Does Roundup go bad?

[CMV]

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.

 

[Ford850]

I've had some stored for years with no issues, even after it started to separate and get clumps of gel in it. The biggest thing that affects it is how well the plants absorb the spray ( I always use a surfactant now) and how fast the plants are growing. If not growing aggressively it takes a long time to affect plants, if at all. That's why some instructions say to mow the area and then spray a week or so later, since mowing encourages new growth.

 

[thekkfan]

I'm nursing a 2.5g jug of the same 41% from TSC from 2017, used it fine all last year. Will finish it up in the next tank though.

I've had quick success with it, as well as taking nearly a week for any discoloration or wilting to occur. I would mark it to the high amounts of rain we've had, along with the temps not stabilizing here above 50 degrees at night affecting plant growth. I mean it was 30 again this morning and high of 45???

 

[TractorNH]

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.

I've never had issues with it and I store it in my shed where it goes anywhere from 95 degrees in summer to below zero in winter. I just shake it up before I mix it and no problems. I don't usually noticing effects on plants until 4-5 days after application but it depends on how fast the plants are growing as Ford850 said.

 

[WranglerX]

Usually need 7-10 day to show signs of kill ( don't believe 24 hour burn down statement on container) .... But you will notice a slight color tinge change in 3-4 days....

I am using year old 41% and it is fine.....

Dale

 

[CMV]

Thanks. Maybe I'm just impatient. Not a big roundup user, but thought the large areas we killed off to plant last year got dead pretty quick. Maybe just the type of vegetation there or being warmer/drier time of year.

But good to know - cheaper to get a bigger jug this year, but was afraid if storing over winter ruined it would be wasteful.

 

[thekkfan]

Yup. Usually can get the 41% in 2.5G for $40.

 

[fishheadbob]

It doesn't go bad, but it takes 10 to 14 days to really show die down.

 

[RalphVa]

Best and safest way to use it is to cut and paint the stump with concentrate.

I've never had concentrate go bad. Mix will get stringy stuff in it, which you can fish out to not plug your sprayer.

Ralph

 

[3gunr]

I've had some stored for years with no issues, even after it started to separate and get clumps of gel in it. The biggest thing that affects it is how well the plants absorb the spray ( I always use a surfactant now) and how fast the plants are growing. If not growing aggressively it takes a long time to affect plants, if at all. That's why some instructions say to mow the area and then spray a week or so later, since mowing encourages new growth.

what do you use as a surfactant