Q. I have some birch trees that are troubled by an insect.
What do I do that we are now not able to use pesticides in Ontario? Any suggestions?
A. Having researched the problems with birches, and come to the conclusion that you may have a European birch ‘Youngii’ or Betula pendula ‘Youngii.’ This ornamental tree is quite beautiful with lovely yellow fall colour, but it is a tree that requires more maintenance in the form of spraying than other trees in the birch family.
The tree has a history of being susceptible to the bronze birch borer, which bores its way into the sapwood of the tree, lays eggs in the trunk or branches in August and goes through four instars (stages) over a period of two years. It then exits, leaving a ‘D’ shaped hole in a six-week period, beginning in June and ending in July. The tree will have swollen areas of the trunk, and leaves will be chloric or yellow.
Only a certified arborist could make the final diagnosis of your tree. Having done that, the arborist will know what treatment can be made to your tree. The arborist will have a license for treating your tree.
Find a certified arborist near you on the Landscape Ontario Find a Company page.
I hope this answer helps.
Valerie Liney
Lake Simcoe South Master Gardener
