How to Control Sweet Potato Weevils

Sweet potato weevils are the most serious pest of sweet potatoes. If your sweet potato vines have this pest feeding on them, the plant will soon begin to turn yellow. These insects are easy to overlook because they are subterranean, so keep a close watch on your plants. If the weevil attacks your sweet potatoes, the tuber will be spongy and full of holes that the many larvae tunnel into this edible root. The sweet potato weevil lives in warm climates, especially the Gulf Coast, Hawai‘i and Puerto Rico. The wormy larval stage of this insect causes the most damage; it is white, legless and about 1/3 inch long. Adults are colorful flying insects, less than 1/3 inch long, with blue wing covers and orange/red bodies. They have a long, thin head and body, and look a lot like an ant.

Things You'll Need

• Weevil-free slips or seed potatoes
• Rake
• Fumigants

Instructions

1. Buy only certified weevil-free slips or seed potatoes.

2. Mound soil around stems, which deters larvae from entering the roots.

3. Clean up the garden area at the end of the season with a garden rake, and then plant the sweet potatoes in a different location the following year.

4. After you harvest the sweet potatoes, treat them with chemical fumigants to prevent the weevils from damaging the tubers while they’re being stored.

5. If you can store sweet potatoes in atmospheres with low oxygen and high carbon dioxide, the weevils will not be able to survive.

Tips & Warnings

• Ants and several types of parasitic wasps can function as natural enemies of the sweet potato weevil. A specific nematode can also be helpful in their control when it penetrates the soil and underground tubers and kills the sweet potato weevil larvae.

• Besides sweet potatoes, this weevil also eats members of the morning glory family. It does not affect any other vegetable crops.

• Pheromones, used experimentally, have shown a decrease in adult weevil populations since it disrupts mating.