Aspen Twig Gall
May 14th, 2019
Aspen, cottonwood, poplar.
Galls (swellings) in the new growth of branches give the branch a “knobby” appearance. The damage is caused by an insect.
Little is known about this insect but it is thought to infect the new growth soon after the buds break in the spring causing the resulting gall.
as of yet there is no recognized treatment to prevent the galls. It is thought that spraying the base of the tree in April with Diazinon may control the damage. The galls do not adversely affect the tree greatly if it is otherwise healthy.