The Russian Curse

Turn and run!  Nothing can stop them.  Around every river and canal their power is growing.
Stamp them out!  We must destroy them. They infiltrate each city with their thick dark warning odour*.

Plant hunters have over the centuries introduced many beautiful plants to our gardens but they have also brought in others that have, as they escaped from its confines, become troublesome weeds.  Japanese Knotweed, Fallopia japonica, creates problems by damaging river banks and pushing up through concrete, even entering houses; Himalayan Balsam, Impatiens glandulifera, is pretty enough with their hooked pink and white flowers but smothers native plants.  Both are difficult and costly to eradicate.  But the one that can cause the most trouble – and is undoubtedly the most impressive – is Giant Hogweed.

Long ago in the Russian hills, a Victorian explorer found the regal hogweed by a marsh … he came home to London and made a present of the hogweed to the Royal Gardens at Kew*.

Giant Hogweed, Heracleum mantegazzianum, was introduced to Britain from the Caucasus in  Victorian times and soon became a popular addition to parks and gardens for, although similar in appearance to our native Hogweed, Heracleum sphondylium, these were giants in every way.  Huge flower heads above equally large leaves reaching way into the sky – up to twenty feet or more in exceptional specimens – were something to marvel at. A hardy perennial, the plants shot up over the course of just one summer adding to its popularity, although it can be a few years before the plant flowers after which it dies.  With  up to 100,000 seeds from each plant, it soon multiplied and before long had found its way back to the marshy land adjacent to rivers and canals as in its homeland.

I wonder how long it took the Victorian gardeners to discover the problems associated with the plant for it not only spreads rapidly, it also is extremely toxic.  Covered in sharp bristles that scratch the skin it is the sap from the plant that can cause major injury.  Skin contact with the sap when exposed to sunlight results in severe dermatitis: itching and redness develop into blisters and dark wheals.  These can last for several years.  Contact with the eyes is even more dangerous for permanent blindness can follow.

So what do you do if you find Giant Hogweed in your garden apart from turn and run?  It can be treated with weed killer and the ideal time to do this is when the plants have a large leaf area but before they flower.  It is essential not to handle the plant at any time – even when it is dead – for every part of it including its roots will injure you.  If you are tempted to carry out control yourself (and it may be wiser to call in a specialist eradication company (please, not me!)) then you must wear a complete coverall and full face and eye protection.  You also need to remember that the clothing will also be contaminated and should be destroyed.

Fortunately, Giant Hogweed is rarely encountered in gardens.  You are more likely to find it growing in waste places in the wild and it may be wise to report its presence to your local environmental agency.  Attitudes toward it vary from country to country for this is not just a British pest – it is found in many other temperate regions of the world including the USA and Canada.

Perhaps at this point, I should remind you all that the majority of garden plants are harmless enough and that gardening and plants give a huge amount of pleasure.  Happy gardening!

* The Return of the Giant Hogweed: lyrics by Genesis, 1971

 

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Bonkers about Conkers!

Every little boy – and many a gown-up one as well – loves toplay conkers at this time of year.  Or at least, I assume they still do; it is possible that it may have been banned from the school playground under health and safety grounds.  When you think of it – not only did we frequently impale our hands with the meat skewer we had pinched from the kitchen drawer to pierce the conkers with, we quite often cut ourselves with our penknives as we trimmed the strings to the right length. And what about those shattered splinters flying through the air like vegetative shrapnel – no-one thought about wearing eye protection then.

However, the traditional sport of conkers isn’t threatened so much by legislation as by the recently imported leaf miner moth (Cameraria ohridella) which first appeared in southwest London in 2002.  With no predators it has spread at an alarming rate and now it is reckoned that nearly all trees in England and Wales are infected by it.  The moth’s presence can be detected by the brown-black blotches that cover the leaves, disrupting the trees ability to synthasise fully.  This in turn weakens it which has made them much more susceptible to disease, especially bleeding canker which is now threatening their very existence.   In some years, leaf damage is more severe and the leaves can drop very early indeed.  As a consequence, some trees are looking in very poor shape.
 
 
 


The secret valleyhas numerous mature Horse Chestnuts.  They are fine trees, up to 100ft or more tall and look especially splendid in spring, their white flower spikes contrasting with the freshness of their newly opened green leaves which, at that time of year, are still unblemished.  In the 400+ years since they were introduced to Britain from the Balkans, they have become an integral part of a child’s growing up.  We learnt how branches of the ‘sticky’ buds, the dormant leaf buds, becoming ever more shiny and sticky as the sap rises within the tree, can be cut and forced to open into leaf early in a jam jar of water.  On hot summer days we learnt, usually when lying beneath the trees in their cooling shade, how to make ‘fish bones’ by shredding the leaves with our fingers until just the skeletal veins of the leaves remained.  When we wanted to be nasty we knew that we could hurl the hard, green nutshells armed with their sharp spikes to embed in our enemy’s backs or scratch their legs if they were wearing shorts.  And, of course, we held conker competitions.

