Estratégia de controle de podridão mole (Rhizopus Stolonifer) em uva (Vitis Vinifera brs Carmem)

Abstract

Post-harvest diseases, which affects grape cultures, can cause considerable damage to the fruits during transportation and storage. Synthetic fungicides are commonly used methods able to control these diseases. However, there is a growing tendency of using more reliable and sustainable methods to control post-harvest deterioration. Thus, the present study aimed to present a sustainable and efficient strategy for the control of R. stolonifer in grapes through the use of antagonist yeasts isolated from the fruit as well as the association of the biological control of yeasts to GRAS substances. For this purpose, epiphytic yeasts from samples of grapes of Vitis vinifera BRS Carmen and must in the initial and final phase of fermentation were isolated. The selection of the antagonist yeasts for biological control was based on growing tests for 4, 10, 25, and 37ºC, on the assessment of the production of pectinase and cellulase enzymes, and on the evaluation of the production of antagonistic substances against the phytopathogen. The antifungal effect of various GRAS substances against R. stolofiner was assessed and the ability of yeasts to grown under different concentrations of GRAS substances was verified. Following the selection, the effectiveness of the biocontrol developed by the yeast in grapes against R. stolofiner applying the traditional and integrated biocontrol. It was obtained a total of 38 isolated yeasts grouped in 14 different morphotypes. Among these, two yeasts, identified as Hanseniaspora guilliermondii and Saccharomyces cerevisae, were selected as possible biocontrol agents. For the biocontrol in vivo tests, Saccharomyces cerevisiae managed to reduce alone the incidence of the disease caused by R. stolofiner by 56% and 70% the severity. On the other hand, for the biocontrol integrated to the GRAS substance (sodium bicarbonate) associated to the S. cerevisae the incidence was reduced in 80% and the severity in 84%. The isolated identified as H. guilliermordii decreased alone the disease incidence by 64% and the severity by 74%, and, for the integrated test with sodium bicarbonate, the incidence reduced by 80% and the severity 88%. The results attests that the use of these yeasts may constitute a promising biocontrol strategy able to control soft rot of grapes.