Does weedkiller lose its potency?

LVSteve · Apr 7, 2013

Sprayed some unwelcome guests in my yard last week using Round-Up. Today I noticed that several of the things I sprayed look a little sick but have not gone brown and shriveled up like I normally see. It occurs to me that this weedkiller might be a year or two old and temperatures can exceed 80°F in the garage in the summer.

Should I ditch this can and get new?

Ivan the Butcher · Apr 7, 2013

I have a friend who farms, several years ago they had a spill of about 8 ounces of 100% Round Up when mixing a batch for spraying. The next spring there a dead patch about 4' across, the dead patch grew as rain spread the round up after about 7 or 8 years the patch was about 20 to 30' in size, then it started to fade. In the 128:1 mixture for woody plants, or 400:1 mixture for grasses, it is made to be done killing in a few weeks. The pre-diluted homeowner stuff at home and garden stores is bound to have shorter shelf life. Reapply or replace but absolutely don't let those plants live! That is how Monsanto breed a whole line of Round-Up resistant soy beans. Ivan

Frank237 · Apr 7, 2013

I've been told NOT to let Roundup FREEZE. As it will diminish the effectiveness. If that helps.

CW Spook · Apr 7, 2013

Not letting it freeze makes a lot of sense. Back in the days before the 'civilian' variety was available in garden shops I got a small peanut butter jar of full-strength ag RoundUp from a farmer friend to kill some stubborn thistles in my yard. Man, that stuff is potent!

NYlakesider · Apr 7, 2013

The new Round Up along with most weed killers has been so diluted by the EPA weenies that to make it work you have to do some “creative adjusting” to what’s in the bottle. I prefer the concentrate and you have to read their mixing instructions and do what you must to make it work!

The older stuff you sprayed it and it showed the weed/s were dying fast over night. The new "improved" junk it takes a bunch of days to start showing anything and if you lucky 1/2 of what you wanted killed will die after a while.

That EPA nonsense also applies to ant, bug and bee killers.
They really did a number on what you get, but the price did not come down any.

OLDFED · Apr 7, 2013

We all lose our potency when we get older, sorta like the chewing gum left on the bedpost overnight!

Comrad · Apr 7, 2013

If it's been sitting for a ling time did you shake it up before using?

CAJUNLAWYER · Apr 7, 2013

Read the label. You want the 50% stuff. Also Monsanto's patent on the active ingredient has expired (forget what it was-but look on the label) and Tractor Supply has the generic stiff-same stuff as the roundup for about half the price. I used to get mine from one of the cane farmers-he bought it by the 55 gall drum. Good stuff. I like to mix the 50% concentrate two oz to a gallon of water. Kills them quick enough for me. Tried 2-4D one time using diesel instead of water to mix. Killed the chain link fence with that one

Was years ago and stuff still ain't growing there!!

Remember, when it comes to Agricultural Chemicals improvise and adapt-if it starts smoking RUN otherwise as long you stay upwind and don't get any on you -you ought to be OK

Rule3 · Apr 7, 2013

Round Up is very slow acting. It takes more than one week to effectively kill weeds. Give it at least 2-3 weeks.
Glyphosate is the active chemical, you can buy generic versions now.
It is not selective so it will kill most any green plant, not good to spray in the yard as it will kill the grass. Depending on the type of turf grass there are selective weed killers that kill weeds and not the lawn.

Pete99004 · Apr 7, 2013

CAJUNLAWYER said:
Read the label. You want the 50% stuff. Also Monsanto's patent on the active ingredient has expired (forget what it was-but look on the label) and Tractor Supply has the generic stiff-same stuff as the roundup for about half the price. I used to get mine from one of the cane farmers-he bought it by the 55 gall drum. Good stuff. I like to mix the 50% concentrate two oz to a gallon of water. Kills them quick enough for me. Tried 2-4D one time using diesel instead of water to mix. Killed the chain link fence with that one Was years ago and stuff still ain't growing there!! Remember, when it comes to Agricultural Chemicals improvise and adapt-if it starts smoking RUN otherwise as long you stay upwind and don't get any on you -you ought to be OK

Good, sound advise - stay upwind!!!

Pete

angel71rs · Apr 7, 2013

I bought a quart of this stuff and it smoked the weeds I sprayed it on:
KillzAll Grass and Weed Killer 41% Glyphosate, Hi-Yield Kill Zall

Some stray bermuda grass was a little more resistant till I added a few drops of dish detergent to help it soak into the thin blades. I was not happy with the Roundup I got at Home Depot, probably due to it being emasculated as already mentioned.

Kinman · Apr 7, 2013

For a time being I was a state certified public grounds operator. Glyphosate is dangerous to living plants and people should be very careful applying it. Thats probably one of the reasons that the "Idiots" at the EPA have required a much diluted form to be able to fall into the hands of all the "experts" for home and garden use. Spray drift has accounted for millions of dollars in damages paid out to home owners, orchardists, etc. Glyphosate is incredibly resilient in undiluted form and its run-off is directly related to its danger of contaminating ground water.

darmtn1917 · Apr 7, 2013

I'm currently using a 1gal bottle of Roundup 50% that has been sitting around for 6 years - remember the action is much better dependent on the temp - over 80o is best, under 70o takes 2-3 weeks

ChattanoogaPhil · Apr 7, 2013

(edited out names and fluff)

Roundup Weed & Grass Killer Concentrate has a shelf life of a minimum of eight years. The product may
last beyond the minimum time period though. Many variables in storage conditions can affect the shelf
life of a product. Roundup Weed & Grass Killer Concentrate will not be fully effective one
day and ineffective the next; the product will gradually lose its effectiveness over time. Store both
unopened and opened product containers in a cool, dry place and protect them from extremes in
temperature. Freezing temperatures, for example, won't affect the product, but may cause damage to the
container and could result in a chemical spill. Stored correctly, your product will last at least the minimum
number of years and probably longer.

You may store diluted Roundup Weed & Grass Killer Concentrate for up to 6 months. After that, the
surfactant, or sticking agent in the RoundUp, breaks down due to impurities in tap water. RoundUp
Ready-to-Use products have a 4-year shelf life because they have an added ingredient to prevent this
breakdown in the surfactant. If you store diluted product after use, be sure to mark the storage container
to note both the contents and the date the product was mixed.

Glen Kussow
Consumer Response Representative
The Scotts Company and Subsidiaries
14111 Scottslawn Road
Marysville, OH 43041

LVSteve · Apr 7, 2013

Comrad said:
If it's been sitting for a ling time did you shake it up before using?

Now there's a thought. No, I just cranked up the pump gadget and got spraying. It is the "civilian" strength stuff from Home Depot.

Rule3 · Apr 7, 2013

Ya gotta shake it

Rintimtin · Apr 7, 2013

Buy the concentrated stuff of what ever it is, and mix it yourself. Round Up takes a while to work. And sometimes your weeds can become resistant to a chemical if you use it alot.

ChattanoogaPhil · Apr 7, 2013

Shake shake shake... shake shake shake... shake your Round-up... shake your Round-up.

Viss · Apr 7, 2013

I go to the local farm supply and buy Glysophate, 2.5 gal is $45.00.

I mix 6 0z per gal in a hand sprayer. Kills about everything.

Every year I forget to bring the remainder of the concentrate into a heated area and it freezes. I then have to mix it twice as strong to get the same results.

LVSteve · Apr 7, 2013

I shook it up and retreated the offending weeds. They were mostly forms of bindweed which are always a pain to kill as you don't know how many of the bits you can see are connected underground in mutual support. I'll see what the next few days brings.

Does weedkiller lose its potency?

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