Plants get sick too – scientists as plant doctors

7th June 2022

Article by Victoria Armer & Josie Elliott, edited Ashely Baldwin.

Every day we rely on plants to survive. They provide us with clothing, food, medicines, fuel and even the oxygen we breath. But have you ever thought about how plants get sick?

Plants can be attacked by all sorts of pathogens (a term for any organism that causes disease). These range from microscopic worms and fuzzy fungi to invisible monsters like bacteria and viruses that you can’t see with the naked eye.

Just like how sickness can keep humans out of work, the damage done to plants by any of the above pathogens can stop them from producing all things we need them for. Around 40% of our food today is lost due to damage by insect pests and plant pathogens1.

There can even be plant disease outbreaks, just like we have pandemics. The Irish potato famine of 1845-1957 led to over a million people in Ireland dying, with another 1.5 million emigrating. This death and devastation was caused by a microscopic pathogen called Phytophthora infestans which is an oomycete that infected potatoes and cause late potato blight. Oomycetes are often described as ‘water moulds’ but scientists now know they form their own branch on the tree of life and are more closely related to algae. The pathogen infects potato and tomato plants, at first causing dark spots to appear on the leaves and stems (image below) before eventually causing the whole plant to collapse.

Late potato blight infection. Credit: Scot Nelson, 4.5.22, Flickr

Today Phytophthora infestans still costs the world over $5 billion in losses of potatoes2. Scientists work with farmers to help stop the spread of disease through better farming practices, the use of pesticides or developing potatoes resistant to Phytophthora infestans.

Other plant diseases can change the way the countryside looks. The fungus Ophiostoma novo-ulmi causes Dutch elm disease and gets spread around by elm bark beetles. In the 1960s and 1970s this led to 90% of elm trees being lost from the UK countryside3. As climate change brings warmer weather other diseases have the potential to spread to the UK and scientists are trying to help us prepare.

Plants can even get symptoms similar to those that we humans get too. When a bacteria called Pseudomonas syringae infects horse chestnut trees the bacteria multiply under the tree bark, causing the tree to ooze sticky snot from its trunk. This is called bleeding canker disease.

How would you design a plant pathogen? Do you think you could be a good plant doctor and become a detective for different plant diseases? If yes, then you’ll enjoy the SWBio teams’ Festival of Nature stall.

The SWBio team is a group of PhD researchers around the Southwest of the UK who work on a range of important biological questions, including how to help sick plants and prevent their diseases. We will be presenting a stall at the Festival of Nature Family Nature Party at Bristol Beacon 12th June 10am - 4pm.

Who will be at Festival of Nature 2022 from SWBio?

Erika Kroll – Erika works on one of world most important crops – wheat. She dives into their genes and molecules to try and figure out how to protect them against pathogens.

Elliot Stanton – Elliot is at the frontline of research in how to protect the world against the antimicrobial resistance crisis. He harnesses computers and statistics to learn about the impact of antimicrobial drugs in agriculture.

Ellie Fletcher – Ellie is working to try and make sure we all have enough food to eat as the world’s population expands. She tinkers with plants not at the level of the leaf, or even the cell, instead she’s re-engineering the components inside of plant cells, and making them work better for us.

Ryan Biscocho – Ryan combines being both a biological and computer wizard to read the genetic code deeply enough so that he can try and understand how it evolved. Particularly how this code allowed agricultural domestication of the animals we rely on as food today.

Dunia Gonzales – Dunia is a bumblebee psychologist. She researchers how these plucky pioneers that pollinate our plants are able to navigate the world and create memories. You can also add drone pilot to the list as Dunia’s science includes using drones to take aerial footage of the bees habitats.


Test your knowledge on plants with The Big Plant Pathology Quiz from the British Society for Plant Pathology:

Learn more

The BSPP Plant Doctor Handbook inspired much of this blog post:

These same scientists also have produced a more detailed summary of potato blight:


1 – Food and Agriculture Organisation of the United Nations, 2 June 2021

2 – Money, N., 2007. The triumph of the fungi. New York: Oxford University Press

3 – BBC News, 4 December 2019.