Our Plants, Our Future: Plant Health and Pandemics.

Here, invited speakers from the ‘Our Plants, Our Future’ conference (rescheduled from April 2020 to February 2021) share their thoughts on plant health. One major thread running through this feature is the parallel of the COVID-19 pandemic with the threats we currently face from plant pests and diseases.

“The world’s attention is, understandably and rightly, currently focused on human health. But it is essential that we do not forget or neglect plant health at this time. Recent weeks have shown us how even a perceived threat to the food system can lead to behaviour which overwhelms supply chains. Plants do not just provide us with food but also fodder for animals, fibres like cotton, [and oils and wood] for fuel. Native wild plants support biodiversity and ecosystems. Global plant health has never been more critical if we are to have sustainable supplies of safe and nutritious food, produced in healthy landscapes.”

Doctor Trevor Nicholls, CABI


Our global population is rapidly increasing, accelerating land-use change, industrial output and consumption. This impacts our global climate, shifting local and global weather patterns, altering the geographical ranges of crops. Arid conditions provide challenges for existing crops, struggling to thrive under reduced water and increased heat stress. Warmer and longer growing seasons in temperate climes change conditions, allowing for a variety of new plants and diseases to thrive. Conflictingly, globalisation allows the spread of plant pests and diseases across the planet, introducing new diseases to areas where crops were not previously infected.

“Over the past centuries, crop diseases have led to the starvation of the people, the ruination of economies and the downfall of governments. Today, we face a future blighted by known adversaries, by new variants of old foes and by new diseases. Modern agricultural intensification practices have heightened the challenge and climate change compounds the saga, as we see altered disease demographics – pathogens are moving poleward in a warming world.”

Professor Sarah Gurr, University of Exeter, UK


Modelling the distribution of species has considerable implications for both conservation of plant biodiversity and management of invasive pathogens. Detecting the occurrence of new plant diseases in different geographical ranges informs control strategy and alerts us to emerging risks. Researching plant diseases helps us to understand how pathogens infect their host and spread. Understanding all of these factors helps us to combat plant disease and promote plant health.

“COVID19 reminds us how important plants are to our lives and…how plant diseases can have far reaching impacts. Moved around the world by global trade and exacerbated by the effects of climate change, plant diseases can also profoundly change our lives. This pandemic reminds us of the importance of vigilance in the identification of future risks, and the importance of good methods for surveillance to enable early eradication and containment. The availability of good detection methods enables effective outbreak management and aids the return to normality.”

Professor Neil Boonham, University of Newcastle, UK


Plants are susceptible to a huge range of pests and diseases from the smallest viruses and protists, bacteria, oomycetes, fungi and microscopic nematode worms, to insect pests and parasitic plants.

“As the world battles coronavirus and its devastating effects on human health, another health crisis is unfolding in East Africa. Hundreds of billions of desert locusts are swarming across vast areas of Kenya, Ethiopia, and Somalia, the biggest outbreak in more than a quarter of a century, destroying crops and causing food shortages in areas that are already struggling under climate change.”

Professor Katherine Denby, University of York, UK


To feed a growing population, food production will need to increase to ensure food security without impacts on environmental sustainability. Crop losses due to pathogen attack are considered an important issue since it is necessary to use large amounts of pesticides to maintain agricultural productivity. However, such practices have become economically and environmentally unsustainable.

“The major challenge for new plant pathologists is to find sustainable alternatives that can be used to control plant diseases and ensure food crop yields for the next generations. The key to finding such alternatives is in the knowledge generated by fundamental science.”

Professor Alessandra de Souza, Instituto Agronomico de Campinas, Brazil

Impact of Xylella fastidiosa disease on fruit yield (diseased, left and healthy, right)

“The biggest challenge is to transform scientific knowledge using applied, cheap and safe technology to help agricultural production and ensure food security” says Prof. de Souza, who studies Xylella fastidiosa – a devastating bacterial disease which infects a huge diversity of plants. X. fastidiosa colonises the xylem tissue of afflicted plants, exacerbating impacts of drought and heat stress. This disease causes significant reductions in crop yield and widespread plant death, illustrated here….


Xylella is causing significant damage to crops, the environment and society in southern Europe and is a major threat to the UK landscape and our horticultural industry.

Through the BRIGIT programme we are investigating how Xylella may spread in the UK environment, by assessing how symptoms may develop in plants, the prevalence and movement of insect vectors and how Xylella may move around the country via transport of plants.

Philaenus spumarius f. trilineata (Wiesen-Schaumzikade) insect vector for Xylella credit: Gernot Kunz

We also organise public engagement events to distribute information about Xylella and risks associated with importing ornamental plants into the UK.

All of these components are vital in developing an effective regulatory framework to manage the threat posed by the disease.”

Professor Saskia Hogenhout, John Innes Centre, Norwich, UK


“We are very vulnerable to emerging plant diseases that could rapidly threaten food security across the world…globalisation can lead to disease agents spreading very rapidly around the world.

Wheat blast disease – a devastating problem that leads to complete harvest loss – was unknown in Asia before 2016, but spread from South America to Bangladesh where it has caused very significant damage to wheat production in one of the most food insecure countries in the world.

