I. Porter{ XE "Porter, I." }A, S. MattnerA, J. EdwardsA and P. FraserB
A
Department of Primary Industries, Knoxfield Centre, PMB 15, Ferntree Gully Delivery Centre, 3156, Vic
B
CSIRO Marine and Atmospheric Research, Aspendale, 3195,Vic
INTRODUCTION
Restrictions on fumigant chemicals due to environmental
concerns (eg. Montreal Protocol) and tropospheric pollution (eg.
new volatile organic compound regulations) has caused a surge
in new strategies to control soilborne pathogens, but are
sustainable practices being adopted? Since the early 1990’s
when methyl bromide (MB) was shown to be responsible for
ozone layer degradation, a massive global research effort has
been undertaken to find alternative disinfestation strategies. It
was anticipated that growers would readily adopt practices which
conserved biodiversity and the principles of biological equilibrium. In
reality this has not happened because pathologists have not yet
developed a sufficient understanding of the relationships between
soil biology and plant yield or the mechanisms of disease
suppression in the absence of synthetic chemicals.
After MB phase out, many sectors still use other fumigant
chemicals (Fig 1), as other technologies have not always
provided the same advantages afforded by soil fumigation, (i.e. a
high level of pest and disease control with low risk, and good
quality and high yielding crops). However, a bigger set of factors
is now influencing crop production and crop protection; climate
change, user and bystander safety, increasing prices of water, oil
and inorganic fertilisers and concern over soil health is finally
being recognised. This is causing a shift in grower approaches to
soilborne disease control in crop protection.
Figure 1. The efficacy relative to MB/Pic (67:33) of a large number of
crop protection practices on yield of strawberry plants in a metaanalysis of over 100 international studies (1). Elipse ‐ MB/Pic standard
Also, whilst new strategies are being developed for sustainable
control of soilborne pathogens very little attention is being given
to products or strategies which eradicate soilborne pathogens
and protect industries from incursions from exotic pathogens. In
fact, there is a poor knowledge on the ability of any strategies to
effectively eradicate soilborne microorganisms. Techniques, such
as solarisation and steaming whilst effective on a limited scale
are not totally effective in the field, biofumigants decrease risk
but do not eradicate propagules and chemical fumigants do not
guarantee total eradication. Development of soilless systems
which exclude soilborne pathogens are a key future practice to
eliminate disease, and use of grafting and resistant varieties can
reduce effects of disease (Table 1).
Table 1. Some of the future technologies that will be relied upon to
replace control of soilborne plant pathogens by chemical fumigants C: ‐
commodity treatments
Present Disinfestants IPM Strategies to replace disinfestants
Telone C35 EC Grafting and plant resistance
Chloropicrin EC Biorationals (AG3, Voom)
Methyl iodide Biofumigants
Dimethyl disulphide Endophytes?
Solarisation Biocontrols?
Streaming Strategic pesticides and herbicides
C:Sulphuryl fluoride Soilless systems: Substrates and hydroponics
C: phosphine/CO2 MB Recapture and recycling
IMPACT OF FUMIGANT USE FOR BIOSECURITY
Fumigation of imported and exported commodities is a key
activity for quarantine and preshipment especially to satisfy
phytosanitary requirements of the importing country. MB is the
key fumigant used for QPS and is presently exempt from phase
out under the rules of the Montreal Protocol, although the
European Community has decided to phase out all uses by
March 2010. Although MB is predominantly used to eradicate
insect pests from commodities, it may not have any significant
control of fungal pathogens, however this is not clearly
understood. A key alternative for QPS commodity treatments,
sulphuryl fluoride, also has concerns for use as it has a very high
global warming potential (GWP ~ 4000). Therefore the key to
successful QPS treatments for Australia would be to maintain a
systems approach which only allows imports from regions where
the diseases (eg. Phytophthora ramorum, Guava rust, etc.) are
not known to occur.
The Australian and international scientific community require
answers to some key questions to minimise the impact of
changes to availability of fumigants. For instance, in the future,
will we have strategies to eradicate soilborne pathogens in the
event of an incursion? Is it worth the investment to try to
eradicate a soilborne organism? Why is MB being retained for
use in nursery industries worldwide where high health is
paramount, when its fungicidal properties may be insufficient?
Has Australia identified the major exotic soilborne (and airborne)
pathogen risks? Is Australia really prepared to cope with an
outbreak of a serious exotic soilborne pathogen?
This paper will further discuss some of the future challenges
facing industries when considering adoption of new
bioprotection, biosecurity or crop management practices.
REFERENCES
1. Porter IJ, Trinder L, Partington D (2006) Validating the performance of alternatives to methyl bromide for preplant fumigation. Report of the TEAP, May 2006, United Nations Environment Program, Nairobi, 91 pp.
(http://www.unep.org/ozone/teap/Reports/index.asp)
92.3893 95.78335
Strawberry Estimates with LSIs by Chemical Applied
(Treatments with greater than five observations)
0 20 40 60 80 100 120 TC 3 5 M N a Pi cF o sD e v M B 6 7 M I6 0 TC 3 5 E C M B 5 0 T C 3 5 P ic E C TC 3 5 E C M N a Pi cEC M N a F o s P ic P ic M N a M B 3 0 P ic E CM Na So lF e rt M N aS ol D a z B ioF um Co m p os t S o l M N a N o T r 8 6 123 18 51 24 63 28 21 9 62 13 13 13 10 14 30 2 3 17 77 87
Treatm ent Group and Num ber of Trials
% R es p o n se r elat ive t o MB r- P ic ( 67: 3 3)
Keynote
address
A world of possibilities: the importance of international linkages
Barbara J. Christ{ XE "Christ, B." }The Pennsylvania State University, University Park, PA USA
The issues facing our societies and professions are global in
nature. Plant pathology as a discipline is no different since plant
pathogens know no geographic or political boundaries. Through
the efforts of individual scientists, global networks were
established for scientific disciplines and this has been occurring
through the ages. Many of our professional societies even when
national based have international members indicating the
importance of international networks. The American
Phytopathological Society began their efforts in international
programs in the 1940s and refined their goals in 1983 and again
in 2005. However these efforts did not result in international
linkages that bring together scientific societies. For there to be
linkages across societies there must be assurance of each society
being successful and that ventures undertaken across societies
must complement each other’s strengths and fill in potential
weaknesses. Linkages must seek common goals and interests.
Possible items that could generate linkages across our societies
will be explored. In order to move forward in the 21st century, it
is time to embrace networks of alliances to advance the
knowledgebase and this requires international linkages.