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Sericea/Chinese Bushclover

Lespedeza cuneata

Summary 7

Lespedeza cuneata is a species of flowering plant in the legume family known by the common names Chinese bushclover and sericea lespedeza, or just sericea. It is native to Asia and eastern Australia and it is present elsewhere as an introduced species and sometimes an invasive plant.

Ecological threat in the united states 8

Chinese lespedeza, sometimes called sericea lespedeza, is primarily a threat to open areas such as meadows, prairies, open woodlands, wetland borders and fields. Once it gains a foothold, it can crowd out native plants and develop an extensive seed bank in the soil, ensuring its long residence at a site. Established dense stands of lespedeza suppress native flora and its high tannin content makes it unpalatable to native wildlife as well as livestock.

Impacts and control 9

More info for the terms: allelopathy, breeding system, competition, cool-season, cover, density, fire management, fitness, forb, forbs, frequency, invasive species, litter, natural, prescribed fire, presence, root crown, tree, warm-season

Impacts: Sericea lespedeza has escaped cultivation and become self-establishing and invasive throughout much of the central and eastern United States 5,39,63,113. Sericea lespedeza is recognized by federal, state, and local organizations throughout its nonnative US range as a "highly invasive species" that poses a severe or significant threat to native plant communities [10,47,57,95,146,165,169]. Although it is difficult to determine the traits or mechanisms that allow sericea lespedeza to invade, spread, dominate, and persist in certain areas, the following examples clearly demonstrate sericea lespedeza's invasive tendencies.

When population dynamics were compared between sericea lespedeza and the native slender lespedeza at Washington University's Tyson Research Center near St Louis, Missouri, sericea lespedeza populations were more fecund and grew more rapidly than those of slender lespedeza. Sericea lespedeza experienced significantly less herbivory (<1%) than slender lespedeza (10%) (P<0.05). Sericea lespedeza produced more seed than slender lespedeza, and in field conditions, 17% to 26% of sericea lespedeza seed germinated, while only 2% to 3% of slender lespedeza seed germinated. The population growth rate estimated for sericea lespedeza was at least 10 times that estimated for slender lespedeza. Population growth rate differences were unaffected by differences in herbivory levels. Young, small sericea lespedeza plants were much more fecund than young, small slender lespedeza plants [136].

Sericea lespedeza was also more fecund than native lespedeza species in the Flint Hills tallgrass prairie of northeastern Kansas when sexual and asexual reproductive traits were compared (see the Breeding system, Seed production, and Vegetative regeneration sections). Researchers concluded that sericea lespedeza demonstrated fitness homeostasis, which included a "mixed, well-buffered reproductive strategy" that allowed it "to maintain significant levels of seed and vegetative reproduction under a wide range of conditions" [177].

Impacts on native plants and wildlife: Sites invaded by sericea lespedeza can have reduced native plant abundance and diversity and may be less attractive to vertebrate and invertebrate wildlife. Native plant cover and species diversity were lower on a Kansas oak savanna invaded by sericea lespedeza than on sites without sericea lespedeza. Native grasses and forbs represented 5% and 10% of canopy coverage in invaded plots and 79% and 28% in uninvaded plots, respectively. There were 3 times as many native grass and forb species in uninvaded than in invaded plots. The number of macroinvertebrate species in invaded plots was 65 and in uninvaded plots was 24; the number of macroinvertebrate families represented in invaded plots was half that in uninvaded plots [48]. Based on these findings, Eddy and others [47] predicted that sericea lespedeza invasions could reduce native bird abundance and richness and result in overall decreased grassland biota diversity. Reduced grass forage could also mean losses in land value and livelihood for cattle ranchers. In tallgrass prairie in southeastern Kansas, use by vertebrate and invertebrate wildlife species was 55% and 73% lower, respectively, on sites with than without sericea lespedeza. Native canopy cover was only 16% in invaded prairie. The following factors were suggested as reasons for reduced wildlife use in invaded areas: high stem density, lack of singing perches for birds, loss of canopy openings, and reductions in the seasonal availability of foliage, flowers, seeds, and prey insects [46].

