forestry commission report 1996

summary



Concern was expressed by Mr Nolan of Braintree in Essex over the large number of unhealthy, dying or dead trees in his area. He was particularly concerned that this was an indication of widespread effects of pollution, particularly of ground-water. A site visit was arranged to see examples of the damage and to determine whether the problem was sufficiently serious to warrant a more detailed study.
Though damaged and unhealthy trees were seen during the visit the scale and nature of the damage did not suggest that urgent action was required. Many of the problems found were well-known and some are already the subject of projects or monitoring programmes. Mr Nolan’s view that ground-water pollution was killing the trees could not be supported as trees do not rely on ground-water for their water supplies. However reports of tree damage are always important and form a central part of the work of the Pathology Branch of the Forestry Commission Research Division. The generally poor condition of trees in parts of East Anglia was already known and the adverse effects of a series of drought years are held to be responsible. The situation will continue to be monitored, with particular attention paid to some species such as ash and oak which appear to have suffered severe damage in some areas.






Background to survey


The case was first referred to the Disease Diagnostic & Advisory Service (DDAS) by the Department
of Environment in late November 1995. A reply (Appendix I) was drafted by nay colleague. Robert Strouts, and sent to the DoE to enable them to reply to the enquirer, Mr Buster Nolan. There then followed a series of telephone conversations and letters between Robert Strouts and Mr Nolan which led to the offer of a site visit in late May 1996, As Robert Strouts retired at the end of April 1996, I took up the case and visited the area on 29 May 1996. About four hours were spent in the company of Mr Nolan visiting sites in and around Braintree where unhealthy, dying or dead trees were present. The visit was also clearly of interest to the Local Authority, local press and the area’s MP. The Rt Hon Tony Newton, all of whom expressed an interest in the results of my investigation.

Observations during the visit
Mr Nolan stated at the outset that he felt that I would find good pathogenic causes for virtually all the problems he would show me. His concern, however, was to show me the extent of the damage to trees in the area and the wide range of species involved. The first site was a row of large poplars around a field in various stages of dieback. These trees had been topped and from a cursory examination the dieback appeared to correspond to this action. In addition some of the trees had cankered twigs and thus some of the branch dieback could be due to bacterial canker. En route to the next site some unpr-uned poplars with significant dieback were pointed out to me but it was not possible to examine them. I was then shown a number of trees in the grounds of a school and in grass verges alongside roads in residential areas. In all cases I was able to identify pathogens or non-living/climatic factors that could explain the damage. These ranged from silver leaf. apple scab. Nectria canker, blossom wilt of cherry, drought injury and possible road deicing salt injury or herbicide injury. In the town centre park there were cases, of root disease (Meripilus giganteus on beech), blossom wilt on cherry, drought and insect attack (felted beech coccus and Horse chestnut scale),
Outwith the town I visited two woodlands with significant numbers of dead or dying trees, At the first site there were many dead and dying Scots pine which were found to have suffered from lime-induced chlorosi.s. The site was a typical calcareous woodland in which Scots pine could be expected to fail from age 25 years onwards. The European larch in the wood was also showing the effects of lime-induced chlorosis having lost normal leader growth and developed flattened crowns. Many of the sycamore in the wood were showing the early stages of soot-bark disease as a result of the hot dry summer in 1995, Some sterns had already died while others will undoubtedly do so during the year, The ash in this wood had flushed very poorly but like many ash throughout the country they had been affected by the cold spring, It was not yet clear to what extent there might be more serious problems in terms of dieback and a close watch will be kept on ash by the DDAS during 1996. At the moment all that can he said is that ash look to be in poor condition which may change once they have come into full leaf.
Disease Diagnostic & Advisory Service - June 1996


No more or less than is the case with any living organism, a proportion of any population of trees is always dying or in less than perfect health, With trees, the causes for ill-health range from attacks by pests and diseases through problems resulting from extremes of weather to damage inflicted by man’s activities.
A year or period of years may be marked by a predominance of one or more widespread and eye-catching problems, such as the Dutch elm disease epidemic of the 1970’s or the damage caused by the 1975/76 drought years. Some problems can cause dramatic though localised damage to trees from time to time, such as the incautious use of road dc-icing salt in certain cities in past years or the complete defoliation of oak trees by caterpillars in some localities.
It is probable, therefore, that you have been noticing not one but a mixture of many problems. Information gathered by the Forestry Commission and the DoE on the health of woodland and non-woodland trees during 1995 in England has thrown up nothing out of the ordinary when viewed against the long term picture. The more striking and widespread problems this year
have included frost killing of developing shoots of beech, oak and other species this spring; spring killing of London plane twigs by the anthracnose fungus; killing of English elm re-growth by Dutch elm disease; and fungal leaf Blights of Horse chestnut and wild cherries this autumn.
If there are any specific instances of unhealthy trees that particularly concern you, the Forestry Commission’s Disease Diagnostic and Advisory Service would be pleased to discuss
the matter with you.
[Faxed to Directorate of Rural Affairs, DoE. London on 28th November 1995