OCCURRENCE, DISTRIBUTION, AND ABUNDANCE OF PLANT-PARASITIC NEMATODES ASSOCIATED WITH KHAT (CATHA EDULIS FORSK) IN EAST HARARGHE ZONE, ETHIOPIA

Abstract

Plant-parasitic nematodes have received little research attention in the tropics particularly in sub-Saharan Africa as compared to temperate countries. Despite the daily use and consumption of khat (Catha edulis Forsk) by millions of people across Ethiopia and other countries, very little is known about the associated plant-parasitic nematodes. Consequently, this survey was initiated to study the occurrence, distribution, and abundance of plant-parasitic nematodes associated with C. edulis in East Hararghe Zone, Ethiopia. A total of 300 composite soil and root samples (150 each) were collected from 15 major khat-growing districts in East Hararghe Zone during the 2013/14 growing season. This survey documented eight plant-parasitic nematode genera: Criconema spp., Helicotylenchus spp., Hemicyclophora spp., Longidorus spp., Meloidogyne spp., Paratylenchus spp., Pratylenchus spp., and Rotylenchulus spp. associated with khat crop. Among these, Pratylenchus, Meloidogyne, Helicotylenchus, and Longidorus were the most frequently encountered and abundant plant-parasitic nematode genera with 80, 60, 53.3, and 46.6% frequency of occurrence from soil, respectively. This diversity could be attributed to the cropping pattern of khat, which is mostly intercropped with solanaceous and other vegetables (mainly tomato, pepper, cabbage, potato, and sweet potato), cereals (mainly maize and sorghum), and groundnut by Hararghe farmers. These findings suggest that producers need to monitor and carefully select their cropping pattern. Furthermore, research should focus on the damage potential of these nematode species on khat crop performance to determine the economic threshold level and estimate a cost-benefit analysis on management practices.