Find pictures of potato disease on the Washington State University website. Potato diseases ranges from black dot, early blight and zebra chip to those caused by pest infestations.
Bacterial soft rot, a type of potato disease, appears as soft, gooey black spots on potatoes, shows Washington State University. The disease starts by affecting the leaves, which wilt and start to curl up, adds the Pacific Northwest Plant Disease Management Handbook. The lesions then move down to the tuber. Manage the disease by disinfecting all tools and seed-handling equipment, rotating the crops regularly and avoiding moist and dry soil.
Both early blight and corky ring spot cause lesions on the potatoes and brown spots on the foliage, according to Washington State University. The former marks the leaves with brown spots, while the latter tends to cause a yellowish discoloration on the foliage. Fusarium dry rot, much like bacterial soft rot, causes black lesions throughout the tubers. Dry rot, caused by a white or pink mold, creates a dried, blackened cavity, says the Pacific Northwest Plant Diseases Management Handbook. Treat the fungal infestation with fungicides, particularly when the potatoes are being stored before planting, and harvest the potatoes only during dry weather.