Okay, if nobody here knows, can someone point me towards a resource for diagnosing problems with these kinds of plants? Thanks

Well, you might want to check out root rot - I'm new to Hoyas, but being that the leaves are so far apart, and turning yellow, I think it's been getting too much water. (remedy with re-potting into dry mixture rich in perlite, then water with peroxide solution - 2 1/2tbsp. per gal. water - until it runs out of the pot). Are ther drainage holes in the pot it's planted in? Just a guess, but that's all I can think it would be - you might want to do a search on root rot,over watering,too much light, and maybe mealy bugs on this site if that doesn't work. - I've found this site to be most educating!!!

Yellowing/dropping leaves usually indicates overwatering, so I agree with FC in that regard. But the weird pattern on the leaves might be some kind of pest. Can you describe to us how it's being grown? Direct sun? Filtered sun? Outside or inside? What exposure? Is the potting mix supplemented with anything, or just straight potting mix? When was the last time it was repotted? As FC suggested, does it have a drainage hole? How often is it watered - when it gets dry or on a schedule? (My mom does the on-a-schedule type watering - she can grow some Hoyas, but she kills others...)

A little more detail and maybe we can figure it out.

Denise in Omaha

Thanks guys for your responses. I know some of the answers to your questions, but not all of them. I will call my dad tonight and ask him. Yes, the pot has drainage holes. It is being grown inside in a sunny window. Part of the day it gets direct sun, part of the day filtered sun.

"What exposure?"

By this do you mean which direction is the sun coming from? Let's see, it is a box window, so the smaller pane of glass faces south and the larger pane faces west. I suspect he is not overwatering, since the only leaves that have fallen off have gradually deteriorated from that pattern beforehand, and he's been taken care of this plant for years and hasn't (that I know of) changed his watering habits.

I should also mention that the pattern on the leaves is indented, it is not just a discoloration. So I thought it might be a pest too, but I don't know much about this type of plant.

Again, thanks so much for your help, and I will get back to you with more details.

I suppose he's been growing it in the same place for a long time, but south and west is pretty strong sun for a Hoya, especially this time of year. Now, it's been my experience that obovata is pretty tough (like kerrii) but even those two will get yellow leaves with that much sun. The markings could be sunburn, but the leaves yellowing usually isn't terminal, and if it was too much sun, all the leaves closest to the glass would be turning yellow. My next guess would be water & roots. In a box window, it's out there where it's not getting the air circulation you're getting in an average room (in other words, the air kind of gets "stuck" in there...) This can mean the pot is overheating, which means the roots are getting hot, which is hard on them. It also means it dries out faster and if they get too dry, it's then hard for the roots to pull up the water. If it's been in the same pot for many years, this exacerbates the problem because the soil is old.

If it were my Hoya, I would probably start by moving it outside, under a tree where it will get maybe only morning sun, but will be in bright shade the rest of the day. The fresh air will do it lots of good, and if the problem is too much sun and heat, this should resolve the problem. Also, if there IS a leaf pest problem, the natural preditors will take care of them. I have an australis out on my back deck right now because it's a thick plant that has some mealies that I'm having trouble getting to - the ladybugs and spiders should resolve the problem by summer's end...

If it's been a long time since it's been repotted, I would probably also try to get it repotted into a bigger pot with fresh soil by summer's end. And if you feel that there's a chance that the plant is getting worse and not better, take cuttings to start a new one. I would probably go ahead and take some cuttings anyway. If all goes well, you can always either trade them or stick them back in with the main plant after they've rooted.

Denise in Omaha

Thank you very much Denise. I'm having lunch with him today, so I'll get more info. These sure are beautiful plants.

Okay, I asked him all those questions and he is quite sure he is neither overwatering it nor is it getting too much sun. He said he re-potted it about a year ago, couldn't remember off the top of his head what was in the mix. It has been in the same place for several years and this is a fairly recent problem. And ONLY the leaves with that marked pattern have yellowed. So with all the controls accounted for, it would seem to be a problem beyond light, location and water. He said he thinks it is a pest that is actually burrowed in the leaf. Do you know of any it could be?

