Influence of Empty Oil Palm Bunch Ash on Vegetative Growth and Control of Leaf Blight Disease of Cocoyam [Colocasia esculenta (L.) Schott.] Caused by Phytophthora colocasiae

Field experiments were done to determine the effect of oil palm bunch ash on vegetative growth and control of leaf blight disease of cocoyam [Colocasia esculenta (L.) Schott.] caused by Phytophthora colocasiae in a degraded ultisol of humid forest/derived Savanna zone of Southeastern, Nigeria. The experiment consisted of four rates of empty oil palm bunch ash (EOPBA) namely 0 t ha-1, 1 t ha-1, 2 t ha-1 and 3 t ha-1 laid out in a randomized complete block design (RCBD) and replicated three times. Soil samples were collected from the topsoil at a depth of 0 to 20 cm before application of EOPBA. Samples of EOPBA were analyzed to determine the chemical constituent of the ash applied to the soil. The result revealed that the application of EOPBA gave a non-significant (p > 0.05) effect on percentage emergency of cocoyam at 30 days after planting, the number of leaves at 30, 60 and 120 days after planting except at 90 days after planting which had a significant effect, leave area index at 30, 90 and 120 DAP was non-significant (p > 0.05) except at 60 DAP were a significant effect was observed and cocoyam leaf blight incidence and severity were non-significant (p > 0.05) at 90 and 120 days after planting respectively. The use of EOPBA as a soil amendment and for the control of cocoyam leaf blight diseases caused by Phytophthora colocasiae revealed that it has the potentials of promoting vegetative growth of cocoyam [Colocasia esculenta (L.) Schott.] grown in a degraded ultisol. This study also revealed that EOPBA does not have any significant effect (p > 0.05) in the control of cocoyam leaf blight incidence and severity. Application of 2 t ha-1 was found to be an optimal dose in the enhancement of cocoyam vegetative growth (leaf area index, number of leaves, stem girth and plant height respectively)