Written by Rachel Frost, Montana State University
Successful rangeland weed management plans should be an integrated process that involves the use of several control methods, combined with a well-planned strategy to reduce the impact of weeds on rangelands. The following steps outline a complete integrated strategy for protecting and enhancing rangelands threatened by weeds.
Inventory and mapping - Before a management program can be implemented, the extent of the problem must be determined. An inventory provides information on the weed species present, the size and density of the infestation, and the characteristics of the site including soil and vegetation complexes. This information can also be used to identify areas of potential invasion or possible routes of introduction to a specific land area. Once the information is gathered, it should be incorporated into a map to facilitate planning and implementation of control measures.
Planning and implementation - During the planning and implementation phase, problems are identified and prioritized and paired with appropriate solutions. The economic feasibility of the plan should be evaluated to ensure there are adequate resources to implement all phases of the weed management plan, including post-treatment monitoring and evaluation.
Preventing weed encroachment - By far the most cost-effective method of weed management is to prevent the introduction of weeds in the first place. Prevention programs involve limiting weed seed introduction and dispersal, minimizing disturbance, and practicing proper management. Specific ways to prevent new weed introductions are:
- Use certified weed-free hay, feed grain, straw, and mulch;
- Avoid driving through weed-infested areas and always wash the undercarriage of a vehicle that has been in weed-infested areas;
- Avoid grazing when weeds have mature seedheads.
- Move livestock to a holding area for about 14 days after grazing a weed-infested area and before moving them to a weed-free area;
- Ask hunters and hikers to clean their clothes and equipment prior to coming on your land, especially if they have been in a weed-infested area;
- Minimize soil disturbance when possible; and
- Manage for vigorous, diverse vegetative communities capable of competing with weeds.
Early detection and eradication - Early detection of new weed infestations can facilitate complete eradication of a serious noxious weed before it has a chance to widely establish on rangeland. Weeds spread by establishing small satellite infestations, the advancing front lines of the main invasion. Early detection of these small infestations can lead to successful eradication or total removal of the weed from the area.
Containment of large infestations - Once weed infestations become too large to eradicate, containment is the most cost-effective strategy. Containment of large-scale infestations is beneficial because it preserves uninfested rangeland by treating the borders of existing infestation and preventing the infestation from spreading beyond its existing boundaries.
Select appropriate control techniques - No single weed control technique is appropriate for all areas in a management unit. Control techniques must be chosen according to available economic resources and the environmental considerations of the area. Specific things to consider when selecting the most appropriate control technique include: the target weed species, effectiveness of the control technique, availability of control agents such as insects or grazing animals, land uses, timeline of control, environmental considerations, and relative cost of the control techniques. A combination of control techniques may provide better control than a single technique.
Revegetation and proper grazing management - Revegetation with desirable plants may be necessary on sites without an understory of desirable species. These newly established species can minimize the invasion of rangeland weeds and improve forage quality of the site. A grazing plan with the goal of moderate grass utilization should be established on any management unit with a weed control program. The grazing system should allow ample recovery time between grazing periods for plants to recover and to promote litter accumulation, important for maintaining a health plant community.
Monitoring and evaluation - Any time a management program is initiated, monitoring and evaluation are the keys to determining program success and identifying needs for change in the program. Monitoring involves making observations, collecting data, and keeping detailed records. Ideally, monitoring will detect changes in both weeds and desirable plants, as well as biological control agent populations and soil characteristics such as erosion, bare ground, and compaction. Many rangeland weeds are difficult to control and require a long-term commitment on the part of the land manager to suppress or eradicate the weeds. The adoption of integrated weed management (IWM) strategies is the best way to protect uninfested rangeland and reclaim land with existing weed populations.