The End of the 8-Month 2020 Thistle Removal Season

Thistle’s worst nightmare: my right hand. Thistle’s second worst nightmare? My left.

I’m calling it. Recently I finished clearing one of the last two meadows left with Yellow Star thistle (along Norrbom Road), and since it is drying out and becoming difficult to remove completely, I’m giving it up for this year. We started in mid-January. That means I’ve spent over 8 months going out nearly every day for an hour each day to clear first Italian thistle, then Yellow Star, except for the few “vacations” we’ve had in this time of shelter in place (to be clear, I was going out to pull thistle even during the shutdown of public properties, as I had permission to do so).

The good news is that we are winning. I’ve never cleared this particular meadow before, which means that other sites had been cleared so that now I can turn my attention to the two remaining meadows that still have Yellow Star thistle. Only one of them remains uncleared this season. I fully expect that within three years we will be able to state that there is no Yellow Star thistle to be found from Schocken Hill in the east (Sonoma Overlook Trail’s eastern border) to 4th St. East (the Montini Preserve’s western border). If you have recently visited other public lands in this valley perhaps you can appreciate the import of that statement.

Italian thistle remains a different matter, especially on the Montini Preserve, where it remains prevalent. We had our hands full simply pushing it back from the trail this year. Also, Italian thistle seems to be coming in where we have been clearing Yellow Star thistle, so we need to be vigilant in those areas. The essential problem is that Italian thistle will grow anywhere, whereas Yellow Star thistle prefers open meadows, which limits its coverage.

As I close out the thistle season, I will move to Scotch broom. I even bought a special tool to help pull the largest, most established broom plants. There is one rather bad patch of it on the Sonoma Overlook Trail property, but that seems to be about all of it except for the adjoining Sonoma Cemetery. The issue is that it adjoins the Overlook Trail property, so it should also be removed to protect the trail property.

One other species deserves mention, as there has been a patch of Bellardia strung out along the very top of the Overlook Trail that Richard Dale, Executive Director of the Sonoma Ecology Center, cleared out this year. These are by no means all of the invasive species, but they are some of the most problematic, and certainly those that present an existential threat to these properties if left unchecked.

Later I will provide a final report on the 2020 invasive species removal season, but I thought that the end of “thistle season,” which has so far comprised the bulk of our efforts, was worth noting.

The 2019 Invasive Thistle Removal Season is Over

The weapon of choice: the glove that pulled thousands of thistles.

I’m calling it. Today was the first day I was out on the Montini Preserve and Overlook Trail properties and was unable to spot a single Yellow Star Thistle plant. So I consider this year’s invasive thistle removal season officially over. And what a long road it’s been.

I started pulling Italian thistle at the end of December, when I could pull it and discard it. Later, when blooms began to form we had to bag it in large contractor debris bags and carry it out. We dumped it beside a dumpster in the cemetery, as requested by City staff. As the season progressed, we moved to Yellow Star thistle while the Italian thistle that we couldn’t get to sadly went to seed.

For our next Sonoma Overlook Trail Stewards meeting I will be giving a more formal and complete report, but here it is in a nutshell:

  • Yellow Star Thistle: Although we are clearly making progress, we may be 2-3 years away from complete eradication, except for along Norrbom Road, which has been completely unassailed so far. However, we have reduced the YST so far that we have now given it a setting of “zero tolerance,” which essentially means we are morally obligated to pull everything we see.
  • Italian Thistle: We only recently started to seriously address Italian thistle, and there is a long, long way to go. The Montini Preserve is all but overwhelmed with it, and removal operations were performed mostly along portions of the trail, largely for hiker comfort. On the Overlook, it was successfully removed from the entire trail, back at least 3-6 feet or more. It remains a substantial problem off-trail, although not as bad as the Montini Preserve. We have assigned a status of “calculated and opportunistic,” which means focusing on minimizing its spread by pushing it away from the trail and attacking isolated pockets elsewhere.
  • Scotch/French Broom: There is a bad section of broom near the cemetery that was unaddressed this year, and it is also encroaching on the Toyon Trailhead from the cemetery. Current status: unaddressed.
  • Tocalote: Tocalote is found in scattered areas across the property, but it’s extent is unknown and it remained unaddressed this year.
  • Bellardia: This is also un-assessed and unaddressed but doesn’t seem to be a major problem yet.
  • Others: un-assessed and unaddressed.

We still need to perform a systematic review of invasive species on these properties, but so far our efforts have been focused on removal of those that pose an existential threat to the existence of a diverse ecosystem. And so far we have our hands more than full simply trying to stem the tide.