MANAGEMENT OF PARASITIC ROOTKNOT NEMATODES IN SWEETPOTATO: REVIEW

Abstract

Agriculture is the mainstay in Kenyan economy, it currently contributes to 29% in gross domestic product (GDP) and creates employment of over 80% in the rural population. There are four major sub sectors in the agricultural sector which are food crops, industrial crops, livestock, fisheries and horticulture. Sweet potatoes are based under horticultural crops production which are now constrained by many biotic factors including root knot nematodes (RKN).Root knot nematodes pose a significant threat to a wide range of agricultural crops. The effect of RKNs in sweet potatoes are seen through the formation of galls, which reduce water and nutrient uptake, stunted vines and discoloured cracks in root tubers. These effects cause poor quality of tubers hence yield loss and high costs of production leading to poor income. Root knot nematodes diversity depends on ecological conditions and change of environmental conditions with time. Management strategies to control RKN have been practiced over time; cultural methods including fallowing of fields, intercropping and crop rotation have been used however root knot nematodes have ability to infect a wide host range; use of resistant varieties against RKN were adopted however some resistant genes tend to be silent in soil temperatures above 30ᵒC rendering the crop susceptible; use of synthetic nematocides were then found effective against RKN species however they leave residues on plants which are harmful to human consumption and are environmentally unfriendly hence they were banned. With these challenges scientists are focusing on discovery of nematocides from medicinal plants. The use of medicinal plants especially Canavalia ensiformis has shown 87% mortality rate on juveniles at stage two. Due to limited exploration of medicinal plants, more studies are encouraged on the same for RKN management and increase food security