Invasive Plants

An invasive plant takes over and damages ecosystems

Evolution is a process which has been occurring for millions of years, and plants and animals evolved in various regions to create ecosystems that were in balance. Each species has mechanisms to grow and reproduce to ensure survival of the species. Plants generally need light, water, and carbon dioxide to grow and reproduce by seed or other means. Animals and insects need to eat, grow, and reproduce too. Insects need plants. Many animals eat plants, some eat other animals.

“Weed” is a term reflecting human opinion

A “weed” is simply a plant growing where it is not wanted. It is an imprecise term reflecting human opinion about a plant, and human opinion is not always correct.

The harms caused by invasive plants

Invasive plants can crowd out every other plant, including the native plants that insects and animals in the region rely upon. Invasives degrade the environment and native insects and animals find their resources are diminished. Butterflies may require certain host plants to lay eggs on and for nectar, but if that host plant has been crowded out by invasives, that butterfly will not be able to grow and reproduce.

Examples of invasive plants

There are invasive plants in every region and state, my experience is with the New York and Connecticut area, you should familiarize yourself with what is invasive in your region.

  • Bishop’s Weed, Goutweed, Ground Elder, Aegopodium podagraria (for over a decade we mistakenly thought this was Queen Anne’s lace)
  • Oriental Bittersweet, Chinese bittersweet, Asian bittersweet, Celastrus orbiculatus
  • Japanese Barberry, Berberis thunbergii
  • Autumn Olive, Elaeagnus umbellata
  • Garlic Mustard, Alliaria petiolata
  • Common Reed, Phragmites australis
  • Oriental Lady’s-thumb, Smartweed, Polygonum caespitosum, or Persicaria longiseta
  • Japanese Stiltgrass, Microstegium vimineum
  • Multiflora Rose, Rosa multiflora
  • Burning Bush, Euonymus alatus (I confess I have planted this, but have removed it)
  • Japanese Knotweed, Japanese bamboo, Polygonum cuspidatum, Fallopia japonica
  • Wineberry, Rubus phoenicolasius (for two decades we mistakenly thought these were wild raspberries)
  • Dame’s Rocket, Hesperis matronalis (we mistook this for phlox)
  • Norway Maple, Acer platanoides (me mistakenly thought this was a good Maple, a large professional arborist company even took money for pruning them without advising us that it was an invasive tree species)
  • Privet, Ligustrum genus

How to combat invasive plants

Fighting invasive plants requires knowledge of horticulture, biology, and science. With this knowledge, one can develop a good strategy and then be persistent with implementation. It is a long war against an invader, I believe my military training brings helpful planning methods.

