Tree diseases in the US

Hi, this is Derek Babcock, and welcome to my blog!  
I started this with,  the hope of starting discussion about the amount of trees that are diseased and dying,  not just where I live in Eastern WA,  but in the rest of the US as well. 

I've been a Washington State licensed lawn and tree applicator for almost 30 years, and an ISA certified arborist of almost 15 years.  Much of that time has been spent identifying,  diagnosing and treating diseased trees. In that time, I have never seen as many diseased trees as I see today.  Where I live, there are so many so many Pines and other conifers with needle blight that it is just astounding!  In previous years, I have seen some major disease outbreaks, such as the Shoot Blight that killed many Aspen trees here in Spokane several years ago, but nothing compared to the Needle Blights (Red band needle blight, Dothistrama needle blight) that is occurring over the last 3 years here in Eastern Washington.  You cannot drive down a street in Spokane, for even a block, and not see a diseased Pine, many of them very seriously, and quite a few are dead.  I am also seeing the same with many other conifers, such as Grand, Alpine, and Douglas fir,  and Spruce.  Other Pines such as White and Lodgepole are affected as well.     
I have noticed this throughout the area and it isn't stopping at any state borders.  I have seen it happening in Northern Idaho, and even in Montana where  I recently traveled to Glacier National Park. Traveling over to the western side of the state this spring, I saw literally thousands, (millions?) of young firs turned red/orange with blight, dead.
I have successfully treated the disease with a systemic fungicide and newer penetrating surfactant that is very effective at stopping the disease if treated early. I feel fortunate to have helped many homeowners save their trees, but the amount of trees that are infected , dying and disfigured alarms me.
I am aware that there are major tree disease outbreaks in other areas of the country as well, such as in California, where Sudden Oak Death is killing millions of Live Oaks, and others.  I understand that this may have started by some plants that were brought in by a nursery from overseas, and then infected local Oaks, which had no resistance to the disease. I recently read that the Mountain Pine beetle has in the last several years, killed so many pines in North American that they would fill an area the size of Washington state. Apparently, this has ben attributed to climate change, so the insects are attacking trees at altitudes that they would not have previously, and they are breeding faster.
Back to Needle blight in the Northwest US.  I have not seen or heard if there is a consensus about what is contributing  this huge outbreak. Anyone?