We have a white fluffy mass on the bottom of the leaves. Wondering what it is and how to control it.
Thank you for contacting the Toronto Master Gardeners concerning your Beech Tree.
From your photo it appears that your beech tree is suffering from an attack of woolly beech aphid (Phyllaphis fagi). This type of aphid has only one host and that is the beech tree.
The following information is from one of our archived posts:
“Woolly aphids get their name form the fluffy, wax-like substance that covers their bodies. At first glance you may mistake this for fuzzy mold. These aphids are pale yellow, sap-feeding insects, which are covered by fluffy white fibers, forming dense colonies on young shoots and the underside of leaves where they tend to congregate. Often large numbers of the molting or cast “skins” will be attached to leaf hairs, which gives the leaf a whitish appearance.
These sap-sucking pests generally use two hosts: one for overwintering and laying eggs in spring, and one for feeding in summer. Woolly aphid insects generally feed in groups. They can be seen feeding on foliage, buds, twigs and branches, bark, and even the roots. Damage may be recognized by twisted and curled leaves, yellowing foliage, poor plant growth and branch dieback. Aphids exude a sticky substance called honeydew. If left untreated, plants may become covered with sooty mold, an unsightly black fungus that resembles soot. Though this does not normally affect or damage the plant itself, getting rid of the aphids and their honeydew will help control the sooty mold.
Natural enemies such as lacewings, and parasitic wasps may help to control aphids, but may not appear in sufficient numbers until aphids are abundant.
The best solution to ridding your tree of these pests is your garden hose set on full blast. Spraying them will knock them to the ground and they will be unable to return to the host. Do this every few days until you no longer see any signs of them. Where aphid infestation is abundant you can use insecticidal soap, which is available at your local garden center. Make sure to follow directions on the label. Repeated treatments of both the upper and lower surface of the leaf are necessary in order to control your infestation. You may wish to contact a certified arborist to apply the soap. To find a certified professional arborist in your area to help you visit the Ontario branch of the International Society of Arboriculture here.”
Additional information on this pest can be found at the following link : Woolly Beech Aphid
Good Luck with your beech tree.