North Wales Countryfile

Ash.

As much a part of the British countryside as green hills

and leaden skies.

But this beautiful landscape now faces a terrible threat.

The reawakening of a hidden killer.

Ash dieback, the deadly pathogen that had ravaged trees

across Europe, emerged here on our own shores last year.

It was identified as Chalara fraxinea.

A lethal fungus brought to Britain on windblown spores

and imported saplings.

It's arrival sounded the death knell for our beloved ash tree

and ash dieback became a household phrase.

BBC NEWS THEME

Britain's ash trees under threat.

The Government's emergency committee meet

to discuss the killer infection.

A ban on the import of ash trees will come into force on Monday.

We are all being urged by the Government to wash our dogs,

our boots, even our children, if we venture into woodland this weekend.

In the wake of the 2012 crisis,

and in an effort to protect our trees for the future,

the Government has taken the unprecedented step

of making plant health as important as animal health.

The trouble is it all seemed a little too late for the ash.

So, what now?

Things have gone eerily quiet over the winter as the fungal spores

have lain dormant.

But with life returning to our countryside, the question is,

is the advance of the disease now simply inevitable?

We need to get down in the ground, dodge the nettles, and we are

going to start hunting for fallen...

they're called rachises.

They are basically these bits. You see these bits here.

What will have happened, you see, is last year, the infection would

have occurred down here and then obviously, as it is a deciduous

tree, the leaves fall off, they drop to the ground, the leaves rot

and all we will be left with are little leaf stalks like this.

They will have blackened up but it's not just them.

We want the blackened up and the fungus growing out of it,

the little mushrooms growing out of it. That is what we need to get.

How big are these mushrooms? Something to make an omelette with?

An omelette for maybe a hobbit.

The signs of ash dieback are easy to spot on the trees,

but to understand how it spreads, you need to find

the highly infectious spores that come from the fungus itself.

That's exactly what plant pathologists from FERA,

the Food and Environment Research Agency, are trying to do.

So the brown marks that you see on the bark of the tree, that

tell-tale sign, that's not actually what's giving off the spore itself?

No, not at all. That's non-infectious.

The fungus is actually killing the tissue,

producing toxins and killing the tree.

It's really quite chilling to think something this small

could end up felling something that big.

It's amazing, isn't it?

Paul and I are struggling to find anything

-but one of Paul's colleagues has had some success.

-Look what I've found.

What have you got there? Hang on a second, Ian's got something.

-Really small.

-Hey, that's looking quite good. Have a look at that.

-This one here?

-Right in the middle, have a look at that, Tom.

-Put your hand lens on that one. Look at that.

-Looks like a sort of...

It looks faintly mushroom-shaped but it's very...

You can see it actually growing out of the stalk.

-What do you think?

-Can I have a close look?

That's certainly the best we've found so far, Ian.

-Good job, well done.

-Ian's got it!

The commonly-held view is that the Chalara fraxinea fungus IS now

reproducing in Britain. That would mean nowhere in the country is safe.

But no-one has been able to confirm those worst fears until today.

My goodness. That's quite strong.

You see, this is the sample we put in there. Look at that.

It's coming up. If that goes up, that means it's positive.

So it looks like we've got Chalara in that sample?

We've got the sporing stage of this particular fungus picked up from the

ground which has never been found in the UK before, so this is a first.

The first time we have found this infective stage of ash dieback

-in Britain.

-Absolutely.

This indicates that this is the first-ever finding of it in the UK.

In some ways, you don't know whether to be pleased

or horrified with news like that, do you?

Yeah, I mean, from a pathology point of view it's an exciting finding.

That line is proof that we have infective Chalara in Britain.

-So we've got a positive?

-Yes, that's the positive control there.

Look at this.

-You found it.

-Yes. Honoured(!).

You don't know whether to be honoured or not, really,

with something as dangerous as this, as lethal as this.

-It looks like it is here to stay.

-Hmm.

In any battle, the first stage in beating your enemy

is to know your enemy. And now we know.

As we've heard, it's here to stay.

A slim hope that maybe the infection was just

blowing in from the Continent has just evaporated.

So, does this mean the march of infectious spores

sweeping through our forests is now simply unstoppable?

Professor Chris Gilligan from Cambridge University chairs the

Independent Tree Taskforce set up in response to last year's outbreak.

He's been keeping close tabs on its progress.

