Comparable Effectiveness of Organic Mulch and Conventional Insecticides in Managing Sweetpotato Weevils and Millipede on Selected Sweetpotato Varieties

Abstract Organic produce have of recent been among the positive outlook for health safety in bids to avoid the bad impact of synthetic insecticides to human and the environment. The use of non-chemical control measures has been practiced on sweetpotato weevils with uncertainty. Very often, farmers either do nothing or rely heavily on synthetic insecticides. Field experiments were conducted from 2015 to 2016 to assess the effectiveness of grass mulch in controlling sweetpotato weevils and millipede on sweetpotato tubers at TARI, Kibaha in Tanzania. Comparison was made with Dimethoate 40EC insecticide and a negative control treatment where no weevil management technique was applied. The treatments were tested on four popular and farmer preferred sweetpotato varieties; Ukerewe, Simama, Mataya and Kiegea established on naturally infested fields. Obtained results suggested that the use of mulch significantly (P < 0.05) increased sweetpotato yield (weight) and but did not reduce Cylas puncticollis infestation on roots. The influence of test varieties on C. puncticollis infestation were highly significant (P < 0.005). The effect of dipping sweetpotato vines into Dimethoate 40EC against C. puncticollis and millipedes prior to planting was insignificant (P > 0.05). Conclusively, neither grass mulch nor Dimethoate 40EC insecticides may offer effective control of sweetpotato weevils in pest endemic areas.