'HOBBLE CREEK' MOUNTAIN BIG
SAGEBRUSH SEED PRODUCTION
Bruce L. Welch
Fred J. Wagstaff
Gary L. Jorgensen
ABSTRACT
'HOBBLE CREEK' BIG SAGEBRUSH
This study measured the seed production of 40 randomly selected 'Hobble Creek' mountain big sagebrush
(Artemisia tridentata ssp. vaseyana) plants growing in a
seed increase garden. Results indicate that 2- and 3-yearold 'Hobble Creek' plants planted on a 7- by 7-ft grid produce about 72 to 67 pounds of certified pure live seed per
acre. There was significant variation among plants within
a year and significant variation between years for a given
plant. At $20 to $50 per pound of pure live seed, the gross
income per acre would be between $1,340 and $3,600.
'Hobble Creek' mountain big sagebrush (Artemisia
tridentata ssp. vaseyana) is a superior selection of big
sagebrush (Welch and others 1986). It is the only big
sagebrush, to date, to be named and released as an improved shrub for use on mule deer and domestic sheep
winter ranges (Welch and others 1987). Agencies involved in the naming and releasing of 'Hobble Creek'
were: Utah Agricultural Experiment Station, Utah State
University; U.S. Department of Agriculture, Forest Service, Intermountain Research Station; Utah State Division
of Wildlife Resources; Upper Colorado Environmental
Plant Center; Colorado Agricultural Experiment Station,
Colorado State University; Idaho Agricultural Experiment
Station, University of Idaho; and U.S. Department of
Agriculture, Soil Conservation Service. The naming and
release of 'Hobble Creek' mountain big sagebrush for
commercial production and marketing of seed and plants
represent a significant step forward in making big sagebrush available as a forage plant for wildlife and certain
domestic livestock.
Of 186 big sagebrush selections tested, 'Hobble Creek'
was the most preferred by wintering mule deer and was
ranked in the most preferred group by wintering domestic
sheep (Welch and others 1986). This high degree of preference is the main justification for claiming it as a superior selection of big sagebrush.
'Hobble Creek' ranked in the top third of all selections
tested for productivity Oength ofleader growth) and was
third out of 20 selections in vegetative production expressed as gram per centimeter of stem (Davis and
Stevens 1986; Welch and others 1986). Winter nutritive
content of vegetative tissue is: (1) in vitro digestibility52.6 percent of dry matter, (2) crude protein-11.0 percent
of dry matter, (3) phosphorus-0.21 percent of dry matter,
and (4) above the maintenance requirement for carotene
(Welch and others 1986). Nutritionally, 'Hobble Creek'
mountain big sagebrush ranks very high among winter
forages. Only other selections of big sagebrush rank
higher in nutritive value, but they are not as preferred
by the consuming animals (Welch 1983; Welch and others
1986). 'Hobble Creek' does not contain substances that
lower grass cell wall digestion in ruminant animals
(Hobbs and others 1986).
'Hobble Creek' can be established and maintained on
sites that have deep, well-drained soils with an annual
precipitation of at least 14 inches and preferably more.
Soil textures should not be any finer than a clay loam
(40 percent clay or less). Soil pH may vary from 6.6 to
8.6 (Welch and others 1986).
INTRODUCTION
On mule deer (Odocoileus hemionus hemionus) and domestic sheep (Ovis aries) winter ranges, most forages are
deficient in four nutrients required by the animals:
energy-producing compounds, protein, phosphorus, and
carotene (Dietz 1972; Welch 1983; Welch and others
1986). One species of range plant that can supply the four
nutrients at or above the maintenance requirements of
wintering mule deer and domestic sheep is big sagebrush
(Welch 1983). The evergreen nature of big sagebrush
gives it a winter nutritional advantage over deciduous
shrubs such as antelope bitterbrush (Purshia tridentata),
true mountain-mahogany (Cercocarpus montanus), and
most herbaceous species (Welch 1989). Big sagebrush can
not only increase the nutrient level of winter diets, but is
a more dependable forage source during periods of
drought than are other shrubs, forbs, or grasses
(McArthur and Welch 1982; Medin and Anderson 1979).
Big sagebrush also usually remains available for use
above the snow while other forage classes become covered
and unavailable for wintering animals (Gade and
Provenza 1986). However, not all big sagebrush selections are equal in terms of animal preference, growth
rate, nutritive valqe, or chemical composition (Welch and
others 1986).
