What are my SOD management options?
Sudden Oak Death affects homeowners, small woodland owners, resource managers, and conservation groups. Management options depend on goals and location. Within the quarantine area, options vary depending on whether you are located in the Generally Infested Area, a designated treatment area (identified by Oregon’s interagency Sudden Oak Death program), or an infested area not designated for treatment. Landowners located outside of the quarantine area will not have disease present but should be concerned about SOD spreading past the quarantine area boundaries; therefore, disease recognition and prevention measures are paramount.
Oregon’s Interagency Sudden Oak Death Program works to slow the spread of SOD in the state by surveying for the disease and treating high-risk, infested sites. Eradication treatments are the best approach to help slow the spread of the disease on high-risk sites (sites on the leading edge of the infestation).
In these sites, SOD program contractors cut infected trees (primarily tanoak) and burn plant debris (when it is safe to do so) in a prescribed radius around infected trees, often 300 feet or more. Rapid treatment is necessary to help prevent the disease from spreading across the landscape.
Please visit the Reporting page for information.
Inside Generally Infested Area (GIA)
These are well-established treatments for SOD.
- Cut dead tanoaks for safety and fuel reduction.
Consult quarantine guidelines prior to moving logs or slash (woody debris). Logs can be used for firewood within the GIA. Dispose of slash by chipping or piling and burning. Consult with your local fire agency or forestry office for information on current fire restrictions, permit requirements, and safe burning guidelines.
- Control tanoak sprouts.
Tanoak vigorously sprouts from the stump. These sprouts will be susceptible to re-infection and will continue to spread disease locally. You can treat individual tanoak stems manually or by using herbicide treatments.
For proper application method and chemical selection, see the current edition of the
Pacific Northwest Weed Management Handbook.
Always read and follow label directions.
- Consider protecting surviving tanoak.
In areas of mortality, the trees that survive might be resistant to the disease. Research from California has shown that phosphonate (also called phosphite) treatments may prolong tanoak survival.
Phosphonate is applied either through injection or topically on the bark and trials have shown reductions in girdling at the bole, promoting survival. Follow-up, annual treatments are necessary to provide continued protection. The cost is dependent on the application method and the size of the tree. Tanoak treated with phosphonate may still become infested in the upper branches, providing a breeding ground for further sporulation and spread. At this time, phosphonate is used primarily in an effort to keep important trees alive in infested areas.
More information on phosphonate treatments can be found in the PNW Handbook tanoak section.
- Consider planting species not susceptible to SOD.
Your planting strategy will depend on your location, management goals, and risk tolerance. It is important to recognize that while a number of native plant species are listed as host species on the USDA APHIS regulated host list, not all hosts support the spread of the SOD pathogen through sporulation or die from the disease.
For example, Douglas-fir is susceptible to SOD while growing under tanoak, but it is unlikely that the disease will spread through a Douglas-fir plantation with no tanoak in the overstory. In designated treatment areas, Oregon Department of Forestry will provide guidance regarding planting options.
Examples of native plant species not susceptible to SOD include Shore pine, Port-Orford-cedar, Western redcedar, Red alder, Red elderberry, Coyote brush, Oceanspray, and Chinkapin.
More information about these species can be found in the Sudden Oak Death: Prevention, Recognition, Restoration (2018) by Norma Kline, Sarah Navarro, and David Shaw. This handbook was developed by Oregon State University Extension Service for homeowners, small woodland owners, resource managers, and conservation groups.
Native host plants that are known to spread Sudden Oak Death by sporulation:
Tanoak (Notholithocarpus densiflorus)
Azalea (Rhododendron sp.)
Huckleberry (Vaccinium sp.)
Madrone (Arbutus menziesii)
Manzanita (Arctostaphylos sp.)
Rhododendron (Rhododendron sp.)
Salal (Gaultheria shallon)
Options outside of the quarantine area or Inside Generally Infested Area (GIA)
Treatment options that may be used to promote general stand health but have not been observed to definitively slow the spread of SOD.
- Thin tanoak (as a management trial).
Reduce the density of noninfected tanoak with the objective of reducing spread from treetop to treetop. Mature tanoaks are sensitive to sudden exposure to sunlight. Aggressive thinning can cause the crowns to weaken and decline. Instead, reduce tree density in small steps (for example, remove 10% to 20% of stems in 3-to-5-year intervals).
- Treat with phosphonate (phosphite).
Phosphonate is applied either through injection or topically on the bark. Follow-up, annual treatments are necessary to provide continued protection. Cost is dependent on the application method and size of the tree. Tanoak treated with phosphonate may still become infested in the upper branches, providing a breeding ground for further sporulation and spread. Tanoak in newly infested areas may need to be cut whether or not treated with phosphonate. At this time, phosphonate is used primarily in an effort to keep important trees alive in infested areas. When choosing to treat with phosphonate, consider the risk of disease infestation and expense.
- Consult
ODF forest health program or an OSU Extension forester for harvest options to control the spread of SOD. Extensive harvesting of healthy tanoak outside the quarantine area (infested areas) to control the spread of SOD may not be practical or desirable when weighed against the ecosystem value of leaving it in place. Consider options carefully, depending on location, objectives, and current treatment protocol.
Some treatments are best left to professionals due to safety concerns and the skills required; other treatments need to be approved by local regulatory agencies.
Inside infested area: designated for treatment
These are well-established treatments for SOD.
- Cooperate with Oregon’s Interagency Sudden Oak Death Program eradication treatments in high-priority infested areas.
- Observe the general treatment area and surroundings; report additional dying tanoaks to Oregon Department of Forestry (ODF).
- Replant. ODF will work with landowners to determine planting options.
Treatment checklist
Tree felling
Consult local tree ordinances before cutting trees. Use experienced tree service technicians, as infected trees might be decayed or there may be nearby powerlines, roads, or structures.
Moving logs or vegetative debris
Consult quarantine guidelines prior to work.
Burning
Contact your local fire agency or forestry office for information on current fire restrictions, permit requirements, and safe burning guidelines.
Herbicide use
- Wear protective clothing and safety equipment as recommended on the label. Bathe or shower after each use.
- Read the pesticide label, even if you have used the pesticide before. Follow the instructions on the label (and any other directions you have).
- Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use. Use herbicides responsibly.
Inside infested area: not prioritized for treatment
- Cut hazard trees for safety, fuels reduction, and to control sprouts.
- Treat infested tanoak areas according to the latest ODF Forest Health Program treatment guidelines for SOD to slow the spread of the disease.
- Consider planting species not susceptible to SOD.
- Report new locations of dead and dying tanoak and suspicious symptoms.
Management options outside of the quarantine area
These are well-established treatments for SOD.
- Report dead and dying tanoak and suspicious symptoms on hosts.
- Preserve tanoak ecosystems. Tanoak acorns are a food source for many animals; groves provide thermal cover, and refuge and nesting habitat for wildlife. Tanoak is also important to general watershed function and has important cultural values to Native American tribes.
- Plant trees and shrubs that are consistent with management objectives and risk tolerance. Consider planting a diverse species composition.