Field evaluation of soil -borne fungal entomopathogens for management of sweet potato weevils on Tanzania sweet potato variety in Uganda

Abstract

Pests and diseases pose a big threat to Agriculture and this makes it difficult to attain higher yields; especially for crops like sweet potato. Experiments were conducted at National Semi Arid Resources Research Institute (NaSARRI) in Serere district for two different seasons (2022A and 2022B). During the first and second season of to find out the efficacy of entomopathogens in controlling sweetpotato weevils in sweetpotato. The experiments consisted of seven (7) treatments of fungal isolates that is, No Application Control –NAC (0.00g), Negative Control + tween- NC-Tween (0.01%), K191 (7g), K157 (7g), K020 (7g), K040 (7g) and Positive controlPC (Cypermethrin) and 500ml of water. The experiment was layedout in a Randomized Complete Block Design (RCBD) and replicated three times and the spraying was carried out after every one month from planting. The parameters analyzed were leaf incidence and severity, sweetpotato weevil stem damage and tuber damage. These parameters were collected fortnightly from the first treatment while the yield data was collected at harvest. The result showed K191 treatment produced the highest number of tubers (yield) in season one (45.33kg), and season two (103kg), then the NC (25.0kg) that had the lowest number. While NAC had the lowest weight of tubers with (11.57kg) in season one while second season highest weight of tubers was (16.77kg). K191 had the highest vine weight (43.23kg, 29.70kg) compared to NAC (19.77kg, 25.07kg) in both season one and two respectively while in season two all the EPFS had no significant difference but however PC had the highest vine weight of (43.33kg), K191 also showed the least severity of damaged tubers (1.33) than NC (4.00) in first season, however PC showed the lowest (1.00) severity of tuber damage in both seasons. Overall, the study found out that K191 had a significant impact in controlling sweet potato weevils in the first season than in the second season and this could be likely due to the presence of rainfall in the second season that limits the proliferation of weevils.