I just had some cypress trees dry out and die on my property. I was told it was a root fungus, but who knows, because two other arborists told me something completely different.
But I got to thinking, these particular trees I once had to water by hand since the sprinklers weren't working for a while. And when I was watering them, it wasn't just at the base, I was also spraying water up into the tree itself, into the bark, etc.
Could it be that this somehow washed away a protective coating or something that caused them to die?