Pics would help. Lots of pines have yellow needle tips this time of year, and it's usually pretty normal, but there could be something else going on. As others have noted, reducing the nitrogen at the end of the growing season isn't necessary, though I doubt your problem is related to lack of nitrogen. Fwiw, I feed 20-20-20 miracle gro with fish emulsion right through the growing season until we get our first frost.