Bio-fungicides in Allium sativum (L) had significant inhibition on Phytophthora megakarya (Brasier & Griffin) and cocoa black pod rot disease
Author(s): Ayodele M Ajayi
Abstract: Aqueous extracts from three plants (Chromolaena odorata, Zingiber officinale and Allium sativum) were evaluated In vitro and In vivo for the management of cocoa black pod rot disease caused by Phytophthora megakarya. Four concentrations (20, 40, 60 and 80%) of hot (70o C) and cool (35o C) aqueous extracts were obtained from fresh and dry samples of each plant. Efficacy of extracts was determined by inhibitions of mycelial growth of P. megakarya (In vitro) and disease progression on cocoa pods (In vivo). Treatments were replicated four times, and incubated at 28o C ± 2o C and 75% relative humidity. Data were collected on mycelial growth of pathogen on artificial media and radial growth of infection on cocoa pods. Statistical analysis of data collected showed significant differences among the concentrations of aqueous extracts. Inhibition of mycelial growth increased with increasing concentration of extracts but decreased with increasing days after inoculation. A. sativum was the most effective In vitro. Mycelial growth inhibition of 100% (40% concentration and above) was recorded at 3 days after inoculation. C. odorata was the least effective, as its highest percentage mycelial growth inhibition was 54.12% (at the highest concentration of 80%). A. sativum was also the most effective In vivo. It inhibited infection by 66. 10% and 79.03% (60% and 80% concentrations respectively) at 11 days after infection. A. sativum can be recommended for use in the management of cocoa black pod rot disease.