It is now spreading across the region and is of huge concern.This is just one example of the types of threat we face. International, co-ordinated research and open science initiatives are critical to controlling crop diseases. We must actively anticipate the spread of pathogens, develop durable disease control strategies and build local capacity to combat plant diseases wherever they occur. Open sharing of data, resources and know-how is vital, if we are to meet the challenge of fighting emerging crop diseases.”

Professor Nick Talbot, The Sainsbury Laboratory, Norwich, UK


Detecting new pathogens is key to understanding the timing and location of plant diseases globally. International Collaboration and good communication networks are key to combating plant disease outbreaks. In the UK, around 60% of the food we import is from the EU. Euphresco promotes phytosanitary research coordination and funding in the EPPO region and internationally.

“Plant pests, such as viruses, bacteria, or insects that move through many activities of modern life can cause serious damage to agriculture, the environment and even to human health. In this everyday war, research activities provide knowledge of our enemies (epidemiology, taxonomy, risk assessment), allow us to detect them (monitoring, diagnostics) and to fight them (control measures). As the old saying goes, ‘united we stand, divided we fall’.

“The Euphresco network for phytosanitary research, coordination and funding has contributed to reducing the fragmentation of national research activities by bringing people together, strengthening research capacity and rationalising the use of funds.”

Doctor Baldissera Giovani, Euphresco, Paris, France


Of note, the EPPO Beastie Bug has travelled the globe, highlighting the threat of global travel to plant health.


A fundamental understanding of plant disease allows us to both: 1) predict disease outbreaks and 2) develop new methods to resist plant infection. As our scientific knowledge and developing technologies expose the interactions of plants and disease-causing organisms on a molecular level, we can identify the genes and proteins that are deployed, both by the plant and its pathogen during infection. Finding and selecting new genetic targets as tools to fight plant disease.

“For most people in developed countries, the last 30 years have been a period of health and relative food abundance. The COVID-19 outbreak has now shaken us out of our complacency about our health, and about the value of experts. We should also not be complacent about sustainable food security; we will need every tool in the toolbox to maintain it. A profound understanding of mechanisms of plant disease resistance is crucial as we seek to control crop diseases with genetics rather than chemistry.”

Professor Jonathan D G Jones, The Sainsbury Laboratory, Norwich, UK


Plant and disease genetics are constantly evolving, with new disease strains afflicting susceptible plants and resistant plants providing a pool of genetic resources to combat these diseases. Previously resilient crop cultivars can quickly fall under the pressure of a new disease outbreak.

 

One such disease that has recently emerged in Europe is “Wheat stem rust, a notorious global threat to wheat and barley production. Hence the incorporation of stem rust resistance into wheat cultivars was a cornerstone achievement of the Green Revolution. Here in western Europe, following many decades of absence, we have recently seen the re-emergence of this previously vanquished disease. Rust pathologists are now at the forefront of Europe’s fight back against wheat stem rust, bringing together the latest knowledge of the pathogen’s biology, enhancements in disease surveillance and modern breeding strategies to enhance resilience against this formidable foe.”

Professor Diane Saunders, John Innes Centre, Norwich, UK


Wheat stem rust identified on late sown spring barley in the UK. Black telia (left) and orange uredinia (right) were identified on the stem of a barley plant in early August 2019.

Plant Disease travels across borders from Africa to America, Asia to Europe and Australasia in ever interacting cycles of re-introduction and infestation. In an effort to improve our ability sustain global plant health, new initiatives and networks are an essential tool.

“We currently lack robust data to inform policy (local, national, global) to fight crop loss. The Global Burden of Crop Loss (GBCL) initiative [led by CABI and funded by the Bill and Melinda Gates Foundation] is building a global consortium to tackle this challenge and develop a system to accurately monitor and report losses to agricultural crops caused by pests and diseases around the world.

We need to work together, sharing data and models, to effectively tackle global health challenges – whether human, animal, plant or environmental health.”

Professor Katherine Denby, University of York, UK


“At the same time, the stark reality is that around half a billion smallholder farmers, who help produce almost 80 per cent of the food consumed in Asia and sub-Saharan Africa, already battle a multitude of crop pests and diseases as well as the challenges posed by climate change…For over 10 years, through a global network of more than 4,500 plant clinics CABI has been providing farmers with practical advice on plant health problems, both face-to-face and via mobile technology.

Investment in and experience with technology is helping us to continue to make this information available during the current pandemic. The CABI-led Pest Risk Information Service (PRISE) will continue to play a vital role in helping smallholders mitigate crop losses through timely predictions of pest arrivals – which is particularly important when one considers that around 40 per cent of crops are lost to pests such as the prolific fall armyworm. We have recently launched a BioProtection Portal in Kenya which provides farmers and extension workers with information on safer and more environmentally friendly ways to manage pests and diseases.”

