Using Weed Killer around Cacti

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tumamoc
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Using Weed Killer around Cacti

Post by tumamoc »

I have a serious weed problem in my graveled yard, which also has several large columnar cacti (saguaros mainly). I want to use some sort of spray-on weed killer. I bought a jug of, but have not yet applied, Ortho Ground Clear, which says it kills weeds for up to one year. A year not having to deal with weeds sounds great. However, I am wondering, does the spray penetrate the soil, and by doing so, would it kill the cacti? A couple of these are 15-20 ft high with arms and presumably pretty far wandering radial roots.

This job is too big to pull out the weeds at this point. Any thoughts or suggestions?
DaveW
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Re: Using Weed Killer around Cacti

Post by DaveW »

Found these, but everything they recommend has now been banned in the EU as being carcinogenic.

https://garden.org/frogs/view/75576/

https://homeguides.sfgate.com/weed-arou ... 36441.html

viewtopic.php?t=1514

One way you could try is lopping off most of the weeds then covering them with a piece of weighted down black polythene or old carpet for a month or so to deprive them of light, but whatever you do the seeds will germinate later.
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TimN
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Re: Using Weed Killer around Cacti

Post by TimN »

I used that exact product and have sprayed near my saguaros without any noticeable impact. I sprayed it directly on a nest of Opuntias and it hardly had an impact. The machete, however.....

Palo Verde trees also don't seem to be sensitive to this chemical. My pickax and shovel, however...

I weed within about 3 feet of the plants and spray everything else. Once you get them beaten back it's easier to maintain with a Hula hoe. I don't spray if I'm expecting rain in the next 5 or so days. And don't spray when it's windy.

I've also sprayed fairly close to Echinocactus grusonii without obvious impact.

On other hand, I think I killed one of my orange trees with this product (does not concern me to any great degree). I definitely killed the stump of another orange tree (on purpose).

Unfortunately I don't have any other cactus to test my theory.
Disclaimer: I'm in sunny Arizona, so any advice I give may not apply in your circumstances.

Tim
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tumamoc
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Re: Using Weed Killer around Cacti

Post by tumamoc »

Thanks for the info. I read up a bit more on Ortho Ground Clear and it seems like some pretty scary stuff. I might just go with regular Roundup.
DaveW
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Re: Using Weed Killer around Cacti

Post by DaveW »

Not sure if the UK has banned Roundup yet, but some of our stores have pulled it from their shelves after the American court case. Often these things get banned for use by amateurs, but professionals dressed in "space suits" are still allowed to use them:-

https://www.bbc.co.uk/news/world-us-canada-45155788

However most things that are harmful to plants or insects are harmful to humans in certain concentrations. Anyway best to wear gloves to keep it off your hands, don't wear short sleeved shirts in order to stop it getting on your arms and wash any splashes off immediately and wash after using it.

https://www.baumhedlundlaw.com/toxic-to ... te-banned/
StanleyRoark
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Re: Using Weed Killer around Cacti

Post by StanleyRoark »

Scoop it out to remove the weeds. However, there are still some seeds left. To prevent more seeds from germinating in the pot, see if you can buy pre-emergence weed killer to prevent seed germination.
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tumamoc
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Re: Using Weed Killer around Cacti

Post by tumamoc »

DaveW wrote: Fri Mar 08, 2019 8:51 pmHowever most things that are harmful to plants or insects are harmful to humans in certain concentrations. Anyway best to wear gloves to keep it off your hands, don't wear short sleeved shirts in order to stop it getting on your arms and wash any splashes off immediately and wash after using it.
That's good advice. I usually find myself regretting to have made safe choices.
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Licespray
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Re: Using Weed Killer around Cacti

Post by Licespray »

We use round up to kill opuntia here. So be careful with that.
Ferocactus best cactus :mrgreen:
DaveW
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Re: Using Weed Killer around Cacti

Post by DaveW »

Bayer has been found guilty a second time over Roundup causing cancer. However so far most cases seem to be from regular and long term use, but be careful not to breath it in or get it on your skin if using it.

https://www.reuters.com/article/us-baye ... SKCN1R82KY
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tumamoc
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Re: Using Weed Killer around Cacti

Post by tumamoc »

Thanks for the tip. I usually just do these things with reckless abandon.
DaveW
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Re: Using Weed Killer around Cacti

Post by DaveW »

Similar in the UK but they are called "strimmers" here, presumably because they use "string" to trim with although it's really something like nylon filament. Their advantage is unlike metal blades you can trim up to hard surfaces without damage. If you are trimming on gravel though or anywhere with loose stones wear goggles and make sure nobody else is within range since you don't want gravel being flicked up into anybody's eyes and damaging them.

https://www.which.co.uk/reviews/grass-t ... &gclsrc=ds

I can agree about good strimmer line. I bought a quality make strimmer but the line they use sticks to itself and so stops feeding from the spool. Looks like I will have to find some better line and rewind the spools, otherwise the strimmer itself works OK.

Obviously in a cactus garden you cannot use a strimmer to cut down weeds near the cacti since the strimmer line will damage cactus tissue too unless it has produced an old bark covered trunk like a tree.
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