SOUTHWEST OREGON-The time has arrived for the annual closing of the gates on the western side of the Rogue River-Siskiyou National Forest in an effort to prevent the spread of Port-Orford-cedar (POC) root disease.
The closures were delayed this year, particularly on the Gold Beach Ranger District, due to continued dry conditions on the southwest coast. The recent shift to wet weather conditions has prompted the closures, which typically begin around October 1st and extend through May 31 of each season.
On the Gold Beach Ranger District, the Snow Camp Road (Forest Road 1376), a popular back road between Brookings and Gold Beach, is currently closed. In addition, Forest Roads 3318-310, 3318-240, 1703-110, 1703-150, 1703-190, 1703-140, 1107-220 are also closed. There are also numerous POC closures in effect on the Powers Ranger District. On the Wild Rivers Ranger District, several POC gate closures will soon be in effect and will continue to close as weather conditions change.
POC root disease is caused by the fungal-like pathogen Phytophthora lateralis (PL) that spreads through transportation of infected soil and surface water and root grafts. The closure of specific roads during the wet season protects healthy POC by limiting access to infected areas and subsequent transportation of pathogen spores to uninfected areas.
Some of the POC gates are limiting access to uninfected areas as a preventative measure. Large trees are more likely to be infected than small trees due to larger root areas, although all trees at the edges of infected streams and road side ditches are likely to succumb. The fungus produces spores that can persist in the soil for long periods of time. New infections generally begin when the soils is transferred from an infected population to a non-infected population via human or animal movement.
Soil on vehicle tires and undercarriages can carry the disease to uninfected POC populations and spread the disease into preciously uninfected watersheds. Vehicle transport is considered to be the most probable method of spread along roadways, particularly on high traffic or non-surfaced roadways. Spread on boots and mountain bike tires likely contributes to more localized infections.
The Port-Orford-cedar (also known as Lawson’s Cypress, Chamaecyparis lawsoniana) is a cypress (not a true cedar) that is native to the southwest portion of Oregon and the northwest portion of California. It grows at sea level up to about 5,000 ft elevations in the Klamath Mountains and valleys, frequently near streams. This cypress is a large evergreen coniferous tree, regularly reaching 200 ft tall, with feathery blue-green foliage. The bark is reddish-brown and fibrous to scaly in vertical strips