PREVALENCE AND DISTRIBUTION OF PARASITIC ROOT KNOT NEMATODES IN SWEET POTATO FARMS OF KIRINYAGA COUNTY

Abstract

Sweet potato production is constrained by many biotic factors which include parasitic root knot nematodes. Root knot nematodes (RKN) pose a significant threat to a wide range of agricultural crops. The effect of RKN on sweet potatoes include reduced yields and poor quality of the tubers, high costs of production and hence loss of income. Moreover, development of resistance by RKN has partly rendered various pest management strategies ineffective, therefore risking food security. It is likely more losses may be experienced in future due to ongoing withdrawal of nematocides from the market. Information on distribution and management of root knot nematodes is limited. This study aimed in the isolation and characterization of root knot nematodes from soils and root tubers of sweet potato farms in different agro ecological zones of Kirinyaga County. From the undertaken study, prevalence and distribution of root knot nematodes was analyzed based on early cropping of sweet potatoes between one to two months and post harvested farms. Across all sweet potato farms, identification through microscopy revealed parasitic RKNs that were Meloidogyne species, Pratylenchus species, Trichodorus species among other spiral nematodes (Helicotyllenchus species and Scutellonema species) that are also categorized as parasitic nematodes. Reniformis (Rotylenchus species) were also identified as well as predatory nematodes which were singled out too under microscope observations. Root tubers that were stained pink with phloxine B showed large galls with mature female root knot nematodes under microscopy. Based on the questionnaire answers from farmers, they were familiar with nematode symptoms on sweet potatoes however, awareness of nematodes was low.