Lab 406-994-3150
The following practices should be used to manage potato disease:
This brochure was printed through support from the Montana Specialty Crops Block Grant Program