National Trust responds to Defra’s Plant Security Strategy

Today (April 30) an updated Tree Health Management Plan has been published by the Government’s Tree Health and Plant Biosecurity Expert Taskforce, alongside a wider Plant Biosecurity Strategy.

Reacting to the reports, a spokesperson at the National Trust said: “We welcome the publication of the strategy but it is unclear if there is sufficient funding or resources being allocated to this problem to really make a difference.

“Trees and plants don’t have votes so cuts to Defra’s budgets are sometimes seen as easier for Government but the consequences can be devastating for our wildlife, landscapes and rural economy.”

Somerset site gives glimmer of hope for ash dieback disease

Trees in a Somerset plantation have survived with ash dieback (Chalara fraxinea) for far longer than previously thought possible, suggesting there may be potential to slow the spread of the disease in the British countryside after all.

Only ten per cent of the six thousand ash trees at the Holnicote plantation are showing any signs of the disease, despite having been infected for five years longer than any other tree in the UK so far.

The disease is present in one other small plantation nearby but doesn’t appear to have spread any further – which is at odds with Government predictions which suggests it should have spread further and infected more trees in this time.

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Weekly Witter: Pests and pestilence at the Chelsea Flower Show

Stop the Spread

No it’s not about butter…but tree pests, diseases and invasive species in general. This is the subject of a ground breaking garden at this year’s RHS Chelsea Flower Show.

“The garden will also have a black pool of water with a small living oak tree on a plinth in the middle at the end of the dead avenue.”

The National Trust has joined other organisations as a partner in the  Food and Environment Research Agencies  (FERA) garden designed by Jo Thompson to help raise the profile about the increasing threats we face but more importantly what we can all do about them.

The modern world we live in and our globe-trotting lifestyles combined with our increasing desire for ever more exotic food and plants is only increasing the chance of new pests and diseases and non-native species threatening our countryside, woodlands, forests and gardens.

“be prepared to be shocked… as there are dead (non living) trees at Chelsea for the first time…yes really!”

Since 2003 the National Trust has had to spend around £1m to deal with one disease alone, Phytophthora ramorum no small amount for a charity in these challenging financial times. But add in another 14 or so tree pests and diseases including the dreaded news making ‘Ash dieback‘ and the constant battle to keep our waterways and countryside clear of non-native species which sucks in vast amounts of staff time dealing with what is often a ‘fire fighting’ exercise, you can start to see why the Trust wants to help make a difference.

So was born the idea of working with others to raise the profile of these issues at the most famous garden show in the world, which in it’s centenary year is set to be a media show stopper.  But, be prepared to be shocked… as there are dead (non living) trees at Chelsea for the first time…yes really!  If you don’t believe me and you can’t go in person, check out our videos of the garden at www.nationaltrust.org.uk/chelseaflowershow or tune in to watch some of the television coverage which will be on BBC2 every evening of Chelsea week.  The garden will also have a black pool of water with a small living oak tree on a plinth in the middle at the end of the dead avenue.

But there is beauty as well as we know that this is not a lost cause and we can all do things to help prevent the spread of plant pests and disease.

Here are my top tips of some things we can all do to help ‘Stop the Spread’:

 Taking some simple steps when gardening or buying and planting new trees, can help reduce the risk:

Ask your nursery/garden centre for help: Wherever possible, buy home-grown trees and plants; they’re more likely to be “acclimatised” to our conditions and less likely to be a home for new pests and diseases or non native species. Don’t bring plant material home from holidays abroad.

Buy small and watch it grow.  Semi-mature trees often grown overseas pose a higher risk of introducing pests and diseases. So be patient and plant smaller trees instead – they’ll often establish quicker too.

Right plant; right place.  A healthy tree or plant is less likely to succumb to disease – try to match a tree to its preferred location, type and size of tree, soil type, available space.

Help it to establish itself.  Feed your tree but avoid over-feeding which can lead to vulnerable soft growth. Consider a mycorrhizal fungi planting treatment to encourage healthy root growth. Use a good stake and tie, but don’t strangle your tree!  Lower leaves in contact with the soil risk picking up disease, so remove them when you plant or use a good mulch.

Give it room to grow.  Space trees as widely as possible to ensure good air movement and reduce humidity.  Prune out any dead and diseased branches and dispose of the waste sensibly.

Keep clean.  Pests and disease are easily spread on soil and plant debris attached to footwear or on tools like secateurs and saws, so clean mud and leaves off regularly.

Don’t stop planting. The worst thing we can do is to stop planting trees. Simple measures like those above will help protect our beautiful woodlands and forests in these difficult times.

 Dispose of garden waste responsibly. Compost your waste properly or dispose of in a responsible way. Don’t dump garden or pond waste in the countryside or water courses

Top tip: When buying look for: healthy, vigorous trees and plants, not pot bound, not too much soft growth. Avoid signs of dieback, leaf spotting, insect infestation and mould growth. Look out for other non -native species species hitching a ride.

