Oh, that's just terrible. Sorry I can't offer any advice -- I would do exactly what you said, try so root some leaves (if they are limp, I'd soak them in water first, I guess). Hopefully after you clean off any dead tissue, at some point new growth will resprout from the center.

Was the petrocosmea the only one that suffered? I'm assuming you used the recommended concentration of neem, and I never had any plants even get spots from that. But I don't think I've ever sprayed petrocosmeas with neem. Sorry to hear about your disaster -- but also thanks for taking the time to post about it, so that others will be more careful with pets and neem.

Alenka, thank you for the condolences. I'm pretty devastated. Yes, I used the recommended concentration. The petrocosmea was the only plant that suffered, as far as I can tell. My Nematanthus tessmannii dropped two of its three calyxes, but it had never bloomed before, so it may just have been having pre-partum jitters.

I've been told that petrocosmea are particularly sensitive to Neem oil. The first few times I sprayed, I took all the pets off the shelves and sprayed. But I have forgotten on occasion and accidentally sprayed them lightly. They weren't affected at all.

Streps and AVs aren't affected at all. When I remember and have time, I spray with Neem oil three times in the fall about two weeks apart. It takes care of the thrips that I may have brought in from the garden.

Achimenes is sensitive to Neem oil. I sprayed it - and now the plants are wilting,

Irina

And the fern too - the leaves turn rusty

I'm so sorry. I recently see one of those plants in person. Pictures just don't do them justice. I imagine they are very slow growers with so many leaves. Did you try and rinse it off and dry the crown, maybe new growth will come back. I hope so. I am glad you shared this info, I didn't know you couldn't use neem on some plants. I have a friend who uses those clorox disinfecting wipes on plants to remove the mildew. tish

Thank you to everyone for your comments. I thought I would post an update for any poor soul who makes the same mistake I did. The inner circles of leaves are slowly plumping up and becoming green again. I have hopes that eventually most, if not all, of the younger leaves at least will return to normal. So all is not lost, but it's not an experiment I would want to repeat.