The effect of climate change on major plant diseases. current secnario and future prospect.

1. Shamsher Alam
Ph.D (Ag.) Plant Pathology
1st year
IGKV, Raipur
Effects of climate change on plant disease
scenario

2.  The earth is surrounded by a thick layer of gases which keeps the planet warm and allows plants,
animal and microbes to live. These gases work like a blanket.
 Without this blanket the earth would be much colder and less suitable for life.
 Weather is the day-to-day condition of a particular place.
 “Climate is the average weather in a place over many year” NASA, 2011.
 “Climate include the long-run pattern of numerous meteorological factors (Temperature, humidity,
atmospheric pressure, wind, rainfall, sunshine etc.) in a given location or larger region.” Gutierrez et
al., 2010.
 Climate change its refers to any change in climate over time, wither due to natural variability or as
a result of human activity (Intergovernmental Panel on Climate Change (IPCC), 2007).

3. Causes of climate change
 Emission of greenhouse gases (CO2, nitrous oxide and fluorinated gases).
 Burning of fossil fuels.
 Deforestation (land utilization).
 Increasing livestock farming.
 Excessive use of fertilizers.
 Use of aerosol sprays and many more.

5. Effect of climate change
 Climate change cause 0.4 million deaths a years world wide and costing the
more than US$ 1.2 trillion. Thus wiping 1.6% annually from global GDP.
 0.74 𝟎
C average temperature increased last 100 years leading to global warming.
 Atmosphere CO2 concentration increase from 280 ppm in 1750 to 400 ppm in
2013.
 Assumed to increase by 3.4 𝟎
C temperature and CO2 concentration to 1250 ppm
by 2095 under the A2 scenario.
 Fluctuate summer and winter duration.
 Precipitation distribution, number of rainy days and shift in season.
 Flooding that threaten health.
 Drought area.
 Intensity of sun radiations.

9. Marco Pautasso et al., 2012
Climate change is just one of the global change drives affecting
plant health
Plant health is just a complex
phenomenon as global change?

10. Global warming
 Global warming is the increase in the average measured temperature of the earth’s
near-surface air and oceans since the mid-twentieth century, and its projected
continuation… IPCC, 2007.
Green house effect
 Retention of heat by atmospheric gases and they become worm the atmosphere. The
reflecting back of heat energy by the atmosphere is called the “Green house effect”.

12. Global temperature rises Effects
Temperature rise in 10
C Thousand of home flooded
Temperature rise in 20
C Glacier disappear
Temperature rise in 30
C Amazon drains out, snow caps on alps
disappears.
Temperature rise in 40
C Ocean rise flooding populated area of
Bangladesh away.
Temperature rise in 50
C Desertification river dry up climate refugee
conflict over water, food and space
IPCC, 2011

13. K.A. Garrett et al.

14. Impact of climate change in plant diseases

15. Carbon dioxide
CO2
Leaf area
Leaf
thickness
Branching
Tillering
Stem
length
Root
length
Dry
weight

16.  Increase canopy size and density, resulting greater biomass of nutritional quality, increase
leaf wetness duration, they promote foliar diseases such as rust, powdery mildew, leaf
spot and blight etc.
 High CO2 condition C:N ratio of plant affected. So plant part slower decomposition, they
initiate pathogen survival on overwintering crop residue and increase amount of initial
inoculum.
 Tobacco plant may decrease in virus infection in higher CO2 condition.
 High CO2 concentration reduced stomatal density, production of papillae and
accumulation of silicon at the site of appressorial penetration and changed the leaf
chemistry. Increase resistance to powdery mildew of barley.

17.  Rice plant grown in an elevated CO2 concentration were more
susceptible to leaf blast because of that lower leaf silicon content, that
increase number of leaf blast lesions.
 Percentage of sheath blight is higher in elevated CO2 condition.
Higher number of tillers observed under elevated CO2 concentration
may have increased the chance for fungal sclerotia to adhere to the leaf
sheath at the water surface.

18. Temperature
 Change in temperature will directly influence reproduction, dispersal and survival between
season.
 In higher temperature lignification of cell walls increased in forage species and enhance resistance
to fungal pathogens.
 Asian soybean rust is caused by Phakopsora pachyrhizi. Kodzu (Pueraria montana) can serve
as an alternative host for this pathogen. If warmer winter allow kudzu to move northward.
Soybean

19. Cont…
 Increased aggressiveness at higher temperature of strip rust isolates (Puccinia striiformis)
Mboup et al., 2012.
 Higher risk of dry root rot has been reported in fusarium wilt of chickpea, resistant varieties
in those areas when the temperature exceed 33 𝟎
C (Dixon et al., 2012).
 Warmer soil temperature to accelerate nematode development compare to cooler resulting
additional generation per season.
 Increasing temperature change the wind velocity.

21. Moisture and rainfall
 Increased moisture benefits epidemics and prevalence of leaf fungal pathogen.
• Rice leaf blight caused great famine in Bengal (1942), 2 million people died.
• Wheat stripe rust outbreak in major production region of China contributed to the 1960s famine.
• Mycotoxin reached a record high (U.S. Midwest, 1993).
• Mycotoxin increases are related to high humidity during harvest (East Africa and South America,
1990s).
• Humid summers drive epidemics of grey leaf spot of maize (Lowa and Illinois, 1996).
Rosenzweig et al. (2001) Global change & Human Health
Apple scab Potato late blight Downey mildew of grapes

22.  Water induced soil transport increases dissemination of soil born pathogen to non-
infected areas.
• Outbreaks of Soybean sudden death syndrome in the north central U.S. (1993).
 Continuous soil saturation causes long-term problems related to rot development and
increased damage by pathogens.
• In Maize crazy top and common smut.

