The original Blob from the movie has a weakness to low temperatures becoming crystallized and inert when cooled down. Why not add a new cool sci-fi class of weapons based on the flamethrower concept but with a cooling rather than burning effect.
Additionally to combat fungus and giant insects a sort of chemical spray could be added in similar delivery get-up, maybe even acid. Bonus points for vehicle mounted equivalents with 100L tanks of substance in question.
e/ looks like there already is a makeshift chemical thrower. had no idea!