Maple, lime, and plum trees dying
About four years ago my neighbor's huge pepper trees started to die. Two years ago these four-foot-thick trees had to be cut down. Two years ago, on an adjacent lot, a pine of about the same diameter started to turn brown. The pine is now dead and has to be removed. A smaller tree on another lot has turned brown and is obviously dying or dead. Last year a 12 year-old Japanese Maple in my backyard started to have dead branches. That tree is now obviously dying. Two years ago a 37-year-old plum tree in my front yard stopped bearing the accustomed amount of fruit. This year the tree bore "cherry-sized" fruit that dropped early. The tree itself has not leafed out as usual. This year a 35-year-old lime tree in my backyard has not borne its usual crop nor has it sprouted out as normal. Now! Here are the obvious questions. Do we have a tree plague that has invaded our area? (We live near the Bay close to San Francisco.) Why are the trees dying? What are possible solutions?
My gut tells me that it may be Phytophthora Root Rot, though it is not often that it affects such a wide area. It spreads through the soil and spreads best in wet conditions. Here is more information on it: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74133.html
If it is not Phytophthora Root Rot, it sounds like it is certainly some other soil borne disease. It would be best to consult your local extension office to see if they can determine what it may be.