We know something about the rate of spread across the continent,

so we can use that to think then about how to model and predict

what's going to happen to the spread throughout the UK.

And you've got a little bit of the green,

-particularly on this Kent and East Anglia area.

-That's correct.

And as we run it forward, you'll see the year changing up here

and the intensity of the colour changes.

With red indicating high probability.

Wow. We've now moved nearly ten years hence to 2022.

And you've got red area which is high risk,

still predominantly in a south-easterly area.

But some risk affecting all of England

and quite a bit of southern Scotland as well.

If predictions are correct, we ARE going to see the disease

gain a stranglehold over the next decade.

But there are still things all of us can do to slow its progress,

from brushing off our boots and tyres, to monitoring

and reporting damaged trees in our local area.

Generally, though, when you look at our intervention, are we talking

about delaying the spread of this disease

rather than having a hope of stopping it?

We're not going to stop it.

It would be very unlikely that that would occur,

when, as we saw, that spread right across the continent of Europe.

So actually, delay is really important because it buys us time

to find ways of fighting it?

It really is important to delay the epidemic where we can.

I suppose it gives more time for our ingenuity to find

-a way of fighting back?

-Absolutely.

The prospects don't look good.

But, as I'll be finding out later, the battle isn't over yet.

The North Wales coastline.

Rocky, weather-beaten cliffs hug the Irish Sea.

A typical coastal scene on the face of it.

But look a little closer and you'll find something quite bizarre.

A living labyrinth.

Surely one of the most intricate things that

mother nature has ever created?

It might look a little bit like a sponge,

but believe me, this stuff is really quite solid.

And it's built by one of the finest ecological engineers out there.

The honeycomb worm, or Sabellaria alveolata.

Their reef-like homes

are predominately found on the west coast of the UK

and are currently recognised as a threatened habitat.

But a couple of marine scientists from Bangor University

are undertaking some pioneering research to try and help

regenerate reefs that might be struggling.

I'm meeting Dr Andy Davies to find out more about how

they build these peculiar homes.

How are you doing, Andy? It looks like a moonscape, this.

The tunnels are built from sand and shell by the worm colonies,

who favour safety in numbers.

There are many, many hundreds of them, if not thousands in this area.

And they all grow together in, like, a semi-detached

and a terraced housing style to form this honeycomb.

So they're known as the honeycomb worm.

As you can see, the tube is formed by individual worms here.

The further down it goes, the more safe it is from predators.

-You love these, don't you?

-I do. I love them. Anything which is reefy.

Well, I've never seen them until today

-and I might start loving them, too! We'll see how we go.

-Brilliant.

In the same way that coral reefs support a host of marine life

in the tropics, these sand tunnels built by these humble worms

are massively important for biodiversity on our shoreline.

Fellow worm fan Steve Newstead

works alongside Andy at the School of Ocean Sciences.

These marine-minded chaps love the worms so much,

they are studying them in a way they've never been studied before.

They are the first scientists to develop test tube worms,

rearing larvae under laboratory conditions,

to get a better understanding of their crazy tube-building ways.

-How are you doing, Steve?

-Hi, Ellie.

-What is it about these worms you love so much?

-These worms are great.

They form these fantastic hummocks,

these sand formations that we find on the shore.

They are habitat engineers, OK.

What they are doing is creating niches,

pockets for other species to live within them.

They are providing an attachment site for possible algae

to start growing.

They are also providing some protection from some water

movements, in maybe the lee of the water and so on.

They provide this function that enhances the biodiversity.

Wow. So we can see them coming out now, they are under the water.

You can see the little black hairy feelers that are coming out.

That's them feeding when they are submerged in water.

They will come out of the tube by a few millimetres.

And they will extend their tentacles out

and capture organic particles and filter feed that way.

And then all of a sudden they will retract?

They will retract in when a predator or something comes along.

My big head, in this case. How do they build these amazing structures?

They are unique because they excrete a biological cement, where

they will collect sand grains from around them, from the water column,

and they will excrete this cement and then stick them together.

They are almost building like a dry stone wall around themselves.

They will do that straight after their larval stages.

And they will then build this tube for the rest of their life.

To give the worms the best start in life,

the boys grow them on slates in sea-like conditions in these tanks.

-Can we have a look at one?

-I will just show you this one here.

These little ones, around eight weeks old,

are forming the first tunnels.

