Noxious Weeds

“Outside of their native origins, noxious weeds become oppressors with no known natural competitors to keep their populations in check. These silent invaders quickly begin to out-compete native plants, … forever changing our landscapes. Unlike other ornamental(s), … noxious weeds are nothing short of ecological time bombs.”

From Salt Lake County Weed Control Program

Many species of exotic and invasive weeds exist 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

Class 1B: EDRR

Class 2: Control

Class 3: Containment

*Bermudagrass (Cynodon dactylon) shall not be a noxious weed in Washington County and shall not be subject to provisions of the Utah Noxious Weed Law within the boundaries of that county.

Class 4: Prohibited

County Listed Weeds

*Added to State Noxious Weed List in December 2015.

State land managers, local governments, and property owners are responsible for controlling weed species on the state’s noxious weeds list, and local weed species of concern if necessary. Weed control includes both lands under local management (roads, right-of-ways, parks, etc.) as well as enforcing weed laws on private lands. State law provides county weed managers the right to treat weeds on private lands (assuming proper notice is provided) if the landowner is unwilling or unable to treat the problem themselves, and seek reimbursement  or apply liens for the work.

Local Weed Control Programs Include:

• Davis County Public Works (no online content)
• Morgan County Weed Program
• Salt Lake County Weed Control Program
• Tooele County Road Department
• Weber County Weed Department

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

• Davis County Resource Assessment (2012)
• Morgan County Resource Assessment (2013)
• Salt Lake County Resource Assessment (2013)
• Tooele County Resource Assessment (2013)
• Weber County Resource Assessment (2013)

Regional and State Weed Management Plans Include:

• DWR Invasive Weed Control (2009)
• Antelope Island Resource Management Plan (2009)
• Final Great Salt Lake Comprehensive Management Plan and Record of Decision (2013)
• Utah Strategic Plan for Managing Noxious and Invasive Weeds (2004)

Weeds on federal lands are managed by each land management agency. The US Forest Service (USFS) addresses weeds in their 2003 Revised Forest Plan with the goals of preventing and reducing weeds across the Wasatch Cache National Forest.[2]  They further clarified weed management in the 2006 Noxious Weed Treatment Program EIS [3], in which the USFS targets species from state and local noxious weed lists.

The US Bureau of Land Management (BLM) does not address weeds in the 1988 Pony Express Resource Management Plan. [4] Information on BLM’s nationwide strategy for weed management is available on their Invasive and Noxious Weeds website.

Prevention and early treatment are the most cost effective best management practices (BMPs).[5] Clearly, small areas are much less expensive to treat than those left to spread across the landscape. However, many weeds have expanded to large-scale infestations and can only be treated with substantial effort and cost. Each species of noxious weed has a unique seed dispersal method, making treatment highly variable across species.

Prevention

Noxious weeds are easily spread through contaminated agricultural machinery, livestock feed, hay, straw, soils, sod, nursery stock, and manure. Preventive measures begin by thoroughly cleaning agriculture machinery and equipment (which has come in contact with weeds) before it is transported to another location. Vehicles transporting seed, feed, and other agricultural materials should take measures to prevent spilling and spreading materials during transport. Transportation of topsoil, fill materials and construction equipment can also spread weeds.

Treatment

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

• Chemical control and containment (hand, vehicle, aerial)
• Mechanical  treatments (mowing, discing)
• Biological (insects, grazing livestock such as goats and cattle)
• 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:

• Bonneville CWMA.Tooele County, Salt Lake County, Utah Department of Transportation (UDOT), US Bureau of Land Management (BLM), and USFS
• Weber River CWMA. Weber County, Davis County, Antelope Island, Utah Department of Wildlife Resources (UDWR), UDOT, and BLM
• Squarrose CWMA. Tooele County, USFS, Utah School and Institutional Trust Lands Administration, and Utah State University, and BLM

Weed control and treatment resources:

• The UDWR compiled an Invasive Weed Control  document which provides specific treatment approaches for seven common noxious weeds.
• Utah State University Extension weed control program provides information regarding noxious weeds across Utah
• Utah Weed Control Association is a professional organization consisting of weed control specialists in Utah
• Natural Resources Conservation Service provides detailed noxious weed information
• UDOT Chemical Guide for State Noxious Weeds

Weeds create significant economic impacts that need to be considered in each county’s resource management plan. Economic losses in the United States from weeds was over $20 billion.[6] It is estimated that without the use of herbicides revenue losses to the agricultural sector would increase about 500%. [7]

Economic considerations for counties include:

• Direct expenditures. The UDWR allocates $200,000 annually to treat weeds. [8]  
• Reduce Range Carrying Capacity for Livestock and Grazing. Dyers woad infestations can spread 14% a year and reduce range carrying capacity by 38%. [9] The BLM estimated weed costs in the west for control and lost production at $100,000,000 a year. [10]
• 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. [11]
• Weed control impacts. Fire is a control method often used to treat phragmites, but smoke is a large 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. [12]