During this month of May, I have twice visited the RSPB’s reserve at Dungeness to bird watch – something I haven’t done per se for many years – my former work and time always requiring me to look at the ‘bigger scene.’ Presumably due to our changing climate, these two outings were something of an update for me personally. Firstly, I saw a pair of Great Egret fly across a marsh, these, I have never seen in this country.
Secondly, while sitting in the sunshine having a sandwich there this week, I twice counted 7 Hobbys in view at the same time, they sweeping the skies capturing insects on a brisk easterly wind.
Just before I was about to get out of bed this morning, another new birding experience – that of laying in bed and watching swifts hawking high above the big oak immediately at the end of the garden – lazy twitching!
I have been watching with interest across the past few weeks of this heatwave, the behaviour of the carrion crow population in a part of Seaford that I frequent.
The local crow population near the seafront area (who appear to be rather benign, urban relations of the rural hunting type that I’m more familiar with) and seem very social together. They number up to some 15 birds and here is the point of interest, spend much of the hotter part of the day on neighbouring roofs and ridges in an attempt to stay cooler in the slight breeze that these higher vantage points presumably provide.
Saturday, July 7th. Had a beautiful, enjoyable afternoon, including a trip down Memory Lane! Went to an Open Garden event in aid of the Family Support Group at The Long House in West Dean near Seaford. The owners have over the past six years created an extensive, beautiful but compartmentalised cottage garden containing a wide variety of plants.
After, we visited the nearby churchyard and church. I used to know the village well and a number of its then inhabitants when I lived and worked over the hill at Exceat during the 1970’s and 1980’s.
Upon leaving the village spotted one of the last fair-sized elms in the area starting to die from Dutch Elm Disease. Further up the valley at Lullington and especially sad for me, one of the last sizable elms has at last surrendered to this dreadful disease. It is the only example in the area of a Smooth-leaved Elm of the variety diversafolia.
I managed the East Sussex Dutch Elm Control project between 1997 and 2004. Due to mis-management and cost-cutting, it unraveled two years later and failed, after a total of some 30 something years and the expenditure of millions of pounds of public money.
As I drive about here in Sussex and further afield, I often notice dying ash trees and from time to time whole groups – especially of smaller semi-mature trees: the wooded downland escarpment above Eastbourne; Filching, Glynde, Jevington; even west Wales. Judging from the large numbers, I can only assume ash dieback is the cause. Added to this is the stress being caused by the current hot, dry weather exasperating many diseased and weakly trees of other species.
https://www.forestry.gov.uk/chalara. (You can also report diseased ash trees via this link). Confirmed findings as at midday on 1st June 2018:
10-kilometre grid squares with one or more Hymenoscyphus fraxineus (Chalara) infections confirmed in the wider environment:
|2012||2013||2014||2015||2016||2017||2018||Total||% of all 10k squares in country|
|Isle of Man||0||0||0||1||1||0||1||7.1|
The progression of numbers and appearance of new grid squares over time should not be interpreted as an indication of the rate of spread of the disease. It only indicates when infection sites were found, not when the fungus first arrived at the site, which in many cases cannot be known.
- Video – How to identify Chalara dieback in the forest
- Video – winter symptoms
- Video – spring symptoms
- Symptoms picture guide
- Printable guide
- Pest alert
- Identifying ash trees
- Symptom images
Because ash trees have many genetic variants and occur right across the UK, they come into leaf at different times. Ash is also one of the last tree species to flush, sometimes taking as long as six weeks to do so, and can often occur as late as the end of May. Trees in the colder north flush later than trees in the warmer south. Some ash trees will break-bud, or flush, earlier than others, and some buds will produce flowers rather than new shoots. Some variation will be more apparent in older trees.
Some shoots on ash trees will fail to flush altogether, while others will flush normally before showing signs of ill-health or dieback later. These events might mean that the trees are damaged in some way, but shoot death and dieback in ash trees can have a number of causes.
