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Oklahoma Invasive Species
Oklahoma State University

Sericea Lespedeza

Country of Origin: Asia
History:

In 1896 the North Carolina Agricultural Research Station was the first in North America to plant sericea lespedeza.  The USDA first imported seed from Japan in 1924 and started to study its use for erosion control; they found that it served that purpose very well.  They determined that sericea can handle drought conditions but does extremely well when the annual rainfall is over 30 inches.  These factors are what brought it to the Midwest after the dust bowl and it was planted on many strip mine locations during the 1930s in Kansas and Missouri.  Sericea was not widely used as a forage until the 1940s when the USDA had developed a variety that can grow anywhere in the eastern 2/3rd of the U.S. Where the winter temperature does not drop below –17 degrees F.  It was found to be a good source of hay and to be very beneficial to wildlife.  The most recent establishment of sericea came from the Conservation Reserve Program (CRP), created by the 1985 farm bill.  The native seed harvested for the program came from a site contaminated with sericea lespedeza.  At the time it was not widely accepted as a weed.        

 

Currently in Oklahoma, Sericea lespedeza can be found in all counties except for the panhandle region.  This is most likely due to the regions low annual precipitation.  Oklahoma’s government has yet to call sericea a noxious weed despite the attempts of many citizens.  Oklahoma has granted no legal status for sericea.

Intended Use: Forage Crop and erosion control
Mode of Invasion:

A germination rate of only 20 to 30% is often found however sericea lespedeza is capable of producing large amounts of seed every year.  This number has been found to be close to 1000 seeds per stem making total production for one acre to be from 300 to 850 pounds of seed.  With there being 350,000 seeds per pound the low germination rate can be overlooked.  Although it has not been proven it is expected that a seed can last in the soil seed bank for 20 years or more.  It has been found that that the spread of sericea in local areas is from the transport of seed on animals, hay, and vehicles.

Species Description:

There can be one or multiple stems on sericea lespedeza that are woody plant like.  With this plant being a deciduous perennial a taproot proportional to the height can be found allowing it to store large amounts of carbohydrate reserves.  The crown is located 1 to 3 inches below the ground so that there can be new growth each year.  There is a high leaf: stem ratio with leaves being trifoliate and having short petioles.  Leaves are pointed at the base are rounded at the tip.  Generally leaves are not longer than an inch and less than a ¼ of an inch wide.  There are small silky hairs on the underside of the leaf.  Seed are very small ranging from 1/16 to an 1/8 of an inch in size and are oval in shape.  Flowers appear in late summer and range from dark purple to a whitish-yellow.  Sericea lespedeza is most often confused with slender lespedeza, which is a desirable forage in some hay crops.

Map of Occurrence:

map
Figure 2:  Distribution of sericea lespedeza in the United States. (KSU Extension Handout)

Effects of Invasion:

Sericea lespedezas’ bushy nature allows the plant to choke out the plants that surround it.  The large taproot contains large amounts of carbohydrate reserves make it possible to grow taller than other native plants blocking out the sunlight.  Another factor that aid sericea in its invasion is that since it produces tannins livestock tend to avoid grazing in contaminated areas.  This often results in the overgrazing of other parts of the pasture making it much easier for sericea to spread. It has also been found that it produces allelopathic chemicals that harm the germination and growth of native plants in Oklahoma such as the tall grasses, Bermudagrass, fescue, and ryegrass. 

 

Sericeas water use efficiency is very low making it somewhat of a droughty species.  It has the tendency to use its large roots to soak up all available moisture and store it in the taproot of the plant.  The plant is also a legume giving it a the ability to fix its own nitrogen however those quantities are lower than other legumes and very little of that nitrogen is ever used by other plants.

Control:

The best management practice is prevention altogether but in most cases that is not possible.  If sericea has just moved into a new track of land, spot spraying each plant before it produces seed can be the least cost method.  When the plant has been established for several years the manager must realize how much seed is now out there and that complete plant removal will take several years of intense management with burning, grazing, and spraying interactions.  The manager now has to not only remove all plants but also the seed bank.  Before the application of chemical an attempt should be made to make as many seeds germinate as possible.  The seeds act like any other legume in that they need to be scared and then exposed to sunlight for germination.  A producer can encourage this by removing the vegetation.  Mowing, intensive grazing, and burning are all good ways to do this.  The seed needs to be exposed during March to early April.  Burning in the early spring has been found to encourage germination very well.  The intense heat scares the seed and the total removal of plant residue provides the needed sunlight for germination.  Grazing can now be used as a control mechanism.  A young new sericea plant has not yet been able to produce tannins so while it is still in an immature stage it can be palatable to livestock.  Yearling cattle tend to be the least selective when compared to mature cows so they would be the ideal choice for the intensive grazing section.   

 

There are several grazing systems to use, season long grazing will provide the fewest results; an intensive short duration grazing system is more ideal.  An example would be to double the stocking rate for half of the growing season ending in mid July when the plant starts to mature.  The goal is to have the area stocked so that the livestock will be forces to eat the plant while it is still palatable, this will add stress to the plant and keep the native vegetation short so that a good chemical application can be made.  This intensive grazing has forced the plant to use large amounts of energy into growing, just before the sericea starts to flower is when its energy reserves are the lowest making it the most vulnerable and the best time to apply an herbicide.  Sericea lespedeza starts to flower in mid July to early October.  Most common broad leaf herbicides nave no effects but there are some chemicals that can kill to top growth.  Pasture Guard™ and Remedy™ applied in late June to mid July have been known to work.  It is important to spray when the plant is most exposed.  This is before the native plants start to mature.  2 to 3 weeks after the chemical has been applied the plant will start to turn yellow, it is important to come back at this time to spot spray areas that were missed.  This process may have to be repeated for several years in order to completely remove all plants and seeds.  

 

Removal of sericea before the bud stage can slow its spread.  Mowing or haying before the flowers begin to appear forces the plant to continue to use energy with out producing seed.  When cut for hay sericea can be used to improve the forage quality of the crop.  The tannins are removed during the curing process allowing for the protein to become palatable.  If sericea is used in a hay crop it is very important to do so before any seed is produced.  The use of goats and/or sheep has also been shown to control sericea lespedeza.  The tannins do not bother the smaller ruminants and their behavior to select higher quality forage leads them to seek out and over consume the legume.

References:

Altom, J.V., J.F. Stritzke, D.L. Weeks. Sericea lespedeza (Lespedeza cuneata). Control with Selected Postemergence Herbicides. Weed Technology Journal of the Weed Science Society of America 6(3):573-576. 1992.

 

Ecology and Management of Sericea Lespedeza. Oklahoma Cooperative Extension Fact Sheets.  http://www.osuextra.com

 

Sericea Lespedeza: History, characteristics, and identification.  Paul D. Ohlenbusch, Bidwell. 2007. Kansas State University Extension Services Handout.