Stimulation of nematode-destroying fungi by organic amendments applied in management of plant parasitic nematode

Abstract

A screenhouse experiment was conducted to evaluate the effect of cow manure, chicken manure and their combinations on nematode destroying fungi, nematode community and growth of tomato (Solanum lycopersicum L.). The amendments were applied at the rate of 5% w/w in all the treatments. Isolation of nematode destroying fungi was done using the soil sprinkle technique. Nematodes were extracted from soil using the modified Baermann technique. Tomato growth was estimated through plant height and dry weight. Application of the organic amendments resulted in significant differences (p≤0.05) in occurrence of nematode destroying fungi amongst the treatments. The nematode destroying fungi occurred at frequencies of 50, 29.4, 17.6 and 2.9% in soil amended with chicken manure, cow/chicken combination, cow manures and the control, respectively. Eight species of nematode destroying fungi were identified in this study. The fungus Arthrobotrys oligospora (Fresenius) was most dominant fungus in all the treatments including control pots with an isolation frequency of 38.2%. Addition of organic amendments into the soil also resulted in an increase of bacterial and fungal feeding nematodes and reduction of plant parasitic nematodes. Specifically there was a 225, 96 and 62% increase in bacterial feeding nematodes and 391, 96 and 74% increase in fungal feeding nematodes in soil amended with chicken manure alone, combination of chicken and cow manure alone in that order. Numbers of plant-parasitic nematodes were 92% lower in soil treated with chicken manure compared to the control. Plant height and leaf widths were highest in plants treated with combination of cow and chicken manures. The plants mean dry weight were 6.6, 5.6, 2.0 and 1.5 in combination of chicken and cow manure, chicken manure alone, cow manure alone and control, respectively. This study has therefore, revealed that organic amendments stimulate the occurrence of nematode destroying fungi in the soil and also reduce plant parasitic nematodes. In addition, the combination of cow and chicken manure stimulates plant growth