If Guerneys is selling a peach they call "semi-dwarf" it is probably on a
standard such as Baily. Do they even grow their own trees anymore?
I recommend you order a peach on a typical rootstock from someone like
Adams County Nursery, Cummins or the like. Why buy from some corporate,
mail saturation advertised company with a mediocre customer rating?
[nafex] Contender peach on dwarf,
Alan Haigh, 10/06/2013