# Will Roundup kill my palm tree **URL:** \ **Category:** Factual Questions\ **Created:** [May 18, 2010, 11:50pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947 "2010-05-18T23:50:25Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Darryl\_Lict](https://avatars.discourse-cdn.com/v4/letter/d/7cd45c/32.png) [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)\ **Post date:** [May 18, 2010, 11:50pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/1 "2010-05-18T23:50:25Z")
I’ve got a couple of magnificent palms that look kind of like a Canary Island Date Palm. There are weeds growing in the bark of the trees. Can I spray Roundup on the weeds without killing or otherwise damaging the palm trees? ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [May 19, 2010, 12:30am UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/2 "2010-05-19T00:30:28Z")
Round-up gets absorbed through the leaves of plants and transported to the roots. It quickly breaks down in the soil, so it shouldn’t damage plants that are simply growing near the weeds (as long as you make sure you only spray it on the leaves of the weeds). If the weeds are actually growing in the bark of the palms, though, I wouldn’t risk it. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [May 19, 2010, 3:54am UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/3 "2010-05-19T03:54:40Z")
Roundup is not effective against woody plants. It is not too good against poison ivy, f’rinstance. However, this business of weeds growing _in the bark_ of palms is a bit unusual (to me, anyway). I would try weed killer first (something like Weed B Gon) rather than a defoliant. It’s not urgent so I would use the most benign, low-risk approach first. A lawn & garden shop where you can buy the stuff should be able to advise you. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 19, 2010, 10:54am UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/4 "2010-05-19T10:54:27Z")
> [@Darryl Lict](#): > > Can I spray Roundup on the weeds without killing or otherwise damaging the palm trees? Provided that the bark isn’t broken and the soil isn’t _very_ sandy, you’re safe. > [@CookingWithGas](#): > > Roundup is not effective against woody plants. Palms are not woody plants. Glyphosate will kill them readily. > [@](#): > > However, this business of weeds growing _in the bark_ of palms is a bit unusual (to me, anyway). Not so much the bark as the remains of the leaf bases.[It’s very common in wetter climates.](http://okeechobee.ifas.ufl.edu/images/Boston1.jpg) > [@](#): > > I would try weed killer first (something like Weed B Gon) rather than a defoliant. Glyphosate is a weed killer, not a defoliant. > [@](#): > > It’s not urgent so I would use the most benign, low-risk approach first. Glyphosate vs. a cocktail of Dicamba, MCPA and 2,4-D. I know which one is lowest risk, and it ain’t Weed B Gon. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [May 19, 2010, 12:00pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/5 "2010-05-19T12:00:22Z")
roundup will kill woody plants if applied to leaves, green bark or fresh cuts in the wood. this is dose dependent, a woody plant with a large root will take many applications. roundup doesn’t penetrate hard bark. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 19, 2010, 12:32pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/6 "2010-05-19T12:32:15Z")
> [@johnpost](#): > > roundup will kill woody plants if applied to leaves, green bark or fresh cuts in the wood. It \*might \*kill \*some \*species if applied in that manner. For many more species it will produce abnormalities in growth and little more. The mode of action of glyphosate makes it less than ideal on plants with woody tissue. It’s not the size of the root system per se, it’s the amount of growth going on throughout the plant. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [May 19, 2010, 1:17pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/7 "2010-05-19T13:17:00Z")
> [@johnpost](#): > > roundup will kill woody plants if applied to leaves, green bark or fresh cuts in the wood. this is dose dependent, a woody plant with a large root will take many applications. roundup doesn’t penetrate hard bark. > [@Blake](#): > > It \*might \*kill \*some \*species if applied in that manner. For many more species it will produce abnormalities in growth and little more. The mode of action of glyphosate makes it less than ideal on plants with woody tissue. It’s not the size of the root system per se, it’s the amount of growth going on throughout the plant. the larger the root, the larger the plant, the more growth that needs to be inhibited; also the agent is spread through more tissue. in lower doses it does produce abnormal growth, it will do this on weeds as well. it is much more effective on emerging plants because of its inhibition on new growth, on mature plants it takes longer to affect new growth. ---
**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:** [May 19, 2010, 2:17pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/8 "2010-05-19T14:17:04Z")
It’s unlikely that you will apply Roundup in a high enough volume or concentration to kill a mature palm tree. However, any plant that you describe as “magnificent” deserves better protection than “unlikely.” Try a non-herbicidal approach first. ---
**Author:** ![Wile\_E](https://avatars.discourse-cdn.com/v4/letter/w/c37758/32.png) [@Wile\_E](https://boards.straightdope.com/u/Wile_E)\ **Post date:** [May 19, 2010, 4:33pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/9 "2010-05-19T16:33:39Z")
I had a weed palm growing in a very inconvenient spot. I applied a tree killer to it, a few of the fans fell off but it survived. I had to take a saw and lop off the top and paint it with tree killer twice before it died. IME palms are hard to kill even if you’re trying to kill it but I don’t know how delicate your palms might be, mine was one of our native palms that sprout up everywhere. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 20, 2010, 8:47am UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/10 "2010-05-20T08:47:51Z")
> [@Wile\_E](#): > > I had a weed palm growing in a very inconvenient spot. I applied a tree killer to it, a few of the fans fell off but it survived. I had to take a saw and lop off the top and paint it with tree killer twice before it died. See, there’s your problem. Tree killers are designed to kill broad leafed plants. Palms aren’t broad leafed plants, and are therefore largely unaffected by many aboricides. You would have been better off using glyphosate. ---
**Author:** ![Wile\_E](https://avatars.discourse-cdn.com/v4/letter/w/c37758/32.png) [@Wile\_E](https://boards.straightdope.com/u/Wile_E)\ **Post date:** [May 20, 2010, 4:52pm UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/11 "2010-05-20T16:52:30Z")
> [@Blake](#): > > See, there’s your problem. Tree killers are designed to kill broad leafed plants. Palms aren’t broad leafed plants, and are therefore largely unaffected by many aboricides. You would have been better off using glyphosate. Well, I couldn’t find anything that said it killed palms. I even asked at a nursery, since I also had some Brazilian Peppers that needed to die I figured I would try that stuff out on the palm, too. Like I said I had to cut the palm way back a couple times. I would think you’d need a heck of a lot of roundup to take out a full sized palm. ---
**Author:** ![Darryl\_Lict](https://avatars.discourse-cdn.com/v4/letter/d/7cd45c/32.png) [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)\ **Post date:** [May 21, 2010, 8:31am UTC](https://boards.straightdope.com/t/will-roundup-kill-my-palm-tree/539947/12 "2010-05-21T08:31:39Z")
Thanks for the answers. I’ll try a more benign approach, like pulling out all the damn weeds. Grrr!