Pests & Diseases in Sweet Potatoes

Disease

• Root rot, a serious threat to the sweet potato, presents itself as dark spots on the surface of the root. The spots, or lesions, often increase in size while the sweet potato is in storage, and eventually the disease can rot the entire root. Another sweet potato menace, Fusarium wilt, yellows the leaves of the plant before the foliage starts to sag. As the disease progresses, the plant's growth remains stunted or it might die. Fungi cause both root rot and Fusarium wilt.

Beetles

• A variety of beetles attack the sweet potato. Adult beetles typically feed on the leaves of the plant, which rarely causes serious harm. However, the larvae of some species can produce significant damage when they target the root. The larvae, or grubs, of the white-fringed beetle, the click beetle and the cucumber beetle all feed on the root of the sweet potato. Control requires treating plants with a recommended insecticide. Follow all label directions.

Nematodes

• Nematodes, tiny worms in the soil, cause a condition called root-knot in many garden and agricultural plants, including the sweet potato. Root-knot attacks the roots of the sweet potato, resulting in the plant's weak growth as the roots cannot supply the rest of the plant with enough moisture. Only tests of the plant's roots and the soil can confirm the presence of nematodes. Unfortunately, no insecticides exist to rid the soil of nematodes. Removing the plants to an area free of nematodes is a good option, but you must test the soil to ensure that the worms are not present.

Prevention

• Prevention remains the best strategy for dealing with pests and diseases of sweet potatoes. Purchase disease-free plants and disease-resistant varieties of sweet potatoes. Ensure that your garden has as few weeds as possible, as they can increase the insect population. Avoid wetting the leaves when watering, which might make the plant more susceptible to disease. Keep the garden area free of plant debris. Avoid planting sweet potatoes in the same area of your garden for several consecutive years. Don't plant them in a spot where tomatoes grew previously.