Can Soil Amendments Reduce Disease Severity in Trees?

2016 | Dr. Glynn Percival, R.A Bartlett Tree Research Laboratory, University of Reading, United Kingdom

During their life cycle, urban trees are susceptible to attacks by many pathogenic fungi and bacteria that, if uncontrolled, can result in high mortality rates. Control of these diseases is primarily through the use of synthetic agrochemicals. Increased tolerance to commercially available agrochemicals, failure of many chemicals to adequately control diseases once a tree is infected and increased legislative restrictions regarding the use and application of agrochemicals means new techniques of disease control are now of fundamental and economic importance. It is widely known that trees can defend themselves against pathogen infection through a wide variety of mechanisms that can be either local, constitutive or inducible. Developments in plant protection technology have led to the formulation of several soil amendments that have been shown to induce or “switch on” a plant’s own defence mechanisms. These include chitin, phosphites, biochar (a form of activated charcoal) and pure mulches i.e. a mulch made from a single tree species such as willow or eucalyptus. Preliminary studies have found a single soil application of these amendments provides long lasting, broad spectrum control of several fungal, bacterial and viral pathogens. Importantly these amendments act by organic means so are not subject to government legislative restrictions that relate to synthetic agrochemicals. Aims of this investigation are to investigate the efficacy of a range of commercially available soil amendments singly and in combination on controlling two worldwide economically important tree diseases i) apple scab (Venturia inaequalis) a foliar biotrophic pathogens and ii) Phytophthora root rot (a root invasive pathogen).

Year: 2016

Funding Duration: 3-5 years

Grant Program: Hyland R. Johns Grant

Grant Title: Can Soil Amendments Reduce Disease Severity in Trees?

Researcher: Dr. Glynn Percival

Key words:

Peer Reviewed Publications from Grant:

General Audience/Trade Publications:

  • Percival, Glynn. 2017. Can We Vaccinate Trees to Protect Against Diseases? Part 1: The Science Behind the Theory. Ontario Arborist Magazine. June/July 2017, pp. 22-24.
  • Percival, Glynn. 2017. Can We Vaccinate Trees to Protect Against Diseases? Part 1I: Putting Science into Practice. Ontario Arborist Magazine. August/September 2017, pp. 20-22.
  • Percival, Glynn. 2017. Controlling Tree Diseases: Thinking Outside the Box. ARB Magazine. Issue 176, pp. 42-46.

Short Discussion Articles/Conference Proceedings:


For more information on this project, contact the researcher via TREE Fund at