Paper presented at the Symposium on Cheatgrass Invasion, Shrub DieOff, and Other Aspects of Shrub Biology and Management, Las Vegas, NV,
April 5-7, 1989.
Bruce L. Welch is a Principal Research Plant Physiologist, and Fred J.
Wagstaff is a Range Economist at the Intermountain Research Station,
Forest Service, U.S. Department of Agriculture, Provo, UT 84606; Gary L.
Jorgensen is a Range Technician at the Intermountain Research Station,
Ephraim, UT 84627.
167
This file was created by scanning the printed publication.
Errors identified by the software have been corrected;
however, some errors may remain.
'Hobble Creek' can be established by direct seeding, by
transplanting bareroot or containerized stock, and by a
technique we term "mother plant." It is the production
of seed needed for the establishment by the direct seeding
technique that is the subject of this study. What follows
is a description of establishing a seed increase garden of
'Hobble Creek' and results of the first 3 years of
production.
Next, the medium was cooled, moved into a clean potting room and placed in Tinus root-trainer books (21.5 in3 ;
1.5 by 2 by 7.25 inch). Tinus and other brands of roottrainer books having longitudinal grooves prevent spiraling and reduce balling of the roots. Also, the root tips are
air pruned, which aids in reducing root balling. These
root trainers were placed in sets of eight into wooden
crates and filled firmly to 1 inch from the top. This space
provided a water basin. We sowed about five to eight
'Hobble Creek' big sagebrush seeds on the surface of the
plant-growing medium and covered the seed with number
3 sandblasting grit 1/s-inch deep (Jacobson and Welch
1987). A fogger was used in the mornings and evenings
to keep the seed moist until 2 weeks after germination.
Six weeks after germination, seedlings were thinned to
one per container.
We recommend starting the containerized stock in May
in a greenhouse, placing the stock outside during the last
part of August, then planting on the site just as soon as
the soil is frost free. This takes advantage of early spring
(April) moisture. However, for this study containerized
stock was started in January and transplanted to the
garden in May. We did this to speed up garden establishment. Planting containerized stock in May meant that
the stock needed watering during the summer months of
June, July, and August. By following the stated recommendations, summer watering can be avoided.
Containerized stock of 'Hobble Creek' was transplanted
to the garden in May 1986. Planting was done on a 7- by
7-ft grid. This equates to about 900 plants per acre. The
7-foot grid allowed a garden tractor to be used for weed
control. We planted about 1,800 plants.
From these plants, 40 were chosen at random to study
seed production. Each plant was labeled with a metal tag
attached to a wooden stake. When the seeds were ripe
(mid-November), each plant was harvested with hand
clippers. Seed stalks from individual plants were placed
in separate plastic bags. The bags were opened and the
SITE
The garden site is located 4 miles south of Nephi, UT,
at the Utah State University, Nephi Agriculture Experimental Station. Soils of this site are of the Nephi series
(Nephi silt loam). This soil is a deep, well-drained alluvium derivative of sandstone, limestone, and shale. Soil
permeability is slow with an effective rooting depth of 5 ft
or more. The pH range is from 8.2 to 8.6. Average annual
precipitation ranges from 14 to 16 inches. Frost-free periods are 100 to 140 days. Clay content varies from 15 to 35
percent (Trickier and Hall 1984).
The garden site was first used to raise small grains.
An orchard offour-wing saltbush (Atriplex canescens) was
established on the site, but it was winter-killed about 3
years later. The site was then planted with crested
wheatgrass (Agropyron desertorum) for about 6 years
before the present seed garden was established. Garden
preparation was accomplished by killing the grass with
chemicals and tilling with a springtooth tiller.
Containerized stock was used for establishing the seed
increase garden. Seed was obtained from the 'Hobble
Creek' breeder block located in the mouth of Hobble Creek
Canyon.
MATERIALS AND METHODS
In producing containerized 'Hobble Creek' stock, we
used a plant-growing medium composed of sphagnum
peatmoss, horticultural vermiculite, sandy loam soil, and
number 3 sandblasting grit. We screened the peatmoss
and soil through 0.5-inch hardware cloth prior to mixing.
