How can I kill the root of Ash tree growing btwn concrete?

Hi there! I have been working round the clock for the past few years on our yard, but I didn't notice this tree growing about a foot under the lip of our deck. It was covered by other flowers growing in front of it, and now that I'm finally ripping out all the invasives and planting natives here, I've discovered what a mess this is.

On the left, there is the wooden post for our deck, submerged in concrete below it. Less than two inches away, there is a GIANT slab of flat concrete that appears to be at least 3, possibly 4' long, and at least 4" deep. (Under an inch of soil too...) Given it's location UNDER the deck, I cannot easily lift this slab. On top of that, I discovered a gray-covered small cord running along the length of the slab about 5" deep, so I don't want to go there.

I grabbed my small camping ax and held the 1" trunk back as much as possible, and hacked it away right next to the concrete. What can I inject in this to kill it, without poisoning the nearby native plants?

I'd like to avoid having to buy something for this (e.g. RoundUp), not to mention, I hate the thought of giving that company any of my money. Is there something I can find in my kitchen or cleaning cupboards that I could use to inject into the root, or pour on it? Borax and vinegar maybe? I'd like to backfill quickly and finish planting my Foxglove Penstemons please! =)

Thanks for your help!

Peace,
Carrie Anne

For the best results (Chemical) there is a root / tree killer called Root Out which is used after you cut a tree back to just the stump.
Once you do this, you drill holes in the stump and use a food funnel to pour in the powder into the drill holes, then you lay waterproof material over the whole stump and tie in place to secure, this powder eventually rots the stump way down to roots, it should also kill the roots.
This powder that is held within the trunk cant reach neighbouring plants and as it is withing the roots it cant damage other roots growing close by.
the other thing to use as this is a young tree, is brush killer, this is used for weedy brush like brambles etc, again you would paint this into your tree trunk and the chemical cant be spread to other plants or wind blown to other areas.
I know what you mean about using chemicals believe me, I think people turn to those first before thinking what damage will run off do to waterways etc, but to be fare, there is under certain circumstances (like your situation) where there is occasionally no alternative, so look at this stuff as a last resort, or get machinery in to remove the concrete slab, I don't think on this occasion you will be able to have your cake and eat it all the same time. hope someone can come up with different solution's and wish you much luck for the job at hand. WeeNel.

The longer that tree root is allowed to grow, the stronger it will be and harder to kill. I had an hybrid elm cut down 3 years ago because it was rotten and sick. I worried every time we had wind. I hired a proffessional tree cutter who even ground up the root down to 4". Every summmer I get new growth popping up from the root underground, IN MY NEW GARDEN.

I have tried to dig out the roots some of which are 3-4" diameter. I am now finally spraying with Roundup for hard to kill trees and bushes. Eventually, the tree will get tired of sending up shoot. Even this year I had to do likewise. Hybrid Elms are weedy.

Sometimes you do what you got to do.