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Climate Change and Crop Diseases

Climate Change and Crop Diseases. RP Thakur ICRISAT, Patancheru, AP, India University of Mysore, 16 Sep 2010. Outline. Introduction Impact on agriculture Effects on crop diseases & management Conclusions. Introduction.

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Climate Change and Crop Diseases

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  1. Climate Change and Crop Diseases RP Thakur ICRISAT, Patancheru, AP, India University of Mysore, 16 Sep 2010

  2. Outline • Introduction • Impact on agriculture • Effects on crop diseases & management • Conclusions

  3. Introduction • 1896: Svante Arrheinus (Swedish Chemist-Nobel laureate) : role of CO2 in regulating global temp; doubling of CO2 trigger rise of 5-6 C • 2006-07:IPCC 4th report &Al Gore’s “An inconvenient truth”- Oscar award and Nobel prize • 2006- numerous public debate,political discussions and global/regional/national conferences

  4. Introduction Some definitions Climate: statistical description for means and variability of key weather parameters for a given area over a period of time – usually 30 years Climate change: any change in climate over time, whether due to natural variability or as a result of human activity Coping strategies: peoples’ long experience in dealing with seasonal variation of weather factors Food system: activities related to production, processing, distribution, preparation and consumption Food security: an operative system that can provide safe and nutritious food to all people, at all times at affordable price for leading active healthy lives

  5. Introduction IPCC predictions • Increase in temperature globally • Extreme changes – more frequent higher temp, less frequent lower temp • Increased/decreased intensity of precipitation events in some regions • Changes in storm patterns – influence global movement of pathogens • Icreased precipitation in both summer and winter in high latitude regions • In Asia precipitation will increase in summer

  6. Introduction Facts about Global Food Security • World population is 6.8 billion; 9.2 billion by 2050 • 80% live in developing countries, where the population increases 1.9% per year • >800 million people do not have adequate food • 1.3 billion live on less than $1 a day • 50% of poor live in Asia, 25% in Africa, 12% in Latin America in marginal land and fragile ecosystems • Global food production 5 billion tons/yr; required 10 billion tons by 2050

  7. Impact on Agriculture Food production under severe threat due to: -higher average temperature - changing rainfall pattern and rising sea levels - more intense extreme events- drought, flood, hurricanes - rise of 2C likely to have severe impact on environment- natural ecosystem-agriculture - change in monsoon rains, melting of glaciers, increased water salinity - all these affect crops and their diseases

  8. The cost of climate change By 2050 • 25 million more children malnourished • Wheat yields reduced by 30% and rice yields by 15% in developing countries • Prices increase by 90% for wheat, 35% for maize and 12% for rice • US$7 billion/yr needed to prevent/reduce these impacts Source: IFPRI, 2008

  9. Impact on Agriculture • Variable and uncertain weather - the greatest challenges to small-scale farmers and other resource managers • New technologies and knowledge - hardier crops and better ways to manage trees, livestock, water, soil and fish • Need to address both mitigation of and adaptation to climate change.

  10. Impact on Crop Production • Wheat production will increase in northern Europe and Canada, while there will be decline in the Indo-Gangetic plain (where 15 %) of the world’s wheat is grown • Wheat production will shrink by more than half by 2050- threat to the food security of 200 million people • Maize production to drop by >15% by 2020 in much of sub-Saharan Africa and in most of India- estimated loss to Africa at $2 billion a year

  11. Impact on Crop Production • Countries in the Sahel region of West Africa need to switch to more heat- and drought-tolerant crops, such as sorghum and millet • Rice yields in Bangladesh will decline by more than 20% by 2050 and 50% by 2070 • Temperature rise by 2.3 to 3.8 C and increased rainfall by 2050 will affect: >20% decline in farm income in Andhra Pradesh >30% reduction in sugarcane yield in Maharashtra >12% decline in rice production in Orissa

  12. Impact on factors influencing crop production Climate change Farming practices Crop health Crop pest/diseases Development & Deployment of cultivars/transgenics Crop production & Productivity Organic farming Soil health

  13. Plant responses to climate change • Lack of adaptation time in altered climate • Change in population genetic structure of plant species • Change in abundance of particular plant species • Certain species may succumb to diseases and pests • Problem in maintaining traditional land races/varieties • Likely loss of biodiversity • Shorter useful life of resistance genes • Need for development of cultivars with wider adaptation

  14. Effects on host and pathogens • Changes in plant architecture may affect microclimate and thus risk infection • Increased plant density-increased leaf surface wetness duration- more foliar pathogen infection • Increased frequency of heat and drought may contribute to disease susceptibility/resistance • Elevated CO2 levels - change plant structure- increased leaf area, increased leaf thickness, more number of leaves, higher total leaf area, higher plant biomass- all these would influence infection by pathogens • Elevated O3 can change the leaf surface structure- affecting physical topography and chemical composition, structure of epicuticular wax- may influence pathogen infection- likely enhanced infection by necrotrophic pathogens and root-rot fungi

