Nematicidal evaluation of extracellular metabolites from Trichoderma harzianum against Meloidogyne incognita

The 7 day old cell free filtrate (CFF) of an indigenous nematicidal isolate of Trichoderma harzianum ITCC 6888 caused 92.91 per cent mortality in root-knot juveniles. Its chloroform and n-butanol extracts exhibited significant juvenile mortality of 90.3% and 93.1 per cent at 5000 ppm in bioassays. GC-MS analysis revealed identification of seventeen compounds, in chloroform extract representing 57.3% of the total composition and thirteen compounds in n-butanol extract, representing 36.5% of the total composition Both the extracts were subjected to column chromatography to obtain various toxin fractions. One fraction of n-butanol named, B6, caused significant nematode mortality (58.8 per cent) in root-knot juveniles and none of the fractions from chloroform extract individually resulted in significant nematode immobility or mortality. The results indicate that it is the cumulative effect of various metabolites rather than a single toxin fraction that results in the observed nematicidal effect.