RESUMO
The study explored to develop an eco-friendly herbal fungicide from chloroform extract of Clerodendrum infortunatum leaves. The extract upon activity guided purification using flash chromatography yielded eight fractions F3 through F10. Total phenol and flavonoid contents in the fractions ranged from 0.12-48.25 mg GAE/g and 0.03-25.29 mg QE/g. LC-MS/MS analysis confirmed the identification of seven phenolic acids across different fractions, the total of which varied between 0 and 2.17 mg/g. Emulsifiable Concentrate (20%) formulation was made with the extract and fractions and tested against Phomopsis vexans causing fruit rot disease in brinjal. Of the various fractions, F8 displayed highest antifungal activity (ED50 = 46.8 µg/ml). Antifungal activity of leaf extract/fractions was correlated with total phenol, total flavonoid and total phenolic acids (r = -0.60 to -0.69). Among the phenolic acids, benzoic acid showed maximum antifungal activity followed by t-cinnamic acid. The relationship between phenolic composition and activity is also reported.
RESUMO
A laboratory experiment was performed to study the persistence of imidacloprid from two formulations (Confidor 200 g litre-1 SL and Gaucho 700 g kg-1 WS), and its metabolism in three different soils (Gangetic alluvial soil of Kalyani, lateritic soil of Jhargram and coastal alkaline soil of Canning) of West Bengal following application at 0.5 kg and 1.0 kg AIha-1. Dissipation of imidacloprid in soil followed first-order kinetics and DT50 values ranged from 28.7 to 47.8 days. The shortest half-lives (28.7 and 35.8 days) were observed in the lateritic soil of Jhargram for both liquid and powder formulations. The formation of two metabolites of imidacloprid, imidacloprid-urea and imidacloprid-olefin, was first detected on day 30 of degradation at 28 (+/- 1) degrees C in all three soils.