COMPOSIÇÃO QUÍMICA E ATIVIDADE ANTIFÚNGICA DO ÓLEO ESSENCIAL DAS FOLHAS DE Psidium guajava NO CONTROLE DE Sclerotinia sclerotiorum

Abstract

Guava (Psidium guajava L.), belongs to the Myrtaceae family, and the essential oil of its leaves has generated several studies on its chemical composition and properties. The essential oil can have a direct action on phytopathogens, such as the fungus Sclerotinia sclerotiorum, which causes white mold, which is difficult to control and affects cultures of significant economic importance. Because of this, studies with essential oils as natural alternatives to control this disease have been intensified. This work aimed to analyze the chemical composition of the essential oil of guava leaves and evaluate its antifungal action in vitro on the fungus Sclerotinia sclerotiorum. The extraction of the essential oil was carried out by hydrodistillation and its composition was analyzed by GC-MS. The antifungal test was carried out in Petri dishes containing BDA medium, in which aliquots of 0, 100, 200, and 300 µL of pure essential oil from the fresh guava leaves were in 3 repetitions each. Then, 8 mm of the mycelium of Sclerotinia sclerotiorum was transferred to each plate, being incubated at 22ºC and evaluated after 48 h and until the total growth of the controls. As a negative control, only the fungus was used in BDA medium and, as a positive control, the frowside fungicide at a concentration of 10μg mL-1. Trans-karyophylene and α-humulene were identified as major compounds in the essential oil. The essential oil of the guava leaves in contact allowed 94.9% inhibition, while in the form of steam, it was equivalent to 97.1% inhibition, which proves a high fungicidal potential against white mold.