Dendrobium kingianum with some curling leaves and some whitish
 

I have a 25-year-old Australian Dendrobium kingianum which is now quite big (see photo). Some of the leaves are curling up lengthwise into skinny little rolls. Others are discolored to whitish. Photos of both types of leaves attached.

I found a few mealybugs and sprayed with soapy water as well as manually cleaned each leaf. But it doesn't seem like the mealybugs are related to the other 2 problems--most of the curled or discolored leaves didn't have any mealybugs.

Any ideas? It's starting to get warm and drier here in N. Calif., perhaps it needs more water? or could the mealybugs be in the roots, causing symptoms in the leaves? or is it another pest or disease I can't see?

Also it hasn't been repotted in quite a while--should I repot and split it? any tips for that? and what is the right timing if I do? you can see in the photo that it's just starting to bloom now.

Thank you in advance! this was a gift from my now-deceased grandfather so it's my most prized orchid.

It looks severely dehydrated to me. I am not expert, but I notice the curling of leaves on my kingianum when I withhold water for too long. The canes also seem far too skinny and wrinkly for such a large plant.

That looks like spider mite damage to me. Look at the under side of the leaves with a good magnifying glass or just take a white paper towel moisten it a little and wipe the under side of a few leaves...look at the paper towel, if it looks a little red it is probably mites. That is really a nice sized Den, good luck...Jean

how to cure spider mites?
 

Thank you!

Since I have just scrubbed all the leaves with soapy water, I can't find any spider mites. I will wait a few days and then do the paper towel suggestion. If I find them, then what?

Also if you have repotting advice I'd love it. To split or not to split? wait for it to bloom out or act now to clean roots of pests ASAP?

Ahh, Jean is probably right about the spider mite damage, but it still looks dehydrated to me. =\

I'd wait to repot. These are called the easiest orchids by many, so I would wait to repot until new growth starts if you wish to repot. I would try to keep it as one plant because large plants look and smell amazing.

skinny canes
 

Thank you! I will give it a lot more water right now. I recently read in another thread that they need 2-3x/week in spring/summer--far less than I've been giving. Do you agree with this frequency?
I agree the canes seem skinny and wrinkly. Many of them have no leaves--should I cut those out?
Any thoughts about repotting? should I do it now or wait? When I do, should I split it or just go for a bigger pot? What medium do they prefer? the last time I repotted was years ago and I think I used soil because that's what it was in originally--seems like it should be in bark, do you agree?

I am not familiar with people growing this one in soil, but if that is what it is in, then that could also be contributing to its decline. I have mine in fine bark and it seems to do alright. The watering frequency seems quite normal for a plant outside in bark, but you said you have it in soil. If they actually do well in soil, then I would assume that they need watering less frequently because the soil would not dry out quite as quickly.

outdoors?
 

Thanks for the further thoughts, makes sense to me. I will try fine bark when I get to repotting it after its bloom and leaf recovery.
Did I infer correctly that these can be outside? Mine has always been indoors. I had it outside today for the soap treatment, was thinking of leaving it out overnight since it's so warm in SF tonight. Good idea or no?

I leave mine outside year round here in the bay area. In the winter, I move it to a more protected area and that's it. It doesn't get covered or anything, just out of the rain, in a corner near the house to protect against the elements a little.

You don't get to enjoy the scent quite as much outside and I have had squirrels eat through pseudobulbs before, so there are risks involved.

I have never grown this species but definitely looks like dehydration.

If plant is in Soil, is it possible roots have rotted, and it cant even make use of water?