Missouri's Silent Thief
to look for, you're sure to spot it everywhere you go, especially along roads.
Sericea lespedeza is a warm season legume that stands 3 to 6 feet tall at maturity. It thrives in dense stands, generally crowding out most other types of vegetation. Sericea's stems can grow individually or in clusters with many branches. In late summer the stems become coarse and woody.
Its narrow, club-shaped leaves grow in groups of three along the stem and have short petioles. Each leaf measures 1/4-inch to 1 inch long and 1/16-inch to 1/4-inch wide (wider at the tip than the base) and is round at the end with an inconspicuous point at the tip. Clusters of small, cream-colored flowers with purple or pink markings appear on the plant from mid-July to early October.
There are native lespedezas in Missouri that are beneficial and should not be mistaken for sericea. These include violet, roundhead and slender lespedeza. Slender lespedeza is the most similar to sericea. You can tell the species apart by the shape of the leaves and the color of the flowers. The leaves of slender lespedeza do not have a point at the end, and the plant's flowers are purple to pink.
A single stem of sericea can produce more than a thousand seeds. The seeds float, so the plant spreads easily along riverbanks and lakeshores. Birds and other animals also distribute the seeds. They hitch rides on car bumpers, in tire treads and on haying and mowing equipment.
Fortunately, sericea is fragile during its seedling stages and is slow to establish. Both germination and seedling growth require warm temperatures and an optimum number of daylight hours per day.
Because they can get plenty of sunlight, sericea seedlings thrive in areas where the surrounding vegetation is short, such as grazed or burned pasture. Where other vegetation is dense, however, sericea spreads slowly, if at all.
Sericea most threatens native vegetation when it is mature and well established. The mature sericea plant is tall and dense enough to block sunlight from other plants. It also saps water from the soil. In addition, sericea can emit chemicals from its roots that inhibit the growth of many grasses and decrease their forage quality. Once established, sericea is a tough competitor. Unfortunately for native vegetation, it often gains the upper hand.
Both government and non-government agencies in Missouri are cracking down on the spread of sericea. However, it is a complicated and expensive problem to fix.
Land managers with the Missouri Department of Conservation currently scout statewide conservation lands for sericea. They control its spread by using herbicides in conjunction with late summer burning.
The Missouri Prairie Foundation has been spraying sericea on its land, as well as on select Missouri Department of Conservation lands, using backpack herbicide sprayers. The Foundation plans to employ a crew of four people to combat sericea throughout the summer this year.
For Missouri landowners, the best defense against this invasive weed is early identification and treatment of infested areas. Individual plants in areas of small sericea populations can be treated directly with approved herbicides such as Remedy, Escort or Ally.
Sericea is most successful at taking over disturbed or overgrazed pastures and woodlots, where competing vegetation is short. Therefore, it is important to plant and maintain vigorous, diverse native vegetation wherever possible.
Once it takes hold, sericea may require a combination of measures to control it, including herbicides, mowing and grazing by goats. Cattle will graze around the mature plants, so they are not an effective means of control. Keep in mind that goats must be stocked in sufficient numbers to keep sericea plants under 4 inches tall. Grazing of infested areas should be avoided in September and October because of the risk of spreading seeds during these months.
The use of approved herbicides is very effective in the spring after a mid to late summer mowing. That's when the plants are building root reserves for the following year. Once the sericea infestation has been reduced to only a few plants, spot spraying of herbicides is a good way to protect your land from becoming infested again.
Despite the efforts of government agencies and a handful of informed private landowners to rein in sericea, it continues to propagate at great cost to Missourians. Not only do we have to pay out of pocket to battle this invasive plant, we are also losing our wealth of native natural resources to it.
For assistance or information about identifying and controlling sericea lespedeza, contact your Conservation Department office or an office of the Natural Resource Conservation Service, soil and water conservation district or university extension. The Sericea Lespedeza Multi-State Work Group has a website.