• IMPORTANCE TO LIVESTOCK AND WILDLIFE
• PALATABILITY
• NUTRITIONAL VALUE
• COVER VALUE
• VALUE FOR REHABILITATION OF DISTURBED SITES
• OTHER USES AND VALUES
• MANAGEMENT CONSIDERATIONS

IMPORTANCE TO LIVESTOCK AND WILDLIFE:

Broom snakeweed provides little browse for domestic livestock [90]. It is of minimal value to cattle and horses [71] but does provide fair quality winter browse for domestic sheep when green forage is scarce or lacking [62,71]. Utilization by domestic sheep on winter ranges of Utah and Nevada may reach 9.8% to 15% [41,47]. However, Green and others [40] report only light (less than 3%) use by domestic sheep in west-central Utah. Summer Angora goat use may be fairly heavy on burned-over Arizona chaparral [54].

Broom snakeweed can be toxic to domestic sheep, goats, and cattle particularly during winter or early spring when poor forage availability forces animals to consume large quantities [15,62,95]. Domestic goats are fairly resistant to broom snakeweed toxicity [68]. Saponins present in the foliage can cause illness, death, or abortion in livestock [95,100]. However, toxicity apparently varies with phenological stage and substrate. Higher toxicity levels are often associated with periods of rapid growth, such as early leaf development, and with growth on sandy rather than calcareous soils [76]. Broom snakeweed is also a secondary or facultative absorber of selenium which may cause illness or death when consumed in quantity [62]. Carpenter and others [15] report that “production losses from snakeweed poisoning are not significant with only a light infestation."

Broom snakeweed provides only poor quality browse for most large ungulates. It is however, important to pronghorn in some areas, particularly during spring and summer. In parts of Utah, pronghorn utilization may reach up to 28% [90]. Broom snakeweed is considered a preferred pronghorn food in Carter County, Montana from September through December and is eaten in March in northeastern Colorado [87,96]. Broom snakeweed is eaten by mule deer in some big sagebrush-grass communities of northern Utah and south-central New Mexico [4,59]. It receives moderate use by desert mule deer in parts of Texas and Arizona [55]. Broom snakeweed is a winter food source for bighorn sheep on the Cinnabar winter range of Montana [53]. In northeastern Colorado, bison consume broom snakeweed particularly during March and October [79,80].

Broom snakeweed is a major food source for black-tailed jackrabbits in Kansas and south-central New Mexico [22,27]. In a New Mexico study, use of broom snakeweed by the black-tailed jackrabbit was highest in summer and winter [31].

Broom snakeweed seeds are readily eaten by a wide variety of small birds and mammals. Seeds of broom snakeweed are an important winter scaled quail food in parts of southeastern New Mexico [23]. Broom snakeweed seed forms part of the spring and summer diets of the lesser prairie chicken in eastern New Mexico [24]. The banner-tailed kangaroo rat, Ord’s kangaroo rat and northern grasshopper mouse also eat broom snakeweed seed [7,70].

PALATABILITY:

Broom snakeweed browse is relatively unpalatable to most big game species and to domestic livestock. However, results of a Utah study indicate that it is preferred by pronghorn during spring and summer [90]. Broom snakeweed is described as "at least moderately palatable" to domestic sheep in Idaho [72]. Seeds are palatable to a variety of small birds and mammals. Palatability of broom snakeweed has been rated as follows [26]:

                        CO       MT      ND       UT      WY

Cattle                  poor    poor     poor    poor     poor
Sheep                   fair    poor     poor    fair     poor
Horses                  ----    poor     ----    poor     poor
Pronghorn               ----    poor     poor    fair     ----
Elk                     ----    poor    ----     poor    ----     
Mule deer               ----    poor     poor    fair     ----
White-tailed deer       ----    ----     poor    ----     ----
Small mammals           ----    ----     ----    fair     ----
Small nongame birds     ----    ----     ----    fair     ----
Upland game birds       ----    ----     ----    poor     ----
Waterfowl               ----    ----     ----    poor     ----

NUTRITIONAL VALUE:

Broom snakeweed is rated poor in energy and protein value [26]. Nutritional content is documented as follows [41]:

                        Protein     Crude      Ca      Phosphorus
                        (%)         Fiber (%)  (%)     (%)  
Before grazing          6.62        24.0       1.13    .079  
After grazing           6.53        24.8       1.13    .079     

          Protein   Ether     Ash    Ca    P     K     Mg    Mn    
          %         Extract%   %     %     %     %     mg/kg---
November  11.8      11.9      5.3    0.69  0.18  1.38  40    140
December   8.4       7.3      4.4    0.62  0.13  0.91  27    298
March     15.2       4.9     14.7    1.32  0.24  2.74  69   1427                