-Still quite delicate.

-Really, still quite small.

We have the settlement here, on the slate plate, OK.

And these are the small hummocks and the small tubes we have got there.

The aim is for these slates to eventually be attached to

existing reefs, so the youngsters continue to grow

and strengthen communities in areas where they may be struggling.

But to find out which reefs need a bit of help,

Andy and Steve monitor them using a sophisticated bit of kit.

A balloon on a string with a precariously-dangled camera.

OK, Ellie, now we've got the balloon up,

what we want to try and do is slowly walk the camera over the reef.

What the camera is doing is it is taking images every four seconds.

Once we've stitched the images together,

we'll get this panoramic view of the reef.

-You are basically mapping out where this honeycomb reef is?

-Absolutely.

Once you've got that, what are you going to do with it?

We want to try and see how the reef changes over time.

We want to map this over the years and see how much it grows,

how much it reduces,

to try and get an understanding in the changes of the reef itself.

I love the way it is just a balloon and a camera.

-It is like super-accessible science.

-That's it, very simple indeed.

-No lab coats required for this?

-Not at all. No!

So, aerial images to show scale, plus a bit of close-up counting

using this grid split into centimetre squares.

We just put that on there.

Should roughly equal how many worms there are in this bit of reef.

Simple. OK, five per centimetre square, I think.

-Five per centimetre square?

-Yes.

-Perfect.

-All right.

So, five worms in one centimetre square works out

as 50,000 in one metre square.

Multiply this by the total area of reef, 77 metres square, equals

a rough estimate of 3,850,000 worms, all living in one amazing reef.

So have you found, by doing this survey over time, that there

have been more of them or less of them? Have they changed at all?

Since in about the last year, we have seen the reef expand,

about 20 to 30% in size. It can grow very quickly.

By doing this, and mapping year on year, season on season,

we can see how the reef expands or contracts.

So things are looking OK here in North Wales at the moment,

probably thanks to this pair keeping an eye on them.

But the honeycomb reefs are at a constant threat of storm damage,

cold weather, and human feet trampling on them.

It may not be as exotic as the Great Barrier Reef, but these

amazing sand tunnels stuck together by biological cement, by the tiny

honeycomb worm, are hugely important to the biodiversity on our coast.

The ash dieback epidemic that swept through mainland Europe is here.

And there's no way of stopping this deadly fungus,

Chalara fraxinea, from spreading throughout the UK.

So if we can't save our treasured ash, does it mean it will go

the same way as elm in the 1970s and become a rural rarity?

The Woodland Trust has other ideas.

It's recently planted thousands of young trees at Pound Farm

in Suffolk, right in the firing line of the disease.

In the wood over there are thousands of infected trees.

In fact, it was one of the first places where ash dieback was seen.

So, with the wind blowing as it is, from there to here,

it won't be long before infection is rife in this field.

So, we can expect these young saplings to soon

succumb to the disease.

So why plant healthy saplings right next door to an infected wood?

According to the Woodland Trust's Austin Brady, there is

method in this madness.

So this is one of your sacrificial ash, is it?

Yes, if we take the vole guard off this young ash tree,

you can see this is one of 25,000 trees we have planted on two fields

and there are 11 different provenances of ash

from all over the UK. We have deliberately brought them back here

where we know the disease is present, to try and find out

which of these varieties is going to be resistant to ash disease.

It seems almost cruel, to put them in harm's way like this,

-deliberately to expose them to a deadly fungus?

-Exactly.

But what we know is from experience on the Continent, maybe two

or 5% of trees have natural resistance to ash disease.

What we're trying to do is speed up that process and find out

as quickly as possible which of the UK's ash trees might be resistant.

What the Woodland Trust is doing may be a radical step,

but its plans are to find replacement trees,

not a cure for ash dieback.

One thing that strikes me is this is still a sort of...it is a post-apocalyptic solution.

It's not going to save existing ash trees, is it?

You are exactly right. We are going to lose a lot of ash trees

but we don't want to just stand by and watch that happen.

We are doing what we can to try and breed some resistant trees

-for the future.

-The scale of the task is huge.

130 million ash trees across the country.

Are we seriously talking about potentially replanting that number?

I think in some woods, if the ash disappears, there will

still be a woodland and some of those woods will recover.

In other parts of the country, the impact could be more serious,

where ash is a dominant part of those woods and they are the

areas where we really need to think about a different kind of response.

