Question
Kalina Post Oak Leaf 3
I have a very mature Post Oak. Some damage was done to it during construction of our home and it has recovered nicely over the last 4 years. This year we had a hard freeze right when it was starting to bloom, then a few weeks later a bad hail storm. She looked pretty beat up for awhile and now there are these yellow balls that are attached to the leaves. Some type of growth. Almost looks like a spider egg, but bright yellow. They are hollow, nothing inside, just a light fiber to keep its shape. (See attached photos) I asked all around, did numerous web searches and can't find anything about it. Is this some kind of disease or infection? If so how can I treat it? Please help, I sure hate to loose this beautiful old giant.
AnswerLooks like a gall insect called oak apple gall.
This is one of many leaf galls that affect oaks. These galls usually damage the tree less than do twig galls. However, heavy infestations of this and other leaf galls can cause premature leaf fall and are unsightly on ornamental trees.
Adults are very small and dark cynipid wasps with an oval, compressed abdomen. The larvae are small and globe-shaped.
Galls are about .5 to 2 inches (12 to 50 mm) in diameter, and are filled with a fibrous mass. Each contains a single larva inside a hard center capsule. The galls are produced on the midrib or stem of leaves. Galls formed during spring are green, but become light brown on drying with a thin, papery shell. Oak-apple galls occur principally on red, black, and scarlet oaks.
Oak-apple galls, usually initiated during spring when the young leaf is being formed, sometimes appropriate the entire leaf for its own purpose. The biology is poorly known, but it probably has alternate generations on different host parts.
Natural enemies are usually sufficient to control wasp populations. Galls can be picked or pruned off small ornamental trees.
They generally cause very little health problems with the oak tree. The only thing they could cause is a leaf fall sooner than normal. Really nothing to worry about.
Here is a web site that will give more information on oak apple gall.
http://en.wikipedia.org/wiki/Oak_apple
