Modelagem dos efeitos de Debris nos mecanismos de sobrevivência de Fusarium oxysporum F. sp. Passiflorae

Abstract

Fusarium wilt caused by Fusarium oxysporum f. sp. passiflorae (Fop) is considered the main fungal disease of passion fruit culture. The pathogen can survive for long periods in the soil in the form of chlamydospores, besides exerting saprophytism. Preventive measures to control this pathogen are difficult. Among the strategies for its management, biofumigation by incorporation of cabbage and wild cassava has been studied. The objective of this work was to quantify and model the influence of different plant materials on the survival phase of Fop under laboratory conditions. A pathogenicity test was performed using two methodologies. The variables evaluated were: mycelial growth in infested substrate, followed by plating to determine the number of Colony Forming Units (CFU), production and germination of chlamydospores on contact with the debris in six periods of incubation times. The mycelial growth, as well as production and germination of chlamydospores were submitted to analysis of variance and grouped by the Scott-Knott test at 1% probability. The areas under the mycelial growth curve (AACCM) and chlamydospore germination (AACGC) were calculated. The incorporation of cabbage and wild cassava caused a fungistatic effect under Fop promoting reduction in mycelial growth, number of CFU, production of chlamydospores in all the tested isolates, besides interfering in chlamydospores germination. The debris inhibited the 78% of the isolates germination and reduced the germination of the other isolates. The reduction in the production and germination of chlamydospores is a promising data since these resistance structures allow the pathogen to remain viable in the soil for many years.