It seems that this is the year it must happen. The oldest plant in our garden is an Acer palmatum ‘Atropurpureum’ that was a young plant just a couple of feet tall when we moved in over thirty years ago. I know it’s the oldest because it is the only plant still left that was here back then so removing it means not just that the oldest plant goes but that everything in the garden has been planted by us.
It is now around 12 feet tall, branching into a number of stems quite low down. Last year I removed a couple of sizeable limbs that had died; it is now clear that less than half of what remains is going to come into growth this spring. Cutting out all the dead would leave only a couple of branches and I imagine it’s only a matter of time before they go the same way. The decision is made; it’s quite a big job but one I can manage myself, I just need to get a few other things out of the way first.
I think I know what started the tree’s terminal decline. We seem to have had particularly dry springs in recent years. This year is shaping up to be another. Last May was exceptionally hot and dry and looking at the output figures for my solar panels, April was very sunny too. Many trees, Acers included, expect there to be a plentiful supply of water when they come into leaf and will make rapid growth for just a couple of months in the spring before a terminal bud forms and the wood ripens up ahead of the coming winter.
Maybe, if the Acer was standing alone or in the company of other deciduous trees and shrubs, the moisture would still be there below the surface. Unfortunately, within feet of it are an evergreen Ligustrum lucidum ‘Excelsum Superbum’, taller in fact than the maple, and a large Camellia which is about six feet tall. There is also a carpet underneath it of an evergreen Epimedium. All three will have been steadily working through the available moisture such that when the Acer started into growth there wasn’t a lot left.
A number of years ago much the same thing happened to a sizeable Acer grosseri hersii. The moisture it was relying on to fuel its spring flush had been taken up by a nearby conifer. It broke bud, barely grew at all, an inch or two, then suffered twig dieback for the rest of the summer. The following spring it became clear that real and lasting damage had been done and in fact it never recovered. After seven or eight years of it looking miserable I put it out of its misery. I cut the stump, which had a diameter of six inches or more, flush with the ground. Later that summer a couple of Dahlias nearby started to die and on closer inspection it turned out that they had honey fungus. I checked the tree stump and there were the characteristic fans of fungal mycelium under the bark. That winter I set to and dug out the stump and as much root as I could. All smelled of fungus, and mycelium and rhizomorphs were everywhere.
I’d be very surprised if the Acer ‘Atropurpureum’ isn’t suffering from the same thing. The drought last year left it in a weakened and vulnerable state and with honey fungus (Armillaria) present, it was a sitting duck. I’ve been checking up on Armillaria and it doesn’t make for comfortable reading. The tree will almost certainly die, there isn’t anything I can do for it. Digging out the roots would reduce the amount of substrate the fungus has to live on but is just about impossible given its size and proximity to other large plants. The fungus is all too likely to spread to them too.
Oddly enough, the first list of resistant/susceptible species I looked at has Japanese maple down as resistant and privet (the Ligustrum is a privet) as susceptible. I’ve lost Camellias to it before so I know they are susceptible, though they put up a fight.
I suppose it could be a different disease, Verticillium or Phytophthora cinnamomea for example, but given that I know Armillarea is present and it is still the number one disease diagnosed by the RHS pathology service, it seems the most likely. It would make very little difference, whatever it is, it’s killing the tree and there is nothing I can do about it. When I take it down it may be possible to be more certain about what it was that killed it. If I find diagnostic symptoms, I’ll photograph them and do another article.
Looking at the 2016 picture of the garden there are a number of big plants that are no longer there. Behind the right hand edge of the Acer is a Magnolia, between the yellow columnar Taxus and the pale Pittosporum is a big conifer and behind that (actually mostly in the neighbour’s garden) a hazel. Above the glasshouse at bottom right are two sizeable pines. All have gone in the last five years and given how crowded the garden was becoming in 2016, all for the good. Everything gets bigger and eventually something has to go or a sunny garden becomes a shady garden then a woodland. I even have to grudgingly admit that the big oak in next doors garden, which was overhanging ours by several feet, is not missed at all.