Controle alternativo do míldio e da antracnose da videira com extrato aquoso de cinamomo (Melia azedarach L.) / Alternative control of downy mildew and anthracnose of grape aqueous extract of chinaberry (Melia azedarach L.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2011

RESUMO

The objective of this study was to evaluate different concentrations of aqueous extract of chinaberry (Melia azedarach L.) on the control of downy mildew (Plasmopara viticola) and anthracnose (Elsinoe ampelina) of grapevines cvs. Isabel and Cabernet Sauvignon. For all experiments the aqueous extract of chinaberry was prepared by addition of fruit with seeds dried and ground to distilled water (1:10 w/v), followed by maintaining the suspension at rest for 48 hours in a closed recipient in the presence of light and after filtration with sheer fabric. For the experiments in vitro the extract was sterilized by membrane filtration in Millipore 0,22μ. In the experiment in the greenhouse, it was studied the following concentrations: 0, 30, 40 and 50 mL L-1 of chinaberry aqueous extract (1:10 w/v), and a treatment with bordeaux mixture (1:1:100 w/w/v), on the severity of mildew. In field conditions, the experiment was carried out in a commercial vineyard for two consecutive cycles (2009/2010, 2010/2011), where it was evaluated increasing concentrations of chinaberry extract, besides an absolute control (no treatment) and a standard treatment with bordeaux mixture, on both diseases. The disease severity in grapevines leaves was determined by visual assessments by diagrammatic scale, which has notes that correspond to 0 to 100% injured leaf area, and subsequent determination of the area under the disease progress curve (ADPC). In the germination test, it was verified higher inhibition of P. viticola for the treatment with chinaberry extract at 50 mL L-1, with reduction of approximately 67.0%, after two hours incubation. In relation to E. ampelina, the chinaberry extract at 50 mL L-1 decreased the diameter of the colony in 99.4%, while for sporulation; there was complete inhibition from the concentration at 20 mL L-1. In the germination experiment the concentration of 50 mL L-1 reduced in 84.8 e 90.8% after 12 for 24 hours incubation of E. ampelina conidia, respectively. In greenhouse conditions, chinaberry extract at 40 and 50 mL L-1 showed 70.0% and 86.0% reduction on downy mildew severity, respectively. In the first cycle on field experiment, the chinaberry extract at 40 and 50 mL L-1 showed 34.0 and 31.0% decrease on mildew severity, respectively. In relation to anthracnose, the concentrations of 30, 40 and 50 mL L-1 reduced disease severity in 44.3, 47.2 and 48.1%, respectively. However, in the second cycle, for both diseases, the use of vegetable oil as an adjunct masked the effect of aqueous extract of chinaberry. The isolated application of vegetable oil (Natur L Óleo), decreased mildew and anthracnose ADPC in 76.3% and 64.0%, respectively, similar to the results obtained with all concentrations of chinaberry extract and the bordeaux mixture. Based on these results, aqueous extract of chinaberry has great potential for the control of downy mildew in grapevines, as well as the use of vegetable oil.

ASSUNTO(S)

santa bárbara vitis spp. extratos vegetais produção orgânica agronomia santa barbara vitis spp. plant extracts organic production

ACESSO AO ARTIGO

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