Crop diseases will rise in some areas, fall in others

Scientists at the University of Exeter have found that a changing climate will increase the burden of crop diseases in some regions, while lowering the impacts in others.

The risk of crop diseases is likely to decrease in tropical areas including Brazil, sub-Saharan Africa, India and Southeast Asia, as pests and pathogens move away from the equator. Meanwhile, the burden will grow at higher latitudes, particularly in Europe and China.

According to the study authors, these changes will “closely track” variations in crop productivity expected under global warming. 

Climate models predict that crop yields will be boosted at high latitudes as a result of rising temperatures. At the same time, crop productivity in the tropics is not expected to change significantly.

The researchers also report that there could be major changes in the mix of crop diseases affecting the United States, Europe and China.

“Plant pathogens already cause devastating production losses globally,” said Professor Daniel Bebber of Exeter’s Department of Biosciences and the Global Systems Institute.

“Our previous research has shown that crop pests and pathogens are moving away from the equator, and this new study estimates risks from pathogens in the coming decades.”

“Our results show that climate-driven yield gains in temperate regions will be tempered by the increased burden of crop protection.”

“Rapid global dissemination by international trade and transport means pathogens are likely to reach all areas in which conditions are suitable for them.”

Temperatures and other weather conditions have a strong influence on infection rates by plant pathogens.

The study authors used existing data to analyze the minimum, optimum and maximum infection temperatures for 80 fungal and oomycete crop pathogens. They used various computer models to compare current yields and future yield projections for 12 major crops.

Study co-author Professor Sarah Gurr said the changing pathogen mix in each area could have a major impact.

“Plant-breeding and agrochemical companies focus on particular diseases,” said Professor Gurr. “In the UK, for example, wheat breeders focus on resistance to Septoria tritici blotch, yellow rust and brown rust – but those threats could change.”

“Agriculture has to plan and prepare for the future – and that future is almost here,” said study co-author Thomas Chaloner. “We have only got a few decades, and crop breeding can take a long time, so we need to think about resistance to pathogens that haven’t arrived yet.

“A lot of pathogens – especially those currently found in tropical areas – are seriously under-researched.”

“We need to invest in understanding these diseases, which could become increasingly prevalent in the key crop-growing areas of the world.”

The study is published in the journal Nature Climate Change.

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By Chrissy Sexton, Earth.com Staff Writer