By Aaron Hathaway
Read the product label to make sure it’s safe to apply around trees.
In the previous article “What’s the difference between Roundup and Roundup for Lawns?,” we discussed the difference between those two products. It’s also critical to understand the difference between other Roundup formulations such as Roundup Weed and Grass Killer and Roundup Max Control 365.
Before we get into understanding the chemistry of the different Roundup products, it is important to define a few herbicide-specific terms:
- Non-selective: A herbicide that generally kills any plant on which it is applied; e.g., glyphosate.
- Selective: A herbicide that kills only specific plants and does not affect other plants; most often, these herbicides kill broadleaf weeds and annual grassy weeds like crabgrass, but are safe to apply to the lawn.
- Residual: A herbicide can have soil residual, which means it sticks around (or resides) in the soil for a time and continues to do its job; these residuals can range from one to 300 days long.
Non-selective herbicides
Roundup Weed and Grass Killer is used to kill broadleaf and grassy plants. These products are ideal for targeting weeds in gardens and landscape beds, cleaning up edges where a lawn meets a landscape bed, spraying within empty mulched areas or killing an area in preparation for a new lawn or garden. Some of these products include diquat or pelargonic acid to speed the visual results of the products as it can take up to seven days to see weed injury from glyphosate alone.
Do not apply these products within a lawn to control weeds—it will kill everything and you will have to reseed or sod your lawn.
Non-selective herbicide products |
|---|
Trade name | Active ingredients | What is different? |
|---|
Roundup Weed & Grass Killer Super Concentrate | glyphosate | “Normal” Roundup. |
Roundup Weed & Grass Killer Concentrate Plus | glyphosate and diquat | Diquat added for faster visual results. |
Roundup Precision Gel Weed and Grass Killer | glyphosate and pelargonic acid | Pelargonic acid added for faster visual results. |
Roundup Ready-To-Use Weed & Grass Killer III | glyphosate and pelargonic acid | Pelargonic acid added for faster results and gel formulation for wiping on weeds. |
Roundup Concentrate Poison Ivy Plus Tough Brush Killer | glyphosate and triclopyr | Triclopyr added for specific activity on vine weeds like poison ivy. |
Non-selective with residual herbicides
There are similar products described as non-selective with residual. These Roundup products add imazapic, which has a long soil residual. This product helps to keep treated areas free of weeds even after the glyphosate kills them. Users should be careful to treat areas they don’t plan to seed or plant in that season (even up to 12 months for certain products). These products could be useful in hardscapes with weeds growing in cracks, along fencerows and in gravel driveways.
Do not apply these products within a lawn to control weeds—it will kill everything and you will have to reseed or sod your lawn.
Non-selective with residual roundup products |
|---|
Trade name | Active ingredients | What is different? |
|---|
Roundup Concentrate Extended Control Weed & Grass Killer Plus Weed Preventer | glyphosate, imazapic and diquat | “Normal” Roundup with residual control of weeds. |
Roundup Ready-To-Use Extended Control Weed & Grass Killer Plus Weed Preventer II | glyphosate, pelargonic acid and imazapic | Ready-To-Use formulation replaces diquat with pelargonic acid, but you get the same effect—faster visual results. |
Roundup Concentrate MAX Control 365 | glyphosate, imazapic and diquat | The amount of imazapic is increased to make the soil residual longer—all season. Cautions: Do not apply over rootzones of trees or shrubs; do not apply on slopes where desirable plants are found down-slope. |
However you use these non-selective products, especially those with residual, be aware they can kill any plant they contact. So, if you spray a hardscape and a rain quickly comes, the water could move the product to adjacent plants. If you use a sprayer to apply these products and don’t effectively rinse the material out of that sprayer, a subsequent use of the sprayer could also kill desirable plants. These mistakes could be further compounded if the materials involved were non-selective with residual.
Remember:
- Know what you are purchasing.
- Read the labels of these products thoroughly.
- Apply these products according to label recommendations for their intended use.
- Reference to commercial products or trade names does not imply endorsement by Michigan State University Extension or bias against those not mentioned.