Take note of odd things to learn and remedy problems

Lilac broom and oak canker. Found 'em while pruning, took pictures, went home, researched them...

The broom is caused by a microorganism and will gradually kill the shrub. Common lilacs are tolerant of it but many of the others including dwarf 'Miss Kim' (Syringa pubescens patula) and tree lilac (S. reticulata) are susceptible. Ash trees (Fraxinus) are also susceptible.(We in ash-less, emerald ash borer infested Michigand tend to be surprised to realze that some regions still have thriving ash trees.)  So don't prune between a lilac that shows these symptoms and any other lilac or ash without sterilizing your clippers and saw.

Belw: The proliferation of weak and dead twigs at the base made us say, "What?!"

Below: When we got home we searched our books and on line for the keywords lilac/Syringa, proliferation twigs/broom.

Thank you, University of Minnestoa Extension!

 

Oak cankers

Oak canker fungi get a start on weak young (barkless) twigs. Unless the majority of branches are affected, it's not a big problem for the tree, which outgrows an infection or sheds badly damaged twigs. This tree was indeed letting the few affected branches atrophy; we pruned them out but the tree was doing that naturally!