Controle biológico e alternativo da antracnose do pimentão

Abstract

The bell pepper (Capsicum annuum L.) is one of the most important vegetable crops cultivated in Brazil. Among the diseases affecting this crop, anthracnose is considered one of the most important in the world, being caused Colletotrichum spp. Currently have intensified the search for alternative methods of controlling plant diseases through the use of biocontrol agents and plant extracts, because this method is secure, efficient, economic and are not pollutants. The goals of this work were to isolate yeast bell pepper fruits; evaluate the pathogenicity of Colletotrichum spp. from bell pepper and indicate the most aggressive; evaluate the Killer factor of yeasts and in vivo and in vitro, and use these as biocontrol comparing them with the use of mancozeb fungicide in controlling anthracnose of bell pepper; investigate the use of plant extracts of Piper marginatum and Azadirachta indica in controlling anthracnose. The isolate was confirmed as pathogenic Colletotrichum scovillei. The yeast Rhodotorula mucilaginosa L6, Candida duobushaemulonii sp. nov. L15 and Candida natalensis CG27 reduced lesion size, percentage inhibition of lesion size in postharvest bell pepper fruit and mycelial growth of Colletotrichum scovillei. In pre-harvest, C. natalensis was the most efficient species during the three periods (7, 14 and 21 days). The yeasts were effective in inhibiting the mycelial growth of C. scovillei in vitro by producing volatile compounds. The yeast R. mucilaginous produced Killer toxin. The methanol extract of P. marginatum at 1000 and 2000 ppm concentrations were effective in controlling Colletotrichum scovillei in vitro. Only hexane extract of P. marginatum to 2000 ppm was effective in controlling this pathogen. On fractionation of the methanol extract of P. marginatum, the ethyl acetate fraction in amounts vanishingly smaller than the other fractions, controlled C. scovillei in vitro. Compound 12 showed antifungal activity to Colletotrichum scovillei in vitro and in post-harvest and was more efficient than the mancozeb fungicide in vitro and in control postharvest C. scovillei. The use of yeast and Piper marginatum extracts and compounds were effective in controlling anthracnose caused by Colletotrichum scovillei in bell pepper, being a promising alternative to the search for formulations for use in the field and after harvest.