Field Evaluation of Various Plant Biocides in the Control of Black Sigatoka Disease in Plantians

Abstract

A field experiment was conducted at the Federal University of Technology, Teaching and Research Farm, Owerri in 2005 to evaluate the efficiency of using seven plant biocides (extracts) in the control of Black Sigatola disease in plantains. The experiment was carried out using the randomized complete block design with three replications. The Treatments include: Azadiractha indica (neem plant), Vernonia amygdlina (Bitter leaf) Ocimum gratissium (Nchanwu) Pergularia sp (utazi) Allium sativum (garlic), Citrus aurantifolia (lime) and Piper guinensis. (African Black Pepper). Data on disease development and efficacy of each plant biocide were collected at flowering on 5 plants of maturity per plot using the youngest leaf spotted (YLS) method. The proportion of the leaf area showing symptoms was scored on a scale of 0 to 6. A disease severity index (DSI) which also had a low DSI was also calculated were analyzed using the analysis of variance. Pair-wise testing between means was done using the Duncan New multiple range test at 5% level of probability. Results indicated that the ethanol extracts of plant biocides from Azadiractha indica and Piper guinensis were significantly (P. = 0.05) more effective than other plant biocides as observed from the youngest leaf spotted (YLS) assessed at flowering after 8 spray applications. The DSI recorded two weeks before harvest has 1.6 for Azadiractha indica and 0.8 for Piper guinensis which confirmed results from the YLS assessment. It is hereby strongly recommended to apply ethanol extract sprays of Azadiractha indica and Piper guinensis extracted at the rate of 20g plant material dissolved in 100ml ethanol due to its high level of fungitoxic ability on Black Sigatoka disease in plantains. It was also observed that ethanol extract of plant materials was more effective and efficacious in fungitoxic ability than the water extracts respectively.