I'd say a pest is probably the problem, but it's one beyond the scope of what I've encountered in my quarter century of growing. Hope someone else can be of more help.

Denise in Omaha

One of the plants I received from Hawaii has a similar problem (only mine have circular holes). I believe it is a fungus, perhaps something like Anthracnose.

Flea beetles can cause similar damage, but I don't see any signs of insects.

I'm actually debating whether or not I should destroy the plant... I don't want my other hoyas getting infected.

I posted you quest for info on the 'pest management forum'. Hope someone will come and help you out:-)

Fingers crossed!
Diane

Here is a link that might be useful: the link to where I posted.

Thank you very much canttype, and everyone else for your help. I'll check the pest forum for responses. My dad is going to go to the local botanical garden and see if they have any ideas. They have a large hoya collection. He also mentioned he couldn't find any systemic insecticide at the nurseries around here, only sprays. He hasn't checked the net yet, but I'm sure he'd find it there. Thanks again everybody who offered ideas, I so appreciate the advice I get from these forums. :)

It looks like a pest problem to me. I grow hoyas outside , which means that mine are continuously subjected to varying conditions - good and bad. Just keeping up with aphids this time of year is exhausting.

I had a good look at my obovata. It shows a couple of leaves with similar pattern. I don't know for absolute certain , but it looks like some type of leaf miner to me.
Determining which pest can be difficult, because there are hundreds of flies , beetles and moths which mine leaves at their larval stage. Leaf damage can show patterns that are long and winding, blotches or galls. The 'mines'can be an entryway for fungus or bacteria , eventually causing a leaf to turn yellow and then fall off.
A systemic pesticide like Orthene will work, but I wouldn't recommend this in a case like this , because usually with a houseplant, we discover the 'evidence' too late. This part of the life cycle is quick. The larvae have pupated and 'left' !! So the plant gets 'toxified' for no reason. Many nurseries, esp. the Big Box stores are 'trigger happy' and they'll give you plenty of advice on how to solve problems with dozens of products. Remember , they're in the business to send people to the cash register with a smile and an opened wallet !

I am very biased in favour of Denise's ideas. Put the plant outside. Let it get fresh air and all the natural elements,( not fire ! ).
I see very little leaf miner damage on anything in my yard, because I strive to create an environment where I rely on natural predators like birds , spiders and parasitic wasps.

I would nurture some new cuttings and find a suitable place outside , where the plant can 'enjoy' the summer.

Florajilly

This is Ksha's dad. It should be noted that there are two cuttings of H. obovata growing in the pot. They have both done well during the two and a half years or so since I obtained them as rooted cuttings. Done well that is until this last spring when I first noticed the leaf problem.
The two cuttings are winding around one another and therefore share the same conditions of light, water and humidity, plus being in the same pot. Only one of the plants is having the problem. The other seems unaffected or at least much less seriously affected. The struggling plant not only experiences the leaf problem on once healthy leaves like the ones in my daughter's photos, but when it attempts to put on new leaves they grow to be about half size then become dark and flacid and soon drop off.
I am still wondering what is going on.

I think you should check the roots of the plant in question. It could be that the one plant is doing OK and the roots are getting all they need, but the other one has hardened or dried out roots, or even root mealies. You may have to just uproot the one plant, take cuttings from it and start over. Try not to disturb the roots of the other healthy plant too much.
Marcy

My Hoya is featuring the same characteristics as in the photos posted above. Does anyone know what is actually causing this, and what I can do about saving my plant?
Kristine

Kristine,
If your hoya has the same characteristics as the one in the photo, I'd recommend reading this thread for the possible causes, since that's exactly what this thread is about! (plus, there are many possible causes listed)

Good luck,
Gabi

Thanks for your reply Gabi! I did read over this thread. I was hoping that someone might have a more concrete reason for me as to why this yellowing and brown burrowing is occuring. I am going to give some of the solutions a try to see if any of them work, but I thought I might get lucky and find that someone knows exactly what is causing this. I am bumbed, because I just purchased the plant about 4 mos. ago. It is young, and I hate to have to take cuts and start over so soon!
Kristine