Avaliação de métodos alternativos no controle de Phytophthora SP em laranja pêra e limão cravo

• Ano de defesa: 2011
• Autor(a) principal: Soriano, Wagner Teixeira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Alagoas; BR; Programa de Pós-Graduação em Agronomia; UFAL
• Palavras-chave em Português: Essential oil; Plant extracts; Hydrothermotherapy; Oomycete; Gummosis; Óleos essenciais; Extratos vegetais; Hidrotermoterapia; Oomiceto; Gomose; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA
• Link de acesso: http://repositorio.ufal.br/handle/riufal/255

Phytophthora spp are responsible for a major disease of citrus crops. The difficulties of control and the impact caused by the use of agrochemicals have led the search for alternative control methods. Thus, this study aimed to evaluate the control of Phytophthora sp using natural products, thermotherapy, and Trichoderma spp rhizobacteria. Experiments were performed to evaluate the effect of manipueira, Ecolife ®, neem oil, eucalyptus oil, citronella oil, oil of Piper aduncum and fungicide (metalaxyl + mancozeb) at different concentrations, as well as the effect of rhizobacteria and Trichoderma spp, on the inhibition of mycelial growth of the pathogen in potato-dextrose-agar medium. Orange fruits variety pêra inoculated with a suspension of the pathogen (20 sporangia/fruit) were sprayed with oils and plant extracts (5 mL/fruit) or underwent thermotherapy in a water bath, at different temperatures, to assess the ability of the treatments decrease in the percentage of injured areas. Seeds of cravo lemon were microbiolized and sown in test tubes containing water-agar and incubated at 28 °C under constant light, to assess the ability of microorganisms to colonize the root system. In another experiment, microbiolized seeds were sown in pots and infested autoclaved substrate, kept in a greenhouse for 45 days. The incidence of the disease and the promotion of growth were measured at the end of the incubation period. In all tests were used a randomized design and means were compared by Tukey test (5%). Among the concentrations of oils, extracts and the fungicide concentrations stood out: manipueira 20%, citronella oil 1.5%, eucalyptus oil 1.0%, oil of Piper aduncum 0.5%, Ecolife ® 1.0%, neem oil 1.5% and fungicide 2.5 g. L-1 showed that the percentage of inhibition of mycelial growth of the pathogen, ranging from 73.8% to 100%. Some of rhizobacteria and Trichoderma spp tested were able to inhibit the mycelial growth of the pathogen. Treatment with oil of Piper aduncum presented the injured areas in the smaller fruits with an average of 8.57%. The disease control was obtained treating orange fruits variety pêra at 52 °C for three minutes and 50 °C, 51 ºC, 52 ºC and 53 °C for five minutes. The isolates of rhizobacteria have the ability to colonize the roots of citrus, but Trichoderma spp didn‟t show this behavior. All isolates studied had the ability to control the severity of disease caused by Phytophthora sp under controlled conditions. Alternative methods showed promise in control of Phytophthora sp.