VALUE AND USE
SPECIES: Carduus nutans | Musk Thistle 



WOOD PRODUCTS VALUE : 
NO-ENTRY


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
NO-ENTRY


PALATABILITY : 
Musk thistle is not palatable to livestock because of its long sharp
spines [17,32].


NUTRITIONAL VALUE : 
NO-ENTRY


COVER VALUE : 
NO-ENTRY


VALUE FOR REHABILITATION OF DISTURBED SITES : 
NO-ENTRY


OTHER USES AND VALUES : 
Musk thistle provides a source of nectar for high quality honey [29].


MANAGEMENT CONSIDERATIONS : 
Musk thistle is listed as a noxious weed in 16 states (mostly western
and midwestern) and 5 Canadian provinces [5,7].  It can be a severe
problem in alfalfa (Medicago sativa) fields, pastures, and rangeland
[7].  Musk thistle does not tolerate cultivation so it is not usually a
problem on annual cropland [5,24].  Control depends on preventing seed
production [26].

Musk thistle is effectively controlled with herbicide applied during the
rosette stage.  Herbicide application techniques are described [2,5,17,22,29].

Two weevil species have been introduced from Europe to control musk
thistle.  Thistlehead weevil (Rhinocyllus conicus), introduced into 23
states (including Montana in 1969), is well established and has reduced
musk thistle density in the United States [24,36].  The larvae bore into
and feed on the flowerheads.  The larvae not only damage developing seed
but also reduce viability of remaining seed [24,32].  A flowerhead with
nine or more larvae has less than 2 percent viability of remaining seed
[32].

The rosette-feeding weevil (Trichosirocalus horridus) inhabits roots and
stems.  It is only effective against small, nonvigorous musk thistle
rosettes [24].  It was introduced into Montana in 1978 and, by 1991, was
only established at a few sites [36].

The two introduced weevils combined with sulfonylureas herbicides may
control musk thistle [2].  Application of 2,4-D while primary blooms
were in the late bud or early bloom stage reduced musk thistle but did
not reduce survival or reproduction of either weevil [37].

Tall fescue (Festuca arundinacea) competes effectively with musk thistle
and is recommended for planting on roadsides and other disturbed sites.
Few musk thistle seeds planted in 1-year-old tall fescue germinated, and
those that did germinate did not reach reproductive stage.  When tall
fescue and musk thistle were planted simultaneously, musk thistle grew
and reproduced, but seed production was not optimum.  Musk thistle
control was greatest when the two introduced weevil species were present
in addition to the tall fescue [19].

Mowing may be an effective control method if it occurs during full
bloom.  Musk thistle harvested at full-bloom stage had only 26 good
quality seeds per plant.  Plants harvested 2 and 4 days after full bloom
produced 72 and 774 good quality seeds per plant, respectively [26].

At springs, seeps, and marshy valley bottoms in eastern New Mexico, musk
thistle is invading populations of Mescalero thistle (Cirsium vinaceum),
which is federally listed as threatened [34].

Related categories for Species: Carduus nutans | Musk Thistle