Agriculture Reference
In-Depth Information
creased temperature, which allow for overwintering of this oomycetes in
new areas (Bergot et al., 2004). Research has shown that host plants such
as wheat and oats become more susceptible to rust diseases with increased
temperature; but some forage species become more resistant to fungi with
increased temperature (Coakley et al., 1999). For example earlier onset of
warm temperatures could result in an earlier threat from tomato late blight
(caused by
Phytophthora infestans
) with the potential for more severe epi-
demics and increases in the number of fungicide applications needed for
control. Rising temperature would increase fertilizer requirement for the
same production targets and result in higher GHG emissions, ammonia
Climate_change_and_agriculture
).
15.4 EFFECT OF MOISTURE CHANGE ON PLANT PATHOGENS
AND DISEASE
Moisture also affects both host and pathogens in many ways. Increase in
moisture level facilitates infection in several cases such as in apple scab,
late blight, and several vegetable root pathogens. Other pathogens like
the powdery mildew species tend to prosper in conditions with lower (but
not low) moisture. Several climate change models predict frequent and
extreme precipitation that could result in more and longer periods with
favorable pathogen environments. Some climate change models envisage
higher atmospheric water vapor concentrations with increased tempera-
ture, which would favor pathogen and disease development.
15.5 EFFECT OF ELEVATED CO
2
ON PLANT PATHOGENS AND
DISEASE
Elevation in CO
2
level is a major impact of climate change and it can affect
the host and pathogen in multifold ways. Researchers have shown that
with increase in CO
2
level, higher growth rates of leaves and stems ob-
served for plants which may result in denser canopies with higher humid-
ity that favor pathogens. Another ill impact of increased CO
2
level is lower
plant decomposition rates, which could increase the crop residue on which
disease organisms can overwinter, consequential higher inoculum levels
