TABLE CONTENTS

Bacteria as Natural Enemies of Plant-parasitic Nematodes
Noel, G.R.
U.S. Department of Agriculture, Urbana, IL, 61801, USA.
Sustainable farming seeks to prevent soil erosion and contamination of groundwater and air.
In order for sustainable production systems to become viable, control of economically
important pests must be accomplished with minimal or no applications of pesticides.
Management of nematodes may include crop rotation and genetic resistance, but often
requires application of nematicides. Genetic resistance is not available for many crops, and
when available, may not be durable. Development of biologically based alternative methods
of nematode management for integration into sustainable crop production is needed. This
paper will discuss biological control of nematodes with bacteria. Endophytic bacteria such as
Rhizobium etli associated with induced resistance, rhizosphere inhabiting, toxin producing
ectoparasitic bacteria such as Pseudomonas synxantha, and the endoparasitic bacteria,
Pasteuria spp., will be considered.
Factors in Soil Suppressiveness of a Disease Complex
Westphal, A. (1), L.J. Xing (1) & S. Conley (2)
(1) Department of Botany and Plant Pathology, Purdue University; (2) Department of Agronomy, University of
Wisconsin, Madison, WI.
Sudden death syndrome (SDS) of soybean, caused by Fusarium virguliforme, is
synergistically increased by the presence of Heterodera glycines. These two pathogens
combined account for the highest yield losses in soybean in the U.S. In Indiana, soils
suppressive to this disease complex have been discovered under soybean monoculture in
infestation trials with F. virguliforme and H. glycines in the majority of long-term trials.
Concomitantly, foliar SDS symptoms and population densities of H. glycines were increased
in preseason-fumigated plots compared to non-treated plots. This was novel because soil
suppressiveness often is limited to pathogens of a single group of microbes, e.g., prokaryotes,
basidiomycetes, hyphomycetes, or plant-parasitic nematodes. Objectives of this project were
to determine how this suppressiveness develops and how it is maintained. In several trials, the
effects of factorial infestation patterns with the pathogens on the development of
suppressiveness were determined. In one trial, none of various cereal cover crops had
negative effects on soil suppression, and plots remained in the same status of suppressiveness
when bioassayed with soybean. Data from this project suggest that suppressiveness against
the soil-borne SDS disease complex spontaneously develops under different conditions and
that it withstands disturbances and thus will be useful for sustainable disease management.
5 th International Congress of Nematology, 2008 151