Several studies suggest that sericea lespedeza can limit growth of woody vegetation. In a plantation on sandy, droughty soils south of Aiken, South Carolina, height of 3-year-old sand pine (Pinus clausa) seedlings grown in the presence of sericea lespedeza was significantly (P<0.05) less than that of seedlings grown without sericea lespedeza. In stands where sericea lespedeza was dense, sand pine survival was about 50% of that in plots without sericea lespedeza [91]. On the eroded, heavy clay soils of a plantation in the upper Piedmont of South Carolina, loblolly pine seedlings with sericea lespedeza seeded between the rows were 9.3% shorter and had 13.2% less diameter than those without sericea lespedeza. Within 6 years of seeding between tree seedling rows, sericea lespedeza had encroached densely around the tree seedlings [121]. Along a transmission line right-of-way in Georgia, sericea lespedeza developed solid stands and "crowded out or overcame" woody species common to the area within 2 years of planting [139].

Not all studies investigating sericea lespedeza invasions, however, have reported losses in species richness or diversity. In a field study at the Waterloo Wildlife Experimental Station in southeastern Ohio, removing sericea lespedeza did not affect plant species richness or diversity. The researcher suggested that sericea lespedeza's invasive characteristics may be reduced in the northern part of its range [41]. Wright and others [178] characterized sericea lespedeza as "non-aggressive" when seedling emergence of various grasses and legumes commonly used for erosion control were compared in controlled experiments, and according to Hoveland and others [82], sericea lespedeza seedlings "are weak and compete poorly with spring and summer weeds" in Alabama. Even once established, sericea lespedeza may not necessarily become invasive. A Kansas State University Cooperative Extension bulletin reports that in some areas sericea lespedeza grows in ditches, fences rows, or pastures without invading adjacent "well-managed" rangeland and pastures [125]. In pairwise competition experiments conducted in an old field in Tennessee, sericea lespedeza was intermediate in terms of dominance over the 2-year study. Broomsedge bluestem ranked as the most competitive species. In artificially created field communities, orchardgrass (Dactylis glomerata) dominated the 1st growing season, and orchardgrass and broomsedge bluestem codominated in the 2nd growing season [50].

Potential factors influencing impacts: Some studies have identified characteristics and mechanisms by which sericea lespedeza limits the growth of associated vegetation and persists in natural habitats. The characteristics and mechanisms include shading, high water use, herbivore release, allelopathy, other physiological traits, and climate change.

Shading: Field experiments in upland old fields in Jackson County, Illinois, revealed that sericea lespedeza's shading of adjacent plants is important to its successful replacement of native species. Plots where sericea lespedeza was not manipulated or treated had the lowest cover of native species (5%). On plots where sericea lespedeza was treated with herbicide, had its stems tied back, or was clipped near ground level, native species cover was greater (15-20%) [14].

Water use: Ohlenbusch and Bidwell [125] report that sericea lespedeza requires more water than other warm-season plants to produce foliage. Because of this, sericea lespedeza may outcompete neighboring vegetation for water [125].

Herbivore release: At the Konza Prairie Biological Station, sericea lespedeza is "aggressively invading" tallgrass prairie. When researchers compared herbivory levels between native roundhead lespedeza and sericea lespedeza, the total percent leaf area reduction and total percent leaf area missing were significantly greater for roundhead lespedeza than sericea lespedeza (P<0.001) [67].

Allelopathy: Sericea lespedeza is thought to be allelopathic. There is speculation that tannins leached from foliage may have negative effects on associated plants [32,125,149]. Root, stem, leaf, and fruit leachates may negatively impact germination and growth of grasses and forbs [32,41,43,92,125]. In a greenhouse experiment, sericea lespedeza root exudates significantly reduced (P<0.05) the germination and/or emergence of Bermuda grass, bahiagrass, and some tall fescue cultivars [92]. In laboratory experiments, germination of Canada goldenrod (Solidago canadensis) was significantly inhibited by leachates from sericea lespedeza fruits (P<0.0001) and leaves (P=0.0221). Germination of purpletop tridens (Tridens flavus) and Canada goldenrod were significantly lower in soils collected from plots with than from plots without sericea lespedeza (P=0.0107 and 0.0010, respectively) [41]. In another laboratory study, germination of big bluestem (Andropogon gerardii), indiangrass (Sorghastrum nutans), and Kentucky bluegrass (Poa pratensis) was reduced 15% to 27%, 25% to 37%, and 47% to 60%, respectively, when seeds were exposed to sericea lespedeza stem or leaf residues. Germination of little bluestem (Schizachyrium scoparium) and growth of grasses were unaffected by sericea lespedeza stem or leaf residues [43].

