Book of Abstracts (PDF) - International Mycological Association

IMC7 Tuesday August 13th Lectures
questions that concern us are: 1) Are simple resupinate
forms evolutionarily more labile than complex forms? 2) Is
there a general trend toward the evolution of pileatestipitate
forms? 3) Can we reject the hypothesis that the
loss of ballistospory is irreversible? To address these
questions we are employing binary and multistate
maximum likelihood methods to develop and test models
of fruiting body evolution, using a large (ca. 500 species)
phylogenetic tree derived from rDNA sequences.
111 - Concepts and approaches during 50 years of
biological control of fungal plant pathogens
J.M. Whipps
Horticulture Research International, Wellesbourne,
Warwick, CV35 9EF, U.K. - E-mail:
john.whipps@hri.ac.uk
There are now more than 80 products near to or on the
market that have biological control activity against plant
pathogens in soil, root, aerial and post-harvest
environments. Most of these been developed relatively
recently in response to environmental concerns which have
forced reductions of fungicide and fumigant use and
availability. Bacterial products are dominated by
Pseudomonas, Burholderia and Bacillus species and fungal
products by Gliocladium and Trichoderma species. With
the exception of products based on Agrobacterium
radiobacter for control of crown gall, Phlebiopsis gigantea
for control of stem and root rot of pine and some
Trichoderma-based products, few have been on the market
for 10-20 years or more. Indeed, several have come and
gone. Key features for achieving a successful biocontrol
product must be cost-effective and reproducible disease
control. In the last 15 years, the importance of
understanding the ecological interactions between a
biocontrol agent, its target pathogen and host plant before
this can be achieved has gradually become appreciated.
Against this background, several successful biocontrol
agents have been selected, screened for activity,
characterised and then undergone registration and
marketing. Reassessment of the concepts and processes
involved in natural disease suppression has also provided
novel biological approaches to disease control.
112 - Biological control of fungal plant pathogensrecent
advances and future perspectives
C. Alabouvette
INRA-CMSE UMR BBCE-IPM, BP 86510 21065 DIJON
Cedex, France. - E-mail: ala@dijon.inra.fr
Two different approaches have been described to control
plant pathogens: either introduce a selected biological
control agent or enhance naturally occurring biological
control. The first approach has been the most commonly
followed during the 30 last years. Most emphasis was
devoted to the study of the modes of actions of selected
antagonists and less to the study of the conditions required
for successful application. More recently, the development
of molecular tools led to the creation of transformed
biological agents possessing several modes of action, or
having other beneficial traits such as a greater ability to
survive or colonize the target. These 'improved strains' are
supposed to possess an enhanced biological control
activity, but demonstrations in nature of these advantages
are still missing. Biological control of fungal pathogens
remains very limited due to the narrow specificity of the
biological control agents and the inconsistency of their
efficacy. Today there is a renewed interest for studying the
effects of organic matter and compost amendment on the
soil inoculum potential, with the objective of enhancing the
natural potential of suppressiveness that exist in any soil.
Whatever the method used, biological control should be
part of an integrated pest management strategy. Research in
this field requires an holistic approach taking into account
not only the microbial interactions and the plant defense
reactions but also the whole agronomical system.
113 - Premier bacteria and fungal plant disease
suppression
D.M. Weller
USDA-ARS, Washington State University, 367 Johnson
Hall, Pullman, Washington 99164, U.S.A. - E-mail:
wellerd@mail.wsu.edu
Take-all, caused by Gaeumannomyces graminis var. tritici,
is an important root disease of wheat worldwide. Take-all
decline (TAD) is the spontaneous decrease in the incidence
and severity of take-all that occurs with monoculture of
wheat or other susceptible host crops after one or more
severe outbreaks of the disease. In Washington State, USA,
TAD develops in wheat fields because of the build up of
strains of Pseudomonas fluorescens, which produce the
antifungal metabolite 2,4-diacetylphloroglucinol (DAPG).
DAPG producers are abundant in other suppressive soils.
Whole-cell repetitive sequence-based (rep)-PCR with the
BOXA1R primer distinguished 17 different genotypes (A
through N) within worldwide collections of DAPG
producers. Genotype D, which is primarily responsible for
TAD in Washington soils, aggressively colonizes wheat
and barley and suppresses take-all when applied at very
low doses (as few as 10 2 per seed or gram of soil). Field
studies have verified that introduced populations of
genotype D strains are sustained throughout the growing
season, survive between crops, and reestablish on the roots
in successive years above the threshold required for
suppression of take-all.
Book of Abstracts 37