TABLE CONTENTS

Cover Crops and Biofumigation for Managing Pratylenchus spp.
MacGuidwin, A.E.
Department of Plant Pathology, University of Wisconsin, Madison WI, 53706
Root lesion nematodes, Pratylenchus spp., are important pests in many crops worldwide both
as primary pathogens and as collaborators in disease complexes. There are few crops with
host resistance to Pratylenchus spp. and chemical control is expensive, so cultural tactics are
crucial for sustainable production in infested fields. A wide range of cover crops has been
tested for efficacy against Pratylenchus spp. Two of the most widely documented cover
crops are forage pearl millet and marigold. Some cover crops are more effective, or only
effective, against Pratylenchus spp. when incorporated as green manures for biofumigation.
Our work demonstrates the potential of cover crops and biofumigation for managing P.
penetrans and the early dying pathogen Verticillium dahliae. Forage pearl millet
(Pennesetum glucum) as a cover crop and rapeseed (Brassica rapa) as a green manure were
successful in suppressing P. penetrans and the potato early dying disease and increasing
potato yield in field trials. Variability in the efficacy of these management tactics from field
to field and year to year was high. Ancillary studies indicate factors that might explain, in
part, inconsistent results in the field: the distribution of nematode populations among soil
and root habitats, a relationship between nematode activity and the uptake of isothiocyanate
compounds, and the role of microbial activity in the toxicity of decomposing residues to
nematodes. There is a high rate of success in killing nematodes with crops and their
decomposing residues in simplified laboratory systems. Duplicating that success in the field
requires knowledge of the mechanisms responsible as well as an improved understanding of
the temporal and spatial dynamics of nematodes in the field.
Amendments for the Suppression of Radopholus similis in Bananas in
Australia
Pattison, A. (1), J. Cobon (2) & R. Sikora (3)
Queensland Department of Primary Industries and Fisheries (1) Centre for Wet Tropics, South Johnstone,
Queensland 4859; (2) 80 Meiers Rd, Indooroopilly, Queensland 4068; (3) Institut fuer Pflanzenkrankeiten,
University of Bonn, Nussallee 9, 53115 Bonn, Germany
Radopholus similis remains an economic constraint to sustainable banana production for
many tropical countries. Nevertheless, R. similis may be suppressed by enhancing soil
organisms that are antagonistic to plant-parasitic nematodes. A large range of amendments,
with varying chemical compositions, are available, and may have varying effects on soil
properties depending on application rates. To obtain a better understanding of how soil
amendments may change the antagonistic potential of banana soils, it is necessary to
understand changes in soil ecology following their application. Glasshouse experiments were
conducted to determine the optimum types of amendments to suppress R. similis in bananas,
followed later by a field experiment.
In a glasshouse experiment, banana plants were grown in field soil amended with nine
different amendments, with known nutrient contents, at a rate equivalent to 40 t ha -1 . Banana
plants were inoculated with 860 R. similis and grown in the soil amendment mix for 12-15
weeks. At harvest, there were significantly fewer R. similis in the roots of bananas grown in
soil amended with lucerne hay, grass hay, banana residue or mill-mud relative to the
untreated soil. These amendments had high carbon compositions.
5 th International Congress of Nematology, 2008 38