Tom:

EMLA 27 is the weakest growing apple rootstock I've ever heard of. I doubt that it will hurt your sidewalk. In fact it requires staking to hold the tree up. It will also runt out quite easily. That is a condition where vegetative growth becomes very weak. So don't let it bear a large crop until it has reached the height and spread you require.

The Fruitnut

EMLA 27 was too wussy for just about any application except potted trees for us. Bud. 9 bore early and heavily, and was easy to train as a Belgian fence.

The nature of dwarfing roots are much different than seedling roots; they're fine, soft, and quite brittle, most unlikely to disturb concrete walkways or foundation. Seedling roots are tough, rope-like, and can be invasive.

You can plant Bud. 9 only about a foot away from the sidewalk (speaking as a gardener and a General Contractor).

I bought 3 apple trees recently all with EMLA 27 rootstocks. All trees are going to be grown in pots... I was curious about the growth on this rootstock. I have heard from others about pruning off the buds to prevent fruiting, because the tree would be less vigorous and would have reduced yields later on. Hearing it again in this post makes me wonder if I should even leave a few buds on now or completely prune them all off (The tree is supposely a little over a year old). I was tempted to taste a few apples from the first fruiting. An apple or three should'nt have much effect on vegetative growth?

I looked up Bud. 9 and although it's a bit more vigorous than ELMA 27 I can keep it where I want it with pruning. Thanks. Now to see what's available on each rootstock. Tom