mom/teacher:

Black knot cannot be got rid of once established. Infected limbs should be pruned off cleanly well below the infection. If this ruins the tree, then it's time for a new tree. Infections like black knot are best dealt with by prevention, not cure, and about the best you can do is dormant spray with a strong copper solution. Even this may not be effective in an area with high disease pressure, and you should tell us where you live so we can better understand what kinds of diseases you may be facing.

Black knot is less common on cherry trees, but still possible. Cherries more often suffer from bacterial disease, which develops limb cankers as it progresses over the years. This can cause limb dieback and the eventual demise of the tree. The prevention recipe is the same, since nothing can cure bacterial diseases once underway.

There are different perceptions of what is sour and what is not. Tart cherries seem sour to some people; others like to eat them right off the tree. The ordinary uses for tart cherries are pies, sauce and other prepared desserts that use some sugar. However, any cherry is edible if it tastes good to you. If not, leave them for the birds. If you want to plant a cherry tree of known characteristics and quality, order in from an online or mailorder nursery that can clearly identify the variety you are planting. No point in waiting years without knowing what kind of fruit will be produced.

Don Yellman, Great Falls, VA