The secret clues to be found in a dying oak tree

British oak trees are under threat from a disease known as Acute Oak Decline. Mainly affecting mature trees, it can kill them within four to five years of symptoms appearing. However, while researchers like myself have been looking into what causes it, and trying to find a way to prevent it, our work has been hindered in part by the fact that we have to follow a set of scientific rules known as Koch’s postulates.

For more than 100 years, scientists have identified which single organism causes a disease according to these postulates. However, more recent research into both plant and animal illnesses has shown that these are too strict, and that we need to start considering how multiple bacteria interact to cause a disease in what is called a “pathobiome”.

A pathobiome is essentially a community of interacting bacteria that together cause a disease in animals and plants. Acute Oak Decline, for example, arises from several bacteria which together degrade the trees’ vascular tissues, preventing transport of water and nutrients to the branches and leaves. We have recently identified two bacteria as causative agents of Acute Oak Decline – Brenneria goodwinii and Gibbsiella...