Category Archives: rhododendron

Tools of the trade

Give us the tools, and we will finish the job … Winston Churchill, 1941.

Although this one might take some time … Sunart Diarist, 2019

Rhododendron jungle

Rhododendron jungle

Whatever the job, having suitable tools usually makes it much easier. And safer.

One of my top priority jobs at the moment is clearing a large amount of heavily overgrown rhododendron from our plot. The site is steeply sloping in places, with lots of protruding rocks. The only access to the extremities of the site is on foot, so portability is paramount.

Some of the rhododendron were cut back 10-15 years ago but the roots were not killed off. Consequently they regrew, even more vigorously than before. The dense growth makes ‘bushwhacking’ through some of the denser thickets almost impossible.

This makes safe use of a chainsaw problematic.

Handtools

After a bit of trial and error I’ve settled on using a small number of tools that make short – or at least manageable – work of the rhododendron bushes, some of which are 4-5m in height.

Like a hot knife through butter

Like a hot knife through butter

The Wilkinsons Sword pruning saw costs less that £20. Its coarse teeth are razor sharp and cut on the pull stroke. The blade is a good thickness and the teeth clear the cut efficiently, preventing jamming.

The handle is fixed, slightly soft, reasonably comfortable and provides excellent grip. I’ve used folding pruning saws in the past and, not being rigid, they feel much less secure in use. To protect the saw, or to protect anything the saw is in contact with, there is a sheath with a useful belt loop.

I use Screwfix site gloves to improve the grip and prevent blisters.

This handsaw easily cuts through rhododendron stems up to 3″ in diameter (which is a very large bush). The relatively short (250mm) and shallow (top to bottom ~35mm) blade easily fits between the growing stems, making short work of clearing dense regrowth.

Oops

Oops

Smaller stems are best tackled with loppers. I’ve had mixed success with Fiskars PowerGear Anvil loppers. My first pair failed dismally on a smallish rhododendron bush. I’d only had them a month or so and they were replaced under warranty. The current pair are sharp and effective but I’m careful not to ‘overface’ them by tackling stems or branches that are too thick.

Slash and burn

Having felled the main stems of the rhododendron I use a Fiskars billhook to clear off the side branches, leaving a long stem for cutting up into firewood.

Sharper than a sharp thing

Sharper than a sharp thing

I’ve got a couple of these Fiskars billhooks. The older version is more curved at the end with a less pronounced hook (I think it was called their brush axe). It’s much less useful than the one pictured above. The hook means you don’t have to bend down quite so much; you can pull stems towards you with the hook. The blade is good and easily cuts through stems up to an inch or so in diameter.

Using these brush hooks efficiently requires a bit of practice. Once you get the hang of things they can be used to quickly strip off the side branches from a stem, then slice the top off leaving it ready to cut up for firewood.

The handle is hard and a bit slippery in the wet. Use of the rubberised-palm site gloves pictured significantly improves the grip.

Power tools

Rhododendron burns well (and carves well). To stack and dry it before burning it needs to be cut into suitable lengths. You can do this with a handsaw, or the pruning saw shown above. However, it’s a painfully slow process if you’ve got a hundred ~3-4m stems, all needing to be cut into 50cm lengths 1.

This is where a chainsaw saves the day. However, a chainsaw (usually) needs to be held with both hands. Since rhododendron stems tend to be relatively long and light they need to be held securely to use the chainsaw on them.

A useful third hand

A useful third hand

The Mitox Saw Horse and chainsaw holder acts as a third hand. The chainsaw 2 is held securely on a pivot with the chain protected with a metal cover.

The chainsaw can used used singlehanded simply by depressing the trigger and pivoting it so that it cuts through the stems 3. The latter are held down with the left hand in the “V” of the saw horse.

This is easier to do than describe. It feels very safe and secure in use. The left hand 4 is kept well away from the chain and, with suitably straight stems, you can cut multiple lengths at once.

Mitox saw horse

Mitox saw horse

The saw horse has a length guide, folds flat for storage and has broad metal feet that work well on uneven ground. It needs to be assembled after delivery. The instructions are clear but very small. You’ll need a socket set for assembly and it’s worth noting that the wrench sizes stated in the instructions are incorrect.

If you look around you can find these saw horses for anything from £50 to £100 … shop around!

Safety first

Anything with sharp edges, loud engines or rotating blades needs to be treated with respect. Using appropriate safety gear gives you confidence and can protect from disaster.

The Screwfix Superlight site gloves are a couple of quid a pair and provide some hand protection and much improved grip on hand tools. They will not protect you from a chainsaw or poorly used slasher or brush hook. For the former you need proper chainsaw gloves. For the latter you need to use the brush hook more carefully … keep your hands well away from the blade.

I always wear safety glasses when working in the garden. Current models provide much improved visibility and comfort than the super-geeky old-fashioned laboratory overglasses. For less than a fiver you can save your sight from whippy foliage and flying wood chips.

