Effect of humic acid on Meloidogyne incognita (Kofoid & White) Chitwood infecting banana (Musa spp.)

Humic acid, a natural by-product from lignite coals, was evaluated for its potential to control root-knot nematode, Meloidogyne incogntia infecting banana. Hatching of M. incognita eggs was inhibited 50%-100% following incubation in 0.08%-2.0% humic acid in vitro. Exposure of juveniles (J2) of M. incognita to different humic acid concentrations significantly affected the mobility of J2 in vitro. The percent immobility of J2 increased with concentrations of humic acid up to 0.08%. In pot experiments, soil treatment with humic acid reduced the root galling in banana plantlets. All the humic acid tested concentrations (0.04%, 0.08%, 0.2% and 0.4%) significantly reduced the nematode soil density by 53.5%-56.7%, root infection by 61.9%-63.8%, egg population by 61.9%-63.8% and reproduction rate by 55.7%-56.6%. A significant improvement of growth of banana plantlets in terms of number of leaves, pseudostem height, girth, weight, root length and weight was noticed in humic acid treated pots. Humic acid did not suppress growth of the biocontrol agents Pseudomonas fluorescens and Trichoderma viridein vitro. Results suggest that soil treatment with humic acid at 0.04% not only offers significant nematode control but also improves growth of banana.