The plant-growing medium formulation was four parts
screened peatmoss, three parts vermiculite, three parts
screened soil, and three parts of number 3 sandblasting
grit. An alternate formulation is four parts peatmoss,
four parts vermiculite, two parts "Turface," and three
parts of number 3 sandblasting grit. Regardless of the
formulation used, a package of fertilizer was added
during mixing of the medium. Table 1lists the fertilizers
and the quantities used per cubic foot of plant growing
medium. Plant-growing medium and fertilizer were thoroughly mixed while dry in a concrete mixer. Next, water
was added until the mixture maintained a ball shape
after being hand squeezed. After mixing, the medium
was transferred to a soil cart where it was treated with
aerated steam. This treatment heated the medium to
175 °F for 30 min. Aerated steam treatment controls
many soil-borne plant pathogens. We used the methods
described by Nelson (1984) to produce disease-free containerized stock.
Table 1-Fertilizer mixture used for the production of containerized
'Hobble Creek' big sagebrush stock. The amount of
fertilizer indicated is for each cubic foot of plant growing
medium
Fertilizer
Amount
Grams
Dolomite
Ground limestone
Horticultural gypsum
Calcium nitrate
Osmocote (slow release fertilizer N,P,K)
Super phosphate
Trace elements
Chelate iron-138
168
176
176
100
32
32
26
5
2
seed stalks air dried in a heated greenhouse for about 2
weeks. To prevent the formation of mold, seed stalks
were stirred daily within the bags. After drying, the seed
and chaff were separated from the stalks by hand. Next,
the seed and chaff were screened to remove the larger
particles of chaff and further separated by use of an air
seed cleaner. Seed purity and percent oflive seed (tetrazolium test) were determined for all 40 seed lots. Production is expressed as grams of pure live seed per plant.
Table 2--Seed production for forty 2- and 3-year-old 'Hobble
Creek' mountain big sagebrush plants. All data expressed as grams of pure live seed per plant
Plant
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
RESULTS
The data from this study are given in table 2. Pure live
seed per plant for 2-year-old plants varied from 0 to 136.6
grams. The mean was 36.3 grams of pure live seed, with
a standard deviation of 36.6 grams. This would equate
to a yield of about 72.0 pounds of pure live seed per acre
(900 plants per acre). 'Hobble Creek' seed has sold for
$20 per pound of pure live seed. Gross income per acre
per year would be about $1,440. (First harvest is about
18 months from transplanting.)
Pure live seed per plant for 3-year-old plants varied
from 0 to 112.8 grams, with a mean of 33.9 grams and
a standard deviation of29.9 grams. This would equate
to a yield of about 67 pounds of pure live seed per acre
(900 plants per acre). Gross income per acre per year for
3-year-old plants would be $1,340.
Raising 'Hobble Creek' seed is a potentially profitable
venture. Two major benefits are: First, 'Hobble Creek'
seed could be produced on sites that may not be tillable,
such as rocky soils or steep slopes (so-called waste land),
and second, because of the late date of seed maturity
(mid-November) harvesting of seed occurs at a time when
for most farming operations labor is at a surplus. Harvesting seed is a labor-intensive operation.
We recommend the following for establishing a 'Hobble
Creek' seed garden:
1. Plant containerized stock as soon as the frost has left
the soil.
2. Establish plant spacing at either 7 or 3.5 feet.
3. For areas with wintering mule deer, build deer-proof
fence. Deer browsing can reduce seed stalk production
(Rodriguez and Welch 1989; Wagstaff and Welch in
press).
169
Seed ~roduction
2-year-old
b~
age class
3-year-old
- - - - - - - Grams - - - - - - 68.1
14.8
10.0
37.4
0.6
41.8
78.5
1.3
23.1
56.1
3.1
29.8
39.5
45.3
35.4
19.0
57.2
3.4
108.0
10.9
3.2
52.6
126.2
dead
11.0
0.2
62.8
44.3
79.0
11.1
0.5
1.6
2.4
34.2
0.2
77.4
47.4
41.0
33.7
0.6
23.3
4.3
42.3
61.9
40.5
40.6
37.4
77.7
18.9
14.8
0.0
112.8
70.5
97.3
75.4
42.8
92.8
6.5
136.6
11.7
4.3
29.3
17.7
56.7
4.0
3.2
8.9
48.1
20.2
55.0
100.7
17.6
51.9
44.3
0.0
16.0
0.5
8.3
0.0
0.2
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