4? 0 cr.)
FS 52
January 1977
Yellow Starthistle
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Yellow starthistle (golden starthistle) is an
annual with alternate leaves. Stems and leaves
are covered with cottony hair. Basal leaves are
deeply lobed and branched from the base. Tap
roots are brownish. Seeds are either shiny black
or tufted. The Latin name is Centaurea solstitialis.
Yellow starthistle is found in foothill rangelands, new clover and alfalfa seedings, cultivated
fields, and waste areas. It grows 1 to 3 feet tall.
It reduces yields and contaminates the seed from
cereal crops. The sharp spines on the flowers
interfere with livestock grazing in dryland pas-
tures.
Control methods
It is essential to prevent flowering and seed
formation. Young plants, from seedling to early
overall application, will reduce injury to clovers.
Silvex, MCPA, 2,4,5-T, dicamba, and picloram
also will control yellow starthistle. In legumes,
use 2,4-DB. Always follow label instructions.
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rosette stage, are most easily controlled. Because of delayed germination of some seeds,
two or three cultivations or herbicide applications may be necessary during the growing Nonselective herbicides
season. Burning or flaming before bloom kills
Nonselective herbicides may be used on nonyellow starthistle.
cropped areas such as roadsides or industrial
sites. Both foliar sprays and soil-active herbiSelective herbicides
The choice and application of herbicides depends upon the field situation. In cereal grains,
cides are used.
Foliar sprays. Use amitrole-1 pound ac2,4-D will control yellow starthistle and other tive ingredient per acre, paraquat-1/2 pound
broadleaf weeds. In pastures, use 2,4-D as di- active ingredient per acre, or 2,4-D-1 pound
rected on the label. Spot spraying, rather than acid equivalent per acre.
OREGON STATE UNIVERSITY
EXTENSION
r-) SERVICE
Extension Service, Oregon State University, Corvallis, Henry A. Wadsworth, director. This publication was Produced and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Extension work is a
cooperative program of Oregon State University, the U. S. Department of Agriculture, and Oregon counties.
Extension invites participation in its programs and otters them equally to all People, without discrimination.
Use 1 quart of wetting agent per 100 gallons
water with amitrole, paraquat, and 2,4-D
amine formulations. Use 40 to 50 gallons of water
per acre. If you use amitrole, for example, apply
of
40 to 50 gallons of spray per acre, containing
pound active material and a half-quart of
1
wetting agent.
Soil-active herbicides. These materials give
tion.
Pesticide warning
The user of any pesticide is responsible for
residues in a crop or for problems caused by
drift from one property to other property or crops.
Always follow the label instructions.
Drawings, and some of the information included
in this Fact Sheet, appear courtesy of University of
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season-long weed control. They should not be
applied where roots of desirable plants may be
present. Rainfall is necessary to leach these
chemicals into the soil before the weeds are up.
Use atrazine (AAtrex ®), simazine (Princep ®), bromacil (Hyvar X ®), diuron (Karmex
®), karbutilate (Tandex ®), or monuron (Telvar
0) at 2.4 to 4 pounds active ingredient per acre.
This will be 3 to 5 pounds of 80 percent formula-
California Extension Leaflet 2741.
Revised by Martin Zimmerman, Gilliam County
Extension agent, and Homer M. Hepworth, Extension
agronomist, Oregon State University.