Purdue University
Agricultural Extension Service
Lafayette, Indiana
Mimeo E-32
Revised

CONTROL OF POTATO INSECTS

Potato Leafhopper: This small insect is the most destructive pest of potatoes in Indiana. Both the adults and nymphs suck the juice from the foliage and cause a condition known as hopperburn or tipburn. At first, the leaf margins turn slightly yellow and later curl and turn brown. In severe cases, the foliage is entirely destroyed, and the plant dies long before normal maturity. This pest feeds on a wide variety of weeds and cultivated plants, including beans, apples and alfalfa. They migrate into the field in late June, while later generations continue to migrate in throughout the summer. DDT formulations, discussed later under "Control Measures," are especially effective in killing this pest.

Flea Beetle: This small beetle is usually abundant early in the season when plants are small. They eat numerous small holes in the foliage and can seriously check plant growth. Commercial growers should use dieldrin or heptachlor in the first and third applications of their regular spray schedule. When dieldrin or heptachlor fails to control flea beetles, the grower should change to endrin or to one of the phosphate compounds, such as parathion or Diazinon.

Colorado Potato Beetle: This common pest is seldom serious except in home and community gardens, where insect control is usually haphazard or entirely lacking. Both the beetles and their red slug-like larvae feed on the foliage and can be controlled by DDT.

Aphids: Aphids or plant lice often become a serious problem on potatoes, especially in cool, wet seasons. The insects increase rapidly and are difficult to kill on plants with a heavy growth of foliage. DDT sprays made with wettable powders may favor aphid increase, while those with the emulsion help to hold them in check. Malathion as a dust or spray is suggested for the home gardener. Commercial growers who are equipped to protect themselves against parathion poisoning will find this material, and certain related compounds, excellent for the control of aphids. Follow all precautions CAREFULLY. Use one pound of 15 percent wettable parathion in water for one acre. This can be used with the various fungicides and can replace one regularly-scheduled DLT application. Other phosphate compounds, including malathion, Guthion, Diazinon and Trithion, are also effective.

Tarnished Plant Bug: This insect is a general feeder on various weeds and cultivated crops. On potatoes, both the adults and nymphs "sting" the terminal growth.

Blister Beetles: Several varieties of these long-legged, elongated beetles attack potatoes and related crops in home gardens. The beetles move into edges of the field and strip the leaves as they migrate from plant to plant. Fields treated regularly with DDT are not damaged. In small gardens, a mixture containing 50 percent cryolite dust or five percent chlordane is effective.

Control Measures

DDT as either a dust or spray will control leafhopper, Colorado potato beetle and tarnished plant bug. Although dusts are not as effective as sprays, dust mixtures a 30 to 40 pounds per acre will give good results. As a spray, DDT is used at a rate of two pounds of 50 percent wettable powder or two quarts of 25 percent emulsion con-