I think I effed up

I often spot-treat with roundup and carefully avoid my desirable plants. Yet this year, a lot of stuff seems to have drift damage. I think I ruined my peas, and the potatoes are yellowing a bit, too.

Peas in particular are consistent with google photos of herbicide damage. Potato damage is very slight but also looks like what I saw online.

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A few years ago I explained to my wife that we could safely apply roundup to the bishop’s weed (snow on the mountain) that was invading the space where a low-growing evergreen shrub had become nicely established. All we had to do was to carefully spray our gloved hands with roundup and then wipe the weed’s leaves.

I was wrong.


I hate weeds. They get so ridiculously out of hand to where you cannot get them out in some cases without hurting another plant, even manually.


I just wanna know if I’m totally screwed or there’s a chance that at least some of them will recover.

Tomorrow will tell, but I think you’ve got at least a chance of survival on at least some of them.

As I understand it, the nightshades are particularly susceptible, so that does not auger well for the spuds, but yours look pretty healthy from here. Some of the peas look better than others. I guess you just have to hope and wait. It’s a real kick in the seat, I know. Good luck to you.


I just need to come up with a better weed solution. I used a straw mulch around the peas, and then the damn straw started sprouting.

Maybe I need to look more into pre-emergents.

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Well, the potatoes don’t look too bad, but there are a couple plants that are about two weeks behind the others, and they are a bit darker green. They weren’t really up yet when I had sprayed Roundup.

The one in the picture, if you look near the bottom a couple of the inner leaves have some yellowing near the middle. That’s a classic sign.

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Some of them will make it unless they got a direct dose(rather than drift).

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For the potatoes, I also wonder if latent freeze damage may actually be the culprit.

Freeze is more like blackening on the tips and edges of leaves


Prowl H2O labeled for all peas pre. Potatoes also.

Yeah. I may have to plunk down the moolah for it.

But how do I use it, isn’t it a a pre-emergent? Since peas are direct-seeded. I find that half the weeds I deal with come up before the damn peas usually germinate.

About half the affected peas are now pushing green growth again.


Came across this…

Glyphosate (Roundup)

Glyphosate is the active ingredient in Roundup and numerous other products. Different formulations of Roundup and other products utilize different surfactants and additives, but in every case glyphosate is the active ingredient. Glyphosate kills plants by binding to an enzyme called EPSP synthase. When bound to EPSP synthase, the enzyme cannot function and the plant cannot produce three critical amino acids. Plant death ensues.

Glyphosate has a high Koc value (24,000 mL/g) and therefore rapidly and tightly adsorbed to soil particles and organic matter. As described above, turbid water with soil and sediment will greatly reduce herbicidal activity.

Hard water also affects glyphosate. Ca, Mg, Fe, or Na can form a complex with the glyphosate molecule so that it is unable to bind to EPSP synthase. If glyphosate cannot bind to the enzyme, it will not provide control.

Adding ammonium sulfate (AMS) to the spray tank overcomes adverse effects of hard water. The ammonium cation preferentially attaches to the glyphosate molecule and thus prevents Ca, Mg, Fe, or Na from doing so. When ammonium is attached, the molecule binds readily to EPSP synthase and the herbicide functions normally.

Some plants contain high levels of Ca in their intracellular spaces. Just like hard water in a spray tank, high Ca levels between plant cells can reduce Roundup effectiveness. AMS in the spray tank also alleviates physiologically-induced Ca interference.

Adding AMS (assuming water is not hard) only improves effectiveness against plants that have elevated Ca levels described above. Velvetleaf ( Abutilon theophrasti ) and quackgrass (Agropyron repens) are the most notable plants where adding AMS (even when water quality is perfect) enhances control with glyphosate.

Interesting. Does it imply that you could help protect non-target species by spraying them with somewhat dirty water prior to spraying glyphosate nearby? Or am I reaching too far?

That’s a stretch, are you willing to subject wanted plants to roundup with a dirty water protect? Not me.

After you plant your peas, before they germ, cover spray the soil and water in. 1.5 oz./1000ft sq.
Apply with 1 gal. of water, no surfactant. And as always, read and follow the label directions.:grin:

Hey just wanted to follow up on this how did they end up doing???


An interesting side note is that rhubarb is immune to roundup. Two years in a row I sprayed a plant that was on a bad spot, it did not wilt a single leaf.

Pretty well, actually. They recovered and bore good crops.

Well that’s good to hear. I recently did the exact same thing and mine are showing very similar symptoms. Although I am doubtful that they’ll recover… Rookie roundup sprayer and was definitely going too slow while spraying so more drifted than I thought was. Time will tell. Thanks for replying!