Manejo pós-colheita de Colletotrichum gloeosporioides em maracujá amarelo

Abstract

The use of alternative technologies, such as natural products and resistance inducers, is effective in reducing of pathogen population, disease severity and, consequently lower losses. The objective of this work was to determine the effect of alternative control on C. gloeosporioides in yellow passion fruit, at post-harvest quality and at production of enzymes linked to resistance induction. The mycelial growth index and the conidia production of the pathogen were evaluated, isolated from fruits with typical symptoms of the disease and cultivated in BDA, arranged in a completely randomized design. The treatments were AgroMos® (3 ml. L-1). Agrosilicon (3 g. L-1), Acibenzolar-S-methyl (ASM) (0,4 g. L-1), Ecolife® (3 ml. L-1), Proagrim® (3 g. L-1), RockSil® (3 g. L-1) and essential oils of Carapa guianensis, Cymbopogon citratus, Copaifera officinalis, Eucalyptus citriodora, Foeniculum vulgare and Ocimum basilicum in the concentration of 1%, fungicide Tiabendazole (100 ml i.a. 100 L-1 water) and the control (distilled water). The treatments were diluted to BDA culture medium, distributed in Petri dishes and about on the same a colony disc of C. gloeosporioides. The plates were kept at 25 ± 2 °C for eight days and the evaluations were performed daily by measuring the diameter of the colonies and the production of spores. The treatments were applied on fruits by immersion for 5 minutes and performed the daily. Evaluations of disease severity with the utilization a diagrammatic scale was performed during fifteen days, being four replicates per treatment. In the physical-chemical analyzes were evaluated mass loss, peel firmness, longitudinal and equatorial measurements, coloration, pH, soluble solids, titratable acidity, SS/AT ratio, vitamin C and juice portion. It was measured the activity of peroxidase, phenylalanine ammonia lyase and polyphenoloxidase enzymes in treated fruits. Resistance elicitors and essential oils of C. citratus, C. officinalis, F. vulgare and O. basilicum influenced negatively at the mycelial growth and sporulation of C. gloeosporioides. All treatments provided reduction of area below the anthracnose progress curve and maintained post-harvest quality in fruits of P. edulis. The enzymatic activity of peroxidase, phenylalanine ammonia lyase and polyphenoloxidase was not stimulated by essential oils and only polyphenoloxidase presented lower activity in fruits submitted to ASM, AgroMos® and Proagrim®.