Starting in July 2022, a number of iNaturalist observations made near San Diego showed Rhus integrifolia with a broom-like proliferation of pink buds. Because of the host plant, the timing, and the location, these observations were initially identified as caused by Leptosillia pistaciae (Pistachio Canker). However, the symptoms described and photographed in the 2018 article by Vitale et al. describing pistachio canker (under the name Liberomyces pistaciae) were not a match.

As of when this page was created at the end of 2025, the cause of the brooms remained unknown.