Other physiological traits: Sericea lespedeza, once established, can be very persistent. In a field study to investigate sericea lespedeza's seemingly high competitive and tolerance abilities, researchers compared potentially important physiological and morphological characteristics of sericea lespedeza and 2 native tallgrass prairie species: western ragweed (Ambrosia psilostachya) and big bluestem. From June through September, sericea lespedeza generally had the highest total and specific leaf area values, which could lead to greater light absorption, carbon capture and assimilation, and shading of other species. Researchers also found that sericea lespedeza had the most constant photosynthetic rates, stomatal conductance rates, and photosystem efficiency levels, which could convey a high tolerance to adverse growing conditions [1].

Climate change: If future climate changes result in increased moisture as well as carbon dioxide, sericea lespedeza may become even more invasive. During field experiments in Tennessee, researchers used open-top chambers to evaluate the effects of several possible temperature, carbon dioxide, and moisture regimes for sericea lespedeza. Proportional cover of sericea lespedeza was greatest for wet treatments regardless of temperature or carbon dioxide conditions. Late in the growing season, proportional cover of sericea lespedeza was greatest in plots with ambient temperature, elevated carbon dioxide levels, and wet treatments. Proportional cover was lowest at ambient temperature, elevated carbon dioxide levels, and dry treatments [93].

Control: Controlling sericea lespedeza will likely require multiple treatments over several seasons. Established plants may sprout in response to mechanical damage of aboveground tissue (see Asexual regeneration and Physical or mechanical control). A seed bank will likely be present on infested sites, providing the potential for seedling establishment for many subsequent years (see Seed banking). Despite seemingly successful control of preexisting populations using several different control methods, sericea lespedeza can quickly reestablish and increase to levels equal to or exceeding initial abundance [89]. Despite seemingly successful control of preexisting populations using several different control methods, sericea lespedeza can quickly reestablish and increase to levels equal to or exceeding initial abundance [89]. Subsequent monitoring and follow-up treatments are likely necessary for long-term control. Control should be prioritized to limit the establishment of dense stands [32,125]. Using modeling techniques together with fine-scale, spatially explicit field data collected from herbicide treated, mowed, and combination treatments in tallgrass prairie, Emry [49] found that in treated plots the probability of sericea lespedeza colonization was low, but the probability of persistence was high.

There appear to be 2 potentially useful strategies for dealing with sericea lespedeza posttreatment establishment from the seed bank. One strategy is to suppress seedling emergence and survival. Maintaining a substantial amount of plant residue or ground cover in early spring can reduce available light at the soil surface, thereby reducing seedling establishment [64]. However, seedling establishment and survival can occur where ground cover and other vegetation is dense [125]. Grazing or burning early in the growing season, through the removal of existing litter and vegetation, could encourage sericea lespedeza seedling establishment [64]. Effective suppression of seedling emergence will be partly determined by the quantity, hardness, and longevity of seeds in the seed bank (see Seed production, Seed banking, and Germination) and could be limited in long-infested sites with dense stands. Grazing and burning could be useful in depleting the soil seed bank, which represents the second strategy for dealing with soil-stored seed on infested sites. Grazing or burning may stimulate seed bank germination (see Biological control and Prescribed fire sections) [64]. Following stimulation of germination and seedling establishment, follow-up control methods will be necessary. For more information on possible follow-up and integrated control strategies, see the Chemical, Biological, Physical or Mechanical, and Integrated control sections below.

