Weed of the Season: Kudzu
Pueraria montana var. lobata
Kudzu eating it’s way north
Kudzu has long been notoriously known as the vine that ate the south. Now it is eating its way into the Baltimore landscape and the greater mid-Atlantic areas. Kudzu “eats” through forest ecosystems by fast, vigorous growth and large leaves that grow over other native plants like a blanket shading them from sunlight. Some southerners have even named it “mile a minute” to characterize its aggressive growing habits. However, Kudzu should not be confused with the tropical mile a minute vine invader, Persicaria perfoliate (sometimes called Asiatic tearthumb), that we are more familiar with in Maryland. This annual herbaceous invader although damaging to young trees and shrubs and a nuisance in our natural environment has not caused quite a much devastation as Kudzu has in many parts of the southeastern US.
Kudzu, a native of China of other parts of southeast Asia, was first introduced into the US in at the 1876 World’s Fair Centennial Exhibition in Philadelphia as an ornamental and forage crop as well as a hardy grazing plant for cattle, goats and other livestock. However, the vine did not gain widespread use and popularity until 1930s when the great depression and dust bowl hit the United States. In response to the nation’s farm crisis, Congress established the Soil Conservation Service which launched a marketing campaign to encourage farms suffering from soil erosion and barren land to plant Kudzu. Since Kudzu is fast growing and a legume (in the pea family, Fabaceae), it quickly establishes over disturbed soils and fixes nitrogen back into the soil which made it attractive to plant to attempt to restore the eroding and nutrient depleted topsoil of US farms. As Kudzu became established this plan backfired as Kudzu began taking over not only farms and surrounding woodlands but also man-made infrastructure such as barns, cars, telephone poles and other utilities.
What makes this vine grow so aggressive? Kudzu is a semi-woody climbing perennial vine. What makes this invader deadly is its root systems and quick vegetative growth. The bulk of Kudzu’s biomass is contained in its root system making it very hard to eradicate. Any fragments of roots left in the ground will likely resprout. The long tap roots can extend up to 6 feet and grow to 7 in or more in diameter, weighing as much as 400 lbs. Kudzu spreads through vegetative expansion by rhizomes, runners (stems that root to form new plants) and by vines that root at the tip. As many as 30 vines can grow from one plant and each vine can grow to 32 -100 feet in length with stems up to 4 in diameter. Established plants grow quickly, up to 60 feet per season and one foot per day.
Kudzu does not produce large quantities of seed. In fact, those attractive and fragrant flowers hanging in long purple clusters that you may see appearing this summer from July through later summer, only produce about 1-2 viable seeds for each cluster of pods. Each hairy brown flat long pea-like pod contains anywhere from 3-10 seeds. The leaves are alternate and compound with 3 usually lobed leaflets as shown in the identification photo below.
As mentioned previously, Kudzu prefers milder temperate to tropical climates with at least a moderate amount of rainfall. So, in the past Kudzu has mostly been an issue in the southeastern US where winters are mild and summer temperatures reach above 80 degrees F. However, as our climate changes and we see increases in precipitation in drier climates and warmer winters, we will also begin to see Kudzu establish more readily in Maryland and the northeast. Kudzu prefers open sunny areas. As it spreads along forest edges it smothers trees, understory shrubs and herbaceous plants with its leaves, girdles tree trunks and pulls down and uproots trees with the weight of its vines. As it kills and uproots trees, they fall opening up the canopy and providing new sunny clearings for Kudzu to continue to spread.
Luckily, Kudzu is currently not present or wide-spread through all of Baltimore City’s parks. So, if this is the case, then why is this invader species so important? Well Baltimore City Recreation and Parks (BCRP) and its partners (such as weed warrior volunteers and friend’s groups) hope to take a proactive approach to the battle against Kudzu. This approach is called Early Detection and Rapid Response (EDRR). EDRR efforts target either new exotic recently introduced plant invaders that have not yet shown their level of invasiveness in a particular area or species that are known to be invasive but have only recently been introduced to an area. Natural Resource managers view this as the best second line of defense against invasive species. The first line would be prevention of introduction all together! Early Detection efforts include land surveys with both professionals and citizen scientist using GIS collections tools such as Arc Collector and the Mid-Atlantic Early Detection Network (MAEDN) . Once an infestation for an EDRR is spotted, Natural Resource Managers and Volunteers can act quickly to devise a management plan and implement an eradication or control program. Anyone can help report observances of Kudzu (regardless of whether they are in city parks, vacant lots, forest patches or roadsides and medians). Invasion does not abide by property lines so control must be a team effort!
So, what can you do to prevent the spread of Kudzu? First, report it using the MAEDN app! It’s free to download. Secondly, become a weed warrior and help organize a volunteer event by filling out the volunteer request form online! You don’t have to be a certified Weed Warrior to volunteer, but we strongly encourage it! If not already certified, registration is still open for the next class series this September! BCRP has already partnered with the Friends of Wyman Park and the Fairwood Forest Patch with Baltimore Green Space to organize volunteer removal efforts for Kudzu. See this helpful slide show for step by step Kudzu removal and control techniques for Kudzu on your private property.
Photo: Kudzu roots removed from Wyman Park.
Third, don’t plant or propagate Kudzu! There are wonderful native alternative vines such as Ground Nut, Apios americana, a perennial herbaceous vine that is also in the pea (Fabaceae) family. This vine has edible tubers and seeds and produces an attractive and fragrant pea shaped purple flower. Although this is a climbing vine, it is herbaceous not woody so it will die back to the ground every year and will not girdle trees or spread as vigorously as Kudzu.
Photo: Purple pea shaped flowers and compound leaves of Maryland native vine Ground Nut.
Now what do you do with all that Kudzu once you remove it? Well Kudzu has been used as a medicinal and edible plant in traditional Chinese medicine since at least 200 BC. The roots, flowers and leaf has been used to treat everything from alcoholism, headaches, stomach aches, high blood pressure, circulatory problems and even stroke or diabetes.You can also eat it! There are some unique Asia as well as Southern cooking recipes that can be found online. Check out this resource for sample recipes and how to prepare Kudzu! Due to the abundance of Kudzu in the south, some creative artisans have even used it to create intricate basketry and other art as shown in the photo below from master basketry artist, Matt Tommey. Check out his website for resources on how to weave Kudzu! In Japan, Kudzu was used as a traditional raw material for clothing textiles. In the some areas of the southeastern US, textile artists are experimenting with ways to utilize this traditional craft to make modern fabrics that can be marketed competitively.
Photo and art by Matt Tommey