Controle biológico em morangos in natura

Abstract

The culture of the strawberry is quite susceptible to the gray mold disease caused by Botrytis cinerea, resulting in large losses in post-harvest. Because of this, it is sought by means of biological control using yeast killer antagonists inhibit the growth of fungus, and consequently the deterioration of fruits, besides contributing to the decrease in the use of synthetic fungicides. In this study 18 was isolated yeast samples of corn and wheat crops and 12 (66.67%) characterized as positive killer against at least one of pattern sensitive strains used. Four of these yeasts showed broad spectrum of killer action, when submitted to antifungal assay on solid medium at three different inoculum concentrations (105, 106 and 107 cells / mL) against 105 spores of B. cinerea. All yeasts showed antibiosis and / or nutrient competition when used at a concentration of 107 cells / ml, however two yeasts, identified as Candida kefyr T19B and Saccharomyces cerevisiae Am34 showed satisfactory results against the filamentous fungus with evidence of antibiosis. These two yeasts showed maximum killer activity when cultivated for 96 hours, but a small percentage of inhibition of spore germination in antifungal assay on liquid medium. The fungicide used for susceptibility testing and compatibility, fungus and yeast, respectively, was Manzate WG, where only C. kefyr showed compatibility with it. The in vivo test showed promising results regarding the use of the yeast C. kefyr, the biological control of B. cinerea in strawberries, with a percentage of efficiency of 37.5%, in 5 days, suggesting thus, further study on this yeast in order to reduce the use of fungicides.