Disease of Potato Plant


Potatoes are a staple in the diet of many people around the world. They are considered a reliable and easy-to-grow bulk crop that can be stored away for the winter months. Plant potatoes in nutrient-rich, well-drained soil in brightly lit areas of your garden. Potatoes are prone to disease but you can take preventative measures that will guarantee a healthy harvest.

Late Blight

Late blight, responsible for the Irish potato famine in the 1840s, is considered to be the most devastating of the potato diseases. Plant leaves develop dark green, greasy-looking spots that later turn black. As spots get bigger, a white fuzz will show up on lower leaves. Late blight can occur at any time and if left to progress, will kill the potato plant. Control late blight by planting healthy tubers and by removing all potatoes from the garden before winter. If blight appears on leaves, spray them with a fungicide. Copper fungicide provides the best protection in the damper, cool conditions favored by blight.

Early Blight

Early blight develops on the leaves of the potato plant in July and August when plants begin to mature. It appears on lower leaves in the form of dark circle-shaped spots that can be about 1/4 inch in diameter and look like a small target. Spots may show up on tubers and stems. When early blight appears on leaves before flowering, spray a fungicide on plants to keep infection from spreading to other leaves. Early blight will occur on all vines late in the season; this does not affect the crop yield and treatment is not necessary. Proper fall cleanup will help prevent early blight in next year's potato crop.

Wilt Disease

Two forms of wilt disease affect potato plants. They are caused by the fugi Fusarium sp and Verticillium sp. Signs of wilt disease is yellowing of the lower leaves of the plant, they may droop or curl downward. Leaves can have dark spots and a bronzed coloring. Symptoms may appear on one side of the plant but most times wilt disease affect the entire plant. Wilt fungi will survive on tubers, it may also survive in soil for up to seven years and can affect tomatoes, peppers and eggplants if they are planted in infected soil. Wilt can't be eliminated but you can minimize it by growing your potatoes in different spots of your garden each year.

Potato Leafroll Virus

Leafroll is a virus that is found in seeds of tubers and is spread by aphids. Signs of leafroll is a reddish or yellow discoloration of lower leaves on plants. Leaves will eventually roll upward and plants may become stunted in their growth. Control potato leafroll virus by planting disease-free seeds and use mineral oil sprays to stop aphids from spreading the virus.

Potato Virus X and Potato Virus Y

Potato Virus X is the most widely spread of all the potato viruses. Sometimes called Mosaic virus, it is characterized by a mild molting of the foliage. It is most damaging to plants when combined with Potato Virus Y or Potato Virus A. When these viruses combine, a disease known as Rugose Mosaic occurs. Signs of this disease are crinkling and browning of the leaf, tuber necrosis and plant death. Potato Virus Y infected plants exhibit molting, leaf drop and premature death may occur. Potato Virus Y becomes even more damaging when mixed with other viruses such as Potato Virus A and Potato Virus X, Potato Virus Y will cause extensive damage to potato plants. The virus is transmitted by aphids and human activity. Other plants such as Tobacco, tomatoes and peppers are hosts for the viruses. Control Potato Virus X and Potato Virus Y by using insecticides or mineral sprays to reduce disease-spreading aphids, and be sure to plant disease-free seeds each year.

Keywords: potato blight, potato disease, potato virus

About this Author

Amy Deemer has been writing since 1992. Her articles on family life and pets have appeared in the family section of "The Herald Standard" newspaper. Deemer has an Associate of Arts degree in liberal studies from Westmoreland Community college.