Plant extracts and antagonistic fungi as alternatives to synthetic pesticides in management of fungal diseases of tomato

Incorporation of biological pesticides in integrated pest management has lately been considered effective in production of safe food for human consumption, aesthetically valuable for the prime markets and increase in crop yields. Despite their efficacy, synthetic pesticides are generally expensive, not easily degradable and leave harmful residues on food products. The objective of this study was to evaluate the effectiveness of plant extracts in managing fungal pathogens of tomato. In-vitro tests were conducted between July and October 2016 to screen crude plant extracts for activity against economically important fungal pathogens. Plant samples were collected, blended to fineness and extracted in ethanol. The filtrate was concentrated by evaporating ethanol under vacuum. The poisoned food technique was used to evaluate effectiveness of the crude plant extracts against the test pathogens. Activity of the crude plant extracts was determined as inhibition of fungal colony growth. All plant extracts inhibited colony growth of the tested pathogens. Turmeric extract was the most active of these plants. Alternaria solani was the most susceptible pathogen while Rhizoctonia solani was the least. The observed potential of plant extracts in inhibiting growth of pathogens in-vitro is an indication of their potential to manage the diseases caused by those pathogens. Local environment should hence be explored further for more plants with antimicrobial potential and their active constituents identified and formulated. Sensitization of farmers in the use of natural products in disease management in place of synthetic pesticides should be encouraged for sustainable agriculture.