In all cases where sericea lespedeza is targeted for control, no matter what method is employed, the potential for other invasive species to fill its void must be considered [17]. Control of biotic invasions is most effective when it employs a long-term, ecosystem-wide strategy rather than a tactical approach focused on battling individual invaders [107].

Fire: For information on the use of prescribed fire to control this species, see Fire Management Considerations.

Prevention: It is commonly argued that the most cost-efficient and effective method of managing invasive species is to prevent their establishment and spread by maintaining "healthy" natural communities 107,141 and by monitoring several times each year [85]. Managing to maintain the integrity of the native plant community and mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [79].

Perhaps the best initial step to prevent establishment and growth of sericea lespedeza populations in uninvaded areas would be to prohibit seeding or planting in nearby areas [149]. As of 1991, however, sericea lespedeza was still listed as a conservation plant useful for erosion control and wildlife food and cover in the Northeast [105]. When introducing native seed into wildlands, only clean, pure seed should be used. Sericea lespedeza reportedly spread west in Kansas and Oklahoma on Conservation Reserve Program (CRP) lands when seeded as a contaminant in grass seed [125].

In regions lacking established sericea lespedeza, vigilantly discouraging its deliberate or accidental planting and watching for its establishment could aid weed control agencies. The state of Colorado has done this [30].

Weed prevention and control can be incorporated into many types of management plans, including those for logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [166]. See the Guide to noxious weed prevention practices [166] for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.

Cultural control: Altom and others [3] suggest overseeding cool-season grasses in combination with herbicide treatments to suppress sericea lespedeza.

Fertilizing infested areas may reduce sericea lespedeza abundance [144]. During field experiments in an upland old field in Jackson County, Illinois, sericea lespedeza cover, density, and biomass were lower on fertilized than unfertilized plots. Cover was significantly reduced after just 1 year of fertilizer treatments, and biomass and density were significantly reduced after 3 years of annual fertilizer treatments (P<0.05) [14]. Other authors consider sericea lespedeza to be more competitive on nutrient-poor than on fertile sites [6,65]. While the addition of nutrients may reduce the abundance of sericea lespedeza, understanding the effects of these nutrients on the ecosystem as a whole would be necessary to determine its usefulness and viability as a management technique.

Physical or mechanical control: Digging or pulling sericea lespedeza plants is considered difficult because of extensive root development [149]. Sprouting from the root crown following aboveground damage is common (see Vegetative regeneration). Disking in established sericea lespedeza stands increased rather than decreased growth [152,154].

Some sericea lespedeza control may be provided by carefully timed and repeated cutting or mowing, but these methods alone may not kill mature plants and could damage desirable associated vegetation [32]. According to Guernsey [65], mowing or cutting sericea lespedeza, especially early in the growing season, may result in vigorous regrowth. In central Japan, frequency of sericea lespedeza was greatest on sites mowed 3 to 4 times/year when areas of a ski resort were compared [98]. Complementary control methods, in addition to cutting or mowing, could improve control. Stevens [149] suggests following spring mowing with a midsummer herbicide treatment.

Field experiments at the Agronomy Research Station in Stillwater, Oklahoma, showed that potential for sprouting after clipping generally increased with increasing age of sericea lespedeza seedlings. Sprouting was sparse for seedlings ≤6 weeks old (<15%) but profuse for seedlings 9 to 15 weeks old (70-80%). Seedlings as young as 15 weeks produced seed. Removing the top growth of first-year plants before they formed branches (at 7-8 weeks old) provided the greatest potential for control. Clipping at 12 to 14 weeks old was effective in preventing seed production [54].

Some research suggests that cutting or mowing to control sericea lespedeza populations is most effective when root carbohydrates are lowest; however, mowing operations in the field often failed to provide control. Times of lowest root carbohydrate storage are June according to Farris [54] and during flower bud production according to Smith [144]. According to Guernsey [65], cutting in late fall may weaken plants by reducing carbon storage. On upland old-field plots in Jackson County, Illinois, sericea lespedeza density and cover increased on plots mowed annually in the spring and annually in both the spring and fall. The author suspected that mowing facilitated seedling establishment by increasing sunlight and reducing competition from autumn-olive (Elaeagnus umbellata) [14]. In the tallgrass Welda Prairie in Anderson County, Kansas, time of mowing (mid-June, mid-August, or both) had little effect on established sericea lespedeza populations, but plots mowed in August had 3 times the number of seedlings as those mowed in mid-June or at both times [49].

