Resumen

CARNEIRO, Solange Monteiro de Toledo Piza Gomes; PIGNONI, Ericka; VASCONCELLOS, Maria Elizabeth da Costa  y  GOMES, José Carlos. Effectiveness of neem extracts in controlling the powdery mildew of bean plant. Summa phytopathol. [online]. 2007, vol.33, n.1, pp. 34-39. ISSN 0100-5405.  http://dx.doi.org/10.1590/S0100-54052007000100005.

The neem, Azadirachta indica, has been studied in the last years for the use in controlling plant pathogens. The objective of this work was to evaluate the effect of the neem oil, seed kernel extract and leaf extract on the control of the powdery mildew of the bean plant under green house conditions. The emulsified neem oil was tested for concentrations between 0.25 and 2.0% and sprayed before or after the appearance of the symptoms of the disease. The seed kernel extract was produced under laboratory conditions by grinding the kernels in distilled water, which was sprayed 48 hours before or 24 hours after the inoculation of the pathogen. It was also evaluated the efficiency of a commercial leaf extract at the concentrations of 0.25 and 0.5% which was sprayed after the appearance of the symptoms. The results of this work showed that the neem oil was efficient in the control of the disease when applied before or after the appearance of the symptoms. The seed kernel extract controlled the disease at the three tested concentrations. On the other hand, the leaf extract was not efficient in the control of the powdery mildew of bean plant.

Palabras llave : Azadirachta indica; alternative control; Phaseolus vulgaris; Erysiphe polygoni.