I left a key part out of my above post. Obviously, if you hook several zones from the controller into one zone on the Fertigator, when one of the controller zones kicks on, the low voltage power would also follow the wires back and attempt to open all zones you have attached to one node on the Fertigator. (Most likely the controller wouldn't have enough power to open all the zones and you would have PSI, GPM, and voltage issues.)
So, with this in mind, I do understand I would have to also install some sort of capacitor or a one way voltage flow on the lines coming from the controller to the Fertigator.
This might sound confusing, but I still think it might work and save a few bucks.