Do I have a contaminated patch in garden, and how to fix it?

There is a small patch in our garden where everything struggles and then dies after a few months.

A magnolia stellata, a rosemary and now a columnar cherry.

It's right next to the stump of a large ash tree which was felled before our time. Might I be right in supposing that whatever might have been added to the stump to kill it might have contaminated some of the ground around? Ivy seems ok, and various perennial weeds like brambles! Bulbs come up too, and the Buddleia has just about has clung to life (after looking like it might not!).

If it is the effect of some chemical added the stump, how can I fix it? I'm not going to be able to dispose of lots of soil as it's at the top of a very steep hill!

Thanks from a first-time poster!

 

Is it possible that the Ash was felled because it had Honey Fungus?
If so, you could try growing HF resistant trees & shrubs, such as those under 'rarely affected' in this pdf from the RHS:
https://www.google.co.uk/url?sa=t&s...kQFnoECCIQAQ&usg=AOvVaw0YY8P6TFm9d7pLsO_HDurU

I've not heard of stump killer leaking into surrounding soil although it's possible. Most stuff available has limited life and breaks down.

 

I've found it difficult to get plants to establish near old tree stumps.
I would think it more likely to be the effect of the tree roots in the soil.
Very large amounts of manure have generally helped in this situation.
You might also consider the rather arduous task of removing the stump...

 

If you think Honey Fungus is a possibility try some herbaceous perennials or annuals and see how they go.

 

How long ago was the Ash tree felled? Have you been told that stump killer has been used and if so, how long ago? Do you have a photo of the site that may help with suggestions. The soil may need a lot of preparation before trying to plant again ie lots of organic matter.
Honey fungus is unlikely to kill perennials and annuals.

 

Perhaps the roots are still alive and kicking and using up all the water and nutrients. Our tree man used a stump grinder to destroy everything.