Climate change and plant diseases

Abstract

Global atmospheric concentration of radiatively active gases has been increasing largely due to anthropogenic influences. Rising concentration of CO2 is affecting agriculture and natural ecosystems by directly influencing plant growth and productivity. Crop yield, for instance, increases by an average of 17% from a ‘fertilization effect’ of elevated CO2. Other interacting elements of climate including temperature and rainfall are also changing. There is heightened concern for global food security under a changing climate and many commentaries and projections are available. But projections come from studies that largely ignore the impacts of pest and diseases. This is despite weather being a key driver of plant diseases and many disease forecasting models routinely use short-term weather data for disease management. Plant disease epidemics have historically caused famines killing and disrupting human lives and continue to hamper quality and quantity of agricultural produce and thereby threatening food security. Several reviews and books have speculated and predicted how the adaptive capacity of agriculture may be affected by shifting disease dynamics due to changing climate. Much of the literature has been pre-occupied with impact assessment and risk mapping. A synthesis of current information on host and pathogen biology and their interaction under changing climate to identify gaps in knowledge has been lacking. More importantly, there is precious little on strategies that may be required to manage diseases under a changing climate. For instance, whether the current physical, chemical and biological control tactics including the disease resistant varieties would offer effective protection or whether there is a need to develop and deploy new management strategies have never been addressed. This compilation of twelve reviews and overviews on selected topics synthesises the limited published literature and unpublished work, highlights gaps in our knowledge and addresses ways to improve understanding and management of plant diseases under climate change. While the emphasis has been on collating and reviewing empirical evidence and approaches rather than projections from modelling, various articles have not ignored key aspects of modelling research in coping with complexity and uncertainty in climate change, in dealing with changing geographical distribution of hosts and their pathogens or in modelling the dynamics of pathogens in plant canopies. Internationally recognised contributors have used their research experience and scholarly aptitude to critically review existing knowledge, identify gaps and offer opinions on the way forward. Contributions are more than a review of literature; they offer opinion, approach, strategy, critique and road map to help make progress in this neglected field of study. This effort will be worthwhile if members of the plant protection community including researchers, educators, plant protection specialists and practitioners, policy makers and general public interested in issues of climate change, plant disease and food security find it useful and benefit from this compilation. Inspiring students, researchers and specialists to consider climate change in the context of plant pathology research and policy development will be an added bonus. This special issue of Plant Pathology is dedicated to the late Professor David F. Karnosky in recognition of his significant contribution to plant pathogens and diseases under elevated CO2 and O3. Dave was a visionary and pioneer in global climate change research. He founded the Aspen FACE research project and made significant contributions to global climate change science and forestry. The United States Forest Service has dedicated a laboratory in Rhinelander, Wisconsin to his memory. My thanks and gratitude goes to all authors who have generously given their time to contribute to this special issue; the reviewers, who evaluated and offered countless useful suggestions to improve the papers; Bruce Fitt for editing the papers which I have co-authored; Richard and Jenny Shattock for their inspiration, support and patience; and to the British Society for Plant Pathology and Wiley-Blackwell.