SallyRZ

I love the suggestions for a huge replacement tree! My hope was that ultimately you would say it wasn't a drill hole, and from what has been said there's now enough doubt there for me to worry about it a lot less. Cornish wood burner, I do see what you are saying but the building work (2007) came not after but before the tree (and the lavender too), which appeared by itself maybe a year or so later and then lasted for several years until it died suddenly, so that's why I'm not sure that whatever rubble etc may have been left beneath the soil can have caused that to happen (and I do appreciate your point about the ivy too - it's just the way the neighbour attempted to deal with it that was so wrong). Growforest, agreed, it's not a very lovely tree, especially now it's dead...so with that and everything else that's been said, I realise it's now time to move on and think of a practical way to use that undersized patch of soil. I'll dig it over first to see what's under there and also do a test planting to see if anything decent can still live there. Once again, very many thanks for all your wise comments and advice.

Sorry for the missed questions. I too thought initially that it was odd that the hole was on our 'side' (and so high up too). But we are on a bus route with regular traffic and a bus stop opposite, so it would have looked less suspicious to be working from our side. And it's easy to see when we're out if you spend as much time looking out of the window as the neighbour does...while this might sound paranoid of us, for example I did once come back to find his gardener leaning over the back garden fence and cutting two parallel horizontal lines through the ivy on our ash tree, about 18 inches apart, in order to remove that section and therefore kill the ivy above. He said he hated the ivy and that it was "smothering" the tree (not sure why he was bothered about that) and he wasn't at all embarrassed about being 'caught'. So you see, he has form. No effect on the ivy, by the way, as he didn't get to complete the job. And he hasn't tried since. MattyF, are you saying this does look like a drill hole, but that you wouldn't have expected it to have been able to kill the tree? Cornish wood burner, you have a point, especially as nothing can be done, and he'll certainly deny it. I'll think about that (but definitely mention it in some non-accusatory and puzzled way in passing the next time he wanders by with a complaint). Billhook, I was thinking too that the hole might be too shallow for a chemical, but from what others have indicated it does seem possible. I then wondered whether something injected into the tree and therefore down to the roots could somehow spread to nearby plants? The weeds grow back there, so it's not as if the section of earth as a whole is completely resistant to anything living. Haven't tried to plant anything yet though to test that. I appreciate your recommendation about a camera but feel a bit reluctant to take that route as I don't want to become too (even more?) obsessed about what next door gets up to ie becoming like the neighbour himself. Sloth, yes, the chuck-scored outer circle is exactly what it looks like. And thank you, I will see if a friend of a friend (there must be one) can have a look. The tree is not very old (the section of earth was only put there 8 years ago, and as I say the tree just started growing there over time) and not very tall. Here are a couple more photos, including one showing the hole from above. I hope they're clear enough. The hole on the right hand part of the tree, about halfway between those two parallel branches. Very many thanks again for reading this and for all your help.

I will see if I can take a better picture tomorrow (the top isn't pointed but I can see it looks that way in the photo).

You're right really, Stubby - it's just that after 20 years of him moaning about the trees (he has no greenery in his garden and so doesn't much like any of ours near the property boundary), conversations are normally one way ie he whinges, then turns his back. And it's not as if the trees aren't pollarded regularly. One of those childish disputes I'm sure you come across a lot in your line of work! But next time he comes round for another whinge, I will ask him in the way you suggest, and watch for the shifty expression... I did wonder whether just one drill hole not very deep and quite high up would have been enough to kill the tree, but from the comments it's obviously possible. Thank you for all the quick replies.

In case this is relevant, the only other living thing in the earth around the tree was a lavender bush, which died at the same time.

The hole isn't quite wide enough for a pencil but I put a needle in and it went in about 9mm. I can't smell any chemicals, but then again it's been a few months and I didn't know to check at the time. All the other dead limb ends look like this (ie a couple of rings round, and there isn't a hole as such):

A few months ago, a small tree which had established itself in our front garden (sorry, I don't know the type) suddenly started dropping its leaves and within a few days it was dead. As the tree is by our fence, and the neighbour had recently complained about the leaves touching his phone wire, I assumed he was the culprit. I've just read that one clue to poisoning is the presence of drill holes, and while there's nothing around the base under the soil, I think I've found one about 30 inches up. I realise there's no proof, especially at this late stage, but I was wondering whether the attached photo does show a drill hole, or is it just a coincidence?