Planting stock of either plant slips or seed potatoes should be obtained from sources certified as weevil-free or from known weevil-free areas. If seed is selected locally at harvest time in generally infested areas, however, the Potatoes should be treated thoroughly with 10 percent DDT dust applied at the rate of 1 pound to 6 to 8 bushels of seed. The treatment will prevent the establishment of infestation within the seed and kill any already existing weevils if they emerge from the potatoes.

Sweetpotato parts and scraps should be removed from the field after harvest. Storage banks or houses should be cleaned and sprayed with DDT as soon as potatoes are removed. Fields previously planted to sweetpotatoes should be plowed at least twice during the winter and all volunteer sweet-potato plants destroyed.

The sites for seedbeds should be located on land that was not planted in potatoes the previous year. Fields to be planted in potatoes should be removed as far as possible from the seedbed and be located preferably on land which had not been planted to potatoes the previous season. Plants and tubers in the seedbed or mother rows should be destroyed as soon as sufficient plants have been produced.

The storage of sweetpotatoes in commercial kilns used to be a problem because of the spread of weevils from infested potatoes to noninfested potatoes in storage and the dispersal of large numbers of adult weevils at the end of the storage period from the kilns to adjacent planted fields. A new treatment for stored table-stock potatoes does much to solve the problem. Visibly infested potatoes are culled out and the potatoes to be stored are then dusted with10 percent DDT dust. An inexpensive duster, operated on the principle of an air blower, is used that can treat a crate at a time at the rate of about 600 crates an hour. Only one-twentieth of a pound of dust is applied to a crate. The treatment will not destroy weevils already in the potatoes, but it will kill all adults upon emergence and prevent any spread of the infestation. It is desirable also to dust or spray the kiln with DDT before the crated potatoes are stored.

SWEETPOTATO WEEVILS also develop in certain morningglories and related plants of the genus Ipomoea. The insect-host relationship is not entirely clear, but apparently the wild seaside and marsh morningglories are important as hosts. Certain of the cultivated morningglories may have to be considered in eradication projects that involve urban districts. The weevil breeds in the seaside morningglory (Ipomoea littoralis), but chemical weed killers will control the plant. Infestation of the marsh morningglory (Ipomoea sagittata) is rarer, but the species may harbor the weevil enough to permit reinfestation of potatoes grown following the termination of a nonplanting period in an eradication area. These two wild morningglories are found only in limited sections of the sweetpotato-growing areas, mostly in the coastal and tide-marsh margins. In controlling the plants with a herbicide, it is desirable that DDT be included in the spray. The DDT will kill any weevils present or those that might emerge from the plants before the action of the herbicide is complete.

THE SUCCESS OF A CAMPAIGN against the weevil depends largely on the cooperation of every grower, packer, and Storage operator. Programs to inform all individuals of the aims of the campaign in areas of commercial potato production in Louisiana have helped greatly in getting full support. The keystone of the endeavor is a county or parish committee of growers, storage operators, dealers, representatives of civic and other organizations, and public officials. The committees sponsor meetings of growers and school groups to discuss the problem and methods. Exhibits and publicity material are presented by Extension Service specialists, county agents, and State and Federal agricultural workers.

FOR SOME YEARS the States infested by the weevil have maintained quarantines to prevent spread of the pest to weevil-free areas within the infested States as well as to noninfested States. The enforcement of the quarantines is primarily a responsibility and function of State plant quarantine officials but the Bureau of Entomology and Plant Quarantine aids in the enforcement as a means of assistance in the eradication and control work. The quarantines of infested States and noninfested States regulate the movement of sweetpotato plants and parts thereof (including vine cuttings, slips, and potatoes), other species of Ipomoea, and other plants that may be found to be hosts of the sweetpotato weevil.

Fumigation with methyl bromide or another approved treatment is required for the movement of table-stock potatoes from any of the infested areas to any of the States maintaining quarantines. The sweetpotato-producing States have additional regulations pertaining to the certification and movement of seed potatoes and plants.

From the beginning of the cooperative Federal-State eradication and control work, Federal inspectors have assisted the States in enforcing the nonplanting restrictions and in carrying out other control and eradication measures. Between 1937 and 1951, control and eradication work was done in 106 infested counties in 7 States. Of the 16,169 infested properties found in the counties, 12,327 were freed of weevils. In 1951, there remained 3,842 infested properties in 73 counties of the 7 States. No weevils were known to be present in the other 33 counties.

R. A. ROBERTS, an employee of the Bureau of Entomology and Plant Quarantine, holds degrees from Texas Agricultural and Mechanical College and Iowa State College. He has conducted research on insects and has worked on cooperative Federal-State insect control projects since 1926.