VALUE AND USE
SPECIES: Centaurea solstitialis | Yellow Starthistle 



WOOD PRODUCTS VALUE : 
NO-ENTRY


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
Livestock browse yellow starthistle in the rosette and early bolting
stages [40].  Consumption of yellow starthistle over an extended time
causes an untreatable neurological disease in horses called equine
nigropallidal encephalomalacia [29].  Yellow starthistle is not toxic to
ruminants [40].

Ring-necked pheasant, California quail, house finch, and American
goldfinch were observed eating large quantities of yellow starthistle
seed in southeastern Washington [32].  Yellow starthistle was used in 1
of 32 nests built by Bell's vireo along the Santa Ynez River, California
[28].


PALATABILITY : 
Yellow starthistle is palatable to livestock in the rosette and bolting
stages.  Sharp spines on flowerheads deter grazing during the flowering
stage [32].


NUTRITIONAL VALUE : 
Yellow starthistle is acceptable forage for ruminants.  Protein levels
ranged from 10 to 13 percent and 11 to 13 percent during rosette and
bolting stages, respectively.  Acid detergent fiber was between 26 and
32 percent [40].


COVER VALUE : 
NO-ENTRY


VALUE FOR REHABILITATION OF DISTURBED SITES : 
NO-ENTRY


OTHER USES AND VALUES : 
NO-ENTRY


MANAGEMENT CONSIDERATIONS : 
Yellow starthistle is an important rangeland and pasture weed in western
North America.  It rapidly invades overgrazed rangeland and other
disturbed sites.  Once established, yellow starthistle is difficult to
eradicate.  Effective control involves a combination of herbicide
treatments, biological control agents, establishment of competitive
perennial grasses, and livestock management designed to prevent
overgrazing.  Although yellow starthistle can be temporarily controlled
with spring herbicide treatments, it establishes from long-lived seed
after chemicals have dissipated [39].  In addition, yellow starthistle
exhibits a high degree of phenotypic plasticity and may be able to adapt
to specific chemical or biological controls [41].

Herbicide application rates and yellow starthistle susceptibility are
described [4,27,39].  Picloram-resistant strains of yellow starthistle
have recently been observed [6,22].  Establishment of perennial grasses
after herbicide treatment is necessary to prevent reinvasion by yellow
starthistle.  Grasses with early growth, strong seedling vigor, and a
large root system with good lateral spread have the greatest potential
to compete successfully with yellow starthistle [3,18,20].

Most authors recommend initially controlling yellow starthistle with
herbicides while grasses establish [18,20,26,30], but grass seeding of
yellow starthistle-infested sites without initial herbicide treatment
has been tested [20,26,30].  An infested site in Idaho was disked and
seeded with 12 perennial grass species.  Only intermediate wheatgrass
(Thinopyrum intermedium ssp. intermedium), pubescent wheatgrass (T.
intermedium ssp. barbulatum), and crested wheatgrass (Agropyron
cristatum) were able to establish.  They did not begin to suppress
yellow starthistle seed production until their third growing season
[26].  Prather and Callihan [30] suggest established pubescent
wheatgrass may be able to deny resources to yellow starthistle
seedlings.  Without herbicide control, seeding of orchardgrass (Dactylis
glomerata) and tall oatgrass (Arrhenatherum elatius) did not improve
forage on an infested northeastern Oregon site [20].

Fertilizer increased yellow starthistle densities in northeastern Oregon [20].

Well-timed mowings or controlled grazing with cattle can contain large
yellow starthistle infestations.  Yellow starthistle continues to grow
after heavy grazing but produces fewer seeds per plant.  Intensive
grazing in May and June reduces yellow starthistle size, summer and fall
canopy size, and seed production in annual rangeland [40].  Mowing
during the early flowering stage minimizes regrowth but plants should be
monitored and mowed again if regrowth and flowering occur [39].

Biological control agents which utilize flowerheads have the greatest
potential for controlling yellow starthistle [10,41].  Biota associated
with yellow starthistle in southern Europe have been described [7,35].
Five insects (a gall fly, a seed fly, and three weevils) have been
released in the United States, the first in 1984 and the most recent in
1992.  The four earliest released insects are established but their
effectiveness is not yet known.  A rust fungus is undergoing field
testing.  Insects, release dates, and establishment information are
described [10,24,41].

Related categories for Species: Centaurea solstitialis | Yellow Starthistle