Back once again with the renegade master. Or rhododendron again. The same woods that would take about twenty minutes to amble through, that we have been working in for a good eight days now.
Not that I'm complaining, I am getting paid for those eight days after all so, from a very self-centred point of view, the more the merrier. However I feel I should add some more detail about the rhododendrons themselves, after doing a little research on them.
You see, previously, my source material had been mostly hearsay, with the bit about rhodos coming from Nepal being sourced from reading Tintin In Tibet when I was twelve.
Now Tintin is great as I'm sure you'll agree but, a source of cutting-edge botanical knowledge it is not. In fact, it turns out that Rhododendron ponticum is a native to Spain and Portugal, and it was from there that it was introduced to Britain in the 19th century.
The problems with Rhodo are twofold - firstly, it spreads. It branches out from a central core, and then, wherever it touches the ground, a new bush sets root. This is a thing called asexual reproduction and is definitely not confined to Rhododendrons. As an aside, this means that, when you see a wood thick with rhododendron, it is probably all the same plant, i.e. the same plant making genetically identical clones of itself. Annoyingly, as well as this, the plant can reproduce sexually, with the large pink flowers that are in bloom this time of year being fertilised by bees and then producing seeds, which are blown on the wind and sprout from where they settle. I have seen a garden in the outer Hebrides in Scotland - which is just the sort of poor, acidic soil that rhodos love - with a single rhododendron bush in the garden and then a perfectly tear drop-shaped bloom of windblown rhodo saplings growing in the moorland, downwind.
This in itself is not such a problem. There are plenty of species that are a pest - or a complete thug from a gardening point of view - but still part of a healthy ecosystem. Brambles and nettles spring to mind. However, wherever rhodo establishes itself, it will shade out the ground underneath, meaning no light will penetrate to the ground layer and allow anything else to grow. As well as this, the leaves contain a poison that prevents them from being eaten by anything and, when the leaf falls off the plant, drops to the ground and forms a poisonous leaf litter that prevents anything else from growing.
Going back to nettles and brambles, both of these plants are food species for caterpillars but, as we just mentioned, rhodo is a food plant for nothing at all.
All great so far for the rhododendron. Then, along we come with our chainsaws and glyphosate and our attempts to redress the matter. The first stage is the fun bit - getting out their with chainsaws and cutting the living heck out of the stuff. However, as mentioned, this in itself is not enough. This is not a thing peculiar to rhododendrons. Many plants can be cut down to the base and will bounce back repeatedly, as any gardener knows. Grass is a fairly obvious example of this phenomena. Plants are a complicated system, involving water being sucked from the ground up to the leaves, where they use sunlight to combine the water with carbon dioxide in the air and produce sugar. Or starch, which is a more complicated sugar molecule. This sugar is stored in the roots so that when some guy or gal with a chainsaw chops the plant down to the root, the stored sugar gives enough energy to start sprouting leaves again.
The deal, as mentioned a couple of weeks ago, involves us chopping down the rhodo and then leaving it for a few years (literally one or two years) and then zapping the new growth with weedkiller. We were using glyphosate. According to the blurb: "Plants absorb glyphosate through their leaves and other green parts. From here, the glyphosate moves to the growing points of shoots and roots, where it interferes with the enzymatic production of certain amino acids that are essential for plant growth."
So there you go. It's bad news if you photosynthesise but generally fine if you're anything else. But still, we do have to hit everything hard as, if you miss a bit, it'll still be there, laughing at you for years to come. Which is bad from an ecological point of view although, arguably, good if you're a contractor, specialising in it's removal.
Brownsea island recently announced the complete eradication of rhododendron on the island. By my reckoning, it won't be eradicated from cannon hill woods for a good while to come...
For your further reading:
Precisely why rhodos are evil:
For your further reading:
Precisely why rhodos are evil:
http://www.glyphosate.eu/glyphosate-basics/how-glyphosate-works
Eradicating rhododendron from Brownsea Island
Eradicating rhododendron from Brownsea Island
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