Ash die-back – plague or sniffle?

Kate Nicol [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
Kate Nicol [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
This morning I spent a couple of hours learning about Ash dieback, and other Ash problems (notably emerald ash borer (sounds nice – is deadly!) and other tree problems.  I was invited to attend a focus group (we were quite focussed actually) about how the public would react to various potential solutions to the problems posed by Ash die-back.

It was a little bit difficult to know what the problems with Ash dieback are. Will Ash trees disappear from the British countryside or will they not? Perhaps they will disappear from our towns and from Ash plantations, where the genetic diversity of the trees (mostly planted) is thought to be low, and maybe they will get a bit rarer in our woods, but maybe not very much rarer. It may (or may not) be that our native Ash are sufficiently genetically diverse that they will fight off the fungus in the way that disease resistance usually evolves.

I think I went into the room vaguely thinking that we were facing a new Dutch Elm disease and I came out wondering whether we were perhaps making too much fuss about it. Is this Ash-plague or just a sniffle?

I know I came out knowing more, but being less sure of what to do.  Sometimes life is like that – if you persevere you usually come out the other side.

We, and we were a bunch of journalists, bloggers and authors, chatted around this issue with the help of some people who knew stuff.  Should we consider GM-trees? Should we do nothing? Is it too late? How much would the different options cost? What are their chances of success? What about all those other diseases coming along for other species? Should we chalk Ash dieback down to experience and work harder to stop other diseases developing? Does anyone care?

All these questions were asked, and answered, although I’m not sure that the answers were necessarily the right ones.

I don’t know.

I do know that I was more impressed by where Defra is on this subject than I expected to be.

 

See also Ashes to ashes, a Guest Blog by Peter Marren from 7 November 2012, and my review of the late  Oliver Rackham’s book on the Ash.

 

Likes(27)Dislikes(2)
Website Pin Facebook Twitter Myspace Friendfeed Technorati del.icio.us Digg Google StumbleUpon Premium Responsive

Get email notifications of new blog posts

Registration confirmation will be emailed to you.


9 Replies to “Ash die-back – plague or sniffle?”

  1. People would do well to refresh themselves with PMs sage words.

    Of the commercial enterprise considration, promoted and no doubt supported by politicians who see an 'industrialised' solution to a natural problem as a way forward (forget our track record on bio-security) .... "we don't want to produce a product no-one wants", really?

    Perhaps I'm too cynical of political spin or media marketing of 'instant gratification' or 'quick fix' without risk assessment of potential impacts across a wider 'horizon'?

    But then I'd not like to see our natural environment or rural landscape lose its ash trees, or any native species, so ever an agnostic.

    Likes(3)Dislikes(1)
  2. Mark, I'm pleased to know that you and significant others are on the ash die-back case. And that you say you are more impressed than you thought you would be with where DEFRA is about the situation.

    I know only the most basic facts about the biology of the ash, but mythologically and spiritually, it is of deep significance in the Northern and Western 'medicine' traditions. The ash is arguably Yggdrasil, the great World Tree of Norse mythology, and also a likely contender for the Cosmic Tree in other traditions. In legend, it is the 'female' partner to the 'male' oak, and has many 'magical' attributes. Maybe all easily dismissable nonsense, but we've not 'civilised' ourselves quite out of the enchanted forest, yet. Thank goodness.

    Likes(4)Dislikes(0)
  3. As you say, Mark, we don't know what the impacts of ash dieback will be in the UK -especially because our ash has high genetic diversity and we don't know how much will be resistant. However, we do know that many of the potential human responses - not accepting ash regeneration and promoting specially bred (or genetically engineered) resistant trees, for instance - will reduce the very genetic diversity that is the main hope for a species to be able to survive in a changing world. I don't see any reason to rush into breeding programmes. We should make sure our existing woods and trees are in the best health possible and that trees are able to regenerate (free of excess deer and sheep) and see what natural resistance emerges amongst our native ash trees. This will retain as much as possible of the genetic diversity in the species - which will be needed to ensure it is able to survive whatever catastrophe arrives next.

    Likes(4)Dislikes(0)
  4. Did they tell you how many species are specific to Ash. Elm has a moth but then it was introduced (that dreaded word) much later than ash arrived.
    One observation. Wood pigeons love the flowers. Which I guess are highly nutritious and an safer feed than pecking clover leaves. What will happen as trees die - the remainder will presumably get more predated as I don't see pigeons declining when there are inferior alternatives available eg clover and oil seed rape so any recovery will be slowed down. You just have to see a Bryant and May supported poplar plantation (think match sticks) at flowering time. I have seen 100s of pigeons in one.

    Likes(0)Dislikes(0)
      1. There would be those species that aren't exclusively dependent but benefit greatly which would presumably be a much longer list - bullfinches eating the ash keys for example (which if they are deprived of them will turn their attention to other food sources such as fruit trees).

