Answer: Some commonly used weedkiller ingredients such as Glyphosate are nonselective herbicides. This means it will kill desired plants as well as weeds if the spray contacts their foliage. If this was the active ingredient in the product you used (check the label), your dahlias are probably not going to make it. You might try contacting the manufacturer of the product you used to see if they have any suggestions, but I don't think there is anything you can do once the spray has dried. (If you rinse it off with water right away and dilute it thoroughly it may save plants that have been sprayed by accident.) Always read the entire label and follow the directions exactly when using a weed killer product. I am really sorry.
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