Utilização de resíduos orgânicos no controle de Fusarium oxysporum f. sp. passifloreae em maracujazeiro amarelo

Abstract

This study aimed to evaluate the effects caused by organic waste in the suppressiveness of Fusarium oxysporum f. sp. passiflorae (Purss.), the causative agent in fusariose fruit (Passiflora edulis Sims f. flavicarpa Deg.). Organic waste were: bark of cassava (Manihot esculenta Crantz.), Citronella grass (Cymbopogon nardus L.), leaves of eucalyptus (Eucaliptus citriodora Hooker M.), leaves of neem (Azadirachta indica Juss.) And the babaçu cake (Orbignya falerata Mart.) in different concentrations, in vitro and in a greenhouse to see the strength and the residue more efficient in controlling the disease. Was conducted a preliminary survey of the occurrence of fruit fusariose in agricultural areas in the Island of São Luis in the State of Maranhão, where different isolates were collected for the study. Pathogenicity test was conducted with these isolates with a completely randomized design with ten treatments, referring to ten isolates of the pathogen and three replications, the means were compared by Tukey test at 5% level of probability. Were conducted microbiological and chemical analysis of waste, the total count of bacteria was performed after 24 h and quantification and identification of fungi, 72 h after addition of waste in Petri dishes. Was subsequently evaluated and effect of aqueous extracts of residues in the inhibition of mycelial growth of Fusarium oxysporum f. sp. passiflorae, used at concentrations of 0, 2, 4, 6, 8 and 10%, the experiment consisted of six treatments with five replicates, data x + 0.5 and submitted to the Tukey test at 5% were transformed into probability. Was also evaluated the effect of waste in disease control in greenhouse where residues were incorporated at concentrations of 0, 20, 40, 60, 80, 100 g.kg-¹ of soil, and subsequently inoculated with the pathogen, the was completely randomized design with six treatments and five replications, the experimental unit being a pot with two plants and the average compared to the Tukey test at 5% probability. An experiment was conducted to compare the most effective concentrations of each residue adopting the same methodology as the previous test. According to the results confirmed the pathogenicity of the isolates tested, where the ISO IV showed more aggression, being used in all other tests. Chemical analysis of residues showed high levels of essential nutrients, the babaçu cake of which showed the highest levels. The microbiological analysis showed the residue of eucalyptus and neem with higher amounts of total bacteria, as in the analysis of fungal species were Rhizopus stolonifer, Aspergillus niger, A. flavus, A. ochraceus, Fusarium sp., Penicillium sp., and Mucor sp, and the residue of babaçu showed the highest amounts of fungi. In vitro test performed in all the extracts showed inhibition, where the extracts of citronella babaçu and had a better inhibition of 6%, cassava and eucalyptus and neem to 10% to 4%. In the experiment of greenhouse waste of neem leaves, bark of the cassava cake and babaçu demonstrated positive effect in controlling the fusariose most of the concentrations tested, the most efficient: 20 g.kg ⎯¹, 60 g.kg⎯¹ and 80g.Kg⎯¹, respectively. The best test of the residue, compared to control most of the waste removal had determined the most efficient of neem leaves at 20 g.kg⎯¹ as well as provide high inhibition of the residual disease was the least concentration needed to achieve any effect, being followed by a cake of babaçu 80g.Kg and bark of the cassava 60g.kg⎯¹. Thus the experiment may prove the efficiency of the use of organic waste in the suppression of passion in fusariose, bringing innovative data solutions to plant suitable for farming and development Agroecológical in accordance with the principles that govern in making use of a waste technology low cost and high efficiency for maintaining the health of the agroecosystem and the conditions of rural small and medium farmers.