Welcome to CalPhytos.org – Phytophthoras in Native Habitats
Over the past several years, a first-in-the-USA detection of Phytophthora tentaculata occurred in several California native plant nurseries and in restoration areas. Follow-up investigations have identified numerous Phytophthora species in native plant nurseries and restoration sites. Inadvertent planting of Phytophthora-infected nursery stock into native habitats has the potential to introduce these pathogens into wildlands. Furthermore, many of these Phytophthora species appear to have wide host ranges, capable of causing disease on plants across many families.
The Working Group for Phytophthoras in Native Habitats has formed to determine steps needed to protect wildlands and assist the restoration industry. Read more in “In Brief… Phytophthora plant pathogens in California native plant nurseries and habitats. Why the concern?” (May 2015).
Calendar of Events
See the entire calendar of Phytophthora-related events.
CNPS is supporting clean nursery practices – see the article in the CNPS Bulletin, volume 46, issue 2 (April-June 2016).
UK nurseries are getting involved in a “Keep It Clean” campaign for Phytophthoras, as described in a recent Horticulture Week article.
Phytophthora tentaculata was initially detected in a native plant nursery causing a severe root and crown rot in sticky monkey flower, Diplacus aurantiacus subsp. aurantiacus (Scrophulariaceae) in 2012. Since then it has been detected in several nurseries and a few restoration sites where outplanted stock was found to be infected.
CDFA Plant host list for Phytophthora tentaculata, February 2016
CDFA Nursery Advisory No. 01-2014 Phytophthora tentaculata, November 2014
2010 APHIS New Pest Response Guidelines, “Phytophthora species in the Environment and Nursery Settings.” Includes Phytophthora tentaculata literature review and pictures of the pathogen in culture.
Rooney-Latham, Suzanne; Cheryl Blomquist; Ted Swiecki; Elizabeth Bernhardt. 2015. Phytophthora tentaculata. Forest Phytophthoras 5(1). doi10.5399/osu/fp.5.1.3727. A compendium of information on Phytophthora tentaculata that includes photographs of field symptoms, a table of known hosts and more, geared to a technical audience and containing many photomicrographs. (PDF for download) http://journals.library.oregonstate.edu/index.php/ForestPhytophthora/article/view/3760/3652
Rooney-Latham, S., C. L. Blomquist, T. Swiecki, E. Bernhardt, and S. J. Frankel. 2015. First detection in the US: new plant pathogen, Phytophthora tentaculata, in native plant nurseries and restoration sites in California. Native Plants Journal 16:(1) 23-27. Abstract: Phytophthora tentaculata Kröber & Marwitz (Pythiaceae) has been detected in several native plant nurseries in 4 California counties and in restoration sites on orange sticky monkey flower (Diplacus aurantiacus (W. Curtis) Jeps. subsp. aurantiacus [Scrophulariaceae]), toyon (Heteromeles arbutifolia (Lindl.) M. Roem. [Rosaceae]), coffeeberry (Frangula californica (Eschsch.) A. Gray [Rhamnaceae]), and sage (Salvia spp. L. [Lamiaceae]). These findings are the first detections of P. tentaculata in the US and the first ever on these host plants. Phytophthora species are a known problem in horticultural nurseries, but little attention has been placed on native plant or restoration nurseries. The potential for plant pathogens to be outplanted along with native plant nursery stock is very high, posing a threat to neighboring forests. http://npj.uwpress.org/content/16/1/23.abstract.
A systems approach to producing healthy container-grown plants: webinar with Dr. Jennifer Parke, Oregon State University. April 28, 2015. See all online resources and view a recording at http://uc-d.adobeconnect.com/r91g3to9726/.
Presentations from the Do No Harm Restoration workshop, Palm Desert, November 2015
Exotic Phytophthora Species in Native Plant Nurseries, Restoration Plantings, and Wildlands, video recording. Courtesy of the Central California Native Plant Nursery Network, December 2, 2014
- Plant pathogen movement: around the world on planting stock – Susan Frankel, USDA-Forest Service, Pacific Southwest Research Station (http://youtu.be/KZAlexLWNGY)
- Phytophthora species: life cycle, distribution, dispersal, impacts in California – Ted Swiecki, Phytosphere Research (http://youtu.be/lMw4NpDgCTs)
- P. tentaculata: History, Host Range, and Status in California Nurseries – Suzanne Rooney Latham, CDFA (http://youtu.be/HK4-NMsDbm8)
- Best Management Practices to minimize the risk of Phytophthora and other pests and pathogen introductions into nurseries – Kathy Kosta, CDFA (http://youtu.be/oKEQqDBU3vw)
- Systems approach to Phytophthoras in nurseries – Karen Suslow, NORS-DUC (http://youtu.be/CuPYc9lcCcc)
- Phytophthora Effects on Native Habitat Restoration – Greg Lyman, SF Public Utilities Commission (http://youtu.be/ypRe4nX6fSo)
- Case Study: Incorporating CDFA BMPs at a restoration nursery – Diana Benner, The Watershed Nursery (http://youtu.be/7AEnZp2-_14)
Resources from the “Managing Phytophthoras in Native Plant Nurseries: A hands-on workshop on prevention and early detection,” June 16, 2015
- Workshop agenda and speaker information
- The horticulture behind Phytophthora management
- Hands-on Irrigation Training
- Determining container physical properties worksheet
- Recognizing disease symptoms and sampling plants for the lab
- Examination & sampling for rotten roots and stems – root diagram
- CDFA Protocol for Baiting the Root Ball in a Pot for Phytophthora spp.
- CDFA Flow Through Protocol for Baiting of potted plants to detect presence of Phytophthora spp.
- Video overview of hand-on stations
These draft guidelines were developed to prevent and manage Phytophthoras during various aspects of restoration. This guidance is targeted for use in rare plant and other high-value habitats.
- “Restoration guidance” covers General Construction; Guidelines for Planting at Field Sites; Procedures for sanitizing tools, surfaces, and footwear; and Clean water specifications.
- “Contaminated site guidance” is for restoration sites that has been confirmed to contain an Phytophthora infestation.
- “Holding nursery guidance” presents a set of practices to avoid contamination of nursery stock being held for planting at restoration sites.
Mission Statement (draft as of November 2015)
Working Group Organizational Chart (draft as of January 2016)
Contact Janice Alexander for more details on how you can be involved with the Working Group.