Bioactivity of Leaf Extract of Phyllantus amarus against Fungal Pathogens Associated with Sweet Orange Rot Disease

Abstract

This study was carried out to determine disease incidence and control of fungal pathogens associated with rot of sweet orange using Phyllantus amarus leaf extract. Forty sweet oranges (Citrus sinensis var. Valencia) were collected from the markets and taken to the laboratory. Isolation and identification of the fungi were carried out using standard procedures and the efficacy of the leaf extracts of Phyllantus amarus was determined on the isolated fungi. The result of this study showed that four pathogens (Aspergillus niger, Aspergillus flavus, Penicillum expansum and Rhizopus stolonifer) were identified to be associated with the rot. Rot incidence was upto of 35%. Pathogenicity confirmed the characteristic features similar to the original diseased samples. The effect of the leaf extract of Phyllantus amarus on the isolated fungi shows that the rate of inhibition increases with increase in concentration of the P. amarus extract, The P. amarus extract was effective against A. flavus had the highest zone of inhibition (10.667). The inhibition zone was lesser for R. stolonifer among the pathogens (8.333). Sweet orange should be consumed after harvest or can be stored in refrigerator for period of 1=2 weeks. The fruit should be discarded if  any alteration in color or taste of the fruit is noticed as this can be hazardous to human health.