Chemical use for stopping olives varies

Question: When is the best time to spray olive trees to minimize olive fruit? One of our olives can make a mess on our neighbor’s front sidewalk and entry patio if not sprayed.

Olive flowering peak is around mid-April. The usual homeowner chemicals are Olive Stop and Florel Fruit Eliminator. They work a bit differently.

Florel can be applied once before the flowers open, but Olive Stop must be applied two or three times. These times are when flowers are first opening, again when most are open and a third time when the late ones are opening.

The spray schedule for Olive Stop can last up to two weeks depending on air temperatures. Cooler weather causes flowers to open more slowly than hotter weather. This causes our spray season for fruit control to be longer.

For flower and pollen control, Florel is probably a better choice, but it is a bit more toxic to the trees than Olive Stop. For just fruit control, Olive Stop is fine. Any plants beneath the trees should be sprayed with water immediately after these chemicals are applied to remove what falls on the leaves and minimize any damage from the spray.

With Olive Stop, the chemical has to get inside the flowers as much as possible. This is not necessary with Florel. Watch for sales on these products as we get closer to April.

Commercial applicators have a little bit more selection because they can use products that you can’t. They have products called Embark and Maintain, which are different from homeowner products.

Remember that olives coming from trees that have been sprayed should not be used for human consumption.

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com.