Horse Chestnuts in full bloom on a fine late spring day
 
Now with all the trials of pests and disease plus the dreadful summer weather, conkers are few and those that have matured barely half their normal size.  It has even been suggested that brussel sprout competitions may have to be held instead although I doubt if they will give the satisying dull thud of the real thing even if they were frozen first.  However, this years World Conker Championships have taken place this month as normal – it was first held in 1965 and, unlikely as it seems, attracts competitors from all around the world.  You can find out more by clicking on the link below.
Not all is gloom and doom for the Horse Chestnut for it is now thought that some bird species are beginning to learn about this new food source and research is being carried out by the University of Hull and others to monitor this suspected behaviour.  There is little that we, as gardeners or conservationists can do at this stage to assist other than to report any signs we see of birds feeding on the trees.  We just have to hope that the Horse Chestnut doesn’t disappear from our countryside in the same way that the Elm did in the 1970’s and 80’s.

The difference in size between the two trees is quite marked – as is the autumnal tints of the frost damage part of the smaller one 
 
In the secret valley, we also have a number of the smaller, red flowered Horse Chestnut, Aesculus x carneaca, and this does not seem to become infected to the same degree as the white flowered, Aesculus hippocastanum.  Although they do produce conkers unfortunately they are neither of a size or quality suitable for a serious round of conkers.  Horse Chestnuts, by the way, are poisonous to horses – they get their common name by the scars on the branches where the leaves once were: a perfect horseshoe complete with marks where the nails would be. 
 
When you get to know a place intimately – whether it’s a garden or a landscape – you notice things that the casual observer misses.  In the late spring of 2011, we had a biting frost that killed off not all but some of the new young growth of numerous trees – just where it touched.  Some trees remained unscathed, others  were totally destroyed and some just part.  This is what happened to one of a pair of Horse Chestnuts visible from our little stone cottage.  One tree has always been much more stunted than the other, although as their girths are the same, I assume they were planted at the same time.  They stand side by side but one, when the river bursts its banks is under water for a few days longer than the other.  Is it this that has caused it to be so much shorter or is it this rare burning of the leaves by frost?  It took months for the tree to recover, finally sending out new spring green leaves and flower buds at the end of July contrasting greatly with the remainder of the tree whose leaves had not been harmed.  Likewise, the older leaves turned their autumn colours and fell earlier than the newer ones.  This year the tree, which now looks quite poorly, has reversed with the damaged leaves turning golden – in the ten days since the photograph was taken, they have fallen while the remaining leaves are yet to get their autumn tints.

Almost hidden from view, our old stone cottage stands well above the little winding river

 In 2011, we had a very late frost blackening both the leaves and flowers – it took months for the tree to recover

 

The secret valleywill be a much poorer place if all the Horse Chestnuts succumb to disease and have to be felled.  Let us hope that future generations can play beneath them as we have done.

Sources:
British conkers getting smaller
World Conker Championships
Conker Tree Science Project

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A Sting in the Tail

This year is proving to be one of extremes. Weather wise, first it was snow, then late frosts, then rain, more recently drought and scorching temperatures. And it also seemed to be a similar situation with wildlife. The tree blossom and wild flowers have been amazing with every month some new blooms outrivalling those of the previous month’s.
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Now it seems July is to be the month of wasps. There are hundreds in the garden, indeed probably thousands, and they are everywhere. And if that isn’t bad enough, the very hot weather we’ve been having seems to have made them far more aggressive. Normally they do not prove to be troublesome until the fruit ripens in late summer, this year it’s different. And I’ve already been stung once this week which is very bad news for me – I suffer from a severe reaction, although never yet been hospitalised, fortunately. I keep my drugs and sprays with me – and a mobile phone, in case help is needed – and also keep my fingers tightly crossed. This, like the recent advice from a doctor to stay indoors, is not too much help for someone who earns their living by gardening.
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Fifteen wasp nests in four days has surely got to be a record and so I have been keeping the pest control man busy. It’s a pity to destroy them but better I get them first than the other way round! I remind myself that during the spring they live on aphids and the like and are, therefore, valuable pest controllers themselves. Then I remind myself of the pain, discomfort and swelling, and sometimes injections I get, and they have to go.
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I commended myself on my bravery, taking these photos, as the wasps went into the attack as the chemical jet entered their nest. But such is my devotion to get a new post out – I’m becoing a true blogger news hound!

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My heightend awareness of wasps this week made me also notice these holes in a deserted timber garage. They were the homes of a small colony of wood wasps. Unlike the common wasp which live communally in their hundreds (the largest of our nests turned out to be the size of a football), wood wasps are more solitary, each one occupying their own chamber.

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They are quite placid compared to their aggressive cousins and, I believe, unable to sting a human being. The largest ones look terrifying but this species was small, about half the size of the common wasp. There are about 500 species of solitary wasp in Britain and I can’t identify any of them. I felt totally at ease photographing them inches away and they completely ignored me. Perhaps word had got round what I did to them further down the secret valley!
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I’m now looking forward to the first frosts and a wasp free winter!

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