• Trees: pest, disease and disorder diagnosis

Trees: pest, disease and disorder diagnosis

Our tree health service

Thomson Ecology’s arboriculture team provides a full diagnosis of tree health problems, and offers advice and solutions for how pest and disease issues can be dealt with.  We produce a full written report of our findings and detailed recommendations of the steps needed to ameliorate the situation.

Early diagnosis of tree health problems

There are many common, and also a number of rarer, pests and diseases that affect trees in the UK.  Some are only cosmetic in nature, whilst others can look insignificant yet be fatal. Knowing what you are dealing with is vital in determining an appropriate response.  This is especially true as climate change opens the UK up to new exotic pests and diseases that may have wider consequences than the health of a single tree.

Current threats to tree health

These are some  of the pests and diseases of current concern in the UK:

Emerald ash borer (Agrilus planipennis).

A major pest in the USA, this invasive moth species from Asia causes fatal damage to members of the Fraxinus (ash) genus by boring into shoots and stems, often ‘ring barking’ trees.  It is hoped that the stringent vetting of wood and plants imported into the UK will prevent it from becoming established here.

Sudden Oak Death (Phytophthora ramorum).

This fungus-like pathogen of woody plant species has killed thousands of oak trees in the USA but has so far not been found to affect either of the two native oak species in the UK.  However, it is currently established in the west of England and in Wales, where it is affecting Japanese larch (Larix kaempferi) plantations and Rhododendron ponticum.  A sanitation felling and transportation control program is being employed by the government in an effort to halt the spread.

Red Band Needle Blight (Dothistroma septosporum)

This fungal pathogen is currently causing major problems in pine plantations, particularly those of  Corsican pine (Pinus nigra var. laricio). It affects the needles, limiting the photosynthetic capacity of the trees and resulting in die-back of the crown and potential tree death.  Plantations in Scotland and Thetford Forest are among the areas to be affected so far.

Horse chestnut leaf miner  (Cameraria ohridella)

Previously thought of as only a superficial pest of the horse chestnut (Aesculus hippocastanum), it has now been shown that this moth  can seriously inhibit growth.  Its larvae cause extensive mining damage to foliage, which reduces the photosynthetic capacity of the trees.  The cumulative effect of this and other diseases, such as the bacterial blight (Pseudomonas syringae pv. aesculi), makes for a bleak outlook for the horse chestnut.

Oak processionary moth (Thaumatopoeia processionea).

Currently confined to the Richmond area of West London, the Oak Processionary Moth could become a major problem if it manages to spread.  As well as being a defoliator of several oak species, including our two native oaks, the tiny irritant hairs that the moth  ejects when threatened can cause serious health problems.

For further advice, please contact one of our arboricultural consultants.