Spindle Gall Treatment: How to Get Rid of Those Unsightly Growths on Your Trees

If you have noticed small, round bumps on the branches or twigs of your trees, chances are that they are spindle galls. These unsightly growths are caused by a tiny insect called the cynipid wasp and can be found on a variety of tree species, including oak, maple, and willow. While spindle galls do not usually cause significant harm to trees, they can be an eyesore and may affect the tree's overall health if left untreated.

What Are Spindle Galls?

Spindle galls are small, spherical growths that develop on the branches or twigs of trees. They typically range in size from 1/8 to 1 inch in diameter and can be green, yellow, or red in color, depending on the tree species. Spindle galls are caused by the cynipid wasp, which lays its eggs inside the young buds of the tree. When the eggs hatch, the developing larvae secrete chemicals that cause the tree to form the characteristic gall around them.

How Do You Treat Spindle Galls?

If you have noticed spindle galls on your trees and want to get rid of them, there are several treatment options available:

Prune Affected Branches

The simplest way to remove spindle galls is to prune the affected branches. This method is most effective when the galls are still small and have not yet spread throughout the tree. Use sharp, clean pruning shears to cut off the branch just below the gall, making sure to sterilize your tools between cuts to prevent the spread of disease.

Apply Insecticides

Another option for treating spindle galls is to apply insecticides to the affected areas. This method is most effective when used in combination with pruning, as it can help kill any remaining larvae or adult insects that may be present in the tree. Look for insecticides that contain imidacloprid or thiamethoxam, as these are effective against cynipid wasps.

Use Natural Predators

If you prefer a more natural approach to controlling spindle galls, consider introducing natural predators into your yard. Birds and parasitic wasps are known to feed on cynipid wasps and can help keep their populations in check. You can also try planting companion plants that attract beneficial insects, such as yarrow, dill, and fennel.

Avoid Over-Fertilizing

Finally, one of the best ways to prevent spindle galls from forming in the first place is to avoid over-fertilizing your trees. Cynipid wasps are attracted to trees that are stressed or weakened, so make sure to provide your trees with adequate water and nutrients without overdoing it. Avoid using high-nitrogen fertilizers, as these can stimulate excessive growth and make your trees more susceptible to infestation.

Spindle galls may be unsightly, but they are generally not harmful to trees. If you do decide to treat them, however, there are several options available, including pruning, insecticides, natural predators, and proper tree care. By taking a proactive approach to spindle gall treatment, you can help keep your trees healthy and beautiful for years to come.

Spindle galls on tree branches

Spindle Gall Treatment, pruning, insecticides, natural predators, proper tree care