# Roundup weed killer question **URL:** \ **Category:** Factual Questions\ **Created:** [August 20, 2014, 4:44am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972 "2014-08-20T04:44:08Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![GreenElf](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@GreenElf](https://boards.straightdope.com/u/GreenElf)\ **Post date:** [August 20, 2014, 4:44am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/1 "2014-08-20T04:44:08Z")
To use Roundup, I pour it, along with some water, into a large plastic container with an attached pump spray mechanism. It has worked very well for over a year, but the last time I used it, it wouldn’t spray, so I unscrewed the pump-cover and looked inside. What I saw attached to the the end of the intake pipe was something that looks like soggy toilet paper. I know it’s not really toilet paper, so it’s some kind of fungal, amoeba-type growth. Has anyone had this happen? I’m having trouble removing it from the intake pipe, and don’t want to spend $15 on another container. ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [August 20, 2014, 5:17am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/2 "2014-08-20T05:17:17Z")
I just bought the small spray bottle, squirted it on the weeds direct from the bottle it came in. Worked great. ---
**Author:** ![PorchePine](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@PorchePine](https://boards.straightdope.com/u/PorchePine)\ **Post date:** [August 20, 2014, 5:50am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/3 "2014-08-20T05:50:54Z")
> [@Tim\_R.Mortiss](#): > > I just bought the small spray bottle, squirted it on the weeds direct from the bottle it came in. Worked great. Buying the concentrate is much cheaper. A bottle of concentrate that makes five gallons is about the same price as your little spray bottle… ---
**Author:** ![PorchePine](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@PorchePine](https://boards.straightdope.com/u/PorchePine)\ **Post date:** [August 20, 2014, 5:52am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/4 "2014-08-20T05:52:51Z")
> [@GreenElf](#): > > To use Roundup, I pour it, along with some water, into a large plastic container with an attached pump spray mechanism. It has worked very well for over a year, but the last time I used it, it wouldn’t spray, so I unscrewed the pump-cover and looked inside. What I saw attached to the the end of the intake pipe was something that looks like soggy toilet paper. I know it’s not really toilet paper, so it’s some kind of fungal, amoeba-type growth. Has anyone had this happen? I’m having trouble removing it from the intake pipe, and don’t want to spend $15 on another container. Do you rinse out your sprayer after each use (and run water through the hose and spray nozzle)? I’ve only had problems with clogging when I let things sit around for a while. Try washing it with soap and water. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [August 20, 2014, 5:55am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/5 "2014-08-20T05:55:39Z")
A solution of water and bleach should clear any mold or fungus from your pump sprayer. Let it sit for 30 minutes, pump it up, and spray onto the sidewalk or driveway. That should clean it all out. ---
**Author:** ![HipGnosis](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@HipGnosis](https://boards.straightdope.com/u/HipGnosis)\ **Post date:** [August 20, 2014, 4:12pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/6 "2014-08-20T16:12:13Z")
Go to [roundup.com](http://roundup.com) The site has a ‘Chat with a specialist’ button. Ask them. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [August 20, 2014, 4:17pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/7 "2014-08-20T16:17:28Z")
bleach may be bad for rubber parts. look up sprayer instructions. after use you should rinse out reservoir a few times with water, dumping it where you don’t mind killing plants. then fill and rinse out pimp and hose a few times. dump out. let dry before closing up again. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [August 20, 2014, 4:48pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/8 "2014-08-20T16:48:37Z")
Are you sure it’s alive, or is it just the concentrate settling out and crystalizing? I’ve had experience with that, particularly after a cold winter. Shake vigorously. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [August 20, 2014, 5:02pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/9 "2014-08-20T17:02:41Z")
> [@PorchePine](#): > > Do you rinse out your sprayer after each use (and run water through the hose and spray nozzle)? . We’ve used the same pump sprayer for years,but rinse and dry after each use. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [August 20, 2014, 8:23pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/10 "2014-08-20T20:23:12Z")
You don’t clean your equipment after using? Please don’t tell me you own firearms. ---
**Author:** ![SmellMyWort](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@SmellMyWort](https://boards.straightdope.com/u/SmellMyWort)\ **Post date:** [August 20, 2014, 8:49pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/11 "2014-08-20T20:49:54Z")
> [@Omar\_Little](#): > > You don’t clean your equipment after using? > > Please don’t tell me you own firearms. Not if I intend to store the mixed up Round-up in the sprayer for future use. That doesn’t seem all that odd to me. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [August 20, 2014, 9:00pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/12 "2014-08-20T21:00:15Z")
> [@SmellMyWort](#): > > Not if I intend to store the mixed up Round-up in the sprayer for future use. That doesn’t seem all that odd to me. It should say on the sprayer or in the directions “don’t store stuff in here, rinse and dry after every use.” ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [August 20, 2014, 9:15pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/13 "2014-08-20T21:15:01Z")
> [@SmellMyWort](#): > > Not if I intend to store the mixed up Round-up in the sprayer for future use. That doesn’t seem all that odd to me. If you still have bullets or shells in your firearm, do you store it that way too? ---
**Author:** ![SmellMyWort](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@SmellMyWort](https://boards.straightdope.com/u/SmellMyWort)\ **Post date:** [August 20, 2014, 9:35pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/14 "2014-08-20T21:35:50Z")
> [@ZipperJJ](#): > > It should say on the sprayer or in the directions “don’t store stuff in here, rinse and dry after every use.” Maybe it does, I’m not sure. If it did, then yeah, the OP shouldn’t have kept it in there. But when you buy a spray bottle of pre-mixed Round-up is there an expectation that the sprayer will get moldy and clog up after a while? I don’t think it takes some big stretch of the imagination to consider that someone might mix up a big batch and just figure they will store what they don’t use in the sprayer for next time. ---
**Author:** ![SmellMyWort](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@SmellMyWort](https://boards.straightdope.com/u/SmellMyWort)\ **Post date:** [August 20, 2014, 9:39pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/15 "2014-08-20T21:39:22Z")
> [@Omar\_Little](#): > > If you still have bullets or shells in your firearm, do you store it that way too? Your gun analogy is weird and dumb. ---
**Author:** ![Mallard](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@Mallard](https://boards.straightdope.com/u/Mallard)\ **Post date:** [August 20, 2014, 9:42pm UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/16 "2014-08-20T21:42:47Z")
I used to apply the Roundup to my weedy area with a sprayer too, but it kept clogging unless it was constantly cleaned. I spent a few bucks on a watering can and simply mixed the water/roundup in that an poured it on the weeds. Works just fine. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [August 21, 2014, 12:02am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/17 "2014-08-21T00:02:18Z")
> [@johnpost](#): > > bleach may be bad for rubber parts. look up sprayer instructions. > > after use you should rinse out reservoir a few times with water, dumping it where you don’t mind killing plants. then fill and rinse out pimp and hose a few times. dump out. let dry before closing up again. this. It gunks up sprayers if you don’t clean them. And the patent has expired on the product so you can buy a 5 gallon jug of the chemical much cheaper at farm stores. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [August 21, 2014, 2:56am UTC](https://boards.straightdope.com/t/roundup-weed-killer-question/695972/18 "2014-08-21T02:56:22Z")
Storing unused weed killer in the sprayer seems like a normal thing to do to me. Then it’s ready when you want to kill some more weeds. I don’t have Roundup, but I just checked my Weed B Gone sprayer, and it gives directions for storage in the container. Basically, close the container and don’t let it freeze.