Yellow Starthistle Information
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Prevention
-Avenues of intro
-Suscept landscapes
-Education prog
-Early detection
Developing a Strategic Plan
Prevention
Yellow starthistle infests about 15 to 20 million acres in California, but has the potential to infest nearly 40 million acres (Pitcairn et al. 1998b). Consequently, preventing its introduction is the most cost-effective method for starthistle management and is an essential component of any noxious weed management strategy. The major elements of a management programs are to prevent introduction or re-invasion of starthistle weed seed, reduce the susceptibility of the ecosystem to yellow starthistle establishment, develop effective education materials and activities, and establish a program for early detection and monitoring (DiTomaso 2000).
Avenues of introduction
Yellow starthistle can encroach by establishing small infestations in relatively close proximity to a larger infestation (Sheley et al. 1999a). This can be through natural means including wind, water, and animal dispersal mechanisms. To prevent this type of encroachment, neighboring weed infestations on adjacent lands should be contained. The most effective method of containment is to spray the borders of infested areas with a herbicide (Sheley et al. 1999c).
In many cases, however, introduction of yellow starthistle and other noxious weeds onto grasslands can be associated with human-related activities. Seeds or plant vegetative fragments can be introduced as contaminants of hay or animal feed. This can be prevented by using feed that is certified as weed-free (Sheley et al. 1999c). Transporting soil contaminated with starthistle can lead to new infestations. This is a common method of introducing yellow starthistle seed along roadsides or in construction sites.
Livestock can move starthistle seeds from one area to another by passing viable seed through their digestive system or by transporting seed attached to hair or soil particles. Seed dispersal by animals can be minimized by avoiding livestock grazing in weed-infested areas during flowering and seeding stages or by holding animals for seven days before moving them to uninfested areas (Sheley et al. 1998).
Equipment and vehicles driven through infested landscapes can transport yellow starthistle seed to uninfested areas. Even human clothing can transport seed, particular in soil particles attached to shoes and boots. Equipment and clothing should be cleaned immediately after leaving an infested site.
It is particularly important to control or prevent weed invasions along transportation corridors, including roadsides, waterways, and railways. These areas are typically disturbed sites and, consequently, are more susceptible to noxious weed establishment (DiTomaso 2000).
Susceptible landscapes
Yellow starthistle often becomes established following disturbances, either natural or through human activity. Although starthistle can invade some undisturbed areas, disturbance usually allows for more rapid establishment and spread. Following soil disturbance, sites should be monitored to prevent establishment and subsequent seed production in these susceptible areas. In many cases, disturbed sites should be re-vegetated with desirable species to slow the invasion of yellow starthistle.
Proper grazing can maintain desired plants and provide a more competitive environment. To minimize starthistle invasions, overgrazing is discouraged and grazed plants should be allowed to recover before re-grazing. This ensures that grasses remain healthy and vigorous, maximizing their competitiveness and reducing the potential for starthistle encroachment (Sheley et al. 1999c). Re-vegetation with aggressive perennial grasses can prevent establishment of starthistle (Enloe et al. 1999a, 1999b, 2000). However, communities most resistant to weed infestations are usually composed of a diversity of plant species. This diversity allows for maximum niche occupation and resource capture (Sheley et al. 1999a).
Educational programs
Educating employees and the public can be accomplished by a number of methods. Information can be made available through brochures, posters, internet websites, calendars, scientific papers, and other written media. Educational programs can be conducted for academia, industry, landowners, land managers, or the general public. These can include public seminars, professional symposia, school programs academic field demonstrations, and volunteer field workshops conducted by church groups, environmental organizations, scouts, and several other groups. The media also play an important role in educating the public through radio or television news stories, public service announcements, newspaper articles, public displays, or even roadside bulletin boards. All these educational events or activities facilitate greater cooperation among private, federal, state, and county agencies, industries, landowners, and the general public. In addition, they increase the potential for early detection and rapid response to new starthistle infestations.
Early detection and monitoring
The best management of starthistle is to recognize potential weed problems early, control them before they reproduce and spread, and monitor the site regularly to maintain adequate follow-up control. Understanding the potential threats that may exist on surrounding property can provide an early warning system for weed invasion. One successful method for preventing yellow starthistle invasion is to regularly inventory the area by field surveys or aerial photography and remove individual weed plants before they become well established (Sheley et al. 1999c).
