• Minimizing the Spread of Weeds
  • Best Management Practices
  • Planning and Personnel
  • Minimizing the Transport of Seed and Vegetative Propagules Within a Road Corridor
  • Minimizing the Transport of Weeds From Infested to Uninfested Areas
  • Maintaining Desirable Species
  • Minimizing Soil Disturbance

Some of the following recommendations to reduce or eliminate the spread of weeds during road maintenance will be easy to adopt. Other recommendations may be difficult to implement and could conflict with the customary timing or type of road maintenance practices. Each forest supervisor and district ranger will have to weigh the importance of weed management against the resources and funding available to determine which measures are appropriate for a particular unit. To be successful, road maintenance practices must be part of a comprehensive weed management program implemented cooperatively with all landowners and managers in the area.

Best Management Practices

U. S. Department of Agriculture (USDA) Forest Service Manual 2080 (http://www.fs.fed.us/im/directives/fsm/2000/2080.txt) directs the development and coordination of the Forest Service noxious weed program. Each forest and district is directed to appoint a noxious weed coordinator and develop and implement a noxious weed management program. The Northern and Intermountain Regions (1 and 4) have implemented regionwide 2080 direction (http://www.fs.fed.us/im/directives/field/r1/fsm/2000/r1-2080.doc and http://www.fs.fed.us/im/directives/field/r4/fsm/2000/2080.doc) in the form of best management practices (BMPs) for reducing or eliminating the spread of weeds through agency activities. Northern Region road construction and maintenance BMPs are included in appendix A. Intermountain Region BMPs are similar to those of the Northern Region. All units with existing or potential roadside weed infestations should consider following the BMPs for roads and ground-disturbing activities covered by the Northern and Intermountain Region supplements to the Forest Service Manual.

Planning and Personnel

Evaluate the extent of existing weed infestations and develop strategies to reduce the size of each infestation, prevent the spread of weeds, and stop the introduction of other weed species. Preventing the introduction of weeds to uninfested sites is the most critical component of a weed management program, and it is one of the most cost-effective methods of management.

• Inventory roads for noxious weeds and maintain records of weed species and their locations so planning for road maintenance can include mitigation measures. Road maintenance crews and weed coordinators should collaborate to establish roadside maintenance schedules that will control seed produced by noxious weeds.
  
  
• Give a high priority to containment and treatment for new invader weeds or those that are not well established in the area.
  
  
• Train road maintenance personnel to identify noxious weeds and other invasive plants of concern. These should be marked and reported to the noxious weed coordinator.
  
  
• Use weed crew personnel to assist with road maintenance as scheduling and their skills allow. Weed crew personnel will bring their knowledge of weed species and dispersal mechanisms to the job, helping reduce the spread of weeds during road maintenance.
  
  
• Herbicide use should be specified in planning documents. Planning staff should become familiar with documents such as FS–2100–2, Pesticide Use Proposal (https://fs.usda.gov/wps/myportal/fsintranet/!ut/p/c5/hY_BjoIwAES).

Minimizing the Transport of Seed and Vegetative Propagules Within a Road Corridor

Minimizing the transport of seed and plant parts by vehicles, machinery, wildlife, and livestock is the key to preventing the establishment of noxious weeds.

• Inspect all gravel pits and material sources annually and keep them weed free. Establish and maintain annually updated records of certified weed-free sources. Inspect gravel pits and material sources before each use to ensure that weeds haven't invaded since the last annual inspection. Record the inspection results. Don't use material from any source that is infested with weeds unless the material can be cleaned of seed and other vegetative matter before use.
  
  
• Consider using biological-control agents to manage weeds on roadsides adjacent to land infested with noxious weeds. Because biological-control agents do not eradicate their hosts or eliminate seed production, they are not appropriate for use on new invader species or in situations where eradication or complete control is achievable.
  
  
• Include weed control in the road maintenance appraisal for timber sales. Alternatively, add a special roadside weed management provision to the C section of the timber sale contract. Including weed control in timber sales assures funding to complete the work.
  
  
• Spray noxious weed infestations on or near roads or manage the invaders by other effective means. Controlling weeds near roads will reduce dispersal of weed seed by vehicles and maintenance or construction equipment. Reducing or eliminating the weed infestations will allow better growth of desirable grasses and other plants.
  
  
• Coordinate weed control and road maintenance so weeds are controlled for several consecutive years before major road maintenance or reconstruction. This will reduce the amount of viable weed seed stored in soil on road shoulders, cut slopes, and borrow sites in the project area.

Minimizing the Transport of Weeds From Infested to Uninfested Areas

Cleaning vehicles and equipment is the least expensive and most effective method of noxious weed control.

• Avoid working in weedy areas if possible. Postpone work until weeds have been eliminated from the site.
  
