My serviceberry is covered with white fluff on the underside of most of its leaves. It is producing berries at this time. I have sprayed the leaves they’ve using a product by Safers. This problem happens every summer. The tree is very sparse with branches. Any advice as to his best to save my tree?
Thanks for contacting Toronto Master Gardeners. Based on your description of the white fluff on the underside of the service berry leaves, it seems the tree may have an infestation of woolly aphids. These insects suck sap from leaves. They generally do not do permanent damage to trees because their numbers are controlled by natural predators such lacewings, ladybugs and parasitic wasps. An option is to try to attract a higher number of beneficial insects such as ladybugs, lacewings, parasitic wasps, or damsel bugs to your garden. They will attack the aphids. Planting mint, fennel, dill and yarrow to will attract these beneficial predators to your garden.
For more information on woolly aphids please review the following sites:
https://www.buncombemastergardener.org/tag/serviceberry-tree/
https://www.gardeningknowhow.com/plant-problems/pests/insects/woolly-aphid-control.htm
The sparseness of the branches on the service berry may pose a more serious problem. Generally service berries do best in full sun or partial shade in a moist, well-drained soil. Serviceberries can adapt to living in alkaline or neutral soils but it prefers to be planted in acidic soils. These trees do not do as well in clay soils.
The sparseness of the tree could be caused by root rot related to over-watering or the need for fertilization. It may be worth your while to have a tree professional assess your tree to identify the cause of the sparseness.
To find a tree care professional please refer the Landscape Ontario web site: https://landscapeontario.com/find-a-company