Looks like sun burn to me. You could move it to a shadier location and the leaves will green back up, but you probably won't get as many blooms.

gold_angel just posted this on another thread:

Macgillivrayi - Keep moist, no direct sunlight, Sheltered, semi shaded position, in warm humid conditions, or in cooler conditions in a greenhouse or patio requires a cylindricial wire frame, keep dryer during winter, don't overfeed, slow release fertilizer is adequate, best grown in 30 degree temps no lower than 17 degrees (protect from cold) Single monsoon area. Moderate light, grow dryish in winter.

Was it this same one? Good job resurrecting it and getting it to bloom so many times since then. Too bad Doug isn't still around, bet he would know what to do. Good luck!

http://forums.gardenweb.com/discussions/3292419/is-my-macgillvrayii-cuting-dead

Where did Doug go? He takes some of the best pics/vids I've seen online of Hoyas. (Sorry for going OT.)

I agree with tawnygrisette. Looks like sunburn to me.

all the direct sun it gets is no more than 10am. if that much. The 'Archboldlandia' I have right next to it, gets more direct sunlight than the 'Mac', and it is totally green, it grows more ,but blooms less, with MORE direct sun on it.

At this time of year, i dont think it is even getting direct light till 9am, if that! I am gone at 830am for work, I am going by past sunlight exposure in that area over the years, it isnt like the house or the sun is moving to different places, at the same time of the year, each year. I have had this one in the same spot for, 4 years or more, and this is the first year it has done this. Nothing has been cut down in that area, so no more sun is hitting the spot it is in.

The only thing I have found out about unusual leaf coloring like this ,is a mineral deficiency, something about adding Epson salt to the water a few times, to add magnesium to the soil??. I think it was that. Anyone heard of using those salts to the soil to improve leaf color? Or does everyone think sunburn? **** IF this Doug guy is Doug Chamerlian, I have contacted him,to see what he thinks.

"Kim'...this is not the cutting I got that did die. It is long gone. I have had this plant for 4-5 years, this is why I need to get another 'Mac' , because this one started to do this...and I want another in-case it dies.

I would use seaweed fertilizer for mineral deficiency instead of Epsom salt if it was mine.

Not sunburn...my fungii does this, mostly just the older leaves. I tried Epsom salts, and it helped but didn't cure it. I think it's going to take a repotting, and that's going to be a major undertaking, so I'll put up with it until it gets worse...

Denise in Omaha

I use some stuff called Tappin Roots, mixed at 1/4 strength in a foliar spray, has helped with yellow leaves on the past, and my plants seem to enjoy it. Sort of fits Jan's suggestion, it is made out of kelp and willow extracts.

Perhaps it's iron chlorosis?

The most obvious symptom of iron deficiency in plants is commonly called leaf chlorosis. This is where the leaves of the plant turn yellow, but the veins of the leaves stay green. Typically, leaf chlorosis will start at the tips of new growth in the plant and will eventually work its way to older leaves on the plant as the deficiency gets worse. Other signs can include poor growth and leaf loss, but these symptoms will always be coupled with the leaf chlorosis.

Tawny, that certainly matches the description of the leaves in the picture. If it were mine, I would definitely treat for iron deficiency in light of that information.

Doug read my post and saw my pics. and told me what he thinks. I agree with him, but I am going to try to get some iron in the soil as well. It looks like it is missing something in the Fert. dept. Doug warned me off of epsom salts. It killed a lot of hoyas of a friend of his. I cant risk it, i only have this one, and it blooms all the time. It is in bud now, it just finished blooming last week. So this will be like the 7-8th time this year....so until i get a plant or a cutting that roots, of this 'Mac', I cant risk it with the 'salts'

Care to elaborate? Did he mention a specific nute it was missing? Inquiring minds want to know...

Oh sorry.... He said it looks like i have root damage from wither a period of to much water,or a period of it being to dry. But it more than likely wont die, especially since it is blooming all the time, and is not dropping leaves.

This is very possible, considering he way I water my hoyas, I basically water them when I pass by them ....so I could over water, then they are to dry for a few weeks, But they all nd bloom even more! This si the only big problem,and of course it is THE plant I want to keep alive the most!

He didnt mention any nutrition problem, but warned me to not use Epson salts, that it killed many hoyas of a friend of his, so I am staying away from them. I think it is an iron problem to, so i am going to try and find an iron supplement to add to the fert. program. Maybe get it to green up. Something that can be absorbed by the roots. The hunt begins.

Interesting. I wonder what the pH of your soil is, or if you have a phosphorous build up, which could cause nute lockout. The CalMag supplement Jimmy suggested above would totally help with that. Let us know how it goes! I'm fascinated with fertilizer issues, I should have been a botanochemiscist (I made that word up).

Yes, CalMag or Seaweed fertilizer will help for sure.

Well I bought some 'Miracle Gro Fert. for Acid Loving Plants'. Doug suggested that, and I looked up how to cure the chlorosis. It said in every thing i read to raise the PH with an 'acid loving plants' type of fert. It use to be called 'MirAcid'....It was right next to BIG bags of epson salts! to put all over the lawn.

I'm going to give it a few months try, to see if it greens it up. Tried to find 'cheap' seaweed fert/ none to be found online or at Lowes/Home Depot. Online it is expensive even for a tiny amount, the shipping costs are outrageous! And its a powder! And 'chelated iron' is the price of gold! So...going to see if this raises the PH or not. Hope it doesnt kill my 'Mac'....if it does, I will have a big bon-fire!!!

Chelated iron is a compound of iron with an organic acid. Commercially they use a specific acid but from extensive reading years ago I found out that other ones are just as good. It means you can make your own chelated iron by soaking some decomposed compost in a solution of iron salts, such as iron sulphate, which is fairly cheap. Compost contains a lot of humic acid which works well. The difficulty is that unless you can get a chemical analysis done you don't know the exact concentration you're working with. Also a lot of the chelated iron will have been absorbed into the compost solids. But for anyone willing to experiment a bit it's a cheaper alternative to having to mortgage your house to buy some.

What about Sluggo? It is an "organic" slug bait, and basically just chelated iron phosphate. Would that suffice?

Well I am using an acid loving fert. now,. So I am going to try it and see if it unlocks the iron in the soil. Or raises the PH as Doug said it needed. I got my 2 White 'Archboldandias' to root! I see new growth just poking out now, after a few weeks,They have at least 1 new growth on each one. Now I need to find a cuting of the Macgillvrayii to try and root again. I can root hard to root ones, i guess. But now I have to find a 'Mac' to get a cutting from and try again to root it.

So i will have 3 White, or White with red streaks, plants soon. now that the two cuttings I bought are showing new growth,finally! So they must be rooted. Now I just need to find 'Mac' cuttings, to buy one or two and try to root again.

What happened with this?

nothing has happened. I am waiting for the vines to grow and harden up a bit, and get advise on how to air layer them. The vines are getting longer, and i am waiting. I might just wrap the vines in moss, when i see aerial roots, and see if they root into the moss, cut off the vines and start a new plant. I THINK that will work. But i need the vines to get longer and harden off, cant root soft green stems.