Pathogenic fungi population levels and relationship with orchards nutrient concentration fertilized with composted swine manure

Abstract

Animal waste can be used as an alternative soil fertilizer in agricultural and can improve soil physical feature, nutrients, and add specific biochemical compounds able to enhance or renew the native micro fauna and flora. The objective of this study was to evaluate the effect of different doses of the fertilizers composted swine manure (CSM) and chemical fertilizer (CF) on the population level of the pathogenic fungi Verticillium dahliae, Fusarium solani, F. oxysporum, F. verticillioides, and Trichoderma spp. and the relation of the fertilizers with the concentration of soil nutrients in commercial apple, pear and grape orchards at the edafoclimatic conditions of Santa Catarina State highland. The CF and the Trichoderma spp. were considered as positive control. Each orchard was fertilized with 50 and 100% of the official recommendation doses of DSC and CF at two months interval from August of 2012 to March of 2014. The analysis of soil macro and micro nutrients were performance previously before the collection of soil sample for the pathogenic fungi analysis during all trial. Colonies of pathogenic fungi were assayed by dilution plating from samples of 10 g of soil collected from apple, pear and grape orchards, using potato dextrose agar (PDA) and Sabouraud agar-chloramphenicol (SAC) and expressed as colony formation unit (CFU) per soilgram (g-1). There were significant differences among fertilizers, doses and types (CSM and CF) and the population levels of V. dahliae, F. solani, F. oxysporum, F. verticillioides and Trichoderma spp. The fungi population ranged from 0-45 x 103 CFU/g, 0-40 x 103 CFU/g and 0-45 x 103 CFU/g, in apple orchards, pear and grape, respectively. There was a significant difference among concentrations of nutrients of P, K, and Zn at the apple orchard. When compared to the pear and grape orchard. The CF and CSM fertilizer increased the population levels of Trichoderma spp from zero to 10 x 103CFU/g of soil at the apple and pear orchard when compared with grape orchard. The 50% and 100% of the recommended dose of CSM fertilizer inhibited the population growth of F. solani, F. verticillioides and V.dahliae in approximately in 10 - 20 x 103 CFU/g of soil at the pear and grape orchard. The 100% of CF fertilizer dose increased the population growth of F. oxysporum, F. solani, and V. dahliae in approximately 5-20 x 103 CFU/g of soil at the three orchards evaluated.