NEMATICIDAL EFFICACY OF SOIL FUNGAL ISOLATES AGAINST THE ROOT-KNOT NEMATODE (Meloidogyne incognita) OF TOMATO

Abstract

The root-knot nematode (Meloidogyne incognita) is one of the plant parasitic nematodes that causes serious economic damage on tomato plant. Due to loss of effectiveness and environmental hazard of chemical nematicide, the search for new agents of control has become paramount. Therefore, nematicidal efficacy of soil fungal isolates on second stage juvenile of Meloidogyne incognita was carried out. Soil samples for the isolation of fungi and nematode were collected from botanical garden and infested soil of tomato farms. Fungal species were isolated using serial dilution method while nematode was extracted using pie-pan method. The in vitro antagonistic effects of fungi against M. incognita were assessed in potato dextrose broth. In vivo was carried out in screen house where healthy and sterilized tomato seeds were sown in a 7 litre plastic buckets containing 5 kg of sterilized loamy soil. The buckets were arranged in a completely randomized block design on a bench with three (3) replicates. After germination of the tomato seeds, two weeks from sowing,each bucket was thinned to one plant. One thousand (1000) juvenile second stage (J2) M. incognita were inoculated in four holes round the stem of each plant in a bucket and on the next day 10 ml of fungi culture filtrates was inoculated into the same hole. Four fungal species isolated were; Aspergillus niger, Aspergillus nidulans, Penicillium chrysogenum and Rhizopus stolonifer while nematode isolated was M. incognita. The results of fungicidal activity against M. incognita after 24 and 48 hrs were A. niger (39.28 and 78.47 %), A. nidulans (29.12 and 57.49 %), P. chrysogenum (18.59 and 47.48 %) and R. stolonifer (8.05 and 26.43 %). In in vivo experiment, A. niger gave the highest values for average plant height at maturity, number of fruits per plant and number of leaves per plant (46.43 cm, 10.33, and 69.67 respectively) and lowest value for number of galls per plant root (3.67). Lowest values were recorded for R. stolonifer in average plant height, number of fruits per plant and number of leaves per plant (26.13 cm, 5.33 and 46.33 respectively) and were the highest value for number of galls per plant roots (16.67). The values recorded for A. niger and R. stolonifer differed significantly (P< 0.05). Disease incidence was highest in the control at harvest after treatment with the value 39.49 % and A. niger had the lowest value of 7.18 % at harvest after treatment, the values recorded for the control and A. niger differed significantly (P< 0.05). The results of this study conclude that these fungal species could serve as biological agent for effective management of root-knot nematodes and bio-fertilizer for the enhancement of plant growth parameters.