I can tell you how not to do it; don't use wooden posts that rot out right when your trees are maturing and have a full load of fruit and fail during a wet, sticky snow, snapping your trees off at the graft union.

I use a 10' long 3/4" hard copper water pipe, but it's a bit pricy. Galvanized conduit will rust out underground, you could use a galvanized 3/4" water pipe. Regular treated tree stakes like landscapers use will rot and snap. Treated peeler cores are more durable, but a bit big for individual trees. T-posts like in barbed wire fencing are also a popular option.

Thanks applenut! How exactly do you secure the tree to the post? I have always worried about using treated wood for grape vines or anything in the garden due to the chemicals they use to treat it.

I've used T posts driven in about 4 inches from the tree and 4-5ft above ground 2ft below. Then using heavy cord tie a figure 8 around both post and tree. That's kept mine on M9 and M26 upright.

Thanks for the help!

Arsenic has been banned for years now in wood treatment, its almost all copper now (which causes some issues with galvanized nails rotting out in it). I use black poly tubes to secure it. That is, I used to; I gave up on wussy dwarfing rootstocks and plant on M111 now and forget about staking.

Treated lumber is the only way to go, Arsenic was banned like in 2003 or something. Long time ago!

If using the new copper treated lumber, you might want coat them in paint/tar or set them in concrete. Bare lumber doesn't seem to last very long. I have already seen cases of 50% rot in 5-8 years of ground contact. In contrast, I've pulled 20+ year old CCA treated wood that was still just as heavy and solid as the day it went in.

I use 4' rebar driven halway into the ground, and I secure the tree with galvanized wire strung through left over garden hose. The hose protects the tree from being cut by the wire.