Q. Is there a way to prevent sweet gum tree (Liquidambar styraciflua) fruit from developing?

A. The answer is yes, but it is probably too expensive and too much trouble.

Although there are chemicals that can suppress fruiting on sweet gums, preventing fruit on large, well-established trees is not practical. The chemicals available are hormone-based products that can help reduce fruit set. Applications usually have to be done by a professional arborist.

The first product is ethephon, which is sold as Florel Brand Fruit Eliminator®.  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. Ethephon must be applied at just the right dosage, at just the right stage of flowering (full bloom) and at just the right temperature range; there is risk of plant damage if dosage or temperature are too high.  Because the product must be sprayed on, complete coverage is easy on large, mature trees.

There is another product called IBA or Indole butyric acid which is sold asSnipper® . This product is only available to professionals. It must be injected into the tree while the flowers are still in bud stage in the spring. The micro-injection system used requires a skilled applicator. Timing and dosage are critical. The treatment must be done annually.

You might want to contact a certified arborist for estimates on both of these methods.

Personally, I recommend people learn to live with sweet gum fruit or remove the trees. One way to mitigate the annoyance of the fruit dropping is to mulch sweet gum trees to the drip line. This way most of the fruit falls into the bed under the tree and becomes mulch.