OCCURRENCE OF PLANT-PARASITIC NEMATODES AND NONPATHOGENIC SPECIES OF FUSARIUM IN TOMATO PLANTS IN KENYA AND THEIR ROLE AS MUTUALISTIC SYNERGISTS FOR BIOLOGICAL-CONTROL OF ROOT-KNOT NEMATODES

The occurrence of plant parasitic nematodes and endophytic fungi in to mato plants was determined from different regions in Kenya. In areas w ith regular cultivation of tomatoes, the population densities of all s pecies of nematodes, regardless of trophic group, were high. Meloidogy ne incognita was the predominant plant parasitic nematode in the regio ns investigated. Apparently endophytic fungi were frequently isolated from tomato roots, with Fusarium oxysporum being the most common endop hyte detected. In contrast, irregular cultivation of tomato resulted i n lower overall nematode densities and the absence of Meloidogyne infe station. 5. oxysporum occurred only sporadically. Four isolates of F. oxysporum, which were tested in subsequent greenhouse experiments, red uced M. incognita populations without adversely affecting plant health . Non-pathogenic isolates of F. oxysporum with mutualistic symbiotic b ehaviour are potential biological control agents for plant parasitic n ematodes.