'sanitizing' larger trees seems to slow it down, but you can only take out so much wood, alive or dead. Sanitizing the area around the tree is also a good idea; removing the old leaves and twigs mainly. I am applying this concept to the small ones too. I think site is a big factor - they want lots of sun! If not enough, or if the site changes with light or water during the first bunch of years, they become weak and get the blight or canker. Lots of info out there about Nattrasia and Fusiococcum (sp?), but not many solutions for control. We have fields of root sprouts around here, full of blight and canker. I'm fooling around with thinning the sprouts, picking the strong ones and keeping the site clean. Arbutus is a successional tree, so they are inherintly weak. The odd one in a good spot by the ocean gets good and big, but most of them get shaded out eventually.
I'm all ears for more info too!