  • Properly identify the invasive plant. If you don’t know what it is, you cannot fight it properly. Proper identification means knowing the scientific name (Latin name) of the plant, in addition to the common names.
  • Once properly identified, research expert advice available from scientists, biologists, and respected resources.
  • Educational institutions, government resources, invasive plant working groups are usually reliable sources.
  • Use caution reviewing advice not backed by science, horticulture, or proper sources.
  • Don’t plant invasives.
  • Don’t spread invasives or allow them to spread (see next).
  • Learn how the invasives propagate (reproduce). Is it by seed, by underground rhizomes or roots, or both? If you know how they propagate, you can work to prevent them from spreading.
  • Learn what they like, and what they don’t like, and when.
  • All plants generally need certain things (light, air, water).
  • Most plants do not like certain things (certain herbicides, smothering, etc.)
  • Each plant has specific attributes (certain herbicides that work, tolerance for certain conditions).
  • Work to weaken, control, and eventually eliminate the invasive plants, while keeping conditions suitable for native plants.
  • Controlling invasive plants may require a combination of mechanical, cultural, and chemical (herbicide) control.
  • Mechanical control means things like cutting, pulling, smothering
  • Cultural control means changing human behaviors and habits, what is planted, mulching, watering, etc.
  • Chemical control means application of herbicides and pesticides.
  • Herbicides may have some negative attributes but consider the big picture and greater good. Invasives do great damage to our environment and many cannot be controlled with herbicides. Where required and properly applied, herbicides are necessary to control invasive plants.
  • Prevent it from setting seed (cut, pull, or spray before seed set)
  • Prevent seeds from dropping into the soil (pull)
  • Reduce the likelihood that existing seeds in the soil will germinate (avoid turning the soil, cover the soil with newspaper, cardboard, and mulch)
  • Prevent it from spreading (don’t transplant anything from the area, don’t move soil)
  • Work to weaken and eventually kill the plants
  • Killing the plants are the ultimate goal, but sometimes this can be difficult or impossible to achieve immediately.
  • Weakening the plants is a first step. This can reduce its propagation, spread, and dominance over neighboring plants.
  • Avoid digging. Digging is problematic because of the potential to bring seeds to the surface for germination, and to spread roots or rhizomes.
  • Consider smothering. Smothering roots and rhizomes is an excellent way to kill certain plants, and smothering of seed infested soil prevents germination of seeds. Smothering can be done with newspaper and cardboard with woodchips on top. The smothering effect will last for a few years, and then the newspaper decomposes.
  • Avoid landscape fabric or plastic sheeting, unless you resolve to remove it within a few years.
  • Consider cutting. Cutting the top growth removes an important source of energy for the plant. Then the plant must expend energy from the roots to regrow it. This may not kill the plant, but will weaken it.
  • Imagine an Oriental Bittersweet vine that has grown for 20 years, reaching the top of and smothering a fifty foot tree. Cutting the vine at the base robs the invasive plant of all the future energy those leaves would otherwise capture. It forces the roots to expend great energy to regrow, and gives the tree a chance to recuperate. The vine will live, but greatly weakened.
  • Some say cut the vine and paint the cut with herbicide, which can kill the vine. Good if you can do it or have a team where one person cuts, and the other follows with the herbicide.
  • Consider pulling where appropriate. Some invasives can be hand pulled. For others, the roots are too strong to pull, or hand pulling is of little practical use because roots and rhizomes remain.
  • Herbicide. Properly applied herbicides are important to fight invasive plants. Yes, some herbicides are dangerous to people and impact the environment. But invasive plants do great damage to the environment too.
  • The herbicide needs to be suited for the particular species of invasive plant, applied at the right time of year, and applied properly.
  • Avoid overspray onto other plants.
  • Where overspray is a risk due to nearby plants you want to save, and where herbicide is required, consider painting the herbicide onto plant leaves where practical. (I am doing this on Bishop’s Weed in planting beds since hand-pulling has proved ineffective over the years).
  • Monitor regularly. Realize this will take years to control. Pick a path you can stick with.
  • There is a reason they are called invasive plants. If they have colonized an area, it will take time to remove them.
  • Whatever technique you choose for control, monitor your progress to see if the technique is effective.
  • If invasives have dropped seeds, those seeds can remain viable in the soil for many years.
  • If invasives have extensive roots or rhizomes, it can take years to properly exhaust, smother, or poison them.
  • Consider professional assistance.

Steps we can take

We can all play a role to help reduce the spread of invasive plants, on our property, and the properties we manage or visit. We can also encourage governments to properly manage our public lands, and educate the public about this problem.

Steps government can take

Here are some things government can do:

  • Fund education for consumers
  • Require education and training for licensed professionals (arborists, landscape contractors, etc.)
  • Require arborists and landscapers to notify owners of invasive plants on their property
  • Prohibit sale of invasive plants
  • Fund remediation of lands dominated by invasives
  • Fund non-profits who work in the field to educate and take action.

Conclusion (and disclaimer)

Invasive plants are a threat to our environment, public lands, and private property. We can be better stewards by learning about invasive plants and controlling them properly.

Additional reading and resources

This article is hosted on my website at https://johnbandler.com/invasive-plants where I also include links for additional reading, and it may be more current and with improved formatting. Copyright John Bandler all rights reserved.

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John Bandler

John Bandler

Cybersecurity, cybercrime prevention, privacy, law, more. Attorney, consultant, author, speaker, teacher. Find me at JohnBandler.com