OREGON STATE UNIVERSITY

Demonstrations and Projects: Weeds in the Watershed

Weeds in the watershed logoThe Cameron Tract hosted an evening program in May of 2002 to discuss weeds and weed control options in the Soap Creek Watershed. Dave William, an OSU Extension Specialist in horticulture spoke on weed identification and the importance of defining management objectives and understanding the weed's physiological process in order to effectively control weed populations.

OPTIONS FOR WEED CONTROL:

  1. Mechanical control: removal of plants by hand or machines
  2. Biological control: "the use of living organisms; predators, parasites, diseases, and other antagonists as natural enemies in controlling agricultural/environmental pests."
  3. Chemical control: the use of chemicals to either directly or indirectly kill plants

Management on the Cameron Tract has incorporated both mechanical and chemical control measures. In the spring of 2002, before seedpods had developed, hand pulling and hand sawing were used to remove Scotch broom on the northern portion of the Cameron Tract. A few tansy ragwort plants were also identified and pulled during the same time period.

Following the 1995 harvest on the Tract, herbicides were applied to reduce vegetative competition with tree seedlings. Applications have been conducted on the ground with backpack sprayers.

In the broadest terms, a weed is any plant that is unwanted. Depending on an individual's objectives, a weed to one person, may not be considered a weed by others. Noxious weeds, are those plants listed by a government agency as "a threat to public health, agriculture, recreation, wildlife or property" (reference: http://www.blm.gov/weeds/). Noxious weeds in Oregon are typically grouped into the following three categories:

A= Weeds of known economic importance which occur in the state in small enough infestations to make eradication/containment possible; or which are not known to occur, but their presence in neighboring states makes future occurrences in Oregon seem imminent.

B= Weeds that are economically important and regionally abundant, but which may have limited distribution in some counties.

T= Priority noxious weed designated as a target species for statewide management plan (reference: http://www.oregon.gov/ODA/PLANT/WEEDS/lists.shtml)

Invasive weeds are defined as those plants which "when introduced either accidentally or intentionally, they out-compete native species for available resources, reproduce prolifically, and dominate regions and ecosystems" (reference: http://www.oregon.gov/OISC/).

Like most areas in the Soap Creek Watershed, the Cameron Tract has its fair share of weeds. Since tree regeneration is a key objective on the Tract, the weeds of most concern on the property are invasive weeds and those that stunt or inhibit the regeneration of seedlings. Once the trees are tall enough to restrict the amount of sunlight that reaches the ground, weeds are typically less of a problem for forest managers.

The following list identifies weeds frequently found in the Soap Creek Watershed:

students learning about weedsAdditional information about weeds, weed control and herbicide application can be found here:

LIBRARY REFERENCES FOR CORVALLIS