Evaluation of Mixed Planting and Weeding Regime for the Control of Iroko Gall Bug on Milicia excelsa

摘要

Background and Objective: Iroko gall bug, Phytolyma lata Scott. is a major insect pests of Milicia excelsa (Iroko) which has hampered the establishment of Milicia plantation in many West African countries. This study was conducted to assess the effect of planting M. excelsa with companion plants and weeding regimes for the control of P. lata. Materials and Methods: Six months old M. excelsa seedlings were planted in mixed stands with companion plants (Cedrela odorata, Azadirachta indica and Pierreodendron africanum) seedlings in a separate sub plots in five replicates. Weeding regimes (2, 4, 6 and 12 weeks) were allotted in a separate plot planted with pure stands of M. excelsa seedlings at the spacing of 2×2 m in three replicates. The experiments were laid in a Randomized Block Design (RBD), growth parameters (height, stem diameter and number of branches) and P. lata infestation (number of galls and size of galls) on M. excelsa were observed at two weeks intervals. Infestation and seedling survival were used as indices of effectiveness by subjecting data collected to one way analysis of variance (ANOVA) followed by Turkey’s test. Results: Field infestation by P. lata was significantly (p<0.01) lower on M. excelsa seedlings mixed with C. odorata and A. indica by 26.43 and 17.37%, respectively compared to control. Similarly, the plots mixed with C. odorata and A. indica had the highest percentage Milicia seedling survival 24 months after transplanting. The results were recorded as 52.23% of M. excelsa seedling survival, followed by plot mixed with P. africanum (28.02%) while 24% sole plantation was recorded. Phytalyma lata infestation on M. excelsa seedling was lower in 12 weeks weeding regime by 15% as compare to 2 weeks regime. Conclusion: It is concluded that planting M. excelsa in mixture with companion plants was promising for P. lata management and 12 weeks weeding regime reduced P. lata attack on Milicia excelsa.