Survey of nematode destroying fungi from selected vegetable growing areas in Kenya.

Abstract

Plant parasitic nematodes cause up-to 5% yield los ses to a wide range of economic crops. In Kenya veg etables yield loss attributed to plant parasitic nematodes is estimated to 80%. Over the years, nematode contr ol has heavily on the use of chemical nematicides which unfortunately leads t o biological magnification and elimination of the b eneficial microorganisms in the soil. This has triggered a gr owing interest in search of alternate management st rategies. The objective of this study was, therefore, to document nematode des troying fungi in selected major vegetable growing a reas in Kenya as a step towards developing self-sustaining system for manag ement of plant parasitic nematodes. Soil samples we re collected from five vegetable production zones in Kenya which were Kina re, Kabete, Athi-river, Machakos and Kibwezi and tr ansported to the laboratory for extraction of the nematode destroyin g fungi. Soil sprinkle technique as described by Ja ffee et al., (1996) was used to isolate the fungi from the soil while ident ification was done using identification keys descri bed by Delgado et al., (2001). From the study a total of 171 fungi isolate s were identified as nematode destroying fungi. The highest population was recorded at Kabete area recording 33.9% of the total record, followed by Machakos, Kibwezi, Athi-r iver and the least in Kin are with 24.6, 22.2, 11.7 and 7. 6% of the tota l population in that order. Arthrobotrys was the most frequent genera with a mean occurrence of 7.3 followed by Monacrosporium with 6 and Stylophage with 5.2. A.dactyloides was significantly (P=0.002) affected by the agro-ecological zones wit h the highest occurrence being recorded in Kabete a nd the least in Athi- river. The highest diversity index and species rich ness of nematode destroying fungi was recorded in K ibwezi while the least was recorded in Athi-river. The genera Arthrobotrys had the highest number of trapped nematodes with a total population of 57, followed by Monacrosporium and least was Stylopage with 45 and 36 respectively, within a period of 104 hours. From the study, it is evident that agricultural practices af fect the occurrence and diversity of nematode destr oying fungi and Arthrobotrys can be developed as a bio-control agent for managem ent of plant parasitic nematodes.