When the infestation is as bad as it is, I don;t think foliar applications would have a chance of any success.
I recently read about Brian Head, Utah, where 95% of the trees are dead. I've never skiied there, now I'd be far less inclined to go.
I was at WP back in 92 for a media gathering when I was doing lots of ski photography....some nice skiing for sure, and very nice marketing folks..Joanie Christiansen especially was a fun lady and a good skier too boot. It would be shame to lose those great spruce woods and glades. Skiing the trees is one of my favorite pursuits!!!!! Kinda makes sense, eh!!??