I doubt whether Jeyes Fluid would do the trick, but I suspect that Armillatox would do it, although it would be difficult to prove without labaratory tests on the results.
Howver, a wallpaper steamer/stripper applied to each growbag in turn would probably be able to raise the temperature sufficiently for the purpose, although careful monitoring of the temperature with a soil (or oven)thermometer would help. This is little different in principle from the old fashioned soil steam steriliser which I have had for nearly 40 years and still use occasionally