Posted 1w ago by @WanderingValk

Grey residue on hibiscus leaves..??
Does anyone know what this silvery/grey residue on solely the underside of this #hibiscus leaves could be? Leaves are healthy, then this stuff pops up on the back, then they start yellowing until they look like the final picture and they fall off.

I thought #spidermites, but there’s zero webs and I don’t see any pests anywhere. I’ve treated with peroxide, a sulfur based spray for mites and fungus, and even dunked it in the bathtub for an hour as a cure to drown the potential spider mites. Including daily cold water showerings to knock off any mites. The leaves are still getting this residue and falling. Anyone have any idea what this could be?? I’m at my wits end…
9” pot with drainage
Last watered 4 days ago
So, question, how cold/warm is it in the room you are keeping the hibiscus in?? And is it near a draft??
@Localplantlady so I’m in a desert area of Colorado without ac. So now that it’s summer the day there’s lots of fans going, not on the plant, and it’s super hot in the room. And at night since it’s the desert it gets much cooler. It’s not in a consistent temperature right now unfortunately. Probably 80’s during the day and 60/70’s at night.
@WanderingValk hmm… well, I was thinking if they are physical spots, it could be leaf fungus, if it’s powdery like mold, it could be Botrytis Blight.

I don’t think it’s spider mites because you would definitely see them plus, you shower it. Also, leaves start drooping randomly even if the plant is perfectly healthy other wise.

If it is Leaf Fungus it is not a bad thing, just cosmetic! Normal causes of Leaf fungus are cool, rainy days and lack of air circulation.

I recommend positioning a fan towards the hibiscus for air circulation! It doesn’t need to be right on the plant, just enough to mimic wind! It’ll encourage the drying of the leaves because they don’t like to be wet for too long. Make sure the soil is constantly moist and not sitting in water! Hibiscus are also heavy feeders to try to fertilize once a week during the growing season!

If it’s Botrytis Blight, that’s a problem. Prune all infect flowers and foliage and burn it with fire 🥲 it will live in compost and effect everything it touches.

Try to keep the foliage dry and and improve air circulation on the plant. If problems persist, use a fungicide.

I hope this helps! 🥺 if anyone else has any idea, please share!

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