Background: As part of the Williams Port-Orford Cedar Management Project, a monitoring plan was developed to determine the effectiveness of the proposed silvicultural (includes prescribed fire) treatments to reduce populations of Phytophthora lateralis (PL). Phytophthora lateralis, the pathogen that causes Port-Orford cedar (POC) root disease occurs on an estimated 1500-2000 acres. This is approximately 25 percent of the total acres with POC in the Williams Creek Watershed. One of the primary means of pathogen spread is via running water.
Location: Grants Pass Resource Area (GPRA), Medford BLM, Township 39 South, Range 5 West, Section 9 and Township 39 South, 6 West, Sections 13, 23, and 24.
Funding: Forest Ecosystems Health and Recovery Funds (5900). Roadside monitoring was a portion of a larger monitoring plan for the project. Total planting was five 100 seedling repetitions in areas planned to be harvested and an additional 349 seedlings planted along roads. Total cost was $2500.
Methods: The first step was to map PL incidence. Prior to any treatment activities, 349 uninfected POC seedlings were planted at 55 locations in 5 ditchlines along roads where water that is either known or suspected of carrying PL flows. This data will be compared to subsequent monitoring data after the project is completed to ascertain whether the prescribed treatments had a negative effect on PL as has been theorized. The work builds upon that previously done by the Southwest Oregon Forest Insect and Disease Technical Center (SWOFIDTC). See the May, 1998 SWOFIDTC News for details. SWOFIDTC is and will continue to be involved in design, layout, and implementation of the monitoring as well as the analysis of the results. Compilation of the data and annual reports will be a combined effort between SWOFIDTC and GPRA.
Uninfected POC seedlings were planted as baits for PL. The majority (50 out of 55 planting sites) of sampling locations were along 2 roads in the drainage of the West Fork of Williams Creek: the Low Divide Road (39-5-18.1 and the Bear Wallow Road (39-6-11). Eight 10 cubic inch Port-Orford cedar plugs were planted along each culvert. One seedling was planted at the culvert inlet, one 8 feet uphill along the cutbank, and 6 more below the culvert outlet at 8 foot spacing. The exception to this was where stream crossings occurred. Four seedlings were placed in the stream: two just above and two below each culvert; one along each bank.
Two Williams residents were hired to do the planting. The process was time consuming as the planting tools had to be washed after each individual tree was planted. This was done so PL would not be transferred from one planting hole to another. Planting occurred on 6 days between April 22 and April 30, 1998. After planting, the contractors were required to dig up every tree that had been planted (along with washing of equipment mentioned above) and deliver them to SWOFIDTC at the J. Herbert Stone Nursery in Central Point. Seedlings were retrieved on 4 days between June 3 and June 10, 1998.
Seedling analysis by SWOFIDTC consisted of peeling the bark off of each seedling to confirm the presence of Phytophthora lateralis. Cinnamon- colored inner bark denotes pathogen occurrence. Discoloration size was generally small. Discoloration ranged from a dot barely visible to the naked eye to entire root systems. Tissue samples from under the bark were taken and cultured in a Phytophthora selective medium for one week for those seedlings where PL was suspected but could not be verified visually. Each tissue sample was inspected one week later. The final tally showed that Phytophthora lateralis had flowed through 18 of the 55 locations (33 percent) during the 7 week baiting period. Each planting location was then mapped using GPS equipment in order to create a spatial display of current Phytophthora distribution in this part of the Williams watershed.
Discussion: The number of locations were PL was found higher than anticipated. Planting will be repeated annually for 5 years after treatments are completed. The number of locations that show PL will be compared to the baseline data collected in 1998. Analysis would be conducted to see what effect(s), if any, the removal of POC and prescribed fire has on PL populations. It is postulated that removal of the host species (POC) and a prescribed fire event will reduce PL populations. Repeating the treatments is expected to determine whether the PL populations decline or if different pathogen control strategies need to be developed.
Prepared by: Frank Betlejewski, 2/11/99.
Special thanks to Katy Marshall and Don Goheen (SWOFIDTC) for peeling all those seedlings, Dennis Glover, Doug Miller, and Armand Rebischke for the GIS work, and Dale Rau for overall assistance on the science project.