There has been a flurry of research press releases about progress tackling the scourge of ash dieback. The expected mortality rate for ash in the UK is expected to be around of 50 -75% of all existing ash trees. This is an ecological and landscape catastrophe which is happening in front of our eyes, and no research  breakthrough can stop this. There are some hopeful signs that some trees can recover from infection but whatever we do, we are going to be seeing millions of dead ash trees for many years to come.

(This is a photo I took many years ago of a lovely old ash tree in Stara. I played around with it back then & made it wavering – now it

seems strangely prophetic…..)

Resistance (or more accurately, trees which can tolerate the fungal infection) is increasing in young seedlings. Most small ash seedlings are very susceptible to the disease and are killed within a year  of germinating. Ash has very wide natural genetic variation, so a small number of seedling survive  through natural selection, and  these appear to have much better disease resistance. This means that  we may see more resistant young ash trees growing in the countryside within a few years. Natural selection may not be enough though, as the Ash dieback fungus (Hymenoscyphus fraxineus ) is also evolving at the same time and may become more virulent in the future.

Tree breeding programmes have been able to select some very resistant varieties, and new techniques have been developed to reduce the time for germinating and propagating ash plants.

Resistant varieties planted out in our woods and along our hedgerows will naturally cross with other surviving trees over time to produce a much more robust and tolerant wild population.

Ash Dieback disease originates in east Asia and we may need to incorporate genetic material from Asian ash species into UK plan breeding programmes in the future. Much work still needs to be undertaken, but we will have more resistant trees available to plant out within a few years. Unfortunately, we are still looking at more like 20 -30 years before we see ash coming back at scale in the wild, but with a bit of help along the way, it will return.

Elm is taking much longer to re-establish itself from Dutch Elm Disease, in part, due to its much more restricted genetic make-up compared to ash. There are some pretty impressive semi-mature Cornish Elms (Ulmus stricta) growing near the coast these days, but they still become infected with Dutch Elm Disease before they reach full maturity, thus perpetuating the disease. Probably the best way to conserve Cornish and English elm is to keep it trimmed within a hedgerow where it will be too small to attract any elm beetles so will not be re-infected. There is one healthy elm at Stara by the river in Broad Wood. It looks like a European White Elm (Ulmus laevis) which has good disease resistance. Someone must have planted it about 20 years ago. (Anne: it wasn’t me!)

Last winter, a group of volunteers have been planting some hybrid elms (Ulmus x Wingham) across St Cleer Parish which show very good disease resistance. They provide an important habitat for the white letter hairstreak butterfly which needs elm trees to breed on.

(This isn’t the one in Stara, but it illustrates well what a magnificent tree the elm was and just what we’ve lost. How many more of our well-known and loved trees will we lose as the incidences of different diseases increases? And what can be done to stop this happening?)

Anne: And some more cheerful news, and a cuteness overload (or have I been watching too much SpringWatch & gone all Michaela Stratton?? Anyway, here’s (drum-roll!!)…….