Dentists at Wake Forest Baptist Health say that apples, green beans, cauliflower, carrots, celery and other firm fruits and vegetables promote the flow of saliva.
http://www.healthline.com/health/drooling
It could be a matter of learning how to speak without spraying -- saliva is, after all, an important part of both of our immune system and digestive system. Obviously I don't know what's going on, but just wondering if you're sure you have "excess" saliva or if it's a habit of speaking that some people develop.