Symptoms
Larvae tunnel inside tubers creating yellowish to brown cavities with bitter taste and toxic terpenoids. Vine wilting in severe infestations. Adults create small round holes in vines. Characteristic frass at vine base near soil.
Prevention
Plant only certified weevil-free vine cuttings. Hill soil over tubers to prevent adult access. Practice crop rotation. Harvest promptly at maturity — do not leave tubers in soil.
Treatment
Organic
Apply entomopathogenic nematodes to soil. Use pheromone traps to reduce adult populations. Apply kaolin clay to vines to deter egg laying.
Chemical (last resort)
Apply chlorpyrifos granules at planting. Drench soil at vine base to target adults. Once larvae are inside tubers, chemical control is ineffective.
Affects 1 crop
Sources
MARDI Sweet Potato Production Guide; DOA Extension Bulletin