TABLE CONTENTS

Plant-parasitic Nematodes Associated with Weeds in Developing
Agriculture, with Special Reference to Root-knot Nematodes
N. Ntidi, H. Fourie & A.H. Mc Donald
ARC – Grain Crops Institute, Private Bag X1251, Potchefstroom, South Africa,
Plant-parasitic nematodes are ubiquitous, soil-borne pests that cause significant damage to a
wide range of agricultural crops. Since a variety of weeds that occur in small-scale farming
systems often serve as reservoirs for these parasites, this study focussed on the association
between plant-parasitic nematodes and weeds. A nematode survey was conducted at 44 sites
located in the eastern (Eastern Cape, Limpopo, KwaZulu-Natal and Mpumalanga provinces)
and western (Northern Cape province) resource-poor farming regions of South Africa.
Thirty-seven weed species and 33 genera were identified as hosts of plant-parasitic
nematodes during this survey, which differed substantially with regard to their frequency of
occurrence in the two regions. Cynodon dactylon had the highest frequency of occurrence in
both regions. With regard to plant-parasitic nematodes, 20 species and 12 genera were
reported for the first time in South Africa to parasitise weeds. Root-knot nematodes
(Meloidogyne spp.), followed by Pratylenchus zeae, Helicotylenchus dihystera and
Rotylenchus unisex were generally the predominant endo- and semi-endoparasites extracted
both from root and soil samples in the two regions. Meloidogyne species identified by means
of molecular techniques were M. javanica and M. hapla, with the latter species generally
being predominant at some sites in the eastern region. M. javanica was predominant at some
sites located in both the eastern and western regions. Weeds identified during this study that
maintain plant-parasitic nematodes, particularly root-knot nematodes, could have a negative
impact on crop production when they are not eradicated timely and effectively. This problem
is of particular significance in resource-poor, subsistence-farming systems where literacy and
knowledge levels are low.
5 th International Congress of Nematology, 2008 139