Tree Disease and Pestilence

Not everything about the wildlife in the wood is of a positive nature, with dark forces operating out of sight, vigilance is always required (7/8/23).

My son, Will, and I arrive at Wilderness Wood and spot an interesting piece of kit being put in place close to the staff car parking area. In fact it is Will who spots it and immediately recognises it as a 'cherry-picker', often known as a MEWP (Mobile Elevating Work Platform) to those in the tree surgery business. That's because he has worked as a tree surgeon for 6 years and has an eye for all things tree management.

I approach the owner of the flashy bit of kit and tell him I write this blog. I add that Will is in the business and they shake hands like long lost brothers. It transpires that Dan has engaged one of his many 'friends' in the tree management business to take down a diseased scots pine. The tree’s position poses a problem, since it cannot be felled from the base due to nearby trees and a line of fencing. Falling amongst the former would risk several tons of scots pine resting on the branches of adjacent trees, making it impossible to bring to earth safely and posing a threat to anyone passing nearby. Falling away from adjacent trees would destroy the fence-line, at significant cost. Time to call in the experts.

So the only solution is to take the tree down in bits – perhaps metre sections at a time, with a tree climber working gradually down the tree and dropping the chunks of tree trunk onto the ground below. Will does this sort of thing regularly, most recently in Germany, but tree climbing a disease riddled tree is not a smart thing to do. It would be tantamount to a cartoon character sitting on a branch and then cutting it on the wrong side – the outcome would be a long fall to the ground below, since there would be every chance that the whole tree would snap where it is currently decaying - due to the depredations of a wood-boring insect.

So this is a job for the shiny piece of technology, which we examine with great interest as its 4 legs unfold to form a stable base from which the powered platform rises like some kind of latter-day Jurassic reptile.

We don't hang around for the decapitation of the tree, but you can be sure that none of the wood will go to waste – probably as firewood to keep the home fires burning.

Two friends of mine turn up and I give them a conducted tour of the timber buildings built mostly using trees - such as our soon-to-be-departed scots pine. The wood store and its thousands of hand-made chestnut shingles (or shakes); the Barn, built by the Yarrows before Dan and Emily arrived; the Outdoor Kitchen and its witches-hat roof; the Meeting House; the two chalets and the Bath House (formerly dubbed the Millennium Falcon – think Han Solo/Luke Skywalker). They are well impressed with every one of them and may well be booking a weekend in one of the Chalets before too long.

Once they have departed Will and I set about 'strewing' clipping from my 'wildflower meadow' at home. The principle is that this is about the time when grassland plants drop their seed, so I have collected the cut stems and their attached seed in a bag and now we are spreading it all around Middle Paddock, in the hope that we might be able to enrich this Rye Grass and Clover 'desert'.

We take a walk down towards the new ponds (I have to visit every week, just to see how the water levels are holding up) and as we go my arboriculturist son observes a large number of sweet chestnut trees showing signs of disease. It could well be phytophora (although I should add that other diseases are also available). The 64 million dollar question is what to do about it. One could fell every diseased tree in the wood in an attempt to stop it spreading. On the other hand, the trees may have sufficient immunity to combat the disease unassisted. Phytophora is a genus of fungal pathogens and includes potato and tomato blight amongst others.

We get to the new ponds and I am delighted that the recent rains have filled them still further. What is more, I catch sight of yet another Great Diving Beetle (see blog for 20/07/23), this time in the upper pond. It is early enough in the summer for them and all the other freshwater invertebrates to lay eggs and restore our pond populations to pre-drying out levels. I'm confident that whatever the summer throws at us, we should have water in them from now until May or June next year (maybe even right through next summer?).

As we make our way back up Steep Hill, Will spots still more diseased trees, this time Ash. It is the dreaded Ash Dieback which has been sweeping through Europe for decades, but is now doing the same throughout the UK. There is probably no point in felling these trees, since the disease is now endemic. Ideally the tree in question could be made safe by removing side branches and leaving it to either recover naturally, or if not, keeping it as a monolith suitable for insects and insect-eating birds to utilise. Once side branches are removed and the trunk is shortened, the tree is unlikely to fall to high winds.

Diseased Ash - before and after being monolithed (artists impression)

Will returns to the car, whilst I pause for a brief chat with Dan and the tree surgeon with the cherry picker. It seems Oak Processionary moth is the next threat for British arboriculturalists and tree surgeons to deal with. It is a common problem in Europe, where Will has been busy removing their nests from trees in Germany (they have Pine Processionary Moth there too). Both species have caterpillars which form long lines as they march from tree to tree in search of leaves to strip. As they march along the ground they are protected from predators by their long irritating hairs. Pets and even curious school children are at risk from them so their nests have to be cleared away by spraying with glue to contain the hairs before being grabbed with a bin liner for later disposal. Finally the area around the nest is blow-torched to remove any remaining hairs. Tree surgeons need to wear respirators and all-in-one suits when removing the nests from a tree, otherwise they could have a very uncomfortable, even life-threatening experience.

A fully protected tree surgeon removes Oak Processionary Moth from a tree (Will Horne)

https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/tree-pests-and-diseases/key-tree-pests-and-diseases/oak-processionary-moth/ and https://www.forestresearch.gov.uk/tools-and-resources/fthr/pest-and-disease-resources/oak-processionary-moth-thaumetopoea-processionea/ for more information.

All these diseases are nothing new, it is just that with the demise of natural predators, the planting of monocultures of trees and the global nature of our society, they are now a much bigger threat than they ever were.

Natural, biodiverse ancient woodlands, with all the predators needed to keep these pests in check are the obvious solution to the problem.

Grassland, Heathland, Wetland and Woodland Management

A Century of Leaky Dams and the ‘Wilderness Bridge’