Question
Is there any kind of spray to keep fruitless trees from bearing fruit. The Plums on mine were about cherry size. A person at the golf course said someone told him the had to spray his every other year when he lived in Oregon, but couldn't remember what the spray was. Have you ever heard of anything like that as my tree seems to have fruit about every other year.

Answer
The GOOD NEWS is that there are a couple of products designed specifically for preventig fruit formation in ornamental trees such as yours.

"Florel Fruit Eliminator" is made by Monterey Chemical and is available to homeowners. It's very effective in preventing undesirable fruits from forming on landscape trees/shrubs. It contains the active ingredient "Ethephon", which has been around for many years and is also used for commercial tomato production to accelerate fruit ripening/coloring. (see website below for "Florel" information)

In your situation, Florel is sprayed onto the entire tree during the blooming period and the ethylene, formed by the chemical, will cause the blooms to fall off...thereby preventing any fruit from forming.

The other product that can also help eliminate fruit formation contains the active ingredient called Naphthlalene Acetic Acid (NAA) but it could be difficult to find for homeowner use since it is usually available in larger quantities and it is a bit more difficult to use than "Florel".

http://www.montereylawngarden.com/pdf/fr..