So if an ash tree does not have any leaves on it in April and May, it does not necessarily mean that it is diseased or dying, but by mid-June all healthy ash should be in full leaf.
Mid- to late summer (August and September) is a good time of year to undertake surveys, because once autumn has begun, visual symptoms can be confused with leaves that are naturally changing colour.
In the autumn you might see clumps of sometimes dark-coloured ash keys (seeds), retained on the trees after the leaves have fallen. This is quite normal, but from a distance they can be mistaken for the blackened leaves which can be a symptom of the disease.
If you think you have spotted the disease, please check our symptoms section before reporting it using Tree Alert or one of the Further Information contact points below.
Chalara is caused by a fungus called Hymenoscyphus fraxineus. This fungus has two phases to its life-cycle: sexual and asexual. The asexual stage, which grows in affected trees, attacking the bark and girdling twigs and branches, was the first to be described by science, and was originally called Chalara fraxinea. This gave rise to the common name of the disease which it causes.
The sexual, reproductive stage, which was only discovered some years later, occurs as tiny, mushroom-like fruiting bodies on infected rachises, or stalks, of the previous year’s fallen leaves. Infective spores from these fruiting bodies are spread by the wind on to the leaves of healthy trees in summer. This sexual stage was initially called Hymenoscyphus pseudoalbidus (H. pseudoalbidus) before a taxonomic revision suggested the name should be Hymenoscyphus fraxineus. The International Botanical Congress has also agreed that a single fungus should have only one name, even if different stages of the organism have previously been given separate names. Therefore Hymenoscyphus fraxineus is now widely accepted as the name to use.
Government scientists have set out the most up-to-date understanding of the disease. Their assessment concluded that:
- the spores are unlikely to survive for more than a few days;
- spore dispersal on the wind is possible from mainland Europe;
- trees need a high dose of spores to become infected;
- spores are produced from infected dead leaves during June to September;
- there is a low probability of dispersal on clothing or animals and birds;
- the disease will attack any species of ash;
- the disease becomes obvious within months rather than years;
- wood products would not spread the disease if treated properly;
- once infected, trees cannot be cured; and
- not all trees die of the infection – some are likely to have genetic factors which give them tolerance of, or resistance to, the disease.
Preliminary results from testing of selected fungicides for treating ash trees with Chalara dieback of ash for their efficacy in laboratory tests and field trials are now available on the Defra website.
The fungus is believed to have originated in Asia, where Asian species of ash are able to tolerate it after of thousands of years of co-evolution.
It entered Britain on ash plants imported from nurseries in continental Europe. However, now that infected, older trees have been found in South-East England with no apparent association with plants supplied by nurseries, it is thought possible that it also entered by natural means. These include being carried on the wind or on birds coming across the North Sea and English Channel, or on items such as footwear, clothing or vehicles of people who had been in infected sites in Continental Europe.
Video: history of the pathogen.
Well, here we are in the far west of Wales in the Gwaun valley nestling below the Preseli Hills Mountains; the weather is wall to wall sunshine, not too hot at the moment but that might change…
On the drive down on Friday, 22nd taking the scenic route to the north of the Brecon Beacons, we saw many dying ash trees – ash dieback I wonder? Upon arrival at our little cottage, greeted by swallows, house martins and swifts! Indeed, upon driving around, there are quite a number of swifts over countryside and the local towns -so this is where all our swifts are?
Geologists list it as one of most important meltwater channels in Britain from the last Ice Age. The valley is pure rural idyll, thick with beech and hazel, ash and oak. Sightings of pied flycatcher, wood warbler, redstarts, marsh tit, nut hatch and tree creeper are recorded. We watch from the cottage, buzzards, kite and (our) four young swallows on the overhead cable opposite.
Up on the mountains, bog aspodel, sundew, cotton grass, heathers, western gorse(?) and a small pink flower I shall have to look up upon my return oh and ponies! Farming appears to be fairly benign , it mostly on the intermediate middle ground just above the valley. The road verges are quite floristically rich – the foxgloves are spectacular at the moment!