Oak Decline
Periodic occurrences of decline and death of oaks over widespread areas have been recorded since 1900. These outbreaks, variously named oak decline, oak dieback, or oak mortality, are caused by a complex interaction of environmental stresses and pests and given the name oak decline.
The link address is: http://www.na.fs.fed.us/spfo/pubs/fidls/oakdecline/oakdecline.htm