Pine trees shed needles in the spring and fall (more in the fall than
in the spring, I've noticed). If only some of the needles are turning
brown and falling off, the trees may be going through their annual
shed cycle. If all of the needles are turning brown and the trees look
completely dead, then it's something different.

The white pines, jack pines and red pines growing on our property here
in Wisconsin are going through their shed cycle right now.

A few years ago, a row of pine trees planted next to a golf course on
a major highway in this area turned completely dry and brown from road
salt. The trees were about four feet tall at the time. I thought they
were dead. I figured there was no way they could recover. Today they
are growing and thriving and look as though nothing had happened to
them. Amazing.

LeAnn
http://ruralroute2.com