Ash Dieback in Kent (Chalara Fraxinea)
13th November 2012
Kent now has one of the largest concentrations of confirmed cases of Ash Dieback, Chalara Fraxinea in the U.K. It is hardly surprising really, we have always been vulnerable to invasion from the continent by virtue of our geographical proximity and because these days, the English Channel is not the natural barrier it once was.
Naturally, I have been closely following what has at times been quite a fast moving situation for some time now. But with so much information being regurgitated on the internet along with the customary scare stories it can be difficult for the professionals let alone the public to guage whether or not the threat has been overdone. The fact is, from mad cow disease to the millennium bug and bird flu, we have become used to the media hyping up the next big danger only for it to come to nothing.
The Government, after a slow start is certainly taking this seriously, burning 100’s of 000’s of infected saplings under quarantine national emergency measures and undertaking a nationwide survey to try and establish the full extent of the disease. An acquaintance of mine who works for the forestry commission at Bedgebury Pinetum has been very busy on this over the past few weeks. The onset of Autumn has made the survey more difficult but has also bought some time for proper management plans to be formulated over the winter before the disease spreads again next summer. The full extent of the disease will only become clear when the new leaves appear in spring but what is becoming apparent, is that containment is no longer an option, the disease unfortunately having already spread from new plantings to established woodland.
Despite management measures to slow it, the disease is likely to spread across the country over the coming years, but what impact this will have on the landscape is very difficult to predict. Firstly, it’s important to know that even if Ash trees do go the way of the Elm, it will not necessarily mean a significant long term reduction in the total number trees we see in our parks, gardens and the wider countryside because other species will soon be planted or naturally take their place. Secondly it is useful to understand how the disease works and in this case, it enters the tree through the leaves causing them to curl up and die along with the young shoots. The tree needs these leaves in order to produce food for itself via photosynthesis and build up energy reserves to get through the winter. From studies of infected Ash trees on the continent, it appears older trees with accumulated energy reserves are able to survive and manage the disease for several years and in some cases indefinitely but it is far more deadly to young trees which rely totally on their leaves for energy.
We must hope that the disease will not be as bad as currently feared, but if it is what we can gather at this stage may suggest a gradual decline of our mature Ash population over perhaps 5-15 years as the disease spreads and trees slowly succumb. Mitigating this will be the small number of naturally resistant trees that will not be affected and the new plantings of these genetic strains of Ash that will likely be developed. These new plantings will take a long time to mature and so there will likely be a period where for all intents and purposes, the Ash will seem to have disappeared before hopefully, within about 30 years, we will start to see the next generation of resistant maturing Ash trees making their presence felt on our British landscape once again. Only time will tell.
It is very important that suspected cases are reported so for tree owners who are unsure or concerned about correctly identifying suspected cases, we are now offering a completely free site visit and disease identification service, please contact us via the contact page to arrange an appointment.