Control of Phytolyma lata Walker (Scott.) Attack on Milicia excelsa (Welw.) C. C. Berg seedlings under plantation conditions
In this study, five Phytolyma pest control measures which included: a mono-species plot (protected by mesh netting: T1), mixed-species plot (Milicia + Terminalia), mixed-species plot with foliar chemical treatment (T3), mono-species with foliar chemical treatment (T4) and untreated mono-species plot of Milicia excelsa seedlings (T5), were set up in a completely randomized block experiment with four replications. The total height, collar diameter and number of leaves were monitored fortnightly, while the Relative Growth Rates (RGRs) for height and diameter were estimated after 24 weeks. Data were analysed using descriptive and inferential statistics. The treatment effects significantly influenced height, collar diameter and foliage production, but the block effects were negligible. The highest mean height was in T1 (104.35 ± 2.93 cm), while the lowest was in T5 (68.15 ± 5.37 cm). The RGR for height (median = 0.013 cm-1 week -1) and diameter (median = 0.024 cm -1 week cm-1) were highest for T1, while T5 had the lowest (0.005 cm cm-1 week-1 and 0.012 cm cm-1 week-1, respectively). The provision of a physical barrier (perimeter fence) proved to be the most effective management strategy to prevent Phytolyma infestation, while the mixed-species layout was a promising alternative.
Keywords: Psyllid, Mixed-species plots, Iroko, Relative growth rate