EVALUATION OF DIFFERENT VARIETIES OF SWEET POTATO INTERCROPPED AT DIFFERENT TIMES WITH PEPPER IN THE MANAGEMENT OF SWEET POTATO WEEVIL (CYLAS PUNCTICOLLIS BOHEMAN) IN UMUDIKE SOUTH EASTERN NIGERIA.

Abstract

The African sweet potato weevil (Cylas puncticollis) is the number one constraint to sweet potato production in Nigeria. A field study was conducted at the National Root Crop Research Institute Umudike, Abia state during 2015 and 2016 cropping seasons to evaluate the effect of intercropping three varieties of sweet potato with hot pepper (Capsicum frutescence Linn) on the management of sweet potato weevil (C. puncticollis). The experiment consisted of sweet potato intercropped with pepper using different times of introduction of pepper into sweet potato (i.e. pepper planted same time with sweet potato, pepper planted 2 weeks after sweet potato, 4 weeks after sweet potato, pepper planted 2 weeks before sweet potato and 4 weeks before sweet potato. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replicates. The plot size was 18m2 each. Parameters evaluated included weevil population density, marketable and unmarketable weight of crop tuber, crop yield, root damage, root weight, yield loss and percentage colonization. Results from the study indicated lower insect pest populations were recorded in the intercrop plots (0.70, 1.17, 0.99, 1.05, 0.22 and 1.58) than sole crop plots (2.09, 2.17, 2.02, 2.03, 1.38 and 1.26) in both seasons. Results showed that the introduction of sweet potato 2 and 4 weeks after planting pepper were significant (P ≤ 0.05) and gave lower unmarketable yields of sweet potato roots, lower colonization and lower yield losses of sweet potato roots than the sole crops. Hence, farmers should adopt the practice for effective control of sweet potato weevil especially, during dry seasons when the insect pest infestations are more prevalent.