Chainsaw safety requires chainsaw overtrousers, gloves, steel toe capped boots and a protective hard hat with eye protection and ear defenders. I do without the overtrousers when using the Mitox saw horse as the chainsaw is fixed and cannot come into contact with my legs.

Yes, wearing that lot makes what is already a tough job a hot, uncomfortable and tough job … but it could save your sight, your hearing or your life.

And on that cheerful thought …


 

Nestboxes

The plot on Ardnamurchan is south facing hillside and was originally probably a mix of scrubby birch and oak woodland with dense ground cover of bracken. Over the years rhododendron have infested the site and, despite being cut back severely 10-15 years ago, still predominate.

Nestbox #3 and #4

Nestbox #3 and #4

I’m working hard to clear the rhododendron with the long-term goal of planting more native woodland. In the meantime I’m keen to improve the habitat in other ways that will benefit the local bird population.

Trees

As well as the dense and dreary understory of rhododendron, there are quite a few substantial trees around the plot. These include a number of mature (perhaps 40+ year old) larches, some Scots pine, quite a bit of birch and a few scattered rowan and hazel.

With the exception of the conifers, most of the trees are relatively small. Very few offer hole-nesting birds any real opportunities.

The future tree planting will be aimed at improving the pollen and nectar sources for pollinators (like bees, which need ample early season pollen for brood rearing) and the insect population. Caterpillars and larvae of the latter will boost the food available for the birds.

However, none of these new trees will provide any suitable sites for hole-nesting birds. At least not in the foreseeable future or, in the case of hazel and willow which will probably be coppiced, ever.

Nestboxes

About €60 and horrid

About €60 and horrid

Fortunately, the majority of hole-nesting birds readily use artificial nestboxes. In the ’18/’19 winter I’ve put up about ten in likely looking sites.

There are a huge range of nestboxes available to purchase, though many are pretty hopeless and are little more than garden ornaments. A nest box has to fulfil a couple of relatively simple functions:

  • Protection to birds and nestlings from predators
  • Protection from extremes of weather, in particular rain and excess temperatures

The physical and environmental protection is best served by using nestboxes made from robust materials, like 1″ thick wooden planks. However, because of the high rainfall on Ardnamurchan, I’ve opted to use boxes made from a composite cement and sawdust mix. These are marketed under trade names like Woodcrete (from Schwegler) and Woodstone (from Vivara).

Woodcrete and Woodstone

Nestbox #4

Nestbox #4 – 32mm oval

If you mix sawdust and cement in the correct proportions (apparently about 3.5:1) and press the mixture into a suitable mould you end up with a hard stone-like material that offers excellent protection to birds and nestlings.

Woodcrete and Woodstone are essentially indistinguishable in terms of suitability for nest box construction and – for all I know – might come out of the same factory. They are completely impervious to water and, being stone-like, offers excellent insulation from excess temperatures. It won’t ever rot (and usually comes with a ten year guarantee) and it should be immune to even the most determined woodpecker.

Schwegler manufactures nestboxes from Woodcrete in a variety of designs. The majority of UK suppliers appear to have had low or non-existent stock for the last year. I therefore ended up buying Vivara boxes which are sold by CJ Wildlife and other suppliers, again in a wide range of designs.

I purchased a mix of nestboxes with 28mm, 32mm and 32mm oval entrance holes. These should suit the majority of hole-nesting birds in the area – blue, great and coal tits and possibly redstarts, though I have yet to see them in the area.

I’ve used Woodcrete-type boxes before and they’re widely used by biologists studying nesting birds. The front of the box is removable for easy cleaning, there are well-placed drainage holes in the base of box and they have a secure hook at the back for attachment.

Siting

All of the boxes were firmly fixed 2-4 metres up on the NNW to NNE face of birch, Scots pine or larch trees. There are few cats in the area and the partly-arboreal pine marten could reach them however high I placed them. I therefore chose positions that gave good flight lines for the birds, and reasonable sight lines for me to observe them without disturbing them.

The boxes will need annual cleaning and this is much easier if they’re not high above the ground.

The boxes are about 6kg in weight … another very practical justification not to place them too high.

Nestbox #5

Nestbox #5

Apparently the only way you know if there are too many boxes in an area is if a proportion are always unused. I’ve put up 10 in about 2 acres, with the option of increasing this if needed.

At the time of writing (late March) birds are establishing their territories. Some of the boxes were being irregularly visited, but it was too early for any to be occupied.

Nestbox #2

Nestbox #2


 

Triffids

Ardnamurchan has an unwanted squatter, an evergreen cancer spreading inexorably along the shores of Loch Sunart and – triffid-like – extending its tentacles up the steep, narrow valleys leading up onto the hills.

The invasion is particularly bad around Glenborrodale, the northern bulge of Morvern and the Salen area across the loch, Resipole, Ardery and – further North – Kinlochmoidart and the area to the east of Castle Tioram.

Forestry Commission rhododendron control areas

Forestry Commission rhododendron control areas

I am, of course, talking about rhododendron. More specifically – as there are many varieties of rhododendron – I’m talking about Rhododendron ponticum.