Although mowing has not provided consistent control of sericea lespedeza in the field, several sources consider repeated mowing necessary to decrease sericea lespedeza abundance and/or spread. Several sources suggest mowing at the flower bud stage for at least 2 to 3 consecutive years to reduce stand "vigor" and spread ([144,149], Remaley 1998 as cited in [145]). Some suggest that frequent mowing to near ground level after plants reach 12 to 18 inches (30-46 cm) tall provides some control [32,125]. On droughty or infertile sites, frequent cutting may be particularly effective [65].

Biological control: Insect and mammal herbivores have been tested for sericea lespedeza control. As with most other control methods discussed in this review, biological control may be increased if used in conjunction with other control methods.

Preliminary investigations indicate potential for lespedeza webworm (Tetralopha scortealis) as a biological control agent. Studies and observations from Kansas revealed that lespedeza webworms were aggressive sericea lespedeza defoliators and reduced seed production by up to 98%. While the lespedeza webworm could be a useful biocontol, it also attacks native lespedezas, so it is not likely to be released as a biocontrol [47]. In a field study in Eureka, Missouri, established sericea lespedeza plants were not generally affected by simulated herbivory. Only in the smallest size class (1 branch) did mortality or failure to reach the next size class increase with increased leaf loss. Fecundity, growth, and survival were largely unaffected by leaf losses of 20% to 80%, and even at 80% leaf loss, the population growth rate was high. Researchers concluded that a leaf-chewing biocontrol alone would not likely to provide effective control [135].

Studies have shown that grazing infested prairies by cattle or domestic goats can reduce the abundance and/or spread of sericea lespedeza. According to Ohlenbusch and Bidwell [125], though, cattle grazing may be less desirable on sites with an abundance of grasses because cattle graze the grasses before sericea lespedeza. When grazed and ungrazed sites were observed for 5 years in tallgrass prairie in Greenwood County, Kansas, the largest sericea lespedeza plants and densest sericea lespedeza stands occurred in ungrazed areas. In 2 of the 5 years, the researcher observed heavy grazing of sericea lespedeza by the cattle, which were stocked at moderate densities. Areas grazed by domestic goats had closely-grazed prairie species, denuded resting areas, numerous trails, and uprooted grasses [11]. However, good control of sericea lespedeza by domestic goats was reported in Kansas, where the goats had experience feeding on sericea lespedeza. Domestic goats clipped plants to the ground and fed on stems with seeds. Seed production was reduced from 960 seeds/stem to 2 to 3 seeds/stem. Heavy grazing killed about 25% of plants in the 1st year; after 3 years of heavy domestic goat grazing, nearly all adult plants were dead and seedlings had very little aboveground growth. Domestic goats only ate substantial amounts of grass when sericea lespedeza was gone [73].

Some studies have paired grazing with prescribed fire to control sericea lespedeza. For details, see the discussion on Prescribed fire [33].

Biological control of invasive species has a long history that indicates many factors must be considered before using biological controls. Refer to these sources: [168,174] and the Weed control methods handbook [163] for background information and important considerations for developing and implementing biological control programs.

Chemical control: While several studies report some level of sericea lespedeza control with herbicides [3,64,97,144,180], other studies suggest poor control or negative nontarget effects with herbicides [33,90,97,125,145]

Ohlenbush and Bidwell [125] reported that very few broadleaf herbicides provided good control of sericea lespedeza. Others reported that herbicide treatments in pastures in the Southern Great Plains partially controlled sericea lespedeza but did not reliably increase the biomass of associated grasses and forbs [33]. After studying a variety of herbicides, Koger and others [97] found that no single herbicide was successful in eradicating established sericea lespedeza plants.

