Invaders From Another Place

— Written By Zack Taylor and last updated by
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Invaders. A word that may conjure up thoughts of the movies, maybe images little green men with ray guns from outer space. Today though, we are going to take a look at a different type of invader. They are green, and although they don’t carry a ray gun, they can be dangerous. They may be from a different place, but probably not outer space. I’m talking of course about invasive plants, or as we call them, invasive weeds.

Weeds are defined by the Weed Science Society of America as a plant that causes economic losses or ecological damage, creates health problems for humans or animals, or is undesirable where it is growing. A great example of this is crabgrass in a lawn or crop field. Crabgrass is a common plant, native to the entire continental United States, that is undesirable in lawns, and causes crop losses in agricultural fields. Since it is so widespread, eradication is impossible, and it can even be a valuable forage for cattle. So when does a weed become invasive?

Invasive weeds are defined as those weeds which establish, persist, and and spread widely in natural ecosystems, outside of the plant’s native range. For this one, think kudzu. Kudzu was introduced here from Asia, and is well adapted to our climate. Not only that, here in the southeast, kudzu has no natural enemies or competition, so it easily spreads in our environment. Kudzu can be controlled, but eradication is not feasible since it has become so widespread. Invasive weeds are often introduced as an ornamental plant, like kudzu, then seeds or other reproductive structures are introduced to the natural ecosystem and the plant spreads. Kudzu was once planted intentionally to help manage erosion, and is even a good quality forage for livestock. Goats love it!

Within the category of invasive weeds there is a larger threat, known as noxious weeds. Noxious weeds are plantsdesignated by the federal, state, or local government as injurious to public health, agriculture, recreation, or wildlife. When weeds are classified as noxious, authorities can implement quarantines, or take actions to contain or destroy the plant, and limit it’s spread to other areas. In many cases authorities are allowed to control noxious weeds even on private property.

There are currently well over 100 weeds on the federal noxious weed list. One of the most well known, and more common in North Carolina, noxious weeds is probably hydrilla, an aggressive aquatic weed. Noxious weeds were originally controlled under the Federal Noxious Weed Act of 1974, which has since been updated by the Plant Protection Act of 2000. These acts give the US Secretary of Agriculture the authority to designate federal noxious weeds, and control their spread. Did you know it is illegal to transport a federal noxious weed without a permit? Permit holders are commonly educators, transporting weeds for use in identification classes, or for weed eradication research.

States have the option of identifying and designating noxious weeds as well, which may or may not not be on the federal list, but have significant implications in that state. Most of the weeds identified as noxious in North Carolina are not widespread, but limited to a few counties in the state. Authorities implement programs to contain and eradicate these weeds and prevent their spread further throughout the state. To see a list of noxious weeds in North Carolina, visit

So why am I telling you about invasive and noxious weeds? Well, the first step in preventing these weeds from spreading across our state is to identify them before they become well established in a new place. Recently, a population of the noxious aquatic weed yellow floating heart was found right here in Lee County. Often times, new infestations of invasive weeds are identified by property owners or people who work outside, and around water. If you work outside, or spend time outside on your property as a landowner, you can often recognize when a something doesn’t look right. We become accustomed to seeing certain plants in nature, so when something looks new or out of place it often jumps out at us. If you see a plant that seems unusual or out of place on your property or while working outside, give extension a call at 919-775-5624. We would be happy to help identify the plant, and if it turns out to be a state or federal noxious weed, you may be the one to help stop the invaders.

Zack Taylor is the Agriculture Agent – Field Crops and Livestock for North Carolina Cooperative Extension in Lee County.