The team hard at work

The team hard at work

  • Ian Wright is the National Trust’s Gardens Adviser based in the South West of England.  He advises on all things horticultural at the 30 great gardens in the South West. He has built up an extensive knowledge of plant and tree pests and diseases over his 26 years working for the Trust and in more recent times produced guidance for staff aimed at preventing the spread of pests and disease.  Ian describes himself as ‘almost a tender perennial’ and now ‘lacking the appetite for true British winters’ after working in the favoured climate of the South West for so many years.  Potential sponsors take note… Ian’s greatest dream is to design a ‘Gold winning’ show garden for the National Trust at Chelsea…..any offers?
  • The Weekly Witter is a regular weekly mouthpiece for our many specialists to talk about the news, current affairs, and what’s on their minds at the moment.

Weekly Witter: Out of the strong came forth sweetness

Spring is a time of joy for all naturalists, leaf burst and blossom delighting all of us, not least the entomologist who has suffered a long and bleak winter with hardly a buzz or a flutter of wings. The search for the rare and spectacular is most definitely on and it’s not in praise of leaf or flower that I devote this blog. I’m celebrating a sweet and intoxicating liquor, a dark brown liquid that oozes, bubbles and even gurgles from trees. Sap-runs or flux as they are sometimes known, prove irresistible to insects and insect hunters alike.

There are many reasons why sap might spring from trees, bacterial disease, physical damage or the attentions of wood boring insects such as the chunky larvae of the goat moth which might spend five years developing on the frugal diet of solid wood. Whatever causes the sap to flow from the tree there are rich pickings for insects. Flies, beetles and wasps are all attracted to the sugary secretions. While some of the species such as red admirals and wasps are fairly ordinary, there’s a chance of finding more rare species per square inch than any other habitat I know.

The dark brown streaks on this oak trunk are a tell-tale sign of a productive sap-run.

The dark brown streaks on this oak trunk are a tell-tale sign of a productive sap-run.

The tree in the photograph was in a field at Maidenhead and Cookham Commons and is clearly in decline although the sap runs are a symptom rather than the cause. One of the first things I check for on such trees are the exit holes of the twin-spot wood-borer, a formerly rare beetle that has become much more common as a result of acute oak decline. These beetles, sometimes implicated in the spread of disease leave holes that are distinctive for being flattened on one side, much like a D. There was no sign at all of where this handsome beetle had been, indeed despite seeing hundreds of holes on scores of trees I’d never seen this species in over ten years of trying. Other species though were there in abundance.

Wasps were frequent, along with their bigger cousins the hornet. These, despite their fearsome reputation are luckily kind-tempered; praiseworthy when poring over the trunk with your nose an inch away from where they feed. Sap-beetles, fungus beetles and hoverflies all flocked to the sweet sap. The rare brown tree-ant, a real southern speciality was busy, scurrying across the trunk, drinking sap and seemingly attending hoverfly larvae that were immersed in the syrupy stream. Several hoverflies are known to breed exclusively in sap runs, some of these are tiny and rather dowdy but the inflated hoverfly is a much more robust beast. This inch long fly is a dapper black and orange affair and always a pleasure to see.

The inflated hoverfly, a distinctive sap-run specialist.

The inflated hoverfly, a distinctive sap-run specialist.

Red admiral butterflies had settled onto the trunk to feed occasionally flashing their wings to startle other insects attempting to muscle in. The smell of the sap was even tempting enough to lure a purple emperor away from its sylvan kingdom. After a good twenty minutes of inspecting the insect life on this once mighty tree I thought that the emperor would be the highlight. Just as I turned to walk away, another insect alighted at the foot of the tree, the wings creating an audible buzz as it did so. Its slim shape and spangled appearance gave it away as one of my most sought after species. Agrilus pannonicus, the oak jewel beetle, the twin-spot wood-borer (so good they named it thrice), a Holy Grail that serendipity (and sap) had seen fit to allow me to meet.

oak j Oak Jewel Beetle

Oak Jewel Beetle

  • Peter Brash is a wildlife and countryside advisor for the National Trust. He specialises in animal ecology; specifically birds, insects and bats. As well as the surveying of habitats, wildlife interpretation and engagement.
  • The Weekly Witter is a new regular Monday mouthpiece for our many specialists to talk about what’s on their minds at the moment.

Ash Dieback and the threat to our cultural trees

Brian Muelaner – Ancient Tree Adviser for the National Trust gives his overview of ash dieback and how it could affect our ancient trees:

One would have to have been living in a bubble over the past six months not to be aware that Britain’s ash trees are seriously at threat from Chalara fraxinea, a fungal pathogen commonly called ash dieback. Since this fungus was first identified barely 10 years ago it has swept across northern Europe from Poland causing massive dieback of ash trees of all ages and sizes. It now appears to be deeply embedded within the countryside of England and to a lesser extent Scotland and Wales, putting at risk some of Britain’s most important trees.

