RM43 is a powerful weed killer used in a variety of applications, whether you are preserving your driveway, your barns, your fence rows, or your tennis courts. There’s a lot to know about this popular product, so we’ve gathered some of the most common questions—and answers—here for your reference.

What is the “43” in RM43?

RM43 is a herbicide with that is just over 43% Glyphosate, which is stronger than most commercially available mixes.

Can RM43 be used to clear out an area you plan to reseed later?

RM43 is designed to not only kill existing plants, but also prevent others from coming back, which makes it ideal for fence rows, sidewalks driveways, and around the perimeters of areas that are hard to trim or mow. Because it is so good at what it does, it can keep weeds and other plants from growing for up to a year; to answer your question directly, technically, yes, you’ll be able to reseed it, but not for some time. We’d recommend our Compare-N-Save Grass & Weed Killer if you plan on renovating existing land.

Do I need to spray it on the leaves or the roots?
Spray it on the leaves. The glyphosate in RM43 works best when absorbed through foliage to kill the current plants. Spray as many leaves as possible, being careful that overspray doesn’t land on the foliage of the plants you want to keep; RM43 does not discriminate between weeds and your prize rose bushes. That said, this product is also absorbed through root systems and can offer total vegetation control when applied to the bare ground. For best results, do not cut or mow treated areas for two months following treatment to ensure they won’t grow back.

How does RM43 effect trees?

It can, which is why we recommend utmost care when spraying around new and established trees. The older the tree, the less likely it will be directly affected; RM43 is absorbed most readily through the foliage and minimally through the roots, so the further you spray away from a tree’s leaves and root system, the safer your tree is. Of course, this is with the assumption you want to save your trees. If you want to kill a tree, RM43 can kill it and prevent it from coming back; however, depending on the size of the tree, there may easier, faster, and more economical ways to do so.

How do I dilute RM43?

There are two dilution ratios we recommend, depending on your desired result. For total vegetation control, meaning weed-free down to the bare ground, we recommend a concentration of 7.4 fluid ounces of RM43 per gallon of water, up to ten gallons, with a maximum application rate of 7.4 fluid ounces of product per 1,000 square feet (2.5 gallons per acre) per year. For spot treatment, mix 6oz of product per gallon of water.

When is the best time to spray?

RM43 is effective any time it is used, but optimum performance on most plants is achieved in the late spring, early summer when plants are actively growing. Spray on calm, warm, sunny days for best results. Special note: if spraying woody brush and vines, wait until late summer or fall, after fruit formation.

Have more questions? We have more answers. Learn more about RM43 here.