If you look into getting rid of invasive plant species, you may be aware that common methods involve combining both chemical and mechanical controls together. So, how can there be a debate on which is best if they are often used together? The true debate lies in the species in question. Each species needs to be treated in a different way to effectively prevent it’s spread. There is also the fact that some people might have qualms about using herbicides. Or, perhaps they are not willing to spend energy and time tilling the ground. Before we go on, let’s consider the difference between the two methods.
Mechanical Control: cutting, mowing, girding, chopping, tilling and the use of machines or tools.
Chemical Control: the use of pesticides including herbicides, insecticides, and fungicides.
There are other forms of control methods aside from chemical and mechanical including manual control, prescribed fire, biological control, cultural control and disposal. You can learn more about these control methods from the DNR.
Every invasive plant species should be treated according to it’s individual situation. See below for a list of common invasive species in Indiana and tips on how to effectively treat them.
Common Invasive Plant Species:
Poison Hemlock
* All parts of this plant are poisonous to both animal and human.
Conium Maculatum
Native Origin: Europe
Description: These plants start as a low lying rosette in the first year and can bolt up to 3-10 feet in the second year! They have stout stems with purple spots, small, white flowers with umbrella-shaped clusters (June/July), and fern-like leaves which are arranged alternatively on the stems.
Habitat: Poison hemlock is typically found along roads, streams, trails, ditches and forest edges.
Ecological Impact: This plant contains highly poison compounds that can be fatal to both humans and livestock.
Control and Management: Poison hemlock spreads via seed so effective control must prevent or exhaust the seed supply.
Mechanical: Mowing or cutting may be effective, but should be repeated often.
Chemical: Herbicide application should be performed while the plant is actively growing and before flowering. Follow up treatments will be required. Effective for large infestations. Herbicides used against this plant are Glyphosate and Triclopyr.
(Credit: SICWMA.org)
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Notes: Although eradication is the ultimate goal, it may not be entirely achievable and settling with just controlling the invasion is the only option. Also, if you have very little understanding of invasive species and how to effectively control them, I urge you do further research before attempting to eradicate them. It may also be more beneficial to reach out to your local DNR about invasive species for aid on creating an effective control plan.