Millions of farmers in Africa’s Great Lakes region face rising temperatures. Study predicts how crop disease and pests could spread

“Farming in the Great Lakes region of Africa (which includes Uganda, Rwanda, Burundi, the Democratic Republic of Congo, Tanzania and Kenya) is challenging because of changing environments and ongoing social and political tensions . These tensions include conflict over resources. As a result, agricultural productivity is low and there’s a high rate of food insecurity there. It’s difficult for farmers to manage their farms well when they don’t have enough high quality seed and then also experience extreme weather conditions like floods, drought and heat waves. Armed conflict and crop diseases and pests make the situation worse by damaging crops. Losses to disease and pests are often higher in low-input agricultural systems, where there is limited access to agricultural infrastructure and inputs like fertiliser and pesticides, as is common in sub-Saharan Africa. Read more: Climate change could pose a major risk to cassava in Africa: study sets out what can be done now We are part of a team of plant pathologists who study crop diseases and pests and then come up with strategies to manage and prevent losses. In our latest research , our team sampled 27 crop pathogens and pests on banana, cassava, potato, and sweet potato crops across altitudes in Burundi and Rwanda. We then used machine learning, a type of artificial intelligence, to see how these pests and diseases may spread when the climate warms more. We wanted to identify high-risk locations and potential shifts in particular pathogens and pests under climate change scenarios. Read more: Africa’s most notorious insects – the bugs that hit agriculture the hardest In “climate matching” studies like this one, researchers evaluate a set of species – in our case, pathogens (disease-causing organisms like viruses or bacteria) and crop-damaging organisms like aphids and weevils – and consider how these species may change across a region as climates change. Information about pathogens and pests at a lower altitude gives a preview of the future at higher altitudes, as the higher altitudes become warmer. Our research found that hotter temperatures are likely to change the distribution and dynamics of crop pathogens and pests in the Great Lakes region. Climate change may allow them to spread to new altitudes and regions where they were less common in the past. This would affect food security crops that are key to the livelihoods of millions of smallholder farmers. Climate change can push crop pests uphill into new farmland We used a modelling toolbox to identify which cropland areas can make it easier for pathogens and pests that target specific crops to spread . Our research shows how parts of Rwanda, Burundi and the surrounding area can be pathways for pests and disease to spread through crop fields. Higher temperatures can make this worse. Pathogens and pests like particular conditions. Higher temperatures may allow crop pathogens and pests to spread to new regions where they were less likely to thrive in the past. Read more: Protecting cassava from disease? There’s an app for that We saw that, as the hills and mountains in the Great Lakes region heat up, 44% of the 27 pathogens and pests could become more common at higher altitudes. This means smallholder farmers will need to adapt. Another important finding is that not all pathogens and pests will become bigger problems. We found evidence that 17% may become less common at higher altitudes. This is because conditions may become a bit too hot for them. It’s important for national agricultural programmes to know which pathogens and pests they need to plan for now and in the future. How farmers can adapt and protect their crops Our results provide a foundation for future work to improve decision-making tools that predict where and when crop diseases and pests are likely to occur. Our findings can be used to develop tools for growers and policymakers to make decisions based on climate change realities. Farmers and agricultural stakeholders – extension specialists, government agencies and humanitarian groups – need to adapt so that they can protect crop health and productivity. They can do this through climate-smart agriculture (which involves adopting farming practices that increase food production, help crops adapt to climate change, and protect the environment). At the same time, farmers can implement better crop management practices to reduce food insecurity while building resilience to climate change. As the world heats up, it’s going to become more important for governments to carry out regular pest and disease surveillance, and forecast where plant diseases need management. Knowing which diseases and pests are likely to spread more will be key to planning how to adapt. Read more: These tiny worm-like creatures in the soil can destroy pests but they can also kill crops - an expert’s guide to nematodes There are many opportunities for improving disease surveillance, predictive modelling, and sustainable pest management strategies. When long-term, high-resolution disease and pest data are available for more regions, predictions and strategies can be improved. Farmers will know in advance if they need to grow disease-resistant varieties or change which crops they grow. However, many national plant protection organisations face resource limitations , personnel shortages, and insufficient infrastructure. This limits their ability to implement comprehensive monitoring and response programmes. Read more: Why it’s so critical to continuously monitor and manage plant diseases Another problem is that when crops are poorly managed or abandoned during disasters , pathogens and pests can spread more easily throughout the region. With better information, government agencies and humanitarian organisations can plan in advance to target the most important pathogens and pests, and work to protect the locations that will be hardest hit. Romaric Armel Mouafo Tchinda received funding from the CGIAR Seed Equal Research Initiative, the CGIAR Roots Tubers and Bananas Research Program, USAID Bureau of Humanitarian Assistance (BHA), the One CGIAR Initiative on Plant Health, and the CGIAR Trust Fun, USDA Animal and Plant Health Inspection Service (APHIS). The opinions expressed in this article are those of the authors and do not necessarily reflect the view of the USAID BHA or USDA APHIS. Aaron I. Plex Sulá receives funding from the United States Department of Agriculture and CGIAR. Jacobo Robledo Buritica receives funding from USDA. Karen Garrett receives funding from the USDA, USAID, CGIAR, NSF, DOE, and Keck Foundation. She is affiliated with the American Phytopathological Society. The opinions expressed in this article are those of the authors and do not necessarily represent the view of the USDA or others of these organizations.

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