Wednesday May 6, 2015; 03:00 pm EDT
The Alien that Ate America
Kudzu threatens more than biodiversity
I took a nice boat ride up the Severn River last week, exploring the smaller creeks on the north side of the river and swimming in some of the deeper holes. This is the best time to explore the upper Chesapeake, before the dreaded sea nettles take over.
Kudzu has already invaded large tracts along the river. In some places, like over by Rugby Hall, the shoreline resembles a giant Chia pet. Native trees and bushes have been smothered by the lush green leaves of doom that grow about a foot a day.
Kudzu is a sweet-smelling, climbing vine that comes from Japan and is described as the plant that ate the South because it loves the climate of the southeast and Mid-Atlantic, where it grows prolifically, smothering everything in its path.
Kudzu is not an uninvited guest, like the zebra mussel. it didn’t sneak into America inside a cargo tanker in the Great Lakes or accidentally end up in a shipment of Japanese maple trees. Kudzu was introduced to the United States with great fanfare at the Philadelphia Centennial Exposition of 1876. It was touted as a beautiful ornamental plant that could also double as a beneficial forage crop. In the 1930s, Kudzu was heralded as the solution to all of our erosion problems, and the Civilian Conservation Corps planted it all over the South. Landscape architects and government planners had no idea what they were releasing into the native environment.
Spreading Its Green Tentacles
Once kudzu got a toehold in the United States, it was pretty much unstoppable. It’s currently spreading its green tentacles into the Midwest, New Jersey, Texas, Oregon and as far north as Canada. It is eating up land at wildfire pace, around 120,000 acres a year, and costing the United States almost a billion dollars annually because of lost crop and forest land and expensive eradication efforts.
For years, the Department of Agriculture and private landowners have tried to poison, cut, burn and devour kudzu, but with only marginal effect. Like phragmites on the shorelines of the Chesapeake, it is very hard and expensive to kill. The only thing that stops kudzu is cold weather. The first freeze knocks it dead in its tracks. But come next summer, the leaves turn from grey to green and it takes off from wherever it last stopped.
How does kudzu spread so fast?
It has three different growing strategies. It spreads along the ground like English ivy, another invasive plague on the land. It grows underground, sending out rhizomes in every direction, like dreaded bamboo. And it also produces bean-like seedpods that scatter in the wind and rain.
Kudzu is a favorite of grazing animals like cows and goats. But the Severn — and most of the Western Shore where kudzu is running amok — has little livestock, so its benefit as free forage is pretty much non-existent.
From a medical standpoint, Kudzu is a big winner. The Chinese consider it one of the top 50 fundamental herbs, and it has been used in Asia, Europe, and America for many years to battle chronic headaches, leukemia and joint disorders. Several universities are currently experimenting with it as a cure for alcoholism.
In Asia, it has long been used as a food additive and a summertime beverage. Across the Southern United States, it has been turned into soap, jam, compost and even fuel.
Kudzu is, in fact, a legume or bean, and it has been used around the world, especially in the rainforests of Brazil after forest clearing, to increase the fertility of the soil. It does this by increasing the nitrogen content, pretty much the last thing the Chesapeake Bay needs. Nitrogen from fertilizers, sewer treatment plants and funky air is already turning vast stretches of the Bay into dead zones.
But the news gets worse. The latest studies at the University of Virginia indicate that kudzu releases chemicals that combine in the air to make ozone, which is the main reason why the air around here is almost suffocatingly bad during the Code Orange days of summer.
“People worried about kudzu invasion previously were worried about its effect on biodiversity,” said Manuel Lerdau, an environmental studies and biology professor at the University of Virginia and one of the study’s authors. “We’re saying there are more worries about kudzu than biodiversity. It has an effect on air quality and human health.”
So the next time you hear someone complaining that the government won’t let the Asian oyster be introduced into the Chesapeake Bay, remember kudzu and what happens when the law of unintended consequences is unleashed upon unsuspecting natives.?
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