24. Drought
 Water stress diminish plant vigour and alters C/N lowering
plant resistance to nematode and insects.
• Outbreak of Soybean cyst nematode correlated to drought condition
in north central U.S. (1990).
 Attack by fungal pathogens of stems and roots are favoured by weakened plant conditions.
• Increased incidence of Aspergillus flavus (producer of aflatoxin) in southern U.S. (1977 and
1983).
Rosenzweig et al. (2001) Global change & Human Health

25.  Dry and warm condition promote growth of insect-vector population, increasing viral
epidemics.
• Summer locust outbreak correlated to drought in Mexico (1999).
• Also increased severity of Maize Dwarf Mosaic and Beet Yellow Virus.
 Climate extremes such as drought may increase invasion by Armillaria spp. That are not
normally very pathogenic.

26. Impact on Diseases Management

27. Host resistance
 Pathogen modified host resistance and result in change in the physiology of host-pathogen
interactions (Coakley et al., 1999).
 Host are resistance to disease may be overcome more quickly by more rapid disease cycle,
resulting in a greater chance of pathogens evolving to overcome host plant resistance.
 In USA recent epidemic of Wheat stripe rust (P. striformis f. sp. tritici) increase in
prevalence of strains adapted to warmer temperature and the strains were found capable of
overcome the long-standing resistance gene Yr8 and Yr9.
 Modified host physiology and resistance, eg. A rise in temperature above 20 𝟎
C inactivate
temperature sensitive resistance to stem rust in oat cultivar with Pg3 and Pg4 genes.

28. Chemical control
 Fungicides, bactericide efficacy may change with increased CO2, moisture and temperature.
 Change in temperature and precipitation may alter the dynamics of fungicide residues on the
crop foliage, increased fungicide wash-off and reduced control.
 Morphological or physiological change in crop plants resulting from growth under increase 𝐂𝐎 𝟐
could affect uptake, translocation and metabolism of systemic fungicides.
 Increased thickness of the epicuticle was layer on leaves could result in slower or reduce
uptake by the host.
 Increased canopy size could negatively affect spray coverage and lead to a dilution of the active
ingredient in the host tissue.
 Precipitation may redistribution of the active ingredient on the foliage.
 Higher temperature increase metabolic rate result in faster uptake and greater toxicity to the
target organism.

29. Few others epidemics that have already occurred
Plant diseases Climate change Author
Downey mildew epidemic on
grape vines under climate
change in north-west of Italy
(Plasmooara viticola).
Increase in temperatures and
precipitation
Salinari et al., 2006
Alternaria epidemic of Apple
in Kashmir (Alternaria mali).
Prolonged rains followed by
high temperature.
Bhat et al., 2015
A severe epidemic of Swiss
needle cast (Phaeocryptopus
gaeumannii) disease in the
Oregon coasts.
Increase in temperature during
winter and duration of leaf
wetness during spring an
autumn.
Stone et al., 2008
Nargis Nazir et al., 2018

30. Need for adaptation of novel approaches
 Need for better agricultural practices and use of eco-friendly method in disease
management for sustainable crop production.
 Required weather-based monitoring, inoculums monitoring, especially for soil-
borne diseases and rapid diagnostics would play a significant role.
 Integrated diseases management strategies should be developed to decrease
dependence on fungicides.
 Early warning systems (Tom-cast, Sim-cast) for forecasting disease epidemics
should be developed.
 Used Decision Support System (DSS) like IndoBlightCast, Jhulsacast for
predicting the diseases and forecasting.
 Neem oil, neem cake should be used to reduction of nitrous oxide emission by
nitrification inhibitor.

31. Daniel Patrick Bebber, 2015

34. Conclusion
 Climate change can have positive, negative or neutral impact on individual patho-system
because of specific nature of the interaction of host and pathogen.
 Lack of knowledge of changeable climate effects on plant diseases.
 From a disease management viewpoint, information is generally required for a specific
disease at a field scale.
 Exposure to 5-10 ppm 𝐎 𝟑 for a few hours can cause visible injury to sensitive crops like
barley, tomato, onion, potato, soybean, tobacco and wheat.
 Plant appear to less sensitive to nitrous oxide, only higher concentration cause water-soaked
lesions.
 First year experiment appear no effect of acid rain on four patho-systems like alfalfa leaf
spot, peanut leaf spot (PLS), potato late blight (PLB) and soybean brown spot. In second
year PLS severity decreased with increasing acidity and PLB showed increasing with
increased acidity.

35. References
 Bebber, Daniel Patrick. "Range-expanding pests and pathogens in a warming world." Annual review of
phytopathology 53 (2015): 335-356.
 Coakley, Stella Melugin, Harald Scherm, and Sukumar Chakraborty. "Climate change and plant disease
management." Annual review of phytopathology 37.1 (1999): 399-426.
 Chakraborty, Sukumar, and Adrian C. Newton. "Climate change, plant diseases and food security: an
overview." Plant Pathology 60.1 (2011): 2-14.
 Gautam, H. R., M. L. Bhardwaj, and Rohitashw Kumar. "Climate change and its impact on plant diseases."
Current Science (2013): 1685-1691.
 Ikksheta Sharma, Dr. N. C. Gupta. “Impact of climate change on plant diseases.” Biotech articles (2014):
10-20.
 Nargis Nazir1, Sheikh Bilal1, K.A. Bhat1*, T.A. Shah1, Z.A. Badri2*, F.A. Bhat1, T.A. Wani1, M.N.
Mugal1, Shugufta Parveen1 and Stanzin Dorjey1 “Effect of Climate Change on Plant Diseases.”
International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 (2018) Volume 7
Number 06.
 Pautasso, Marco, et al. "Impacts of climate change on plant diseases—opinions and trends." European
Journal of Plant Pathology 133.1 (2012): 295-313.

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