Noxious Weeds

There are many species of exotic and invasive weeds in the Utah. Some species, however, have more potential to be “injurious to public health, crops, livestock, land, or other property” [1]. The Utah Noxious Weed Act of 2008 had defined 28 noxious weed species into three prioritization categories. In December 2015 the official State Noxious Weed list was updated to include 54 species and prioritization categories were modified as follows:

Class 1A: Early Detection Rapid Response (EDRR) watch list
Declared noxious weeds and invasive weeds that are not native to the State of Utah, are not known to exist in the state but pose a serious threat, and should be considered a very high priority.

Class 1B : EDRR
Declared noxious and invasive weeds not native to the State of Utah that are known to exist in the state in very limited populations, pose a serious threat to the state, and should be considered as a very high priority.

Class 2: Control
Declared noxious and invasive weeds not native to the State of Utah that pose a threat to the state and should be considered a high priority for control. Weeds listed in the control list are known to exist in varying populations throughout the state. The concentration of these weeds are at levels for which control or eradication may be possible.

Class 3: Containment
Declared noxious and invasive weeds not native to the State of Utah that are widely spread. Weeds listed in the containment noxious weeds list are known to exist in various populations throughout the state. Weed control efforts may be directed at reducing or eliminating new or expanding weed populations. Known and established weed populations, as determined by the weed control authority, may be managed by any approved weed control methodology, as determined by the weed control authority. These weeds pose a threat to the agricultural industry and agricultural products.

Class 4: Prohibited
Declared noxious and invasive weeds, not native to the State of Utah, that pose a threat to the state through the retail sale or propagation in the nursery and greenhouse industry. Prohibited noxious weeds are annual, biennial, or perennial plants that have the potential or are known to be detrimental to human or animal health, the environment, public roads, crops, or other property.

State land managers, local governments, and property owners are responsible for controlling weed species found on the state’s noxious weeds list, and local weed species of concern, if necessary. Weed control responsibilities extend to lands under local management (roads, right-of-ways, parks, etc.) as well as enforcing provisions of the Utah Noxious Weed Act on private lands. If landowners are unwilling or unable to address weed problems on their own land, state law provides county weed managers the right to treat weeds on private lands (assuming proper notice is provided) and subsequently seek reimbursement or apply liens for the work.

For the SEUALG region, there are county, state, and federal goals identified in respective planning documents. In general, county objectives for noxious weeds are similar to those of the state; counties support the goals and objectives of the Utah Noxious Weeds Act for all landowners, including the federal government. Counties expect federal land managers to control weeds on public lands.

Local weed control entities:

• Carbon County Weed Board
• Emery County Weed and Mosquito Board
• Grand County Weed Department

County-specific weed control assessments from Utah Association of Conservation Districts (UACD) and Natural Resource Conservation (NRCS):

• Carbon County Resource Needs Assessment (2012)
• Emery County Resource Needs Assessment (2012)
• Grand County Resource Needs Assessment (2012)
• San Juan County Resource Needs Assessment (2011)

Regional and state weed management plans:

• Utah Division of Wildlife Resources (UDWR) Invasive Weed Control (2009)
• Utah Strategic Plan for Managing Noxious and Invasive Weeds (2004)

Federal land management agencies:

• US Forest Service
  • 1986 Manti-La Sal Resource Management Plan [2]
• US Bureau of Land Management
  • 2008 Moab Field Office Resource Management Plan
  • 2008 Monticello Field Office Resource Management Plan
  • 2008 Price Field Office Resource Management Plan

Prevention
Noxious weeds are easily spread by contaminated agricultural machinery, pack stock, riding stock, livestock feed, hay, straw, soils, sod, nursery stock, and manure. Preventive measures include:

• Certified weed-free feed for all stock animals.
• Certified weed-free mixes, mulch, fill, etc., for restoration/rehabilitation activities.
• Thoroughly cleaning agriculture machinery and equipment (which has come in contact with weeds) before it is transported to other locations.
• Prevent spilling and accidental spreading of materials from vehicles transporting seed, feed, topsoil and fill materials.
• Educate landowners, land users, and visitors about the impacts of noxious weeds.

Treatment
Once established, weeds must be treated to control further spread. Treatments include:

• Chemical control and containment (hand, vehicle, aerial)

• Mechanical  treatments (mowing, discing)
• Biological (insects, grazing livestock such as goats and cattle)
  • Tamarisk beetle is a good example for the SEUALG region
• Physical (water removal, flooding, burning)

The Noxious Weeds data combined with the Ownership data can be used to identify large infestation areas within the county and the ownership of nearby land.

Cooperative Weed Management Areas (CWMAs): These provide weed control across large lands areas, like watersheds, without specific consideration of land ownership, to more effectively treat weeds. CWMAs are also used to coordinate treatment efforts and pool resources. Weed control is most effective when all land managers and landowners act quickly to address infestations when they first begin.

CWMAs and their partners within the WFRC area include;

• Skyline CWMA (Emery  and Carbon County)
• Middle Colorado River Watershed (Grand County)

Weed control and treatment resources:

• The UDWR has compiled an Invasive Weed Control document, which provides specific treatment approaches for seven common noxious weeds.
• Denison Mines published a Weed Management Plan for La Sal Mine Complex (San Juan County, Utah). The plan offers specific and helpful preventative measures, control measures, and Reporting strategies.
• The Utah State University Extension weed control program provides information regarding noxious weeds across Utah.
• The Utah Weed Control Association is a professional organization consisting of weed control specialists in Utah.
• The Natural Resources Conservation Service provides detailed noxious weed information.
• The UDOT Chemical Guide for State Noxious Weeds provides information on the prevention of weeds at construction sites

Weeds create significant economic impacts that must be considered in each county’s resource management plan. Annual economic losses in the United States from weeds is over $20 billion [4]. It is estimated that, without the use of herbicides, revenue losses to the agricultural sector would increase by about 500% [5].

Economic considerations for counties include:

• Direct expenditures. The UDWR allocates $200,000 annually to treat weeds [6].  
• Reduce range carrying capacity for livestock and grazing. Dyers woad infestations can spread 14% per year and reduce range carrying capacity by 38% [7]. The BLM has estimated costs in the western United States for weed control and lost production at $100,000,000 per year [8].
• Wildland fire. Contiguous patches of weeds pose significant fire risks, and seeding after wildfire is a necessity to recruit native species rather than weeds.
• Agriculture. Direct control costs, crop and seed contamination, and equipment cleaning costs.

• Wildlife habitat. Phragmites outcompetes native wetland vegetation and chokes out wildlife [9].
• Weed control impacts. Fire is a control method often used to treat phragmites, but smoke is a significant air-quality issue, which must be considered in this region.
• Increased wildfire risk and costs. Many noxious weeds, such as cheatgrass, are very flammable and increase the risk of wildfires. After a fire burns an area infested with noxious weeds, the weeds sprout before native plants and are able to dominate native plant species by quickly taking over water and soil resources [10].
• Recreation impacts. Tamarisk and russian olive grow very thick in riparian areas along rivers making it difficult for river users to access recreation resources. Goathead (puncture vine) causes problems for cyclists and trail users.