I use systemic when they start growing, lime sulfur over the winter (didn't do it this year as trees were outside until late).
Repotting Ponderosas is an interesting topic. I will guarantee this- fail to repot your ponderosas out of the gunk they come from the mountains in, and you live in warm humid place (even just summers) and you will have a tree planted in a septic mess before you know it. The trees grow in the mountains in a mix of granite dust and rotting pine needles and junk (duff). It is dry most of the time (either frozen or drought) and is wet for only short, generally cool, times. There is a faction of folks out there who don't repot or ever work their trees roots, especially collected trees, they will say "leave them alone, never touch the roots", they will also tend to have trees spontaneously die from time to time, after just being a little "peaked" or slow growing.
The best way I have found to kill collected trees is to collect them, pot them up, and then throw them in to a vehicle and drive them somewhere that year. Doesn't always work, but does from time to time. I would rather do the bareroot bonanza, repot the tree at home, and then not move it for a year or two so that it can get its roots well established and hardened off.
