We have a wonderful old Maple of some variety on the street facing, western side, of our house not too far from Ceder Vale Ravine.
It is about 3 or 4 stories high and has a canopy about 35 feet across at the top.
we noticed discolored leaves on the lower branches and this year have seen bulbs of some sort forming.
Can you help me Identify the disease causing this?
Thank you for contacting TMG about your tree. Based on the leaves in the photo and your description of size, I believe you have a Silver maple (Acer saccharinum) which is a tree native to Ontario. They are lovely trees!
The little “bulb” on the leaves are called galls and are formed by tiny mites. Maple bladdergall mite (Vasates quadripedes) is the most likely culprit here. This Government of Canada factsheet provides information and photos of the galls. I have excerpted part of the information below:
“The maple bladder gall mite causes the formation of a mushroom-shaped gall. The green or pinkish-red galls appear on the upper surface of the leaf and, if numerous, may cause the blade to bend.
This mite, which has several generations per year, overwinters as an adult on the trunk or branches. The female feeds on the swelling buds, causing them to produce a mass of excess cells (gall) that enclose the invader.
The females lay eggs inside the gall, and newly hatched larvae feed on the gall tissue and complete their development. The adults exit the gall through a hairy opening on the underside of the leaf in search of an overwintering site. They may also produce additional galls if the leaf tissue is favourable to their development. The maple gall bladder mite is believed to overwinter as an adult.”
Another good source of information about different types of galls may be found here.
The good news is that while they may appear to varying degrees every year, the galls should not affect the health of your beautiful tree.
June 26, 2024