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My new vineyard (planted 2 months ago) has experienced some herbicide drift two weeks ago from a neighboring soybeans field, causing immature and new leaves to cup, finger around the edges and not properly develop into decent leaves. Symptoms seem more consistent with 2,4-D or Dicamba than Glyphosate.

It seems to have been light enough to not kill the growing tips, as the shoots are still rising toward the wire at a good clip. They simply aren't getting decent new leaves on the upper portion of the shoots, so all their energy is having to come from the pre-existing mature leaves down below. I'm hopeful that the vines can overcome this.

My question is whether or not this dooms the use of the primary shoots I'm training to be trunks. Would a light herbicide damage of this nature cause long-term health deterioration or loss of fruitfulness though a trunk whose tissue was formed during this time? The only clear impact I can see now is leaves. The stem itself seems fine. So assuming these shoots reach pencil-size by the fall and are looking good enough for trunk selection in the spring, should I go ahead and keep them at that time? Or should I assume that they have been forever compromised and cut them down next spring and try for new trunk growth next year?

Update Aug 9 - 4 weeks after the herbicide drift event, normal-looking leaf production appears to have resumed. The event caused abnormal (and useless to the plant) leaf formation for a month along several feet of the shoots that will be my trunks, but now that they've reached and passed the top wire and I've pinched off their growing tips, the new bushy laterals the tops are sending out look normal. It must have been a very light herbicide event to have recovered so quickly. I still have a question about whether this permanently lowers the fruitfulness of trunk formed at this time. There's nothing visually to suggest it has.

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Your grapes will recover.

You can check with neighbors as to what they used, probably Roundup, and ask if they'd avoid windy days for spraying.

Roundup (glyphosate) is a non-selective herbicide that, despite court cases, works and dissipates quickly with no more residue than pouring boiling water with vinegar would leave.

Maybe two weeks and completely untraceable.

It's classic for the rampant GMO soybean because that's the unique crop that is unaffected by Roundup despite its otherwise non-selective quality. What makes it the least harmful herbicide is the very fact that it does not select which plants to kill ... other than just about everything you spray it on.

EPA scientists evaluated available data for glyphosate and found:

No risks of concern to human health from current uses of glyphosate. Glyphosate products used according to label directions do not result in risks to children or adults.

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  • I fully expect the vines to recover. While glyphosate is the most likely candidate since the farmers use it in great quantities around here, I can't discount 2,4-D either. I plan to talk to the farmer in question to find out exactly what it was. But my question isn't about eventual recovery, but whether or not this event compromises the stems such that I should re-establish new trunks next year vs. keep the trunks I'm growing now. This is a very narrowly tailored question for grape growers specifically.
    – Paul W
    Jul 21, 2023 at 14:16
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    In my understanding, all new growth, all trunks, and all roots do not retain any harm from the temporary damage. But you are the grape grower and I am not yet. Jul 21, 2023 at 14:47

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