Some findings suggest that sericea lespedeza is most vulnerable to herbicides at times when associated forbs or grasses are also susceptible. Targeted or spot treatments may be useful in reducing negative nontarget herbicide effects. According to a Fact Sheet produced by an exotic plant working group, early to midsummer herbicides treatments provide the best sericea lespedeza control (Remaley 1998 cited in [145]), but at this time, other indigenous forbs are actively growing and vulnerable to herbicides [145]. Researchers recommend spot spraying sericea lespedeza in tallgrass prairies where herbicide-susceptible native forbs grow [123]. Jordan and Jacobs [90] found that herbicide treatments in a grassland in Long Island, New York, were effective on sericea lespedeza but also killed a substantial amount of neighboring, desirable plants. Researchers were able to target sericea lespedeza using wick or glove applicator methods [90].

Although herbicides are often effective in gaining initial control of a new invasion or a severe infestation, rarely are they a complete or long-term solution to weed management [19]. See the Weed control methods handbook [163] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals. Herbicides are more effective on large infestations when incorporated into long-term management plans that include replacement of weeds with desirable species, careful land use management, and prevention of new infestations. Control with herbicides is temporary, as it does not change conditions that allow infestations to occur (e.g., [181]).

The following references provide information on herbicides and application timings that have been effective in controlling sericea lespedeza: Altom and others [1], Smith [144], Griffith [64], Koger and others [97], and Yonce and Skroch [180]. For information specific to herbicides and sericea lespedeza seedlings, see Farris and Murray [53] and Koger and others [97]. Generally, control decreases as the season progresses and plants mature [53]. High temperatures, early frosts, and prolonged drought conditions can decrease herbicide effectiveness [123].

Integrated management: A combination of complementary control methods may be helpful for more rapid and effective control of sericea lespedeza. Wolf and others [176] developed a 2-year management program to decrease sericea lespedeza abundance while establishing more palatable pasture forage. First-year management involved suppressing sericea lespedeza in the spring by mowing, herbicides, or heavy grazing. In the fall sericea lespedeza was mowed again, and sites were seeded with an annual cover crop. In the 2nd year, the cover crop was grazed or mowed to release sericea lespedeza stems for another late spring or summer suppression treatment. In the fall, sites were fertilized and planted to pasture species [176]. Another integrated management plan, presented by Ohlenbusch and Bidwell [125], involved grazing and/or mowing, fire, and herbicide treatments. For timing, stocking, and procedural details, see [125]. In The Wilds area of Muskingum County, southeastern Ohio, researchers used nonselective herbicide treatments, planted herbicide-resistant soybeans (Glycine max), and maintained the soybean crops for 2 years before planting native prairie species. This procedure reduced sericea lespedeza cover from over 90% to nearly 0% [23]. A weed control identification and control handbook for the Upper Midwest suggests fertilizing grasslands with sericea lespedeza in April, burning in late spring, and then heavily grazing sites with adult cattle, domestic sheep, or domestic goats to control sericea lespedeza [37]. Persistent dead stems can discourage grazing, although the reasons for burning the site prior to grazing were not reported (Koger and others 2002 cited in [44]). Other integrated management procedures are described in the use of prescribed fire as a control agent discussion.

Sources and Credits

  1. (c) Suzanne Cadwell, some rights reserved (CC BY-NC), https://www.flickr.com/photos/scadwell/9531012023/
  2. (c) Dalgial, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/c/c5/%EB%B9%84%EC%88%98%EB%A6%AC_4.JPG
  3. (c) Erin Taylor, some rights reserved (CC BY-NC), uploaded by Erin Taylor
  4. (c) Anita, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/61897811@N00/5199976427
  5. (c) Steven J. Baskauf, some rights reserved (CC BY-NC-SA), http://bioimages.vanderbilt.edu/gq/baskauf/glecu--wp29172.jpg
  6. (c) Dalgial, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/4/42/%EB%B9%84%EC%88%98%EB%A6%AC.JPG
  7. Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Lespedeza_cuneata
  8. (c) Unknown, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/22948673
  9. Public Domain, http://eol.org/data_objects/24629396

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