Evaluation of Terminalia glaucescens Chromatographic Fractions on Meloidogyne incognita Infecting Chili Pepper (Capsicum chinense)

Nematodes are widespread organisms and pose a serious problem in vegetable production. The use of synthetic nematicides is a common method of bringing down the nematode population to increase crop yield. This has, however, brought about serious pollution to the environment. Leaves and twigs of Terminalia glaucescens were extracted in organic solvents and then chromatographed on a silica gel column. Chromatographic fractions obtained from the methanol and acetone crude extracts were characterized with UV-visible, FTIR, and GCMS and tested for their potential nematode suppressing activity in field micro plots. Spectroscopic analysis of the fractions revealed the presence of compounds such as aldehydes, acids, ketones, phenols, terpenes, hydrocarbons, and fatty acid esters. The extract fractions of T. glaucescens were applied at 100, 75, and 50 mg·ml⁻¹ at 100 ml each and carbofuran at 0.5, 1.0, and 1.5 kg a.i.·ha⁻¹. The vegetative growth of pepper plants as well as the number and weight of fruits increased significantly in plants treated with the above-mentioned extract fractions. The protective role of fractions compared favorably with the synthetic nematicide (carbofuran). The most effective in reduction of the nematode population, and plant growth and yield was the highest concentration of 100 mg·ml⁻¹. Thus, organic solvent extract fractions from T. glaucescens can serve as a biopesticide and an alternative to the environmentally hazardous synthetic nematicide.