Hi Steve,
I am just wondering what your own reaction is when this happens. If you start making a fuss , pulling him back on the lead, shouting at him etc. you are giving him attention (negative).
What i would try doing is when you see another dog comming stay clam ,say nothing and keep walking, when he does make a lunge give 1 sharp pull on the lead and say "NO" and keep walking forward.
Stay calm ! if you get excited and anxious the dog will too.
DONT USE THE STICK !!!!.
I hope this helps.
Regards,
Shane.