News from the Nursery

Vine Hill manzanita now live in the wild in 3 locations; not just 1

You may recall the history of our own Vine Hill manzanita. If not, let me refresh your memory of the saga of the Vine Hill manzanita.

There was until this January, only one wild population in the world of Arctostaphylos densiflora (Vine Hill manzanita) at our CNPS preserve in northern Sebastopol. It is state listed as endangered, you’d think so with only one population of plants. Until 1975 that property was privately owned and most of it was a vineyard. That year, it was put on the market and CNPS purchased it.

A new home for Vine Hill manzanita

After CNPS purchased the property, Phil Van Soelen, previous owner of Cal Flora Nursery and past chapter president, took on stewardship of this last remaining population of about 20 plants. Over the next 20 years, Phil did a wonderful job of propagating from the last remaining 20 plants and planting those clones on the rest of the property where the grape vines had been removed. Thank you, Phil, for saving this species at Vine Hill.

However, in 2020 our current CNPS steward, Sarah Gordon, noticed many VH manzanitas on the preserve were looking stressed with dead areas. Sarah called me in, since I have been involved with the root rot Phytophthora issues in nurseries and restoration sites since 2014. I tested soil in 4 areas of the preserve and got positive results. Our chapter then hired Ted Sweicki, PhD plant pathologist and leading expert in this field. He tested an additional 12 locations at the site, along with CDFA plant pathologists testing. Results were that the whole 1.6-acre preserve was infected.

Interestingly, the results from Ted showed most likely that the infection came from the remnant plants that were at the top of the hill, next to the road, probably not from planted clones, and probably moved down the hill with the water stream or on the shoes of botanists and others visiting the site. This water borne fungus-like disease moves with soil or in water. At least that is my interpretation from the results.

Therefore, in order to save this species in the wild, we needed to establish new populations of this species. Mature plants could not be moved since they are all presumed infected. The disease enters through the roots and eventually kills the plant as it travels up with water. After receiving a research permit from CFWS in January 2021, I began propagation with tip cuttings, hoping to get clean material ahead of the infection.

Meanwhile, the genomics lab at CSU East Bay collected samples from all 80 VH manzanitas (both natural and propagated) to determine whether the propagated plants that Phil did were a single clone from one natural plant or from multiple remnant plants. Phil had done an amazing job and had planted clones of almost every one of the remnant plants, 20 genetic lines in all. I used that information; to propagate cuttings in 2022 from the genetic lines I had not captured in 2021, resulting in 226 plants ready to plant this winter from 15 genetic lines. Plants from the other lines were either too infected to get clean material or no longer large enough to withstand any material removal.

Thanks to an amazing nursery volunteer team for all their help and support, especially Natasha Granoff for helping collect cuttings, Pat Sesser for helping to prep and stick cuttings, and Natasha and Lynnette for helping to test each set of plants to be sure all were disease free. The whole nursery team potted up rooted cuttings and later into large pots. Penny Dalton has helped me apply Agri-Phos (to slow infection spread), label and monitor the plants at Vine Hill.

During the time plants were growing, we found 2 protected areas with the same type of soil and received permission to plant in those 2 sites. Thanks to Sonoma Land Trust for allowing us to plant in the upper reach of the Lower Pitkin Marsh preserve and to our own Marcia Johnson for permission to plant on her part of the Conservation Easement we steward at Cunningham Marsh.

Milo Baker volunteers plant Arctostaphylos densiflora, Vine Hill manzanita, at Cunningham Preserve
Milo Baker volunteers plant at Cunningham Preserve

In January, we planted at these 2 preserves. 68 plants, from all 15 of the genetic lines we propagated, were planted at Pitkin Marsh. 19 plants, from 12 genetic lines, were planted in at Cunningham by our own CNPS stewards; Judith Rousseau, Alynn Kjeldson, Karen and Dan Thompson, Lynnette Bower, Marcia Johnson, Jan Lochner, and Penny Dalton.

Special thanks to Laguna de Santa Rosa Foundation, with whom we partner in the nursery. They donated 3 person days to haul all the plants and materials for plant protection up to the top of the hill at Pitkin Marsh. Then after our volunteer plantings were rained out twice, they planted the 50 manzanita at Pitkin, put down landscape fabric and built and applied cages at their cost. Lynnette Bower helped with that planting.

These 2 preserves allow the Vine Hill manzanitas to develop into a functioning habitat. But just for insurance most of the other VH manzanitas we grew were taken to Botanical Gardens: East Bay at Tilden, UC Berkeley, San Francisco (Strybing), San Francisco State, UC Santa Cruz, Mendocino, and Humboldt. Thanks again to Penny for driving and her company on those trips.


If you would like to help to water and monitor our 2 new populations of Vine Hill manzanita, please contact me, Betty Young, 707-695-4257.