This winter has been a classic British mish-mash of , well, weather. From September on it did not stop raining until the lock down started,
you know, just when people wantED to go outside after after a long wet and very
drab winter - Sod’s Law.
But what wasn’t in doubt was the fact it had been a warmer winter despite some snow and with all that moisture in the soil when the sun came
out everything sprang into life, many weeks early in some cases. Tulips were
finished long before the end of May, as were Crown Imperials that started
showing bud colour at the end of February, and my Delphiniums showing bud colour
at the end of April - the first are out fully now.
This is not the first time this has happened of course but it is by
degrees more frequent. The weather is changing as it has over millennia,
hotter, colder that is the way it works and man has to adapt.
What has also happened - and I did write something on these
lines awhile back - is that disease in the plant world is also on the move, both
plant derived disease and animal/insect driven. Much has to do with world trade: however stringent measures are to protect a country's biodiversity, something
somehow will always get through. The real worries are those diseases that
affect agriculture and our natural landscape, but our gardens give a mini
replica of what is going on.
The last few years have seen an unprecedented assault on many
native species, in modern times Dutch Elm disease could be seen as the
forerunner for many more and it has been non stop since, many have not reached
their full doom laden predictions, fortunately, many have become isolated to
areas rather than go national and some have petered out, not unlike viruses
that effect man, no one has been able to predict final outcomes in the plant
world any more than the human world with any accuracy, in fact Dutch Elm is one
of the few to fulfil prediction as it did indeed wipe out the species, or
almost.
This list of tree pests and diseases gives an idea of the
attack on our woodlands; not all are as fatal as is spelt out…..
Ash die-back has so far failed to have the effect that was
prophesied; doesn’t mean it wont, but it hasn't so far. The Oak die-back is a slower
one so again it's difficult to say how far it will spread. Horse Chestnut was
an early disaster, killing trees in a couple of years, but it was selective: stands of Chestnut almost within touching distance of diseased and dying ones
are still healthy and many areas have no visible signs. A similar threat to
London's plane trees came some years back when premature leaf drop looked as though
it would finish the capital's avenues, but the sickness mysteriously died away over a few years,
so we can never be sure as to the final outcome.
The pests are in some ways a bigger problem. Warmer weather has enabled some species to spread at an alarming rate,
establishing themselves in short order and the natural predators that exist in
their ‘native’ homelands do not spread with them. A good example and one that I
have had dealings with (and they are winning) is the box tree moth/caterpillar: now
spreading up from the south of the country it reduces box plants to nothing in
short order; for topiary, where box is the favoured tree, it is the end as the
affected areas never recover and the topiary is to all intents finished. Hedges are the same, I lost all my topiary last year to the moth almost overnight; you can
spray but it has to be repeated many times and if you misjudge that is it - the
natural predator in Japan, a hornet, is sadly still in Japan.
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| Box tree, and Very Hungry Caterpillars |
I could do a list of pests and diseases that have hit on my
garden in the last few years that would eclipse all that came before in my
lifetime, such has been the increase; undoubtedly the warmer weather has been
one of the factors in this.
Even ants are on the increase. The size of their colonies is very much influenced by the warmer weather and their activity is dictated by the same, so we have more ants and more activity, but we should be grateful that we do not yet get
Argentine ants that have infested the USA; and Asian super ants, 'super' because
they create super-sized colonies not because they are huge, have so far only been located
in a few sites in the UK - but they will prevail as they always do. We live on
sandy soil and the ant activity already this year is way ahead of any previous
and again little seems to have any lasting effect on them, they simply pop up
elsewhere.
Pests are also getting an easy ride. The harsh winters that
helped to kill off many pests and many diseases are fast disappearing and the
resultant early swarms of pests can be seen everywhere; diseases that lie
dormant underground and await warm weather to spring into action are not having
to wait so long, many appear each year now rather than one in ten.
Many reading this will remember the Leylandii hedging dying
all over the country, brown patches appearing and dying back. It killed
thousands of plants. In some ways this was a good thing as the Leylandii
Cypress is in most domestic situations an unsuitable hedge for a normal garden: fast growth yes, out of control also yes. It should never have been sold for
domestic hedging. The disease is caused by an aphid; there are various aphids
that attack conifers and although spray can be effective, it has to be at first
sign of the aphids, not always obvious, and spraying lengths of hedges properly
is expensive and difficult. To achieve trees is nearly impossible as when I lost a
row of Italian Cypress some years ago, there were enormous masses of grey/black sooty mould that
lives off the sugary residue left behind by the aphids.
One of the problems when dealing with these pests and diseases
is the lack of chemicals that can prevent the infestation or stop the spread of
disease. The EU for reasons only they know, removed many items that worked in
protecting plant life and nothing has taken their place; to be fair, some were toxic after many
years of use and some had questionable long term effects on humans but many did
not, so cheap generic chemicals are removed and in many cases very expensive
replacements appear.
Yes there are some natural remedies that have worked for
years, but many of those are contact only, require frequent application and
still don’t do the job or only partly.
Nature has its own way of correcting things, but globalisation
has made things much shorter term; nature can’t respond at that rate of change
and nor can we. We only look at things from a short term perspective; huge
changes have occurred to our landscape world wide over the earth's life - findings locally of fossilised tropical plants show how we in a temperate zone
have gone from glacial freezing to tropical humidity; all has been accommodated
over time.
Even the evil toxic stuff that man pumped into the atmosphere
during the industrial revolution has had the odd plus side: roses, so popular in
British gardens in those pre and post war years were suddenly changed into disease carriers as black spot took hold of
many of the popular varieties. Why? The Clean Air Act of ‘56, passed after the great smog of 1952, cleansed the air of sulphur, sulphur being the best
chemical for the treatment of black spot and some other leaf diseases: by burning coal we
had unknowingly been spraying our roses
with a fungicide for decades.
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| Arr, the black spot, Jim! |
There will have to be a change in many varieties of plant life
in any case if temperatures go up. Many standard species and hybrids are
naturalised to the current climate, many will adapt, many will not. We will
have to find and breed versions of popular plants and trees that will stand the
new climate, they do this all the time anyway; it will now become a more intense
program or we can simply swap what we grow now for more tropical varieties, that is
already happening and has been going on for many years, in agriculture it is standard
practice and new varieties of staples like wheat that grow in adverse
conditions are being trialled and used on a non-stop program of roll-out.
Climate will always create challenges, it always has. The Earth itself has constantly overcome climate change and so will we. The view of
the English countryside as immortalised in paintings by the likes of Constable
are but a snapshot of a very short period of time, it was very different before
and will be different again; it’s what climate creates.
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| John Constable's 'Wivenhoe Park, Essex' (1816) - held at National Gallery of Art, Washington, USA |
