In a word, "No," you won't hurt the roots. To me the advantage of summer or early fall pruning is that you won't get the bleeding that occurs if you prune in winter or early spring. Bleeding doesn't really hurt the tree but is messy, especially near sidewalks or driveways.
hortster

never heard that theory before ...

raise it as high as you want.. remove any damaged or crossing branches

then kill the grass under there .... and add a 5 foot circle of mulch ...

second pic wont load.. page not found.. but if that is a stake there.. be done with staking..

no fert .... no nothing.. its well on its way in life ...

ken

No that's not a stake. It's a post for a bird feeder. Snakes like to climb the tree and lie in wait for birds to come and feed :)

I'm assuming you mean 5ft radius rather than diameter of mulch?

nope.. i meant a minimum of 5 feet.. if you are willing to go to 10 feet.. tripling the mulch expense.. GO FOR IT!!!!

ken

ps: brrr.. snakes in trees .. i dont know if i could handle the south .... lol ..

Thank you for the very quick and helpful response.

I've got a 25' birch in my backyard which God pruned for me last spring. I finished the job and it dripped heavily for almost two weeks. So I wouldn't do it in spring/rainy season, but it didn't seem to harm it.

It's called a "river" birch for a reason ... they really like (typically grew by) water. Mine starts dropping leaves if it doesn't rain for two weeks. I wouldn't think summer in Georgia would be a good time to spring a leak.

The one I have grows like a weed and I hack it back on an annual basis anyway. In my (amatuer) experience late fall defintely works best.

Gwydify,

Most all the more trusted sources I've seen advise pruning Betula nigra in late spring (especially in warmer areas) or early summer (in cooler areas) to reduce bleeding. Bleeding often doesn't significantly hurt a healthy tree, but it can weaken it and make it more susceptible to other possibly damaging agents. Pruning late in the season doesn't provide sufficient time for the tree to close off the wounds before sap rise the following spring. Here is an example of what I've seen and it agrees well with my experience:

"While most other trees would be pruned in early spring, birches...should only be pruned in late spring (or early summer) after the leaves have reached full size. A tree that is pruned before the leaves have developed will bleed sap depleting the tree of moisture and sugar. Late summer (through winter) pruning is also discouraged because, although there will be no bleeding immediately following pruning, the non- healed cuts will begin to bleed as soon as sap begins to flow in spring."

I added the things in parentheses.