Barking at people when out (mainly men)

[jaynedogs]

Hi newbie here. Wonder if someone on here in the know could give me some advice. We adopted a rescue springer almost 4 months ago, she is well behaved in the house, very loving with kids, cat other dogs, but! she will bark at stranger's mainly men whilst we are out and about. not jogger's and not women in general, unless they are stood still, on mobile phone etc. poppy will also do this if we see people in the fields where we walk, when she gets to know the people (if reg dog walker) she is fine. I would like to know how to deal with this. I dog walk part time, so Pops gets lots of nice walks daily. At night when she has her last walk, she can bark if strange men come past, I know she is not keen on the dark. I have tried to get her to focus on me when I see someone approaching, but I am never really sure if she is going to bark or not. We are her third owner's at least. She does not do this when I pick my son up from school now, but did bark at men to begin with, when we did the school run, but I praised her and asked some of the dads to give her a treat that I had in my pocket, and she is fine in that situation. Sorry for long first post, but I would like to address this asap. What am I doing wrong? Ps. None of the dogs I walk (job wise) do this.