Question
Black Walnut Tree Grow
I have attached pictures taken of my black walnut tree, in my back yard. My tree is 5 years old and has a growth(?) on the tip of almost all of the branches. From the pictures you can see that these growths have appeared as the nuts are almost ripe. I am afraid that they might be some kind of insect eggs. Could you identify the growths? These are not the flowers that appear in the spring that cause the nuts to grow.
If you can identify the growth and they are pests, what action should I take to save my tree?
Thank you for your help.
AnswerIt is one of the leaf gall insects but there are many and I can only guess which species this is--I think maybe wooly leaf gall or possibly coral leaf gall.
They are caused by a tiny wasp insect. The wasp lays its eggs on the leaf bud and the eggs hatch and the tiny larvae drill into the leaf and secrete a chemical that forms the wooly gall. The insect has gone by the time most people see the galls. The galls really do little damage to the tree. The leaf will turn brown where the gall is and may drop prematurely. On a small tree they could cause some growth loss but not enough to harm the tree. To spray for the insect you would have to spray just before the leaf buds break in the early spring. It is not worth the effort since the tree is not damaged. I would fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb of fertilizer per inch of trunk diameter--scatter this evenly around the tree and water in good. The population of wasps varies greatly from year to year so next year there may be no sign of them at all. This will make the tree healthier and even if all the leaves were infested there would be no growth loss.
