HARNESSING COMMUNITY POWER: USING CITIZEN SCIENCE TO TRACK THE INVASIVE TREE OF HEAVEN

MONDAY, AUGUST 4, 2025.  BY MARIA ZUMKELLER, MS.

What if we could all help solve one of the biggest threats to our local ecosystems (including agricultural systems), just by using our smartphones?

That’s the idea behind citizen science: a collaborative approach to research that invites members of the public to contribute observations, data, and local knowledge to support scientific efforts. In agriculture, where threats like invasive species move quickly and quietly across landscapes, tapping into this kind of grassroots data collection can be incredibly valuable.

Citizen Science in Lodi

Tree of Heaven (Ailanthus altissima) is an aggressive and fast-growing invasive tree that thrives in both disturbed and urban areas. As highlighted in a recent Lodi Winegrape Commission blog post, Tree of Heaven isn’t only a concern for it’s aggressive nature, it also hosts the spotted lanternfly, a serious insect pest with the potential to devastate vineyards. While the spotted lanternfly has not yet been established in California, Tree of Heaven is its primary host plant. If/when the insect pest ever reaches California, having Tree of Heaven present would make vineyards and orchards more vulnerable, since the pest can thrive on this tree and spread to grapes and other crops.

The challenge we face is that this tree spreads aggressively, popping up in riparian corridors, along roadways, and even in uncultivated pockets within or near vineyards. Knowing where it is, and how its population is changing, can help growers and land managers respond quickly and strategically. But with so much ground to cover, it’s impossible for one agency or organization to track it all. That’s where citizen science comes in…

A Local Tool for a Local Problem

To better understand where Tree of Heaven is growing in and around Lodi, I created an interactive dashboard fueled by data from iNaturalist, a free app that allows anyone to photograph and report plant and animal sightings.

The dashboard aggregates these community observations that are taken in the iNaturalist app into a map that shows where Tree of Heaven has been documented locally. This visual tool will not only help us keep track of where Tree of Heaven exists, but may also help reveal patterns: How effective were attempts at killing the tree depending on when it was done? Are there hot spots where removal might make the biggest difference?

How You Can Help

Participating in this effort is simple:

1. Download the “iNaturalist Classic” app on ios or android.
2. Create a free account.
3. Locate the Tree of Heaven, especially in or near vineyard properties, riparian areas, or roadsides.
4. Click “Observe” and use your camera to confirm the ID; the app will assist with identification.
5. In the notes section, enter either “Found”, “Inspected”, or “Killed” depending on the status of the tree or group of trees. Found = tree(s) were located but no action was taken. Inspected = tree(s) were located and inspected for spotted lanternfly egg masses. Killed = tree(s) were located, inspected and removed or killed.
6. Click “Share” and your location will automatically be recorded.

Your contributions will feed into the dashboard—helping build a real-time, community-powered view of this invasive tree’s spread. See example below:

A screenshot of an “Inspected” tree located in downtown Acampo taken by user “lodigrowers” on the iNaturalist app.

Finding the tree is not enough. We need our citizen scientists to also inspect the Tree of Heaven for the presence of the spotted lanternfly, especially the hard-to-see egg masses. According to our east coast colleagues who are dealing with tainted winegrape loads due to spotted lanternfly, we could get ahead of the problem by 1-2 years if we are able to find early egg masses in California! If you find an egg mass or an insect, immediately call the California Pest Hotline at 1-800-491-1899 and collect the specimen if possible.

Inspect all Trees of Heaven for these spotted lanternfly life stages. Courtesy of the Pennsylvania Department of Agriculture.
Egg masses (A) can be present year-round and look like clay or mud.
The spotted lanternfly egg masses can be found nearly anywhere.
Nymphs (B & C; black and red with white spots) will likely be present from May through September in California.
Adults (D & E) will likely be present from June/July through the winter.

Growing Smarter, Together

Citizen science isn’t just about collecting data. It’s about building local knowledge, strengthening connections between growers and residents, and empowering communities to take ownership of the health of their landscape.

By tracking Tree of Heaven together, we gain more than just a map; we gain a shared tool for early detection, coordinated response, and ultimately, stronger resilience in our farming systems.

So next time you’re out in the field or walking your dog along a trail, keep an eye out for the telltale features of Tree of Heaven, and snap a photo in the iNaturalist app. Your observation could help protect Lodi vineyards for seasons to come.