Plant parasitic nematodes associated with sugarcane in the Nyanza sugar belt

Abstract

Sampling of soils and roots of sugarcane was carried out in the Nyanza Sugar belt. Extraction of nematodes from the samples indicatd that Pratylenchus spp. was the most important endosparasite in the region. Trichodorus spp., Helycotylenchus spp. and Rotylenchus spp. were the most important ectoparasites. Helycotylenchus and Rotylenchus spp. were most abundant in the Chemilil zone. Other Genera found were Criconemoides spp. Longidorus spp., Xiphinema spp., Tylenchus spp., Paratylenchus spp., Hoplolaimus spp., Tylenchorhynchus spp., Ditylenchus spp., Hemiclcliophora spp., Meloidogyne spp. and Aphelenchoides spp. Population density of plant parasitic nematoes varied from one type to another. Cambisols had a higher number of nematodes than Vertisols. The numbers were more numerous in the second ratoon as compared to plant crop and first ratoon. The endoparasites Pratylenchus spp. was however more numerous in toot samples from plant crop than from higher crop cycles. The effect of planting sugarcane on nematode infested soil was studied using seedlings of three sugarcane varieties Co421, Co617 and EAK69/40 planted in soil infested with nematodes under greenhouse conditions. These plants were less vigorous than the ones planted in heat-sterilized soil. Their tillering was delayed and both the fresh and dry weight of their roots and shoots was significantly lower. The decrease was higher in variety Co421 as compared to the other two varieties. The maximum number of parasitic nematodes around the rhizosphere of this variety was reached much earlier than for o617 and EAK69/40.