Sweet Potato Weevil Damage Influenced by Variety and Harvest Date

Sweet potato weevil is the most serious pest of sweet potato, not only in the Virgin Islands but throughout the Caribbean. It causes damage in the field to leaves, stems and most importantly the tuberous roots. The objective was to evaluate harvest date and weevil damage in 18 sweet potato varieties.  Twelve sweet potato varieties were from in vitro virus-free material and six were Caribbean farmer varieties.  The varieties were established from six node cuttings in a replicated trial at one foot in-row spacing and five feet between rows.  Weevil traps with a male pheromone were distributed throughout sweet potato plantings and monitored weekly.  Harvest was conducted at 100 and 130 days.  Weevils were found to increase during the initial four weeks and stabilized during the rest of the growing season indicating that sweet potato weevils were at a high pressure throughout the growing period in the US Virgin Islands.  All varieties had some weevil damage at 100 days (4-15%), however by 130 days the weevil damage ranged from 4-75%. Sweet potato varieties with tuberous roots near the soil surface were more prone to sweet potato weevil damage then varieties with deeper tuberous roots.  Overall, marketable production was reduced, due to weevil damage, the longer the sweet potato remains in the field after 100 days.