Table of Contents
Witt, M.D. and H.D. Knudsen. 1993. Milkweed cultivation for floss production.
p. 428-431. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New
Milkweed Cultivation for Floss Production
Merle D. Witt and Herbert D. Knudsen
- Study I--Line Ecotypes
- Study II--Hybrid Ecotypes
- RESULTS AND DISCUSSION
- Crop Establishment
- Pod Components
- Floss Production
- FUTURE PROSPECTS
- Fig. 1
- Fig. 2
Field plot studies of milkweed, Asclepias speciosa and A.
syriaca, as a row crop, were initiated in 1985 at Garden City, Kansas.
Potential cultivars and interspecies hybrids were evaluated for their floss
production potential. Milkweed floss is usable as a hollow, cellulose,
insulative, batting fiber and competes readily with the more traditionally used
white goose down, which costs $66.00/kg. Fifteen lines of these two species
yielded a 4-year annual average of 212 kg floss/ha from dried pods that
averaged 21.8% floss. Thirty-five interspecies hybrids yielded a 4-year annual
average of 350 kg/ha from dried pods that averaged 22.7% floss. Approximately
227 pods were required to produce a kilogram of floss. In view of the
high-value application of floss and a projected market use of 1.27 million
kg/year, Asclepias species appear to be worthy of further crop
The genus Asclepias is composed of approximately 140 species worldwide
(Woodson 1954, 1962) with 108 species identified in North America, where this
dicotyledonous plant is a native. Asclepias species are generally
considered as being persistent, perennial, hardy weeds containing cardiac
glycosides that are toxic when ingested by livestock (Muenscher 1975). Because
of the negative aspects of milkweed as a pest, research efforts have most often
dealt with techniques associated with control of these resilient plants
(Timmons 1946; Wyrill and Burnside 1976). At the same time, milkweed has been
of interest to agriculturalists for many years because of its potential
economic value as a new crop (Stevens 1945; Moore 1946; Berkman 1949).
Various plant components have been identified as having potential uses,
including insulative and absorptive materials made from the floss (Adams et al.
1984), and liquid fuel and rubber (Buchanon et al. 1978), as well as oil and
polymeric hydrocarbons (Adams et al. 1987), from the latex sap. The only plant
component used in quantity to date is floss, which emerged as the most feasible
alternative to replace kapok when imported supplies during World War II were
halted. The suggestion of such a potential use (Groh and Dore 1945) was
followed quickly by a report of floss being collected and used as a kapok
substitute (Gladfelter 1946). Eventually 11 million kg of pods were consumed
to fill 1.2 million "Mae West" life jackets.
The currently preferred batting product of high insulative quality is goose
down, but it costs $66.00/kg to import from China. At present, milkweed floss
is being utilized to blend with white goose down or synthesized polypropylene
in insulative batting for such products as comforters, sleeping bags, and
Inadequate information exists on the production potential of milkweed as a
cultivated crop. Initial interest suggested that if milkweed is to be
considered as a crop plant, attention should be given first to selection of
superior strains (Stevens 1945). Naturally occurring interspecies hybrids with
variable characteristics were soon reported (Moore 1946; Nicholsen and Russel
1955). However, we found no evidence that replicated production evaluations of
milkweed germplasm strains were ever conducted. This research effort was
designed to evaluate the agronomic potential and variability of 50 collected
milkweed ecotype strains and hybrids of Asclepias speciosa (showy
milkweed) and Asclepias syriaca (common milkweed) when grown in
monoculture as a new fiber-producing row crop. By providing an alternative
cash crop, milkweed farming could strengthen the agricultural diversity and
economy of the western Great Plains.
Two field studies were established in a small, leveled flood irrigation basin
and treated similarly. Plots were established from seed collected through
efforts funded previously by the Standard Oil Company of Cleveland, Ohio.
Seeds that had been repeatedly water soaked and dried to break dormancy were
planted in 76.2 cm rows in a Keith Silt Loam type soil on May 30, 1985. A John
Deere 71 flex-planter with cone seeding units and disk openers with depth bands
was used to plant all plots with seed placed 1.27 cm deep. A seeding rate of
5.6 kg/ha placed approximately 1,111,500 seeds/ha into the seedbed. Stands
were thinned to 10 cm between plants, when they had reached 8 cm in height on
July 10, 1985. Two adjacent field studies were established.
Fifteen randomly collected entries from 10 states (Colorado, Idaho, Kansas,
Maine, Montana, New Mexico, North Dakota, Oregon, Utah, and Washington)
included 12 showy milkweeds, two common milkweeds, and a single interspecies
hybrid from two parent entries. The accessions were seeded in a randomized
complete block design using three replications with three row plots and 3.04 m
Thirty-five entries originating in Kansas and eastern Colorado and identified
taxonomically by Kansas State University herbarium personnel as naturally
occurring showy milkweed x common milkweed crosses were included. Because of
limited seed quantity, these were seeded in a randomized complete block design
using two replications with single-row 3.04-m-long plots.
