One of my players requested a prerequisite chain change for a spell in our game.
I agree with him that it should be possible to get to Rotting Death without Food College spells. To do that, we need to change the prereqs for Pestilence. Why not Body Control? I see a couple ways you can do that, and incorporated them both. Note this assumes you are using Wizardry Refined in Pyramid 3/60.
Pestilence (GURPS Magic, p. 154)
As written, except:
Prerequisites: Magery 1, Steal Vitality, and one of Decay, Retch, or six Body Control spells including Frailty.
This allows for a longer path, either via Air spells or Body Control spells. You don't need to be able to check for safe food or rot food before you can give someone the plague or the Dwarven Sprue.
By the way, just as an aside, I love that Pestilence has no resistance.