They were still there after a decade, and I suppose they are still.

Many hickory galls are caused by the feeding of aphid-like insects called phylloxera. One species produces pouch-like growths on twigs and leaves.

Severely infested foliage often turns a yellow-brown color and drops from the tree. The pouches open and phylloxera leave the galls in early summer to continue their life cycle. Mar 13, The hollow galls contain the young aphids. In July, aphids reach maturity and leave the galls, which turn black.

Some eggs remain over winter in the old galls and in crevices of the bark. A spray of insecticidal soap, just before the buds swell, will help reduce the numbers of pests. If you repeat this treatment several years in a row, you will be able to significantly reduce the population, and the damage to your hickory tree.

Galls on trees are caused by insects laying eggs inside or feeding on the branches of leaves of trees and other plants. This usually occurs in the spring. The galls, or tumor-like growths, are produced by the tree in response to chemicals injected into it by an adult or larval gall-making bushnotch.bar Jun 16, The damage caused by the galls is primarily aesthetic and does not harm the host tree. Infested leaves may dry out and drop prematurely as the galls dry out.

Hickory gall phylloxera overwinter in the egg stage within the dead female’s body in cracks or crevices of bark, old galls, or fallen leaves. Feb 25, Hickory Tree Diseases. Hickory trees are extremely tough and resilient to disease when they are healthy, and the following are some of the diseases to watch for: Hickory Anthracnose/Leaf Spot – The symptoms include large reddish spots on leaf tops and brown spots underneath.

When an infection is severe, early defoliation may occur.

Oct 13, Here are some recommended trees for us lazy landscapers, but keep in mind that while these trees don't shed as drastically as the five listed above, they do still drop leaves, fruit, flowers, etc. The only truly no-maintenance trees are the ones made of plastic (and even those require a little dusting from time to time!).Images. Sep 01, A reader asked why her oak tree was losing all its leaves summer. If your tree is losing leaves in early summer (June) or late summer (August), find out why.

We outline why oak, maple and ash trees lose leaves in summer. Or if you're seeing tree leaves lose leaves early in the fall, click here!