05/27/2026
Exceedingly helpful info from our friends at Madison County Noxious W**ds District 👍
WHAT KIND OF HERBICIDE SHOULD YOU USE TO KILL YOUR W**DS?
A lot of people hear the word “herbicide” and sometimes assume that all w**d sprays are basically the same. They are not. Different herbicides are designed to do very different jobs. Here is some information to help you know what herbicide you should use to control w**ds on your property.
I put this information together because we have been getting a lot of basic questions about "w**d sprays" lately at our Madison County W**d District office and it seems like perhaps putting some basic herbicide information in a Facebook post would give folks something to save and refer back to the next time that they are shopping for "w**d spray". Hopefully, these basic descriptions of different kinds of herbicides can help you.
Keep in mind, herbicides are designed to work in very specific ways and the labels reflect that. If you do not follow the label, you will cause unintended damage, so follow the label. THE LABEL IS ACTUAL LAW.
-- TYPES OF HERBICIDES -- The Basics
SELECTIVE vs. NON-SELECTIVE
• SELECTIVE Herbicides: These target certain types of plants while leaving others mostly unharmed.
Example: A lawn w**d killer that kills dandelions and thistles but leaves the grass alive.
Why use them? When you want to remove w**ds WITHOUT killing desirable plants like lawns, pasture grass, or certain crops.
Common uses:
-Lawn w**d control
-Pasture w**d control
-Crop production
-Rangeland management
• NON-SELECTIVE Herbicides: These kill or injure MOST plants they contact.
Example: Products used on gravel driveways, fence lines, industrial sites, or before reseeding.
Why use them? When you want total vegetation control or need to clear an area completely.
Important note: Homemade vinegar/salt/dish soap w**d spray mixtures also function as non-selective treatments and will damage or kill most plants they contact.
Common uses:
-Gravel areas
-Fence lines
-Very targeted spot spraying of invasive w**ds
-Site preparation before planting
HERBICIDE “GROUPS” (MODE OF ACTION)
Herbicides are also categorized by HOW they kill plants. This is called the “Mode of Action” Group.
Different groups attack different systems inside the plant.
A few common examples:
• Group 4 — Growth Regulators (Examples: 2,4-D, Triclopyr, Dicamba, Aminopyralid)
These mimic plant hormones and cause the plant cells to grow rapidly until the plant dies. This effect primarily occurs in dicot plants (broadleaf species) and not in monocots (grasses).
• Group 2 — ALS Inhibitors (Examples: Metsulfuron, Chlorsulfuron, Imazimox)
These stop the plant from producing certain amino acids it needs to grow. The plant slowly shuts down. Group 2 herbicides primarily affect broadleaf plants because broadleaf species are generally more sensitive to this enzyme pathway, while grasses can metabolize or tolerate these compounds more effectively in many cases. This makes them commonly used for selective broadleaf control in grass crops and rangelands.
• Group 9 — EPSP Inhibitors (Example: Glyphosate)
These block production of critical proteins the plant needs to survive. Because they work in most plants, they are considered non-selective.
PRE-EMERGENT vs. POST-EMERGENT
Another key distinction is timing:
• Pre-emergent herbicides (Example: Rejuvra/Indaziflam): Applied to soil before w**ds germinate. They create a barrier in the soil that stops seeds from germinating.
• Post-emergent herbicides (Examples: 2,4-D, Glyphosate, Dicamba): Applied after w**ds have already emerged and are actively growing.
A QUICK NOTE ON “NATURAL” OR HOMEMADE W**D SPRAYS
Homemade vinegar/salt/dish soap mixes are often promoted online as “safe” alternatives to herbicides. In reality, these mixtures can still damage soil, water, desirable plants, concrete, and metal surfaces — and some can cause skin or eye irritation.
Homemade w**d spray recipes also do not go through EPA registration, toxicology review, environmental testing, application research, or labeled rate development like registered herbicides do.
It is also very easy to overapply homemade salt/vinegar mixtures, which can unintentionally sterilize soil and damage surrounding vegetation for extended periods of time.
Ironically, some of these so-called "safer" homemade treatments that are concentrated vinegar/salt-based products can be much more corrosive and hazardous to handle than registered herbicides, especially when misused or overapplied.
This is not about “chemical vs. non-chemical.” EVERYTHING involved is a chemical, even the water the herbicides are mixed with. The distinction is whether a product has been evaluated, labeled, and tested for safe and effective use under specific conditions.
Registered herbicides are required to meet those standards. Homemade mixtures are not.
I used AI to make a graphic attached to this post, to simplify all the information written above. Feel free to save it for your reference.
