They may struggle along for awhile, but I can't offer you much hope one way or the other. RU is supposed not to leach underground or to cause damage that way, acts on foliage, but just some mist can cause damage. But there is some controversy about soil affectation. Maybe you turned the cardboard around and had the RU side against the iris or the bottom of it got wet. I thought about using that idea myself but realized that it wasn't fail safe.

It wasn't RU, but careless use of 24D and Weed 'n Feed in my lawn got on a nice, strong, vigorous, huge oriental-type lily, damaged some other plants, too. It still grows and blooms, but every year now it comes back with the same leaves near the bottom turning brown. They aren't as bad this year, so maybe it will eventually work itself out. Who knows? It's very curious that it's a bulb plant, haven't treated around it since, and still the same part of it turns brown. I'm sure that's the reason, and it could be it worked down through the plant and affected the part of the bulb that determines growth of that particular part of the plant.

Not sure what I would do. You could dig out the damaged ones and throw them away or replant in a scrap area to watch them. The ones that weren't affected will have room to fill out the empty space if their rhizomes are pointing the right way. Maybe it doesn't matter; these iris have a mind of their own.

Sorry about your mishap.

Good luck. I don't blame you for using the RU, but I was painting some on weeds, and it is one tedious job. Except for grass, you might want to try hand sprinkling sparingly Weed 'n Feed (granular) around your beds instead, then deal with the grasses separately.

I can offer a ray of hope if it wasn't too much. Mist from my neighbor's RU drifted onto my forsythia. it was damaged but now about three years later shows no sign of damage.

Thanks, that is somewhat hopeful info. I'll try the separating of the damage parts and see what happens next year. B.