Inhibitory Potential of Lime Fruit (Citrus aurantitolia) Bark Extract on Mycelial Growth of Colletotrichum falcatum, Causal Organism of Sugercane Red Rot Disease

Biocontrol of plant pathogens involves the use and manipulation of living organisms or bioorganic compounds to reduce inoculum density and to maintain the pathogen population below the disease threshold level. This study investigated the inhibitory potential of lime fruit (Citrus aurantitolia) bark extract in the control of sugar cane Red Rot fungus, Collectotrichum falcatum. Three different concentrations of the extract (i.e 20, 40 and 60%) was prepared and incorporated into sterilized potato dextrose agar (PDA) plates. Each treatment concentration was prepared in four replicate. The test organism maintained in pure sub-culture was inoculated into the four replicate plates of each of the treatment concentration. The control treatment was also inoculated but the extract was not incorporated in to the medium. Activity of the extract against C. falcatum was determined by the measurement (mm) of percentage inhibition of mycelial growth extension of the organism over a 7-day period. Two way analysis of Variance (ANOVA) and the Least Significant Differences (LSD) at 5% level of probability was used to analyse data obtained from measurement of the treatment replicates. The fungal mycelial growth inhibition was very significant at 40% concentration level than at 20 and 60%.