The horned oak gall is a golf ball-sized growth caused by a small wasp insect (Callirhytis cornigera) which can cause extreme disfiguring and dieback of certain oak species. They are often found on young twigs and have protruding horns through which young females emerge to continue the cycle.
The horned oak gall wasp occurs from southern Canada and throughout the Midwest. It attacks the twigs of pin, scrub, black, blackjack, and water oaks. Infestations on young trees can be the most devastating, but older trees will be dangerously affected as well. Galls prevent nutrients and water from moving into new growth, resulting in severe dieback.
Treatments for Horned Oak Gall
Trunk injection with TREE-äge® (Emamectin benzoate) or TREE-äge® G4 will provide both preventative and curative control depending on the time of year treatment is applied. We recommend treatment in September of this year, or early spring next year. Treatment in September will reduce early pest damage next spring. TREE-äge will provide control for a minimum of a year, and potentially up to two years. Treatment are very effective in managing stem and twig insects when applied as a dilute injection prior to spring insect emergence. The most effective treatments are applied to trees at risk of infestation. Treatment will prevent new galls but will not eliminate old ones and will additionally protect your trees from up to 51 other pests.
Call Rite-A-Way Tree Service for a Free Quote: 314-427-7325. Let Rite-A-Way properly treat your tree to help keep it healthy and increase its longevity.









