TABLE CONTENTS

Weeds Acting as Reservoir Hosts of Root-knot Nematodes and Implications
for Nematode Management Practices
Singh, S.K. (1), U. Khurma (1) & P.J. Lockhart (2)
(1) Division of Biology, School of Biological Chemical and Environmental Sciences, University of the South
Pacific, Suva, Fiji. (2) Institute of Molecular BioSciences, Massey University Palmerston North, New Zealand.
The Genus Meloidogyne is known to have a wide range of hosts including crop plants, weeds
and ornamental plants. A total of 43 weed hosts of root knot nematodes (RKN) were recorded
during a survey of root knot nematode diversity and distribution in agricultural areas from
Fiji. The pathogenicity of RKN on weeds was found to vary, depending on the species
composition as the same weed species acted as good host for some populations while being a
poor host for other populations. A total of 25 weed species were categorized as good RKN
hosts, 18 as poor RKN hosts and 11as non-host to RKN. The presence of RKN on common
weed hosts such as Amaranthus viridis, Ageratum conyzoides, Vernonia cinerea, Physalis
angulata, Coccinia grandis, Momordica charantia, and Cassia obtusifolia has important
implications for the effectiveness of cultural nematode management methods. The ability of
RKN to infect and reproduce on weeds makes them good reservoir hosts. Knowledge about
weed hosts of RKN is important for farmers and extension officers and should be considered
to ensure the effectiveness of cultural control methods amidst concerns for reducing the use
of chemical nematicides. Further research work on the interactions of RKN with weed
species is necessary to improve our understanding about RKN pathogenicity and population
dynamics.
Screening of Locally Available Organic Materials for the Mass Production
of a Biological Agent, Pochonia chlamydosporia Used against Root-knot
Nematodes
Luambano, N. (1), B.R. Kerry (2), J.W. Kimenju (1), R D. Narla (1) & J.W.Wanjohi (3)
University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya; (2) Nematode Interactions Unit, Rothamsted
Research, Harpenden, Herts. AL5 2JQ, UK; (3) Kenyatta University, P.O. Box, Nairobi, Kenya
Pochonia chlamydosporia has exhibited potential that needs to be exploited in the biological
control of root-knot nematodes. Unfortunately, current methods for mass production of the
fungus are not cost-effective in Eastern Africa. The objective of this study was to assess the
suitability of locally available materials as substrates in the production of chlamydospores. In
vitro experiments were conducted in which the organic substrates Tagetes minuta (mexican
marigold) shoots, Mucuna pruriens (velvetbean) shoots, Tithonia diversifolia (shrub
sunflower) shoots, Crotalaria junceae (sunnhemp) shoots, maize stover, cabbage leaves,
maize cobs, bean straw, rice husks, sawdust, filter mud, chicken manure, cow manure and
goat manure were tested, with rice as a control. The materials were ground, mixed with sand
at 50%w.w, inoculated with the fungus and incubated at room temperature (18-23 o C) for 21
days before data on chlamydospore count and viability were collected. Chlamydospore
counts from cultures of M. pruriens and maize cobs were 42 and 43 X 10 6 .g -1 substrate,
respectively, which was significantly different from a count of about 8 million in the rice
grain standard used as a control. The viabilities of the chlamydspores were 78, 72, 70 and
55% in maize stover, T. diversifolia and T. minuta and rice, respectively. This study has
clearly demonstrated that cheaper substrates such as crop residues and green manure plants
can be used in the production of P. chlamydosporia inoculant instead of rice.
5 th International Congress of Nematology, 2008 47