  
• Perform road maintenance such as road grading, brushing, and ditch cleaning from uninfested to infested areas to the extent possible. This will help prevent moving weed propagules from infested areas into adjacent uninfested areas.
  
  
• Wash all agency and contractor off-road vehicles before entering public lands to minimize transporting weed seed. A standardized method and form for recording vehicle-washing inspections may be needed to promote consistency throughout the agency. It may also be desirable to require that all stock and stock trailers be inspected and cleaned before entering public lands. This may not be practical unless the public must pass an entrance station or other restricted entry point to access public land.
  
  
• Wash off-road vehicles and heavy equipment to avoid transporting weed seed from public lands, and inspect and clean livestock after working in or traveling through weedy areas.
  
  
• Wash road graders and other equipment immediately after operating in infested areas. Clean all dirt and plant parts from the undersides of mower decks.

The Forest Service Technology and Development program has developed a high-pressure mobile power washer (figure 9) mounted on a trailer that can be towed by a pickup. The washer can be used by two workers to wash vehicles from top to bottom in 5 minutes or less. The system uses oscillating bars with nozzles to wash vehicle undercarriages and handdirected wands wash more accessible areas. The washer carries 350 gallons of water—enough to wash about 10 vehicles. All wash water is captured on a containment mat for reuse. The water goes through settling tanks and filters to remove mud, weed seeds, plant parts, and even spores. The captured material can be easily removed from the filters for proper disposal. See MTDC Portable Vehicle Washer (0434–2819–MTDC), available electronically at http://fsweb.mtdc.wo.fs.fed.us/php/library_card.php?p_num=0434%202819. A hard copy of the document can be ordered from:

USDA Forest Service, MTDC
Attn: Publications Distribution
5785 Hwy. 10 West
Missoula, MT 59808–9361

Figure 9—The portable vehicle washer developed by the Missoula
Technology and Development Center is being used to clean
a fire engine on the Bitterroot National Forest.

Plans for building the washer will be available through the Missoula Technology and Development Center at the address above. The Technology and Development program is modifying the washer so it will be able to wash large earth-working equipment.

Maintaining Desirable Species

Establishing and maintaining competitive, desirable plants along roadsides and other disturbed areas vulnerable to weed colonization helps prevent or slow the establishment, growth, and reproduction of noxious weeds.

• Raise the mower height to at least 4 inches to help retain existing desirable grasses and keep the soil surface shaded on roadsides that are mowed.
  
  
• Limit brushing and mowing to the minimum road distance and maximum height needed to meet safety objectives.
  
  
• Reseed after construction, heavy maintenance, and other soil–disturbing activities. Where roads are graded once a year or less, seed the roadway's shoulders after grading. Seeding with desirable, rhizomatous grasses will allow faster recovery from disturbances. Consult appendix A for the USDA reseeding guidelines. Natural Resources Conservation Service offices can provide recommendations on species suited for your local climate and conditions. Only use seed that has been certified weed-free for your area.
  
  
• Fertilize desirable roadside vegetation as necessary to maintain plant health. Do not fertilize areas where weeds are present, unless you do so while applying a targeted, compatible herbicide. Where weeds are present, targeted herbicides may eliminate weeds and allow grass and other desirable species to produce lush growth, even without fertilization.
  
  
• To reduce the effects of grading on roadside grasses, grade roads early in the spring before grasses develop seed heads or late in the season after grasses have set seed and become dormant. Local climate will dictate which season will be more practical and effective for grading. In some climates, fall grading requires watering the roadway, which can be very expensive.
  
  
• On highly traveled roads, consider paving or using binders to stabilize the road surface. A stable surface will minimize the need for road grading, allowing desirable vegetation to become well established.

Minimizing Soil Disturbance

Because weed species prefer disturbed ground, don't disturb roadbed aggregates or soil along the road unless it is really necessary. In such cases, reestablish desirable species as soon as possible.

• Evaluate the need to grade each road or section of road rather than following a set schedule for road maintenance. This is especially important in weedy areas or areas that are susceptible to infestation. Do not grade unless you must do so for road drainage, safety, or function.
  
  
• Use only clean fill material from a weed-free source rather than borrowing fill from a weed-infested stockpile, road shoulder, or ditch line.
  
  
• Keep the grader's blade 1 to 2 inches above the road surface when the primary goal is to remove rocks that have fallen onto the road.
  
  
• Consider paving or treating the roadway surface with soil stabilizers such as Road Oyl, Stabilizer, Soil-Sement, or Pennzsupress D to reduce routine road maintenance. Sources for these products are listed on page 16. Some stabilizer material, such as lignite, tends to kill existing grasses and forbs. Weeds will quickly recolonize treated areas and outcompete desirable vegetation, so use caution when applying stabilizers in infested areas.