Ashes, elms and epidemics

The ash grove, how graceful, how plainly ‘tis speaking/ The harp through it playing has language for me. Growing up in New Zealand, I knew fragments of this song and would sing them on car trips with my family long before I actually ever met an ash tree in real life. When I did so at last, I was underwhelmed. Ashes in full leaf are certainly graceful, but they’ve never really caught my imagination. Not surprisingly, European ash groves evoke no wistful memories of childhood.

The leafless ash, though, is a different story: it’s been my key to a new way of seeing the woods in winter. For years, they were just an indistinguishable mass of bare trunks and branches. Then one day I happened upon a reference in a book to the “jet-black buds” of ash trees. Black buds? I began to look more closely. And lo and behold, walking through my local reserve one day, I found a tree that did indeed have bold, black buds. And then another! A whole grove of them! It wasn’t just the colour that was distinctive, it was the shape, the energetic upward curve of the twigs, the symmetrical cluster of the three buds at the tip, vaguely reminiscent of the club in a pack of cards. Suddenly I was seeing them everywhere, and many of the gnarled old trees I’d taken to be oaks turned out to have been ashes all along.

Since that discovery I’ve seen the winter woodland with different eyes. It’s no longer an undifferentiated and uninspiring background, but a varied cast of characters. I can’t identify them all, but it’s an enjoyable challenge. The clues are not just in the buds, but in the bark, the trunk, the arrangement of branches and twigs, the tell-tale leftovers of previous seasons: catkins and cones, clusters of winged seeds or “keys”. Some ashes – presumably those that bear female flowers, or flowers of both sexes (the sex life of ashes is complicated, to say the least) – are draped with untidy looking keys throughout the winter. It’s not their most attractive feature. Come spring, they put on a curious display of flowers: sprays of green stalks with purplish tips. Not the kind of obvious beauty that will win prizes in flower shows, but rather fascinating.

Ash buds. Crabchick on flickr, https://creativecommons.org/licenses/by/2.0/legalcode

Ash flower. Dean Morley on flickr, https://creativecommons.org/licenses/by-nd/2.0/legalcode

Old ash in Admiral's Park, Chelmsford

The same tree close-up

Hollow ash on bank of the Wid

Another tree that I’ve discovered fairly late in life is the elm. I didn’t expect to find elm trees when I came to Europe; I assumed they’d all been wiped out by Dutch elm disease. News of that disaster had made it all the way to my science classroom in New Zealand in the 1980s. But then while visiting friends in Wales a few years ago I spotted a majestic tree with round, winged seeds and curious asymmetrical leaves, one side extending further down the stem than the other. I took a leaf home to compare with my tree guide, and was delighted to learn that this was an elm. Since then I’ve found more elms in hedgerows and parks around Chelmsford, though none anywhere near the size of that tree in Llanberis.[1]

These smaller trees are inconspicuous in summer, melting into the background greenery. They’re at their most striking in spring, when abundant clusters of winged seeds appear on bare branches. From a distance an elm in fruit looks as though it’s covered in pale green blossom. It’s a lovely sight, and this spring I’ve seen more and more of it on roadsides near Chelmsford. My latest elm-related discovery, though, is the preceding phase: the flowers. They’re easy to overlook, but unmistakeable once you’ve found them. It was only this spring, in early March, that I noticed a few twigs with small red flowers in my local reserve. What could this be, and why had I never seen it before? A flick through my Collins Gem tree guide quickly brought enlightenment: it was an elm! In the weeks that followed I was able to observe the flowers morphing into fruits, a remarkable transformation.

My elation at discovering elms was short-lived. On Easter Day I was cycling around the countryside excitedly pointing them out to my companions (could this have been a little annoying, I wonder?). Soon after that, I noticed that one of the elms in my local nature reserve was surrounded by dead trees of a similar height and build. Slender young trees, which had clearly not died of old age. As the spring progressed, the difference between the living and the dead became more and more obvious. I gradually realized that for every healthy-looking fruit-laden elm I spotted in a hedgerow, there seemed to be one or more gaunt skeletons nearby.

