Evaluation of Different Botanicals for the Control of Coffee Leaf Rust (Hemileia vastatrix Berkeley and Broome)

Abstract

Coffee is one of the major foreign currency earners for Zimbabwe, with over 95 % of the total production being exported. Production of coffee is constrained by diseases such Coffee Leaf Rust caused by the fungus Hemileia vastatrix. Chemical control is widely used but it is expensive and not environmentally friendly. Hence this experiment was conducted in the laboratory at Coffee Research Institute, Chipinge in November 2015, with the objective of examining the efficacy of four botanical extracts viz Lemon grass (Cymbopogon citratus), Aloe vera (Aloe barbadensis), Moringa (Moringa oleifera) and Tobacco (Nicotiana tabacum) extracts in three different concentrations (100, 50 and 25% leaf extracts) as compared with Copper oxychloride as a standard fungicide and distilled water as a negative control. The experiment was laid in a Completely Randomized Design (CRD) design with a 4 x 3 factorial structure and was replicated four times. The first factor was the above mentioned four botanicals and the second was the respective concentrations (25%, 50% and 100%). Each experimental unit comprised three Petri dishes. Data on spore germination inhibition percentage was recorded. Results showed that the different plant extracts were effective in inhibiting germination of the spores though their effects were different. There was a strong correlation between plant extract concentration and spore germination inhibition for tobacco, Aloe vera and Moringa. Increase in plant extract concentrations resulted in a marked increase in spore germination inhibition. Of the four plant extracts; Moringa and lemon grass proved to be the most effective while Aloe vera was the least effective. It can be concluded that the four plant extracts are effective in inhibiting fungal spore germination. It is recommended that further studies be done in order to establish the active compounds which are responsible for the anti fungal activities. Also more experiments should be done to determine effects of these plant extracts on other fungal diseases which affect crops.