                        3/29    4/9     4/24    5/18    5/26    6/15

vegetative parts        7.9     7.4     ----    ----    ----    ----
flower                  ----    ----    8.0     12.3    ----    ----
pod                     ----    ----    ----    ----    9.0     9.0

COVER VALUE:

Broom snakeweed provides cover for many small birds and mammals. Larger plants provide resting sites for black-tailed jackrabbits in New Mexico [14]. Broom snakeweed also provides black-tailed jackrabbits with protective cover against weather and predators such as coyotes on heavily grazed ranges of New Mexico [22]. In some areas, broom snakeweed serves as good cover for both Gambel's and scaled quail [37,107]. In Oregon, the Columbia Basin burrowing owl selected broom snakeweed habitat for nesting [39]. Cover value is rated as follows [26]:

                                 MT      ND      UT

Pronghorn                       ----    ----    poor
Elk                             poor    ----    poor
Mule deer                       ----    fair    ----
White-tailed deer               ----    poor    ----
Small mammals                   poor    ----    ----
Small nongame birds             ----    ----    fair
Upland game birds               ----    ----    fair
Waterfowl                       ----    ----    poor

VALUE FOR REHABILITATION OF DISTURBED SITES:

Under natural conditions broom snakeweed quickly invades disturbed sites and can minimize soil erosion [97]. It reportedly stabilizes loose wind-blown soils in mesquite (Prosopis spp.) sand dunes [14]. Broom snakeweed is rated as low to moderate in both long- and short-term rehabilitation potential [26].

Plants may be transplanted or established through seed. Broom snakeweed is well adapted to planting in pinyon-juniper, big sagebrush, northern desert shrub, and southern desert shrub communities [82].

OTHER USES AND VALUES:

Some Native American peoples traditionally used broom snakeweed to construct brooms and as a treatment for indigestion [95].

MANAGEMENT CONSIDERATIONS:

Increases in broom snakeweed may be due to livestock grazing, drought, weather, or fire suppression [44]. Broom snakeweed quickly invades overgrazed rangeland. Cattle sometimes leave broom snakeweed almost untouched while grazing grasses to within 0.5 inch (1.27 cm) of the soil surface [14]. An abundance of this shrub is considered by some authorities as an indicator of range deterioration [62]. Many researchers believe that broom snakeweed may be reduced and species such as blue grama increased by protection from grazing. Grass production increased from 976 lbs/acre to 2,024 lbs/acre during the first year after complete removal of broom snakeweed in Texas [68]. However, increases in broom snakeweed may be due to climatic fluctuations rather than overgrazing [15,49]. West and Tueller [104] maintain that climatic factors are more important than grazing in determining the extent of broom snakeweed populations.

Broom snakeweed populations fluctuate in response to annual moisture patterns, with rapid increases commonly occurring after drought periods [25]. This plant apparently exhibits only a slight response to late-season irrigation [12].

The root system of broom snakeweed occurs at approximately the same soil depth as do the roots of many perennial grasses [60]. Competition for water and nutrients is suspected. Broom snakeweed competition can apparently cause decreases in big bluestem (Andropogon gerardii) and blue grama. However, bottlebrush squirreltail (Elymus elymoides) and black grama appear to be unaffected by the presence of broom snakeweed [49].

Broom snakeweed can be difficult to kill with herbicides, and opinions vary on the optimum time to spray. Clary and others [17] noted erratic results from herbicides such as tebuthiuron in the Intermountain region. Stands were often reduced by applications of pelleted tebuthiuron, but reestablishment sometimes compensated for the loss of the original plants. Detailed information on the chemical control of broom snakeweed is available [17,19,35,66,91]. In cases where application of herbicide is effective, broom snakeweed populations are controlled for up to 5 years, although grazing practices and fall and winter precipitation received after application can also influence results. In some cases, fire can be used in combination with herbicides to extend the longevity of chemical treatment to beyond 5-7 years [92].

Mechanical control is generally ineffective in controlling broom snakeweed [29]. Hoeing the plants just below the soil surface can be effective but is difficult or impractical in stony ground [94]. In Arizona, chaining resulted in increases in broom snakeweed and harrowing in central Arizona reduced populations by only 5 to 10% [34].

Broom snakeweed is susceptible to severe damage by the round-headed borer (Crossidius pulchellus) and mealybugs (Chorizococcus spp.). These insects were believed to be the major factor causing a broom snakeweed die-off in Texas and New Mexico during a particularly dry summer. Eighty-two percent of the mortality was attributed to insects, while the other 18% was thought to be drought-induced [100].

Biological control agents may have potential for control of broom snakeweed [21,36].

Related categories for SPECIES: Gutierrezia sarothrae | Broom Snakeweed