The direct injections of kalk paste seem to have done the trick. I'd say about 90% of the majanos I injected are gone. The ones that didn't die are big, so maybe I need to use more.
It's a pain in the butt to find and inject each one individually, but it seems to have worked. I will have to spend more time on it this weekend, hunting them down. I have a lot more left in my tank.