  15. Effect on plant diseases • Alter stages and rates of pathogen development • Modify host resistance • Change the physiology of host-pathogen interactions • Availability and use of chemical pesticides • Specific to pathosystem • Specific to locations

  16. Effect on plant diseases • Direct, multiple effects on plant disease epidemiology: survival of primary inoculum, the rate of disease progress during a growing season, and the duration of epidemics • Changes in the spectra of diseases • Increase in abiotic diseases associated with environmental extremes • Interactions between biotic and abiotic diseases more pronounced • Changes in plant disease management strategies • Opportunities for introduction of new crops and cultivars • Need for effective systems to detect new pathogens • Forest trees slow to adapt- new strategy for forest management plans

  17. Studies of climate change on plant diseases Climate change studies relate to influence of -temperature, -precipitation, -carbon dioxide, -ozone, -ultraviolet (UV) radiation Greater knowledge required of how these factors affect the physiology of the host plant and the host–pathogen interaction

  18. Effect on plant diseases Abiotic factors & host resistance • Drought- lower infection by foliar pathogens • Temperature – influences R-gene expression and vir genes • CO2 can prevent induced resistance • O3 can weaken physical structure and alter chemical composition- increased infection

  19. Effects on plant diseases Pathogen-vector responses • Many pathogens have limited range of temperature for overwintering/oversummering • Abrupt changes in temperature range will influence their survival abilities and reproduction potential • Similarly, vector population will get affected

  20. Effects on pathogen Virulence, aggressiveness or fecundity • Temp governs the rate of reproduction for many pathogens • Increased T duration – more number of generation- more recombinants – new virulence, more aggressive pop • Increased migration in to new areas

  21. Effect on Host-pathogen interaction • CO2 favours increased disease severity by biotrophic pathogens and some necrotrophs • CO2 increases pathogen load on C3/C4 plants/grasses • Drought can aggravate the effects of soilborne diseases, like Macophomina, Fusaria and others • Temp can also influence HPI

  22. Effects on Plant disease management • Delayed/adjusting planting dates less effective • Increased vulnerability to biocontrol agents • Reduced efficacy of chemical control • Risk of movement of invasive pathogen species • Reduced effectiveness of durable resistance • uncertainty for management method decision making • Changing disease management strategy

  23. Models for disease prediction • Empirical models- regression models with climate variables as predictors and epidemic parameters as response variables • Simulation models based on theoretical relationships • Problems with use of such models: • Model inputs have high degree of uncertainty • Nonlinear relationships between climatic variables and epidemic parameters • Potential for adaptation of plants and pathogens • General circulation models (GCM)- based on fixed changes in temperature or precipitation has been used to predict the expansion range of some diseases- not successful

  24. Effects on ecosystem Pathogen characterization might shift with climate change • Pathogen effect on host survival, physiology and reproduction • Life stages of host vulnerable to a pathogen • Proportion of individual/biomass infected at a site • Spatial distribution of infection • Rate of pathogen effects on host in relation to response and recovery • Functional similarity of infected individuals versus replacements • Frequency and duration of pathogen impact

  25. Key issues with crop/disease modeling Relationship between historical climate data- seasonal forecast data - microclimate data Relationship between environment- inoculum- disease- yield Integration of crop model and disease model Interdisciplinary collaboration of agroclimatologist, modelers, agronomist, pathologist, entomologist, economist and others.. International collaboration Institutional support

  26. Climate information-Disease risk management Microclimate data Crop yield model Plant disease model Met station data Historical climate dataSeasonal climate forecast Crop-disease risk model Econ input Disease risk management tool Econ benefit Crop Management advisory system A conceptual framework

  27. Conclusions.. • CC first affects the disease by increasing/decreasing the encounter rates between host and pathogens by changing the ranges of the two species • Disease severity-positively correlated with increased virulence and aggressiveness of pathogens which are mediated by host resistance that is affected by climate change • CC will affect plant diseases in relation to other global change phenomena- new species, new vectors, shifts in land use, expansion of tropical/temperate areas, loss of biodiversity etc.

  28. Conclusions Increased focus needed on: • How a changing environment affects host-pathogen evolution - pathogen characteristics, such as frequency of generation and proportion of sexual reproduction affect the rate of adaptation - host characteristics, such as life span affects rates of adaptation of both host and pathogen populations • Are invasive plant species better able to adapt to CC and move to new areas rapidly? • Are new invasive plant pathogens and vectors able to adapt quickly? • Local, regional and international cooperation and collaboration needed to understand the problem and find solutions

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