We use some essential cookies to make this website work.
We’d like to set additional cookies to understand how you use forestresearch.gov.uk, remember your settings and improve our services.
Preparing to search
Biotic factors that contribute to oak decline
Oak trees carry a wide diversity of insect species, most of which remain ‘in balance’ with their host trees and cause very little damage. However, if episodes of severe defoliation are a regular factor, this could affect the vulnerability of oak trees to the complex of factors that contribute to the overall decline syndrome.
Most notable among the early season defoliators are oak leaf roller moth Tortrix viridana (below left) and winter moth (below right). Both species have egg hatch times to coincide with bud burst in the spring, and the young larvae feed on the newly expanding leaves. When numbers are high, complete defoliation of trees can occur, but a second flush of leaves later in the season partially offsets the negative effect on trees. However, it is likely that severe defoliation does reduce the ability of trees to defend themselves from attack by other agents.
The recent arrival of oak processionary moth (Thaumetopoea processionea) (left) from continental Europe, which is currently restricted to London and surrounding counties, might add a further highly damaging defoliator species to the range of damaging leaf-feeding pests on oak.
Cookies are files saved on your phone, tablet or computer when you visit a website.
Find out more about cookies on forestresearch.gov.uk
We use 3 types of cookie. You can choose which cookies you're happy for us to use.
These essential cookies do things like remember your progress through a form. They always need to be on.
We use Google Analytics to measure how you use the website so we can improve it based on user needs. Google Analytics sets cookies that store anonymised information about: how you got to the site the pages you visit on forestresearch.gov.uk and how long you spend on each page what you click on while you're visiting the site
Some forestresearch.gov.uk pages may contain content from other sites, like YouTube or Flickr, which may set their own cookies. These sites are sometimes called ‘third party’ services. This tells us how many people are seeing the content and whether it’s useful.