        Likes(0)Dislikes(0)
  5. I was in Norfolk in the summer and found 2 sites with Ash die back. 1 was on Norfolk Wildlife Trust land and 1 on Broads Authority land. Both were told but I never heard back from them to confirm they had done something about it!!

    Likes(0)Dislikes(0)
  6. Hello Mark - well it might not be a plague yet but I don't think it's a sniffle either, not by a long way. If only trees could 'get over' virulent fungal pathogens as a human gets over a nasty bout of influenza! But you're right that we can't really know the effects yet; Rackham wrote that the disease hasn't been studied long enough to know its behaviour in young or old, planted or self sown, woodland or non-woodland trees.

    For what it's worth my own observation, based mainly from roadside views of non-woodland trees, is that the disease is widespread though still patchy. Driving through counties like Suffolk, to the RSPB's reserve at Minsmere in late summer for example and you cannot fail to notice it.

    As has been reported by others it seems to mostly effects young up to middle sized trees, with the strong growth of the former noticeably wilting and blackened and the latter mysteriously leafless. I have seen planted and self sown trees affected in Bedfordshire, with the symptoms varying in extent and severity - and one of the most affected trees I've seen, with multiple branches showing signs of attack was in a village near Exeter, ironically a rare refuge for older elm. By contrast I've yet to see a mature tree that I could say with confidence was seriously affected or even displaying symptoms. In this respect chalara seems almost opposite of elm disease, which has mostly taken the mature trees but left attenuated sucker growth version of each clone surviving, thriving even, on a peverse sort of disease imposed self coppicing cycle. By contrast Ash Disease would appear to be working from youth up, leaving embattled older survivors but as with changes to oak and hazel threatening ash's ability to reproduce (and worryingly threatening the future of coppicing). After the success of ash in the twentieth century - readily establishing in any abandoned sites and even cracks in the pavement - this will be a shock. I do see larger ash with suspicious looking crown thinning too - but without climbing them or testing for the fungus how to tell whether this is chalara, a natural retrenching or some other condition?

    Rackham remarks on the disease apparently waxing and waning year to year, possibly responding to wetter and dryer seasons. I've seen one young tree almost killed to the ground in 2014 and then sprouting vigorously this spring and summer - it was affected again late in this season but less severely. Similarly a tree at a railway station showed symptoms last summer but not apparently this, the small area of affected branch almost disappearing amid the new foilage.

    A comparison other than with Elm Disease might be with Alder Disease, a Phytophthora water-mould which has killed up to between 15-25% of Alders in prone areas in Eastern and Southeastern England and is spreading. There is more than the suggestion that the fungus has been here for much longer than the 'official' date of 2012; there is a report of trees planted by the National Trust in Somerset showing symptoms having been planted in 2001 and surviving with little mortality. I myself have seen a group of older trees near Bedford with some suspicious looking signs. Taken at face value though, if we were to start at 2012 and compare Ash Dieback to Elm Disease we're only at about 1968 - who could have predicted then that within 15 years more than 90% of the mature elms in these islands would be dead?

    If chalara seems likely to be a serious nuisance at best, what seems certain is that the Emerald Ash Borer would be a worse catastrophe than even Elm Disease; there must be a serious risk of it rendering Ash effectively extinct from these islands if it
    got here. It seems to be eclipsing even the famous blight of Sweet Chestnut in the US; this from Rackham's book on the ash:

    "Emerald Ash borer was first noticed in 2002. The authorities imposed quarantine but to little effect ... it has already killed more ashes than there are in the whole of Britain and Ireland... within 11 years of arriving in an area the beetle's population explodes and kills all the ash trees. The dead trees, too many for the tree fellers to get round to them, fall on cars and people's heads. Human health is affected as people suddenly find themselves deprived of their favourite trees and exposed to high temperatures and air pollution."

    My own view is that the battle to contain chalara is well past being lost and it would be unwise to assume that any genetic diversity in ash will give us a get out of jail free card - even resistance does not mean the same as immunity. I'm sceptical of purported plant breeding 'solutions' and even talk of GM as an answer - this just perpetuates the breathtaking complacency that we can bugger about with the landscape, transporting diseases round the world at will, and then plant our way out of trouble. Who has the time or money to make sure 80 million replacement ash trees will reach maturity even if, Owen Paterson style, they could somehow replace the meaning and beauty of naturally occurring ash in the landscape? If Defra has any sense (and the past doesn't fill one with confidence) it will be focussing all it's efforts on keeping the borer out while this might just still be possible.

    More here: http://www.theguardian.com/environment/ash-dieback

    And it's now being called Hymenoscyphus fraxineas not chalara fraxinea - when did that happen?!

    Likes(1)Dislikes(0)

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.