Sweet potatoes are widely grown in Florida. In addition to the traditional moist, orange-fleshed varieties, a dry, white-fleshed type, the boniato, is extensively grown in south Florida. Both types are the same species (Ipomoea batatas), however, and their pest problems are similar.
Foliar pests are generally not too difficult to manage and include agromyzid leafminers, sweetpotato whitefly, (also called silverleaf whitefly), and morningglory leafminer, which is a small caterpillar. Armyworms will also feed on foliage. Natural enemies of these pests can be conserved by using pesticides specific for the pest and avoiding broad-spectrum insecticides, if at all possible.
The most serious pests are those whose immature stages feed on roots: sweetpotato weevil, wireworms, banded cucumber beetle, pale-striped and sweetpotato flea beetles, and in south Florida, Diaprepes weevil and Cuban May beetle. Other white grubs will also feed on sweet potato roots. There are very few soil insecticides available at this time. One of the few that remain, chlorpyrifos, has a 125 days-to-harvest interval which rules out its use with early-maturing varieties. Foliar insecticides aimed at the adult stage can give some control.
Sweetpotato weevil is the most serious pest of sweet potatoes (https://edis.ifas.ufl.edu/IN154). Sweet potatoes fed upon by weevil larvae become extremely bitter in taste so even minor feeding renders the potato unmarketable. Some varieties of sweet potato (Regal, for instance) have some resistance to the weevil as well as other beetle pests but the most popular orange-fleshed variety, Beauregard, is highly susceptible. Of varieties currently grown in Florida, Jewel is the only one with some resistance to insects (flea beetles).
In areas of the state where weevils are not common, it is very important to use only certified slips or transplants from weevil-free areas to avoid introducing weevils. The adult weevil does not have wings, and it and the larval stage are most often moved by transporting infested plants or storage roots (potatoes). During the growing season, keeping storage roots covered with soil helps reduce damage by preventing female weevils from laying eggs directly in roots.
Cultural practices can help reduce insect problems. Ideally, soil should be turned two to three months before planting. Crop rotation is also important. Avoid growing sweet potatoes in the same field two years in a row. New fields should be at least a mile from old fields. Destroy crop residues and culls immediately after harvest and for weevils, empty and clean potato storage areas thoroughly at least a month before harvesting the new crop.
The following table lists insecticides currently registered for use on sweet potatoes.