Control of leaf spot in yam with leaf extracts of bitter melon

Abstract

The use of plant extracts to induce resistance against pathogens has shown to be a promising alternative in the management of plant diseases. The objective was to evaluate the potential of ethanolic extract of Mormodica charantia on management of the Curvularia eragrostidis and enzyme activation involved on defense responses in yam (Dioscorea alata). The isolate of C. eragrostidis was obtained from leaves of yam with symptoms. Mycelial growth and sporulation were evaluated. The treatments were: extract of Momordica charantia 10, 100, 500 and 1000 ppm, acibenzolar-S-methyl (200 mg.L-1), fungicide (200 g.ha-1) and control. The evaluations were done daily, until the 15th day of the application of the treatments. The severity of the disease was evaluated at the end of the experiment, by the size of lesions in each plant. For determination of β-1,3-glucanase and phenylalanine ammonia lyase, leaves were collected in periods of 192 h after treatments application. Fungitoxic action of the treatments in the control of C. eragrostidis in vitro was verified. The M. charantia extract conferred significative levels of protection in yam plants against C. eragrostidis reducing incidence and disease severity. Thus, it was promoted increase in enzymatic activity, preconditioning yam in induced defense mechanisms.