Tree roots invading the soil I prepared for my planted tree

[Orkine]

I got a nice mango (3 gal pot) about a year or so ago and transplanted it immediately into the soil.

I dug a large hole, much larger than I needed because it was not far from a tree that had roots all over the place.  I made the hole large and cleared all the roots in the space.  Replace with nice soil mix and planted my mango.  It has not done very well and in investigating yesterday (I moved mulch aside) I found a lot of fibrous roots under the mulch.  It was exactly the same type of root I had removed in making the hole.
Aparently the large tree just made a whole lot more roots and took over the area i prepared for the mango.  What is the best course of action.

1) Dig up the mango and abandon the location? 
2) dig a perimeter to a few feet all the way around my mango to cut off the tree roots again and this time place a root barrier of some sorts, plastic plain or painted with microkote on both inside and outside.  Can the roots come in from the bottom in this case?
3) Kill the useless but large tree and lets its roots rot in place(so pissed, I am liking this right now)
4) Fertilize enough for both and just know that my mango will continue to be out-competed by a well established tree that roots like crazy

Or is there something else I should do.

It is M4 and I want it to live and do well.  If I am going to do anything I'd like to do it as we are going into the rainy season.

By the way, are there any trees in Florida with roots that put out chemicals to retard its competition?  I ask because the root smell seems to be the only game in town anywhere I have come across it close to this tree.

[Orkine]

Looks like 1 more option from this post is to encourage this plant to do well enough to provide budwood to graft onto other trees.
http://tropicalfruitforum.com/index.php?topic=23441.msg281414#msg281414

It flowered this year but didn't keep any fruit is developed.  Energy it could have spent on growing; perhaps feed it nitrogen to encourage vegetative growth.
'What to do?

[MangoCountry]

How is it not doing well?

[scottsurf]

what is the other tree





had this problem with big ficus tree the feeder roots where as big as my finger the more you fertilze or water the fruit tree the worst it going to gets unless you folar feed,   id cut the bigger tree back  it gets pretty anoying 

it will probally do better in the rainy season   since the large tree has more acess to water and nutrince else where


what is the bigger tree 

maybe take a picture

[zands]

If this is a prime location for your mango tree then make a root barrier from sheet metal...steel. Best way to find good sheet metal is from something being thrown out or at a scarp yard (lol) if there is one in your area

[pineislander]

I am also curious what the undesired tree is, and what you smell from the roots. Key to identification would be pics of tree limb, trunk, leaf and flowers if possible, maybe an analogy for root "smells like a skunk...".

[palmcity]

Or is there something else I should do.

It is M4 and I want it to live and do well. 

Another Choice: Large tree should loose a lot of it's roots if a lot of its canopy is removed. Thus keep large tree canopy where you need it for shade & remove it where new mango needs it for light.  A significant decrease in canopy will result in a loss of roots.  This will give your mango a better chance vs. large tree... Keep trimming large tree as mango trees canopy increases and hopefully you will eventually have your tree shade from M4 at least to an extent.

Also, fertilize/water on outskirts or slightly beyond M4 root zone canopy to encourage M4 roots to expand and discourage larger tree from growing into M4 s  root canopy zone. 

As mentioned, if shade or large tree is not needed... Kill it and let it rot for your new M4 to eat....

[Orkine]

Currently out of town for the day, will photograph and post image.
It is at the edge of property with no shade value.
Close to a small canal which is not a plus for keeping the tree.  Flood protect issue if it fell in the canal during a storm.
My planted trees are further away from the bank.

I could be doing the local water district a favor if I removed the tree.

That's me talking myself into one option 😀

[Orkine]

Here are some photos


It is a large tree, there is a branch damaged during Irma.



I took a divet and flipped it over.  You can see the fine roots.



These are from seedlings growing close to the tree but it shows the leaves.

[pineislander]

Chop it down. It is an earleaf acacia, exotic legume so it actually does provide some nitrogen but also strong competition. The seeds are in pods which look like ears and when freshly opened have black seeds with orange arils. It may re-sprout but I've cut some big ones which couldn't take the strain of coppicing and just died. If you want, within 5 minutes of cutting the tree frill the cambium layer and immediately apply glyphosate concentrate with a paintbrush to finish it off. Chop up the tree and use it for mulch, let the logs dry out then cover with more mulch for aesthetics. If it has set seed they can grow but are easy to pull when young.

https://plants.ifas.ufl.edu/plant-directory/acacia-auriculiformis/

[Cookie Monster]

Yikes, those roots are as bad as bamboo roots. Get rid of it.