Not much you can do late in flower but hold on to your butt and try to get through it.. You can use Dutch Masters Gold and Penetrator to keep it at bay late in flower, but you gotta spray buds 2x a week and about 3 days til harvest and it's godawful expensive and you have to apply a ton of it. There's also Green(something? Guys, help me out here..) that's late safe, will do the same as DMs, but burns hairs.. Then there is milk/baking soda/lemon juice (and all the other ph changing homemade solutions out there) that don't work for beans. Sulpher burners that are awful and, of course, myriads of folk telling you your atmosphere control sucks (which, once you got pm, counts for crap and does nothing but make you sick of talking to people, lol)
Look up Eagle20EW and buy a bottle. Here's the pros and cons...
Pro: You will never (EVER) have to deal with pm of any kind ever again.
Con: It's systemic.
Pro: Only use in veg and it will never show up in your bud at harvest.
Con: If I remember right, it's like $60 something..
Pro: 1 spray, 1 kill, and you use very, very little product at all..
Con: you have to buy a big bottle that you will never, ever even dent unless you share with everyone.
Pro: Your friends will love you because they get theirs for free...
Con: Hmm....
Pro: You will never (EVER) have to deal with pm again.
Now you are the guy that tells other people what their options are when it comes to fighting pm