Q: We recently purchased a brand new home and are extremely happy there. Our only problem is that we inherited a very large sweetgum tree in the back yard. My husband works hard to remove the sweetgum balls, but it seems to be a never-ending task. Is there something we can do to eliminate the production of the sweetgum balls other than removing the tree? The tree is beautiful and offers lots of shade so I wouldn’t mind keeping it, but we absolutely detest the spiny little balls that are covering our back yard.
A: The spiky seed pods of the sweetgum tree are a nuisance to many gardeners.
It is theoretically possible to eliminate the balls each year but it is a difficult process. The chemical ethepon (Florel) releases ethylene gas when it is sprayed onto the tree branches while sweetgum flowers are present in spring.
Ethylene gas is a powerful plant hormone. If the tree is flowering when the chemical is applied, the gas will cause the flowers to drop off. Voila! The tree will be neutered for the year.
The same process can be used to eliminate the fruit on a crabapple, whose progeny might render a sidewalk slippery.
Unfortunately, the entire tree must be sprayed each year and spraying at the right flower stage is critical. Most people find the effort too difficult. If you decide to try, you can purchase ethepon (click for sources).
Snipper is an injectable product that de-balls a sweetgum. It can be used by a homeowner but hiring a certified arborist might be a better solution.
Another alternative for you is to cut down the offending tree and plant a fruitless sweetgum (Liquidambar styraciflua ‘Rotundiloba’) in its place. As you know, the tree is fast-growing and it offers lots of summer sun screen when mature.