I wouldn't use a citronella collar. Many humans think they're more humane than a "shock" anti-bark collar, but I doubt that's true considering a dog's ultra sensitive nose, and considering the fact that citronella lingers and lingers in the air.
I'm not totally against "shock" anti-bark collars, although I do think they should be an absolute last resort after other training methods have been exhausted. At least with them the correction is quick and over with, not lingering like with the citronella.
Spray bottles seem to work on some dogs, but of my dogs and foster dogs only a small minority have viewed a spray bottle as aversive. The majority seem to think getting sprayed is good fun. And of course a spray bottle doesn't work when you're not there. And keep in mind that in the best case scenario all you're likely teaching the dog is to not bark in your presence.
