I am undertaking a big landscape job here on Puget Sound, and there are a lot of young paper-birches with birch gall on each side of the property, mostly twelve to eighteen foot little trees, each with at least a few "knots" in the higher branches, some with a great many of these knots. I have to make the decision whether or not to remove all these birches, & am leaning toward replacing them with fruiting trees. But before I start getting rid of two dozen young trees, I would welcome opinions from anyone with experience with birch gall, since this is my first encounter that I personally had to do anything about, & I'm not at all certain what's best. Some questions:
Can the birch gall mites infect any other shrubs & trees other than birches?
The gall isn't apt to damage the longevity or general health of the tree, but I gather it can make the leaves look pretty crappy. If some or all the birches are left where they're at, will foliage look pretty decent even with gall?
I also gather that miticides don't work very well even for the non-organic gardeners who don't mind using them. I don't want to use such chemicals, but wonder if there are any risks to just ignoring the presence of birch gall mites?
Is the standard advice to remove & replace these trees to be taken seriously?
If I do remove these trees I want to do it now while the mites are dormant & I have a better chance of burning every one of the little bastards. I'm hoping they're not apt to attack the ornamental maples or fruit trees since usually each gall is species-specific & no future birches will be planted. If they are by & large harmless, though, I could view the two- & three-inch knots in the branches as being themselves rather ornamental.
-paghat the ratgirl