Since ancient times, well before the Roman’s came to Britain, ash trees were important for providing ‘tree hay’, particularly in upland situations where the severe climate made it difficult to produce traditional hay. This practice has taken place in upland regions across Europe. Trees were pollarded every three to five years in the summer, removing all of the tree’s branches above browsing height at around eight feet. The branches were collected and tied into faggots and stored under cover till winter when they were fed to the stock.

Muelaner

Ash Pollards in Sweden

The practice still survives in some countries, such as in Sweden, through grant aid to help preserve these biologically and culturally important trees. Farmers still regularly pollard ash trees to feed to their cattle in winter. Ash leaves have a much higher level of protein than traditional grass hay.

The landscape in some of the dales in Cumbria such as Langdale and Borrowdale is littered with ash pollards which are many hundreds of years old, yet these are small hollow trees, kept small from the repeated cutting over centuries. The Trust has restored the practice of pollarding these old trees to prevent their collapse as the limbs become too heavy for the fragile shells of the trunks to be able to support. We have even recorded ash pollards on farms as far south as in east Cornwall, which were almost certainly historically managed to provide tree hay. In Cornwall the wet climate makes producing traditional hay a risky business, so before the advent of silage tree hay was a safer option. 

At Dyrham Park in South Gloucestershire there are several dramatic ancient ash pollards which are the sole remnants of an older landscape now incorporated within the designed deer park. These very fragmented old trees are all that remain of a time before the great landscapers created the beautiful parklands we know and love.

Down in Branscombe in East Devon the ancient ash pollards were used for a very different but equally important purpose. Here the trees’ branches were cut on a longer cycle of every 10 to 15 years to provide fuel for the village bread oven. We forget just how significant a role trees have historically played in providing us with warmth and cooking before coal and electricity.

Muelaner

Ash pollards in Brascombe

All of these trees could disappear in the next decade or two as Chalara fraxinea slowly sweeps across the country. We must continue to survey and record these wonderful old trees as quickly as we can before they are sadly lost forever.

  • Brian Muelaner – Ancient Tree Adviser for the National Trust. I advise on how best to manage these special trees to preserve their natural lives. I am often among trees many hundreds of years old, some are a thousand years or more and still quite healthy. I am coordinating a national survey of all ancient and notable trees on Trust land. To date we have recorded a remarkable 25,000 trees and still have many more properties to survey. I am also compiling an inventory of the hundreds of Trust avenues.

“Government plan for ash dieback could buy us time,” says National Trust

In response to the Government’s control plan on ash dieback announced today, Dr Simon Pryor, Director of the Natural Environment at the National Trust, said:

“It is too late to eradicate this disease, but this plan could buy us time.  If we – Government, landowners and foresters – can all work together to reduce the rate at which it spreads across the country we can find ways to ease its impact on our landscapes and wildlife.  But we must use this time energetically, to explore every possible way in which we can increase the resilience of our trees and woods. 

“The National Trust will be inspecting and where necessary removing and replacing all recently planted ash trees on our land, and we call on everyone who has planted ash trees in the last few years to do the same. 

017 Wood pasture with pollards“This is a pragmatic plan, but there are still many unanswered questions about this disease.  We are pleased that the Secretary of State has said that plant health was one of his top priorities.  But it is vital that he does actually make new resources available to enable Defra, FERA and the Forestry Commission to deliver this plan, rather than rely on others. 

“Once these diseases become established it is clear we can’t eradicate them.  So the one really big lesson from this disaster is that we must stop importing pests and diseases in the first place.  The Government must show real leadership by improving controls over the trade in plants and biosecurity at ports.  We must not be wringing our hands again in a few years time when yet another devastating pest or disease is found.”

Further detail about what the National Trust will be doing

Speaking about what the National Trust will be doing over the coming months Dr Pryor commented: “The Trust has already removed thousands of young infected trees that we had planted.  We will continue our inspections this summer and where appropriate will be removing and replacing infected young trees. 

“But one thing that we and other owners must not do is prematurely fell any older trees simply because we think they might be infected.  We need to ensure they remain safe, but there is still a chance some of these mature trees will pull through.  It is much better for wildlife for the trees to gradually decline than be felled prematurely.  

“We will also be making our woodland available to researchers so they can carry out trials and learn more about this disease.  We have also offered our plant conservation centre as an additional resource for growing disease free native ash which can be planted once conditions have improved.

 “This disease has revealed some alarming practices in the nursery trade, and we are taking a long, hard look at how we can ensure the young trees we plant are healthy and genuinely home grown.”

National Trust welcomes Defra’s new plant importation controls

In response to Defra’s plans for tighter plant importation controls announced today, Dr Simon Pryor, Director of the Natural Environment at the National Trust, said:

“This is a very welcome move, and exactly the sort of action that is needed to prevent more tree pests and diseases being imported into this country.

“We have been very worried about chestnut blight, and were on the brink of stopping any planting of this species on our own land as we couldn’t be sure they weren’t imported or infected. The extension of the inspections to cover a range of species gives us greater confidence.

“This move is particularly important as both oak and chestnut are species which might be appropriate to replace ash with once the extent of ash dieback is known.”