Question
I have cedar trees that line the edge of my property. The gravel in the driveway has turned a rust color, the needles on the cedar trees are also a rust color. Is it possible the cedar trees are causing this rust?

Answer
Brian

It sounds to me like there is a connection between the two.

Normally the rust on gravel is caused by fertilizer.  The chemicals in fertilizer will cause this discolor.  Or overspray from the irrigation system will sometimes cause this.

Your trees may be reacting to chemicals that have recently been introduced to your lawn or the tree itself.  

They may also be reacting to a drought in your area if there is one.

Sorry not more helpfull.
James