Drop Olive Fruit with Chemicals but Don’t Eat Them

Q. Last year our Olive tree had lots of fruit on it and
was very messy. Can you tell me when we should spray the tree to keep it from
fruiting next time?

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

European Olive flowers

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.

European olive flowers growing in the axils of the leaves

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 reach 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 these chemicals do not prevent flowering but only the production of fruit. To prevent flowering (pollen) use chemicals such as Maintain, a chemical normally applied by professionals.

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