Roundup on dormant plant (accident)


#1

I’m spraying a little roundup to kill some early sprouting weeds. After spraying, I realized that the area I sprayed contained two completely dormant perennial hibiscus. The herbaceous kind that dies back to the ground.

Since they don’t have even a smidgen of noticeable above ground growth, do you think I hurt them? My initial reaction is no, since they have no foliage.

Thoughts?

(If you are one of those anti-glyphosate people, just don’t go there. That’s not why am posting this.)


#2

My understanding is that glyphosate only kills growing vegetation that it comes in contact with. No contact with growing vegetation = no plant death.


#3

Probably no harm, unless you dumped what was left in your sprayer right on the plant.
But, depends on dormancy…those are dormant until May most years.


#4

Yeah. Even in warm years, I haven’t seen growth until about 5/1.


#5

Is there a similar but kinder weed killer than roundup? I haven’t checked in on this topic for a number of years, but was just wondering if someone has come up with a newer, safer, better version.

Thx!


#6

I don’t think so (see article below), safest way to kill weeds in a home orchard setting is by using one of those wick based herbicide applicators (example of one here). Looks pretty easy to make yourself honestly - its just a PVC pipe, a valve and a sponge.

Glyphosate, also known by the Monsanto trade name Roundup, is one of the least toxic of the synthetic herbicides available today, a fact that herbicide companies often use to justify its widespread use.

Dicamba is an herbicide that selectively kills broad-leafed weeds (as opposed to grass family plants). It is commonly used in conjunction with other herbicides, such as glyphosate

Dicamba is considered more toxic than glyphosate, but less toxic than 2,4-D, the third most common broadleaf herbicide.

One of the major disadvantages of dicamba compared to glyphosate is that it is much more “volatile,” meaning it easily becomes airborne and drifts away from where it is applied


#7

@BG1977 My personal experience with Roundup & Raspberry plants - My neighbor sprayed it on his side of the fence end of 2018. All my Raspberries on my side were deformed and sick looking and didn’t do well in 2019 BUT they all lived and nothing died. Now in 2020, the raspberries look great!


#8

Regular Roundup has no soil residual activity. There are plenty of products sold with the Roundup label that aren’t straight glyphosate. Now those could have some soil activity.


#9

Glyphosate IS the kinder, gentler weed killer!


#10

I’ve had some accidents with glyphosate. Once I planted about a half acre of sweet corn too soon after spraying a glyphosate burn down and pretty much none of the corn came up.

It helps if you don’t get a lot of rain immediately after spraying, so the glyphosate can have a good chance to bind with the soil (rendering it inactive).

It also helps if your soil is heavily mineralized. Glyphosate is a chelator and readily binds to certain minerals. If your soil is heavy in Ca, Fe, Mg, Mn, you’re going to be better off. If your soil had a lot of sand, that’s bad for rendering glyphosate immobile, and potentially bad for hibiscus.

All that said, your probably fine. I’ve sprayed glyphosate right over the tops of buried peach seed, and they come up fine.

If you’re really worried and it hasn’t rained yet, you can scrape the top 1/2" of topsoil from around your hibiscus plants. That would remove any chance of the glyphosate moving down and being absorbed by the roots. But like I said, I doubt your hibiscus will be harmed if they are fully dormant.


#11

Well, we got 0.5” of rain about six hours later. Soil does have high Ca.


#12

My guess is you’re still fine, since the hibiscus are still a good time away from coming up.

I would be interested in the results. If you remember to, please post back the results and tag me @Olpea if you think about it.


#13

I’ve never seen Glyphosate kill anything that wasn’t actively growing.


#14

I have never had a problem with it killing anything either as long as i didnt get it on the leaves.