Doctor Trevor Nicholls, CABI


Plant breeding is one powerfully effective approach to combating disease: introducing novel resistance traits or new genetic diversity while balancing negative effects such as yield drag or poor quality from the exotic donor. There are many successes, with global research efforts resulting in robust solutions to combat plant disease…

“RAGT are excited to be launching the first European winter wheat variety which has resistance to Barley Yellow Dwarf Virus (a real on farm problem due to removal of Chemistry in 2019). We hope to follow this up with more unique traits from our pre-breeding programmes in the years to come.”

Doctor Ruth Bryant, RAGT seeds, Essex, UK


Biocontrol, when carefully implemented, is another sustainable approach to protecting plant health. Many chemicals are becoming less effective in combating weeds, insect pests and microbes, and evidence is building that control strategies utilising widespread use of some chemicals may negatively impact the environment and even our own health.

“It might seem strange in the International Year of Plant Health to be talking about trying to cause plant death but when one considers weeds and their impact on the crop and natural environment it is more understandable.

For some extensive invasive non-native weeds the only answer lies in their natural enemies and scientists have been using both insects and plant pathogens for biocontrol for over a century, with some notable successes in countries like Australia, USA and Canada and it is starting to be adopted in Europe. The enemy of my enemy is, after all, my friend.”

Doctor Dick Shaw, CABI


Where a few cereal crop species dominate our global food supply and plant pathology research, there are a huge range of diseases afflicting plants from root vegetables, to herbaceous plants, fruits and trees diseases. In the UK, Ash Die Back has headlined recent plant pathology news and triggered a mobilisation of research efforts to detect the movement of this new epidemic and identify ways in which it can be ameliorated.

“The UK is blessed with a magnificent and diverse range of trees. They beautify landscapes and urban areas – providing habitats and food to support wildlife. Yet the threat to the health of our trees from pests and diseases is real and increasing.

Forestry Commission is on a mission to keep our trees healthy, but everyone has a part to play. We want to use International Year of Plant Health as an opportunity to highlight the simple actions everyone can take to help safeguard our trees, woods and forests.”

Doctor Anna Brown, Head of Plant Health Forestry and Contingency, Forestry Commission, UK


“Globalisation allows plant pathogens to move around the world as well as human pathogens. For most of the twentieth century, a fungus called Hymenoscyphus fraxineus and a beetle called Agrilus planipennis were only found in east Asia, where they did little damage to native trees. But about two decades ago, humans accidentally moved the fungus to Europe, and the beetle to North America.

There, they have killed millions of native ash trees, devastating forestry and ecosystem services. We have now discovered genes within ash trees that are involved in resistance to both of these problems, using innovative genome-wide searches. This could enable us to accelerate breeding of more resistant trees, facilitating the recovery of healthy ash populations.”

Professor Richard Buggs, Royal Botanic Gardens Kew, London, UK


Like Dutch Elm Disease, Ash Die Back, Acute Oak Decline and Xylella, there are an ever-increasing number of pathogens and pests threatening trees in the UK and across the world.

“Slow growth and extreme longevity make forest trees, woodlands, and the ecosystem they host exceptionally vulnerable in a way that requires a considered and distinctive response. My group investigate the adaptive immune strategies that allow trees to fight against biological threats. This knowledge is exploited into the development of resistant forests, responding to immediate threats and building resilience to those of the future.”

Doctor Estrella Luna-Diez, University of Birmingham, UK

Ash tree showing signs of Ash-die back disease.

“While our current focus should absolutely be on COVID-19, we can’t forget the fact that other things don’t wait while this human tragedy unfolds. Plant health is one of those things, and the last thing we need is an outbreak of a plant disease on top of COVID-19. It was reported last year in the press that the fungus causing ash dieback in the UK is likely to cost £15 billion over the next 100 years, while just last week it was announced that the bacterium Xylella fastidiosa on olive trees in Italy is set to cost over €20 billion through the next 50 years. This will almost certainly lead to an increase in the cost of olive-based food products for all of us for years to come but may also affect our future generations.

Besides these two pathogens, there are over 1000 other threats from which we need to protect the UK’s plants, and if we let our guard down now, we may be too late to prevent other outbreaks. Scotland’s Plant Health Centre continues to work hard through the current COVID-19 crisis to ensure that we are able to provide the plant health evidence that Scotland’s Chief Plant Health Officer and the wider government need to protect their citizens, and help to maintain our food supply, our environment and our health in 2020 (The International Year of Plant Health) and beyond.”

Professor Ian Toth, James Hutton Institute, Dundee, Scotland


The collective response to the threat and challenge of global plant pests and disease is the importance of:

  • Vigilance in the identification of future risks, actively anticipating the spread of pathogens, employing good detection methods and surveillance to enable early eradication and containment.
  • Development and use of applied, cheap and safe technology to sustain durable disease control strategies.
  • Building local capacity to combat plant diseases wherever they occur and enable effective outbreak management.
  • Promoting international collaboration, good communication networks, co-ordinated research and open science initiatives as key enablers for plant health.
  • Bringing people together and strengthening research capacity with open sharing of data and models, resources and expertise to meet the challenge of fighting global crop diseases effectively.

These strategies will arm us in tackling global health challenges – whether human, animal, plant or environmental health.