I take this as sobering evidence that Dutch elm disease is still active and the species hasn’t made a miraculous comeback. So what is this disease, and why is it “Dutch”? It turns out that it didn’t originate in the Netherlands, nor does it particularly affect the species known as the Dutch elm. Somewhat unusually, it got its name from the nationality of the scientists who first identified it in the 1910s. It is caused by two related fungi, spread by elm bark beetles. The first epidemic, from around 1910 to the 1940s, killed up to forty per cent of the elms in some European countries. The second was much more severe, killing an estimated two thirds of mature elms in the UK (some 20 million trees) in the decade following its accidental introduction in the late 1960s. Most of the rest had succumbed by the early 1980s. It must have been a heartbreaking time for European tree lovers, and I’m glad I wasn’t around to witness it. Today new elms keep growing up, mostly in hedgerows, many suckering from the roots of dead giants. But the disease is still lurking, and it seems that once these young trees reach a certain height the bark beetles can see them and come in to feed, bringing the fungus with them. All that hopeful growing for nothing.

Dutch elm disease is an old and well-known enemy, but there’s a much more recent addition to the ranks of villainous tree-killing fungi, and this one is going after the ash tree. Not surprisingly, given the fate of the elm, there’s a considerable amount of anxiety about the resulting disease, ash dieback or Chalara. The Woodland Trust gloomily predicts that it will kill around 80% of ash trees across the UK; other estimates are even higher. The disease was first identified in 2006, by which time it was already widespread in continental Europe. The UK, however, continued to import ash saplings from affected countries until 2012, when the first cases were found here. This led to a sudden panicked response, with a ban on imports, the destruction of 100,000 nursery trees and saplings, and a meeting of the UK’s emergency committee. Too little too late, some have said – does this sound at all familiar?

I only heard about ash dieback a couple of years ago and I’ve so far been fairly unconcerned, since most of the ash trees I see around me look pretty healthy. Just this spring, however, I’ve started to wonder. One striking fact about ash is that it’s one of the last trees to come into leaf in spring, and this being an extraordinarily late spring, they’re not quite there yet. Most trees are now in partial leaf, but some are still almost bare.  And looking at those bare trees, I’m having my doubts. In the young, planted ash grove in my local nature reserve, there are a few trees that are unquestionably dead, bark already peeling off, no signs of life. Others look as though they might still be dormant – yet those black buds have a slightly dry and shrivelled look. And elsewhere in the reserve I’ve noticed that some of the mature ashes have a surprising number of dead branches. Walking through the reserve recently, I started to look at the emerging leaves with a sense of anxiety – is it just a late spring, or are these trees actually unwell? It reminded me somewhat of waiting for a  teenager to come home at night: as the evening wears on you become increasingly anxious and begin to fear the worst – and then at some point the child appears, slightly tipsy but otherwise unharmed, and life goes on. Here’s hoping those ash trees that are starting to worry me will soon be covered in healthy foliage, and I can put away my fears until next spring.

It seems there’s little we can do about these diseases. Human intervention – importing elm logs from North America and ash saplings from continental Europe – has introduced these pests, but human intervention seems more or less powerless to help their victims. In the case of Dutch elm disease, felling affected trees has been the main strategy. Trimming the elms in hedgerows to keep them out of the sight of elm bark beetles also seems somewhat effective, but of course this means they will never develop their full potential as tall and stately trees. As for ash dieback, the Woodland Trust recommends that we clean our shoes or bike tyres after visiting the woods to avoid spreading spores. This will sound painfully familiar to anyone who’s lived in the northern part of New Zealand in recent years, where the efforts to stop kauri dieback have hugely restricted access to the forest. As a keen walker with an aversion to boot cleaning, I find this sensible advice rather hard to swallow, but I suppose it’s a small price to pay if it does help combat the disease. Now where is that scrubbing brush?

Elm flowers, Chelmer Valley LNR, early March 2021

Elm in fruit, Chelmer Valley LNR, mid April 2021

Elm fruit, early May 2021

Elm fruit and leaves, late May 2021

Rare mature elm found in Chelmer Valley LNR, late May 2021

Leaves of above tree

Fallen twig from above tree with fruit

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[1] Which species of elms am I seeing, and are they all the same? The Collins Gem has two main options, English and wych elm (Ulmus procera and Ulmus glabra respectively); the flowers look similar but the fruits and the leaves are slightly different, and appear in a different sequence: leaves first for English elm, fruit first for wych elm. I can’t find mention of this elsewhere. If the Gem is right then most of the elms I’m seeing are probably wych elms. There are other options, though. Many of the small elms I’ve seen have strangely ridged bark, even on quite slender twigs. It seems this “winged” or “corky” bark is particularly typical of the Dutch elm (Ulmus x hollandica) and the small-leaved elm, also known as the field elm (Ulmus minor). If any readers know more, please get in touch!