Country Gardener

Widely regarded as the authority on gardening in the south west

Strengthen and diversify - or die

Mark Hinsley suggests we need to understand that trees are complex organisms and we need to learn how to look after them – or else!

I recently spent an exhausting three days at the Annual Conference of the Arboricultural Association in Exeter. It was a truly excellent event with an interesting array of speakers. I therefore have much to report.

Firstly, I can report that the demon drink is still demon, so you are going to have to lay off it for another year until I can check again!

Secondly, I can confirm that our tree population is at risk from a number of ‘foreign’ pests, one of which is already here, and two or three that are threatening to arrive. The problem, as I have pointed out before, is global trading. 

Thirdly, it was graphically pointed out that relying on a small number of tree species to provide the bulk of our tree cover leaves us vulnerable to our landscape being devastated by a single uncontrollable pest. 

Fourthly, whilst the environmental and visual impact of millions of dead trees is generally understood, the astronomical cost of dealing with them is not really being thought of or planned for. 

So, what can we do?

If I say to my ‘good lady’ that I am getting a cold, she immediately starts dosing me up with Vitamin C. She knows that, if my immune system is going to fight off the cold virus, it needs to be in tip-top condition. Trees are no different. Our trees are growing in soils packed with pollutants, low in macrobiotic activity, low in oxygen through hard surfacing and soil compaction, deprived of moisture for the same reasons and short of nutrients because we break the nitrogen cycle.  They are also under severe competition because we insist on having lawns beneath them; frankly, they are in no fit state to fight off anything!

The simple remedy equivalent to the Vitamin ‘C’ tablets is mulch.  Cover as much of the ground beneath the canopy as you can with a 100mm settled depth of woodchips, over a couple of seasons and this will give your trees a significant boost to their health and vitality.

If you want to go further there is an impressive new system for compressed air soil injection and the introduction of Bio-Char, which works like an underground mulch, to which a suite of beneficial substances can be added. This system has also proved helpful in supporting trees already under attack by our usual pests and diseases. 

Gardeners are not afraid of the exotic, in fact they celebrate diversity. Plants that originate from the four corners of the earth can be found in most gardens. The problem is the ‘only plant native trees’ brigade in some public and charitable organisations. Their oft repeated mantra would be fine if the only pests and diseases our trees had to endure were also native and if all our growing conditions were comparable to growing in our native unadulterated countryside. Unfortunately, growing in a city street is more like growing in a desert canyon than in a lush English woodland and our native trees have never had to do battle with Asian Longhorn Beetle; so sometimes we need to select trees that do – and have! 

We understand that we are complex organisms as we wallop down ‘good’ bacteria and vitamin supplements to maintain our health and vigour. 

We need to recognise that trees are complex organisms too and that every tree is a community that includes a plethora of symbiotic fungi and bacteria and that the whole community must be sustained for the tree to be truly healthy and strong.

Council tax increase anybody?

Mark Hinsley Arboricultural Consultants Ltd.

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