Impacts on Plant Pathogens - Climate Resilient Agriculture for Ensuring Food Security - page 172

If changes in atmospheric composition and
global climate continue in the future as predicted,
there will be relocation of crops, and their dis-
eases and impacts will be felt in economic terms
from crop loss. Changes in levels of CO 2 , ozone,
and UV-B will infl uence disease by modifying
host physiology and resistance. In addition,
changes in temperature, precipitation, and the
frequency of extreme events will infl uence dis-
ease epidemiology. Changes in geographical dis-
tribution will potentially alter the relative
importance and spectrum of diseases, and new
disease complexes may arise. Evolution of patho-
gen populations may accelerate from enhanced
UV-B radiation and/or increased fecundity in
elevated CO 2 . As a result, host resistances may be
overcome more rapidly. Disease management
will be infl uenced due to altered effi cacy of bio-
logical and chemical control options. Information
gathered so far has been fragmented, and a com-
prehensive analysis of climate change impacts on
diseases is not possible with present knowledge.
Experimental research on a diverse range of dis-
ease systems is necessary to improve comprehen-
sion of climate change impacts. There is a need to
strengthen modeling approaches to impact
assessment, given the multitude of atmospheric
and climatic factors, possible change scenarios,
and the number of disease systems. For instance,
changes in both mean temperature and its vari-
ability are equally important in predicting the
potential impact of climate change (Scherm and
van Bruggen 1994 ). Given that climate change is
a global issue, the focus needs to shift from
paddock-based assessment on specifi c diseases to
a more ecologically relevant spatial unit (Scherm
et al. 2000 ) to consider climate with other associ-
ated changes in land use and vegetation cover
(Luo et al. 1995 ), among others.
Apart from the technical diffi culties listed
above, the most signifi cant limitation to climate
change impact assessment is our inability to pre-
dict how technological and socioeconomic forces
will interact with atmospheric, climatic, and bio-
logical factors to shape the agriculture of the
twenty-fi rst century. Technological progress over
the next 50 years will doubtless revolutionize crop
production and animal husbandry. Hence, even in

the absence of climate change, it would be a
daunting task to predict future agricultural pro-
duction potential. For example, how will land-use
patterns change in response to market demands,
technology, and accelerated population growth?
To what degree will transgenic technology be able
to alleviate crop stresses caused by drought, nutri-
ent limitations, and pests? Will crop protection
chemicals still be available to control insects, dis-
eases, and weeds? Compared with these changes,
the prospect of climate change seems a minor
concern indeed. Nevertheless, climate change and
climate variability add another layer of complex-
ity and uncertainty onto a system that is already
exceedingly diffi cult to manage. Better under-
standing of how these forces interact with biologi-
cal yield constraints such as plant pathogens will
therefore contribute appreciably to the develop-
ment of sustainable agricultural systems.

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