Experience combating olive fruit flies with Surround WP?

[Rrr]

I have 25, 5 year old, 8' tall Mission and Manzanillo olive trees. Good production of olives in the past few years, but the fruit fly is becoming a big problem. Last 2 years all olives we tossed out due to this. Used Monterey Garden Insect Spray with spinosad last year, but didn't help much. An alternative is Dow GF120 (spinosad), but it's so expensive. I also see Surround WP, a 'clay covering' type of spray-on stuff.
Does anyone have experience with this Surround WP product?
We live at 1500 elevation outside of Sacramento, CA.
Thanks

 

[headfullofbees]

Spraying olive trees with seaweed extract helps keeps pests at bay.