Question
Picture 1
Hi,
And thank you in advance for your answer. Your time and expertise is truly appreciated.
I have a stand of trees in my backyard, I'm not sure what type they are and I've notice a growth of something on many of the leaves. I've attached a picture. Is this something that I need to try and get rid of or is this a normal thing.
Thank you again!
AnswerThis is a elm tree and the growth is an Elm Pocket Gall (Aceria ulmi)
The Elm Pocket Gall is produced by small mites that belong to the genus Eriophyes. The green to reddish, elongated galls are produced on the upper surface of American elm leaves. Gall growth is perpindicular to the surface of the elm leaf.
These mites overwinter in bark crevices of the host as fertilized females. Gall growth is stimulated in the spring by the females injecting saliva into the new elm leaves. Mites then move into these galls through open pores on the underside of the leaf. Several generations are completed during the summer. The last generation of the year is produced when the leaf tissue hardens in the fall.
These galls produce little damage to the host plant and therefore, control is rarely warranted.
