Does Roundup go bad?

[sixdogs]

I have found glyphosate (round-up or generic) stored as a concentrate lasts indefinitely with no reduction in performance. Once it is diluted with water it does loose a bit of effectiveness over long periods of time (like a year), but not much. The biggest problem with storing it in diluted form is that crud will develop in the mixture that can clog your spray equipment. It might be the surfactant I put in the dilute that forms the crud though, I am not sure.

For me, crud forms either way. When done with my boom sprayer I rinse with water and spray some out and no crud later.

 

[thekkfan]

I am a fan of a product called Ground Clear. That stuff kills fast, effects are noticed in 24-48 hours, if not sooner.

You do know that's glyphosate with a little imazapyr (root herbicide) throwed in for long term kill.

 

[buster 1]

Had a quart of the generic concentrate (41%) roundup from TSC. Maybe 12 oz left, a little less than a year old, in original container with tight lid, stored in my garage so it went thru hot and cold.

Mixed 4oz in 2 gal water in pump sprayer & did around my house. Couple days later, everything I sprayed was healthy & still growing. Hmmm.....maybe I remembered dose wrong so did remaining 8 oz in 2 gal water and sprayed again. Everything still just thriving.

I'm guessing the stuff went bad. Seemed the same as when new from appearance & smell, but had 0 effect on the stuff I sprayed around the house. I used it to kill off the areas I turned into pumpkin patches last summer. Worked fine doing the initial killing off of that ground cover, but can't tell I've sprayed anything - twice - over past week with it.

A good
I use a cheep dishwashing detergent (all) a Good squeeze help keep the round up penetrate the weed. Some grass weeds have a slick surface so the round up roll off. Just saying. The product does not go bad. May get thick just shake it.

 

[Stan1164]

I buy 20l at a time, last's several years, strengh won't alter.
I use RUM (fretilizer made from worm castings) as a surfactent, works well.
For cut stump, mix roundup 50/50 with water
Stan,
Queensland, Australia.

 

[doneill127]

CMV Hard water has a really bad effect on the effectiveness of glysophate. If I remember it can go as low as 20%. Won’t get into cations and molecular disassociation blah blah blah but below is a cut and paste from Round Up fact sheet about adding ammonium sulfate to hard water and they define hard water as above 100ppm. If you wan to read the entire thing here it I’d
Effects of Hard Water on Herbicide Efficacy
AMS should be added to the water in the spray tank prior to the addition of a Roundup brand glyphosate-only agricultural herbicide. Ensure that AMS is completely dissolved before adding herbicides.
Use 8.5 to 17 pounds (1 to 2 percent by weight) of dry spray grade AMS, or 2.5 to 5.0 gallons of liquid AMS, per 100 gallons of spray solution.
A higher rate of AMS should be used in spring burndown, tank-mixes with residual herbicides, or when targeting tough-tomanage weeds (such as lambsquarters, velvetleaf, giant ragweed, morningglory, thistle, etc.).
A lower rate of AMS can be used for in-crop postemergence applications when daytime temperatures exceed 85° F to reduce the potential for cosmetic leaf burn on the crop.
The spray system should be thoroughly rinsed with clean water after use to reduce corrosion.

 

[sixdogs]

I buy 20l at a time, last's several years, strengh won't alter.
I use RUM (fretilizer made from worm castings) as a surfactent, works well.
For cut stump, mix roundup 50/50 with water
Stan,
Queensland, Australia.

We kill stumps that way but with full strength 46%. Just paint the edge of the stump ASAP after you cut it.

Another thing you can do is kill a tree while it's still standing but "girdling" it. Just make a chainsaw cut around the tree about 3/4" of and inch deep and paint it with Roundup or generic. You can dry firewood on the stump this way or girdle in the fall and come back to it next spring.

 

[slmpd]

Had a quart of the generic concentrate (41%) roundup from TSC. Maybe 12 oz left, a little less than a year old, in original container with tight lid, stored in my garage so it went thru hot and cold.

Mixed 4oz in 2 gal water in pump sprayer & did around my house. Couple days later, everything I sprayed was healthy & still growing. Hmmm.....maybe I remembered dose wrong so did remaining 8 oz in 2 gal water and sprayed again. Everything still just thriving.

I'm guessing the stuff went bad. Seemed the same as when new from appearance & smell, but had 0 effect on the stuff I sprayed around the house. I used it to kill off the areas I turned into pumpkin patches last summer. Worked fine doing the initial killing off of that ground cover, but can't tell I've sprayed anything - twice - over past week with it.

Glyphosphate works better in months with more sunshine. It also helps to wait late enough in the morning that most of the dew has dried on the plant involved. I have some Roundup that's in it's 4th year and works just fine.

 

[Sonny580]

Weed killers only work when temps are above 55 at night and weeds are actively growing. I still use a jug that I have had for 5 years and it still kills. thanks; sonny580

 

[Stan1164]

Tordon herbicide is excellent for a lot of big timber, just put an axe cut into the sapwood and inject Tordon within a couple of seconds.
Kills the tree and stops any regrowth.
You call it girdling we call it Tordoning or ringbarking.
Sixdogs, you are correct, stump has to be painted within a couple of seconds after cutting.
Using 50% water is more cost effective with the same kill rate.