If you want to really grow a dwarf pecan tree what I would suggest is do what I did find you a good section of a tree with healthy branches about the size of your wrist then right at the main part of the branch before the end splits out or branches out LOL strip a layer of the bark off all the way around making a ring around the branch with no bark take some peat moss soaking in water paint some rooting hormone on the area you just remove the bark wrap it with the peat moss completely around the branch then placed a plastic bag around it clear preferably and tape it on both ends it’s called air layering just type in air layering and Google and you will see what I’m talking about. Through that season from the branch back by the end of the spring or next spring cut the branch off on the opposite side of where you air layered it and put it in a pot there you have a dwarf pecan tree by the way I’m the run-on sentence King have a good day God bless hope this helps 
if you are like a pictures of the process email me or message me here I’ll find a way to get them to you I grow bonsai trees and this is what I do to get an older tree with a thick trunk and then I just print it while it’s creating roots to create the shape of the tree I’m looking for.