Growth on leaves

Asked August 12, 2015, 9:55 AM EDT

Found these (see picture attached below) on leaves of several bushes and trees in our backyard. The leaves are shriveling. Any idea what they are and what we can do about them?

Jefferson County Colorado

1 Response

This looks like the hackberry nipple gall, which is caused by insects. Please see this Colorado State Univ. Cooperative Extension fact sheet for more information on galls. You'll see a picture of the hackberry nipple gall on the first page.
Generally, no treatment is recommended as populations fluctuate. Also, gall makers rarely harm trees and shrubs.