If the disease is as serious as we think, we are unlikely to ever

replicate exactly what was there before in terms of ash?

The woodlands will evolve. There will still be ash but less?

Exactly, but woodlands evolve and change, you know,

life and death in the forest is part of the whole process.

Just what's happening here

is something which is a bit too quick and a bit too sudden.

This isn't the only plantation of its kind.

Hand-in-hand with landowners and charities,

the Government has planted a quarter of a million trees

across the south-east,

simply to see which ones can survive the onslaught.

And that means standing back and watching possibly

hundreds of thousands of young trees being martyred to the cause.

While here they're letting nature take its course, there are those

using a more technical approach

to finding a tree with natural immunity.

The basis for this work

can be traced back to one miraculous tree in Denmark.

The story starts just under 100 years ago

on the Danish island of Zealand.

In the 1920s, Danish foresters started selectively breeding ash

for good timber. And they came across this in the forest, tree 35.

They were so impressed by its strong form, that they decided to

clone it along with 38 others

to make sure they had good wood supplies.

80 years later, in the middle of the last decade,

ash dieback hit Denmark.

90% of the country's ash trees were killed or badly damaged.

Among them, the 39 selectively-bred clones.

Except, that is, for tree 35,

which stood tall amongst all the devastation.

There seemed to be something in the genetic make-up of tree 35

which made it able to withstand the full force of ash dieback.

Now, this remarkable tree has led to a scientific

breakthrough in the fight against the disease.

At these laboratories in Norwich,

just a few miles from the epicentre of last year's outbreak,

scientists have managed to decode tree 35's resistant DNA.

So this is how you unlock

the genetic secrets of the resistant ash?

Yes, the first step is to get some ash leaves which are frozen in here.

What I'm going to do is take a small amount of this ash material.

I'm going to put it into one of these tubes here

so that we can break it up.

The John Innes Centre is part of a multi-million pound

international project working to create a formula for a super-tree

for the future, based on tree 35.

The project's head, Professor Allan Downie, is showing me how it's done.

-OK, so, I'm making a sort of ash soup.

-Just drop it in.

And then you'll find a pair of long forceps there

that you can pick it back out again with.

The liquid nitrogen freezes the ash leaf soup

so it can be pulverised into tiny pieces.

-It's like a rather aggressive microwave!

-It is a bit!

So, now that leaf which was a leaf material, it's now a powder,

and what we're now going to do is add a little bit of liquid

to dissolve the DNA.

The DNA is broken down further and purified before technicians

at the Genome Analysis Centre set about the critical

task of sequencing the billions of strands of DNA on a computer.

This incredible and complicated process has allowed scientists

to crack tree 35's DNA code, the first step in creating

an ash tree from scratch that can live with the disease.

We're the first to see these results.

What is on here that is so important, so critical?

We have all of the genomic information from the tolerant tree,

tree 35, on this chip, so all of the DNA sequence is here.

And we did it really quickly. We want to move things forward

and try to understand the genetics of the inheritance of tolerance,

and this is the first step that allows us to build a map

and get an idea of why this tree has tolerance to the fungus.

This has been a very high profile potential environmental

disaster for Britain. We've seen huge coverage on this story.

How does it feel to be maybe part of that solution?

It would be wonderful to be part of the solution,

but the problem is enormous, and really, it would be absolutely

fantastic, but it is going to take a long period of time

and the breeding is going to take time.

For you at the moment, do you think the best chance is breeding up

new resistant or tolerant, as you would have it,

trees rather than trying to protect the ones that are there?

Certainly, for the large population of

ash in Woodlands, I think if we could breed for tolerance,

and identify trees that can live with the fungus,

then that would help greatly, and what we're trying to do here is

trying to give nature a bit of a helping hand by identifying the

right kinds of trees to take forward and do the appropriate crosses.

Whether it's the natural immunity of the Woodland Trust saplings

or a synthetically produced super-tree,

we may be able to fill the inevitable holes that are going to

appear in our countryside with something stronger.

What should be a proud procession of ash is becoming a slow death march.

And there's little doubt that a similar fate awaits

many of our ash trees across Britain.

But there is a glimmer of hope.

The ingenuity of our conservationists

and genetic scientists is speeding the arrival of

a new generation of ash trees which will show the fungus who's boss.