FIELD EVALUATION OF MAHOGANY SEED EXTRACT (Khaya senegalensis: MELIACEAE, (DESV.) A. JUSS) ON BOLL INFESTATION AND YIELD LOSS OF COTTON CAUSED BY BOLLWORM IN ZARIA, NIGERIA

Abstract

Two field trials were conducted at Samaru (110 11' N, 070 38' E and 686m above sea level) and Maigana (110 10' N, 070 37' E and 675m above sea level) in Northern Guinea Savannah ecological zone of Nigeria during the 2016 wet season to determine the effects of three concentration of aqueous Khaya seed extract (KSE) (20%w/v, 30%w/v and 40%w/v) on boll infestation, yield and yield loss of cotton (SAMCOT 9) caused by bollworms. Randomized complete block design was used with four spray application at two weeks interval beginning from 9weeks after sowing. The results showed that lower percentage boll infestation was recorded in Lambda cyhalothrin (27.8%) and 40%w/v (33.3%) than 30%w/v (52.3%), 20%w/v (58.4%) and untreated control (62.2%). Similarly, significantly high seed cotton yield was obtained from Lambda cyhalothrin (1638.9Kg) and 40%w/v (1396.8Kg) treated plots than 30%w/v (832.5Kg), 20%w/v (784.6Kg) and untreated control (779.6Kg). Percentage yield losses recorded from Lambda cyhalothrin (17.8%) and 40%w/v (21.9%) treated plots were found to be significantly lower than 30%w/v (43.8%), 20%w/v (44.3%) and untreated control (45.6%) which recorded the highest yield loss. The result of the boll stripping analysis showed that 50.6% of boll infestation was due to Pink bollworm (Pectinophora gossypiella) while American bollworm (Helicoverpa armigera), Red bollworm (Diparopsis watersi), and Spiny bollworm (Earias spp.) accounted for 25.0%, 13.7% and 10.9% of boll infestations respectively. Therefore, application of KSE in this study at different rates especially at 40%w/v was found to be effective in reducing yield loss and percentage boll infestation of caused by bollworms on Samcot 9.