Revista Brasileira de Milho e Sorgo (Apr 2010)
GREEN LEAVES EXCTRACT OF NEEM (Azadirachta indica) AND APPLICATION TIME ON DAMAGE AND DEVELOPMENT OF Spodoptera frugiperda (J.E. SMITH, 1797) (LEPIDOPTERA: NOCTUIDAE) IN MAIZE.
Abstract
The aqueous extract of neem (Azadirachta indica) leaves has a recognized insecticidal activity against Spodoptera frugiperda (J.E. Smith, 1797) larvae. The objective of this study was to evaluate the effect of neem green leaves extract and application time on damage and development of fall armyworm in maize. Two experiments were carried out at Embrapa Milho e Sorgo, Sete Lagoas, MG, Brazil, under greenhouse conditions. Maize leaves were sprayed with different neem extract concentrations (10000, 7500, and 5000 ppm) and number of applications (1-3). In another experiment, three aqueous extracts of neem leaves (dry ground, green ground and green crushed) were sprayed on maize in the morning (8 a.m.) and afternoon (4 p.m.). In the first experiment, the results showed that maize leaves damage ranged from 0.97 to 1.30 (0 to 9 class scale) for the aqueous extract of neem green leaves applied three times for all used concentrations. Damage on chlorpyrifos-treated and check plots were 0.22 and 7.83, respectively. In the second experiment, no significant difference in maize damage was observed between forms of extract preparation and between extracts application time. In general, the aqueous extractsfrom neem leaves reduced the larval development. At these experimental conditions, it can be concluded that extracts of green ground neem leaves (5000 ppm) applied three times are effective to protect maize from fall armyworm damage. The application time does not affect the efficiency of aqueous extracts of neem for larvae control. All the evaluated extracts negatively affected larval development.
