The worker, identified as 27-year-old Gerson Hernandez of Van Nuys, died about 30 feet up a palm tree in the 1400 block of North Martel Avenue shortly after noon.
Tree trimmers are typically harnessed to palm trees as they cut away dead fronds, which form a ring around the trunk and can suddenly break loose and slide over the person. Investigators said Hernandez was found pinned to the trunk.
An autopsy is pending.