All plots were overhead irrigated for 3 weeks after sowing to aid seedling
emergence. Thereafter, irrigation was applied to plots 2 or 3 times each
summer. Ammonium nitrate fertilizer granules were broadcast each season at
67.2 kg N/ha. Milkweed beetle (Tetraopes tetraphthalmus Forst.) control
was initiated in 1989, using Malathion 25% WP at 0.56 kg/ha. Trifuralin
applications were incorporated between rows each year in early May for weed
Summer harvest of pods began each season when approximately 10% of the pods had
burst open. Ten representative pods from each entry were separated into floss,
seed, and empty shell and weighed. The resulting dry weight proportions were
used to partition total harvested pod weights per plot into calculated
components from 4.18 m2 harvest areas for the line ecotypes and from
1.39 m2 harvest areas for the hybrid ecotypes. Harvest dates over
the years ranged from July 24 to Aug. 15.
Establishment was excellent, with seed germination as high as 80% resulting in
uniform stands. Initial year stands were totally vegetative and reached
average heights of 20 to 48 cm by the first killing freeze. Starting in 1986
and thereafter, the crop began to grow each spring from underground buds in
late April, flowers appeared in early June, and pods were harvested 6 to 8
Plants were vigorous and developed extensive root systems with numerous viable
root buds. Roots spread outward as much as 2 m from the unbordered perimeter
rows by the end of 1986. Root spreading within and between plots was much more
restricted, apparently due to plant competition and between-row cultivation
that excised unwanted shoots so that the 76.2 cm row spacing could be
Harvested plant pods had a similar ratio of component parts for both species
and for the interspecies hybrids (Fig. 1). About 24% of the dried weight of
pods was floss. The seed comprised the largest portion of the pod mass (about
40%). The shell component of 36% included the outer wall (34%) and the central
placenta (2%). The exterior shell surface generally displayed more roughness
with the showy milkweed species than did the shell of the common milkweed pods.
However, shell wall thickness was similar between species.
Average annual productions of floss by the hybrid ecotypes and by the line
ecotypes during the 4 years are indicated in Fig. 2. The hybrid ecotypes as a
group averaged 349 kg floss/ha annually over the 4 years. The hybrid ecotypes
consistently outproduced the line ecotypes. A direct statistical comparison
between the two studies cannot be made. However, in comparison to line
ecotypes, the hybrid ecotypes bloomed an average of 4 days later, stood 5 cm
taller, and produced 58% more pods per area with 71% more pods per stem and 65%
more floss per unit area.
Of the line ecotypes, the 12 showy milkweed ecotypes averaged 207 kg floss/ha,
and the two common milkweed ecotypes yielded a similar level of 187 kg floss/ha
over the 4-year period. Floss yields of the line ecotypes varied with
differing state origins but did not appear to be highest from any particular
state or region.
Yields of harvested floss were high in 1986 and 1988. Yields were hampered in
1987 and 1989. On June 16, 1987, during flowering, hail destroyed
approximately 80% of the potential fruiting sites. In 1989, stands were
reduced approximately 50% due to larvae of the milkweed beetle which had fed
and tunnelled into the plant's root system following the 1988 harvest.
Diseases were not a serious problem, although black bacterial leaf spot, leaf
rust, and pod blight infections were observed late in the season in 1985 and
Milkweed is an obligate outbreeder, so that cross pollination is essential.
Isolated colonies of wild plants were observed to bear few fruits in comparison
with plantings of several colonies close together (Stevens 1945). We had hoped
to provide adequate cross pollination in this study by rearing 50 different
milkweed acquisitions within a 600 square meter area. The close proximity of
these variable strains should have provided adequate pollen for maximum pod
Each single plant stem usually had about four flower clusters with about 40
flowers/cluster. Thus, there were about 160 flowers with two ovaries each, for
a potential of about 320 pod sites/stem. However, this theoretical number was
never approached. The best year (1988) allowed an overall average of 1.56
pods/stem for the variety ecotypes and an overall average of 2.3 pods/stem for
the hybrid ecotypes.
As with all new crops, development of milkweed is a high risk, long-term
venture. At the same time, the need for alternative crops to overproduced
crops has never been greater. A market for a product is a crucial ingredient
in the successful development of a new crop. Fortunately, the thermal
impedance level of milkweed floss equals that of the well known goose down.
This helps provide an already developed market and a major incentive for
addressing remaining considerations in production and processing.
Additionally, the production, harvesting, and floss extraction procedures and
equipment needed by a new milkweed industry closely parallel the procedures and
equipment already in use by the well established cotton industry. In this
study, we have produced floss yields considerably beyond the 56 kg/ha minimum
that we felt would be adequate to compete with goose down. The transition to
greater usage of domestically grown milkweed floss in place of imported goose
down would be a positive step, with substantial benefits for both consumers and
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||Fig. 1. Components of a typical dried milkweed pod. Proportions did
not differ significantly between A. speciosa, A. syriaca, and
interspecies hybrids between them.
Fig. 2. Average floss yield of 35 hybrid ecotypes and 15 line
Last update September 15, 1997