We’re thrilled to celebrate the incredible success of the tree-of-heaven scouting portion of the Invasive Species Scout Project. Thanks to the passion, curiosity, and dedication of our UC Master Gardener volunteers, this community science initiative surpassed all expectations. Over the past year and a half, UC Master Gardener volunteers created one of the most comprehensive tree-of-heaven maps in the state, proving that when volunteers unite around a shared purpose, extraordinary things can happen.

Volunteer-Driven and Statewide in Scope

With over 320 specially trained volunteers participating across 45 counties, the project yielded more than 5,500 mapped sightings of Ailanthus altissima, commonly known as tree-of-heaven. Volunteers completed self-paced eLearning modules to prepare for the field, gaining the skills needed to identify tree-of-heaven and use our digital Invasive Species Scouting Tool to report their findings. These reports contributed to one of the most detailed distribution maps of this invasive species that California has ever seen. Each data point submitted helps researchers and partners like the California Department of Food and Agriculture (CDFA) monitor the spread of tree-of-heaven, an invasive plant that is the preferred host for the spotted lanternfly and stay ahead of the potential spread of this high-priority pest.

Many Paths, One Mission 

The mission was simple but critical: correctly identify and report sightings of tree-of-heaven across California. Volunteers embraced this goal in a variety of ways, some organized monthly scouting events, others documented sightings during their daily routines, and many deepened their knowledge through our eLearning training modules. Whether they submitted one report or hundreds, each volunteer played an essential role in building this statewide dataset. The project has since been recognized by the CDFA as a model for effective, Master Gardener-led early detection, monitoring, and reporting of invasive species.

Looking Ahead: New Opportunities on the Horizon

Although this chapter is closing, the story is far from over. Tree-of-heaven scouting is being retired to make room for new developments and new species-focused efforts. We’re actively exploring future partnerships to continue expanding scouting opportunities and outreach around emerging invasive threats.

Thank You, Scouts!

We want to thank every volunteer who participated in this groundbreaking project. Your dedication laid a strong foundation that will support future research, outreach, and education. 

Stay tuned for what’s next! The success of the tree-of-heaven project proves what’s possible when science and community work hand in hand.