Prevalência de Fusarium verticillioides e manejo de grãos ardidos e fumonisinas em milho

• Ano de defesa: 2013
• Autor(a) principal: Lanza, Fabrício Eustáquio
• Orientador(a): Zambolim, Laércio
• Banca de defesa: Paula Júnior, Trazilbo José de , Ferraz, Silamar , Guimarães, Lauro José Moreira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Zea mays; Micotoxinas; Controle
• Palavras-chave em Inglês: Zea mays; Mycotoxins; Control
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1054

In recent years, trade requirements concerning the health and quality of grains, not only for export but also for domestic consumption have becoming increasingly strict, for particularly those related to mycotoxins contamination. Mycotoxin-producing species of the genus Fusarium are the major cause of low-quality grains due to toxic effects of mycotoxins to animal and human health and rotting grains. According to these considerations, the present study aimed to evaluate the prevalence and geographic distribution of Fusarium species associated with corn grains in Brazil; the fumonisins production potential of Fusarium strains isolated from different corn-planting areas, and to evaluate management strategies for reducing the kernel rot incidence and the levels of fumonisins in corn. To study the prevalence of Fusarium species causing maize kernel rot, corn ears were sampled in fifteen planting areas representative of the main important Brazilian producing regions. The identification of two hundred thirty Fusarium isolates to the species level was based on morphological characteristics and molecular method by PCR with species-specific primers. The quantification of total fumonisins produced by fifty selected isolates was performed by immunoaffinity columns. A number of experiments with different harvest dates, and number and period of fungicides application were accomplished in order to ascertain a reliable management technique for reducing the incidence of pathogenic fungi, and consequently, kernel rot and fumonisins in corn grains. In this study we found that the fungal species Fusarium verticillioides was the main pathogen associated with corn grain in Brazil with 99% prevalence. Other fumonisins-producing species identified was F. proliferatum occurring at low frequency (1%). The species F. subglutinans identified in corn fields in many countries was not present among the two hundred thirty isolates. All fifty selected F. verticillioides isolates produced fumonisins and the potential of fumonisins production was high variable and not related with the geographic region of origin of isolates. In relation to different harvest times of corn, it was observed that the kernel rot incidence and total fumonisins increase gradually according to increased periods of delayed harvest. Fusarium verticillioides and Stenocarpella spp. were the most frequent fungal species identified in different planting seasons. In both kernel rot and asymptomatic grains the infection by F. verticillioides was high prevalent in all crop seasons and the frequency of its incidence varied according to maize genotypes. The incidence of Stenocarpella spp. also varied with the maize genotypes and was predominantly associated to kernel rot. Foliar applications of the fungicides strobilurin and triazoles in a different period of times and number of applications, were ineffective for reducing pathogenic fungi associated with corn grains, therefore the kernel rot incidence and fumonisins level in maize.