Exactly how did this tree die?????

[derwoodii]

As you say OMT Glypho most likely as more common. My experience is its hard to kill a big trees such as this with just Gypho trunk drilling. It would take some time and few return hits plus seasonal timing of job very important.
Other suspect are higher end killers.
Garlon 600 Herbicide active ingredient Triclopyr
BrushOff METSULFURON METHYL
Broad leaf turf herbicides Dicamba / MCPA works a treat with Elms Poplars Willows.
I seen Chlorine (pool cleaners), hydrocarbons and acids used. Even the old copper nails which happily failed.

I kerb my previous advice in trying to recover cost. This mostly fails and brings various forms of revenge.
People who care less for laws, their neighbors rights and beauty of trees are more likely to make a fist than a handshake.

 

[outofmytree]

Thanks for the ideas DW. Have you any PM experience with any of those mentioned? Any tell tale symptons, marks, discolourations or perhaps patterns of decay?

opcorn:

 

[TreEmergencyB]

O no its a Treemendous TreEmergency!

 

[ND_ash]

I use a product called Clarity for control of just about everything except grass
Look it up on the net and read the instructions, it will put a serious hurt on just about any tree if it gets beyond the bark. It's the same as banvel, we use it around the base of wind turbines and sub station to control weeds. I have never killed trees using it on yards but i have stunted some young trees. Works great to control dandelions and many other yard weeds.

 

[derwoodii]

Sadly I was the bringer of death for many a tree when I worked for "dark side" Power Line Clearing contractor. I was proficient in dealing with stumps, full grown trees and sucker growth soon found which chemical gave best results.
Ive seen no typical/predictable response by many trees to various poisons. They all react in many ways. The tell tale is the smell each chemical has its own unique smell.
My new trick is MCPA/Dicamba into Willows/Poplars its cheap & deadly quick. As ND_ash says Clarity is Dicamba.