Rhododendron invasion

Rhododendron is not a native plant to the UK, at least not since the last ice age. Its natural range includes Spain and Portugal, Bulgaria, Turkey and a large swathe of central Asia (Himalayas, Afghanistan, Northern Pakistan, India and Kashmir). Genetic evidence indicates that the plants in the UK originated from the Iberian peninsula. 

The specific name, ponticum, refers to the Pontus area south of the Black Sea where it was first identified by the botanist Joseph Pitton de Tournefort at the beginning of the 18th Century. It was introduced to Britain in 1763 via Gibraltar as an ornamental shrub and was popular in Victorian country estates.

Glenborrodale Castle

Glenborrodale Castle

How and where it first appeared on Ardnamurchan is unclear. It is well established in the Glenborrodale area, particularly around the castle, so it may have been introduced when Glenborrodale Castle was built and the grounds landscaped (1898-1902). Its spread east along the loch would have then been aided by prevailing westerly winds.

What does rhododendron do?

Rhododendron is highly invasive and spreads widely by seeds and suckering, thriving in the damp conditions of Ardnamurchan as well as other areas of western Scotland, Wales and Ireland.

It forms evergreen spreading bushes 2-8m high that quickly outcompete other flora by casting dense shade under the long, dark green, glossy leaves. In Spring it bears lilac, light or dark purple flowers that can appear very dramatic when it covers entire hillsides.

But don’t be seduced by this brief spectacle. Where rhododendron is out of control – as it is on Ardnamurchan – it has dramatic and damaging effects on habitat structure and native biodiversity.

This includes eliminating native plants that are unable to compete for light and the consequent loss of native animals.

The CABI Invasive Species Compendium states that “where R. ponticum is introduced in an area all plant species are threatened”.

One thing rhododendron does not do is ‘poison the soil’ as is often reported. There is no good evidence that rhododendron is allelopathic. James Merryweather has written a comprehensive article on why this piece of folklore probably became established.

Rhododendron has no natural predators. The leaves, flowers and nectar are toxic due to the presence of diterpines, known as grayanotoxins. Therefore the foliage is unpalatable to herbivores and insects. Honey produced from rhododendron flowers contains grayanotoxins and is known as ‘mad honey’. I’ve recently written about mad honey, the mechanism of toxicity and the symptoms in humans on my beekeeping website, The Apiarist.

Rhododendron control

We’ve got a lot of well-established rhododendron on our land. The evergreen leaves provide a sort of semi-attractive, year-round verdant appearance to the site. However, I can’t ignore the damage they’re doing to the flora and fauna.

One day all this will be under rhododendron

One day all this will be under rhododendron

The bushes above are not yet encroaching on the view of Loch Sunart. However, they’re ‘only’ about 3-4m tall at the moment. They will get bigger.

They have to go.

I’m going to write separately on how to control rhododendron once I’ve worked out a reliable way that works best for me. Essentially methods are either manual or chemical, or the double-whammy of both.

Manual methods include mechanical flailing with a modified tractor, so-called ‘Lever and Mulch’ or simply cutting them down with a machete or chainsaw. Chemical methods usually involve glyphosate or similar weedkillers.

The disadvantage of manual methods is that the roots will reshoot unless they are killed or removed. The disadvantage of many chemical methods is that it involves widespread use of rather indiscriminate weedkillers. The local flora is struggling already … I don’t want to make it worse.

I currently favour the ‘drill and drop’ combination of tightly focused topical application of glyphosate, followed by the tightly focused application of my Trusty Husky chainsaw 😉

Or, of course, ‘drop and drill’ which is exactly the same in reverse.

The Day of the Triffids

Triffids are a fictitious tall, mobile, prolific and highly venomous plant species from John Wyndham’s 1951 novel The Day of the Triffids. Of course, rhododendron are not triffids …

The Day of the Triffids movie poster

The Day of the Triffids movie poster

… or are they.

Rhododendron are tall, they’re mobile 1, they’re highly prolific 2 and – although they’re not venomous – they are toxic.

So perhaps the name is appropriate.

I’ve already described how they damage local flora and fauna, but are they a threat to humans?

Well, probably not, though there are several recent cases where tourists or hill walkers have become trapped in dense rhododendron ‘forest’ in the Republic of Ireland.

I’m off to do battle with this lot … if you hear shouting call the emergency services 😉

Rhododendron jungle

Rhododendron jungle


Notes

A brief but thorough account of the damage that rhododendron do to the environment can be found here.

The Day of the Triffids is the 1951 post-apocalyptic science-fiction novel by John Wyndham, a pseudonym of John Wyndham Parkes Lucas Beynon Harris (1903-1969). The novel was made into a film of the same name in 1962. The story is well known, involving a blinding meteor shower, the eponymous carnivorous plants, survivalist groups, the Isle of White and – of interest to a beekeeper – the disablement of an armoured car by pouring honey into the fuel tank.