Yellow Starthistle Information
Prevention
-Avenues of intro
-Suscept landscapes
-Education prog
-Early detection
Eradication
Developing a Strategic Plan
Eradication
Eradication is not often practical for yellow starthistle, but in previously uninfested areas it may be possible to eradicate new small invasions. An effective eradication program is closely tied to prevention. The key element to a successful eradication plan is early recognition of yellow starthistle populations and rapid response to prevent reproduction and the development of a seedbank. Control options in an eradication program are typically limited to mechanical removal, including hand pulling, and herbicide treatment. The objective is to completely eliminate the species from that site, not to manage the population. Eradication is not complete until all viable starthistle seed are depleted from the soil.
Eradication efforts are usually confined to smaller infestations (< 2 acres). These can be satellite populations adjacent to large infestations or isolated invasions far from other infestations. In some cases, eradication efforts can focus on the borders of large infestations (Zamora and Thill 1999). Financial resources, available technology, potential benefits, and social and geographical constraints will limit the size of the infested area that can be targeted for starthistle eradication (Zamora and Thill 1999). In some cases, large eradication programs require re-vegetation to completely eliminate yellow starthistle. Even when all these issues are considered, complete eradication of large infestations is rare.
Developing a Management Strategy
Once yellow starthistle is well established, eradication is not practical without extremely high financial and labor inputs. The ultimate objective under these circumstances is to manage the infested area and contain the large-scale infestation. However, the goal of any management plan should not simply be control of the noxious weed(s), but improvement of the degraded rangeland community, enhanced utility of the ecosystem, and prevention of reinvasion or invasion by other noxious weed species. In severely deteriorated starthistle-infested grasslands, it may be necessary to reintroduce desirable plant mixtures. Ideally, a healthy weed-resistant plant community would consist of a diverse group of species that occupy most of the niches.
An effective yellow starthistle management strategy should include three major goals; 1) effective control of the weed, 2) achieve the desired land-use objectives such as forage production, wildlife habitat development, or recreational land maintenance, and 3) prevent re-invasion of starthistle or invasion of equally invasive species. To accomplish these goals, land managers will require an understanding of the land use objectives, management limitations, and biology of the system.
Understanding the land use objectives of a weed management system is critical to determining the proper management approach. Management strategies will differ if the primary goal is to enhance forage quantity and quality for livestock and wildlife, restore native vegetation or endangered species, or increase recreational value. In addition, selection of the proper management tool(s) and program may depend on a number of factors including weed species, effectiveness of the control techniques, availability of control agents or grazing animals, length of time required for control, environmental considerations, chemical use restrictions, topography, climatic conditions, and relative cost of the control techniques (Sheley et al. 1999a).
One of the most important aspects in developing a yellow starthistle or any noxious weed management strategy is to accurately identify and map lands infested with the weed(s) (Sheley et al. 1998). Knowing where the infestations occur can determine the control method used, assist in prioritizing the management strategy, and identify areas where eradication, containment, or management can be achieved. In addition, this information can prevent unnecessary herbicide treatments and slow the spread of the weed.
Weed infestations should be identified on a map and records should contain weed species present, areas infested, weed density, rangeland under threat of invasion, soil and range types, and other site factors pertinent to successful management of noxious weed-infested rangeland (Sheley et al.1998). Continual monitoring will be necessary to prevent reinvading populations from becoming established. A number of monitoring techniques can be used, including hand drawing infested sites on a map, using GPS (global positions system) units and plotting the data using GIS (geographical information system) programs (Cooksey and Sheley 1998), or more sophisticated techniques such as using aerial remote sensing equipment (Lass et al. 1995, 1996, 2000, Price et al. 1998).
A thorough understanding of the biology and ecology of yellow starthistle, as well as the grassland system it infests, is necessary for long-term management. Much of this information is available in the Biology and Ecology section of this site. In addition to understanding the biology and ecology of the weed, it is important to be familiar with characteristics of the ecosystem. This can include an awareness of other desirable and weedy species present, the potential for invasion into other yet un-infested sites within the area, impact of the management strategy on sensitive species and habitats, soil conditions and range types present, as well as other ecosystem parameters.
A coordinated effort among interested parties, including the general public, private and public landowners, federal, state and county agencies, and environmental organizations can lead to a more effective management plan. A cooperative program can eliminate duplication of effort, reduce avenues for reintroduction, consolidate equipment and labor costs, and decrease the risk of repeating previous failures. In addition, coordinated management teams can obtain cost-sharing grants to manage large infestations more effectively. This is typically achieved through the development of a Weed Management Area (see specific section on WMA or California Department of Food and Agriculture).
Click here to view the "Strategic Plan for the Coordinated Management of Noxious Weeds in California" produced by the Range Management Advisory Committee.
Implementing Strategic Plan
Implementing a strategic plan is the most critical aspect of yellow starthistle management and typically requires input from weed management experts. Before any option can be employed, financial considerations must be addressed and a budget must be prepared to keep project costs within reasonable limits. Limited funding may require prioritizing areas of greatest concern. For example, the decision to re-vegetate must consider direct costs (seedbed preparation, seeds and seeding, follow-up management), indirect costs (risk of failure, non-use during establishment period), and benefits (increased forage, improved ecosystem function, soil conservation) (Jacobs et al. 1999, Smathers et al. 1985).
Control options should include, whenever possible, an integration of mechanical, cultural, biological, and chemical techniques. A long-term commitment of three to five or more years will be necessary in nearly all cases to deplete the weed seedbank. It is not unusual for yellow starthistle plants to be larger after a single year of control (Callihan and Lass 1996). It will require a significant reduction in the seedbank and an increase in the seedbanks of other desirable competing species before dramatic results can be observed. Regardless of the approach employed, annual monitoring and evaluations should be conducted to determine the adequacy of the management plan (Sheley et al. 1999c). Changes in the management approaches may be necessary to adjust to any unforeseen problems and improve the strategy.
Once the desired objectives have been attained, a yearly follow up program will be necessary to prevent starthistle re-infestation. This may involve annual hand pulling, spot herbicide treatments, or even periodic burning (DiTomaso 2000). In addition, changes in grazing practices may be required to ensure that rangeland conditions do not become susceptible to rapid re-infestation. If follow-up is not made for 2 to 3 years following a control program, the grassland will usually become heavily re-infested in a short time.
