Galls are interesting structures that form primarily in trees as swollen masses of abnormal plant tissue caused by fungi, bacteria or insects. There are many different kinds of galls primarily caused by wasps, flies, and aphid insects. Good news is that  they are usually more cosmetic than damaging. However, heavy populations of galls indicate stress in the host trees.

Tiny female gall wasps or cynipid wasps pierce twigs or leaves with her egg laying devices and deposits an eggs inside the plant tissue. Fluids deposited with the egg, and produced by the larva cause the plant cell multiplication process to begin. The larvae develops within a cavity inside the gall, feeding on material produced in the cavity lining. At maturity, the larva transforms into a pupa, and later becomes an adult that chews its way out of the gall.  By causing  trees to form  galls, the gall wasp has provided food and shelter for its offspring.  Although unsightly, most galls are not considered very damaging. Natural control is biodiversity. Healthy plants to have fewer galls. Improve the general health of trees using the Basic Organic Program.

The galls below on the back side of the live oak leaves are no serious problem unless there is a heavy infestation. In that case the tree is definitely in stress for some reason. Apply the Sick Tree Treatment and the population of these galls will diminish.

Remember that the most important step of the  (Sick Tree Treatment) STT is to expose the root flare of the tree.

 Here are some of the interesting galls you will see in trees.