i missed the root pruning. and i noticed that the water is not getting to the center of root mass. so i poke deep holes into the soil in my potted trees yesterday. this seems to help with getting water to the center of root mass.

while doing this, i broke two stakes that i used. i'm thinking about getting 1x13 inch auger to drill hole into the soil. has anyone tried this?

pete

Some years back years when i had similar problem with a plant in container what i did was use a tree root feeder i have.
It has a 2-3ft  tube with 4 holes at end of that tube and a garden hose hooks up top.
I slowly worked tube into the mix massaging as the water was on.
Did a bunch of holes at different angles right into the heart of the rootball toward trunk of tree.
It was very effective in getting the water to the heart of the root ball and anywhere else i wanted . 

A drill and auger would shred the roots, it might twist them right off the trunk even! Stakes break because the grain runs out of them, if you use a straight limb or sapling from a nice hard wood like osage or black locust it will never break, but will probably split the length when it dries. Try a good shovel handle if you have one with a broken head, they are almost always straight grained and made of ash.

I agree about the auger causing more damage to roots than is necessary.  However, anything solid that is pushed into the growing mix will worsen the problem.  Use a hollow tube to pull a plug out.  The goal is to add room for the roots to grow in without compacting the rest of the root zone.  Copper tube is a good choice since it is usually thin walled and rigid.