Global food security is one of the most important issues for the future of humanity. A new study from the University of Exeter provides information on the effects of global warming on agriculture, in particular on plant diseases and crop yields.
The relationship between agriculture and climate change is mixed: on the one hand, the agricultural sector is a contributor to global warming, but it is also both a victim and a potential solution The University of Exeter study, published on 5 August in the journal Nature Climate Change, examines the impact of climate change on plant diseases and crop yields. Plant pathogens are a burden on agriculture, and this burden can be quantified in two ways: by measuring yield loss or by the cost of disease control.
The impact varies depending on proximity to the equator
Taking into account future climate variations, the researchers based their study on the minimal, optimal, and maximal infectivity temperatures for 80 fungal and oomycete pathogens to determine the diseases pressure on crops in tropical areas such as the Amazon basin, sub-Saharan Africa, India, and South-East Asia. They were able to determine that the pressure exerted by these diseases should drop in the future. However, the risks will increase the further we go away from the equator making Europe and China more vulnerable.
Rising temperatures will also affect crop yields: unchanged in the tropics but higher at higher latitudes. However, the benefits will be tempered by the cost of protecting crops from pathogens.
In a previous study, researchers found that pest species tend to move away from the equator, which explains the expected increase in disease incidence in these areas. Like all living organisms, pathogens and pests have their preferred environmental conditions, which determine their ecological niche and hence the area of the globe where they thrive.
Evolution of Pathogens
Temperature fluctuations thus influence the mix of pathogens that threaten plants in a given area. According to the researchers, “significant changes in the composition of pathogens could occur in the United States, Europe, and China”. The impact of globalization on the spread of pests should not be overlooked. With the expansion of international trade and transport, any species can be found anywhere in the world where it can thrive under the right environmental conditions.
The mixing of pathogens could become a real problem for which we must prepare now. Sarah Gurr, the co-author of the study, notes that “plant breeding and agrochemical companies focus on specific diseases”, but threats can change rapidly, so resistance to a particular pathogen species may no longer be useful.
There is a lack of research on the subject, and scientists stress the urgent need to conduct and invest in more to determine which future pathogens will threaten regions and how to protect against them. To this end, researchers will select and develop plant lines that are genetically resistant to the diseases, for example through cross-breeding. Another option is to use pesticides, although this is not ideal for the environment and our health.