Help! Stuff on back of Hoya leaf, good or bad?

I need HELP! Please, pretty please?

(actually I do need help, but my Hoya also needs help and I think y'all could probably help it before you could help me.) ^_^

I got this H. blashernaize (?sp?) in a trade a year ago and had totally forgotten about it. :( I am such a bad plant mom at times! I found it hiding out on the deck behind some other plants, none worse for wear. It got light and apparently enough water from when I spray everything with the hose. It just got lost in the menagerie for awhile and I have no idea what this stuff is covering the back of a few of the leaves. I noticed this patch of gray "stuff" on the back of three or four leaves and I hope it's nothing bad but I have no clue. I can't remember ever seeing anything like this on any plant before. It's almost like the back of the leaves are scabbing over if that makes sense. Is it some sort of scale? Doesn't look like any scale I've seen before. Or, could it be some sort of fungus? Oh, I hope it's nothing serious and that someone can tell me what to do or if it okay to just leave it alone. It only seems to be on the reverse sides of the leaves, the tops look fine. Thanks bunches, for any ideas and suggestions.

I'd start by nipping off the affected leaves. No idea what it is though, but I want to know because I think I remember seeing it on one of mine awhile back. Just nipped off the leaf or leaves and forgot about it.

Christine

Lin,
I have no idea what it is, I have two hoyas that have it and one of them is H. blashernaize. I did noticed that the it stooped putting out new growth, I sprayed it with fungicide but it's still the same. I hope someone knows what is that crust. I was told it was some kind of bug, but I haven't seen any at all.
Lourdes

I did try to clean one leave, but it got worse and I lost it. Should I try again?

edited to add text

This message was edited Jun 1, 2009 5:11 PM

Reading tropicbreeze's post "picture (Hoya, or not a Hoya?)" seams that hers has it too.

Does it look like this?...indented but no entirely thru the leaf?
Front

Back:

I have been told it is sunburn...Ted Green had it on a leaf and said that's what it was. Joni...it is more of a crust than an indentation. I really haven't a clue...but would cut off the leaf/leaves and spray with a fungicide.

BTW - last night we sprayed a hoya with a 16% solution of citric acid and NOTHING happened to the hoya!!! We did a test trial on an Eriostemma and a hoya and no affect!!! Citric acid is one of the weapons of choice against a tiny little frog that has invaded our area...the Coqui...noisy as heck and we zap the ones we can find around the house....

Lourdes...is Texas A&M a Land Grand College? If so, they would have a University Extension Service that could diagnose the problem....

Carol

Thing is mine are indoors there is no way it's sunburn . . .

The H. blashernaize has it in all the leaves so if I cut them all I'll have no plant =(

You are so right Carol, Texas A&M is a Land (Sea and Air) Grand College and I have two sons there, (Now on vacation) But I'll have one of them check it out for me, thank you for the idea !!!!

As soon as I know something I'll let you know.
Lourdes

This is how bad my H. blashernaize is =(

What I did with my Krimson Queen when she had it bad was to nip off the worst leaves and then let her grow again for a year, and then nip off the rest of the affected ones. The newer leaves didn't have it. I never did know what it was, but I suspected it was a bug that had gotten in the house somehow, maybe a whitefly.

Christine

Thanks for the input everyone!

Joni, that looks like fungus on the leaves, at least I've seen stuff on plants before that looks like that, and I thought it was fungus. What my blashernazie has doesn't look at all like that. It's gray in color and the only way I can describe it is it's like a huge scab covering the reverse side of the leaves.

Carol, nope, it's not sunburn. This hoya has never been in direct sun since I got it a year ago. It's under a covered deck, full shade.

Lourdes: That's exactly what mine looks like .. it's just on blashernaezii (still not sure of the correct spelling), no others have it, Thank Goodness! Let me know if you find out what it is. I'm going out to clip the affected foliage right now, if it is something bad I sure don't want it to spread to other plants!

A closer picture:

Lourdes: I forgot to say, my plant looks like it's grown a bit since I saw it last. Since it was hiding and I totally forgot I had this one, I'm not sure how long that gray growth stuff has been on there. I tried scraping it off with my fingernail but figured that probably isn't going to help. I've been googling for images of plant diseases and still haven't come up with anything.

I wouldn't think it would be sunburn if the tops of the leaves aren't damaged unless it could have caught reflection from your pool water?

Seems that I have seen it on one of my plants. I need to go look at my plants closer... 8 (

I have this condition on a couple of Hoyas as well, and it is for sure not sunburn. It seems to happen mostly on plants with leaves like H. blashernaize. For me it generally happens on slow growers and on the oldest leaves. Sometimes the plant will put on a spurt of new growth, which will look totally healthy, but after that growth spurt slows more leaves will become affected. If I had to guess as to cause, I would lean towards physiological - maybe missing a micronutrient or getting too much of another nutrient; maybe it got too wet or too dry at some point. If it is fungal, it never spreads to other plants. I have had these touching other plants for months at a time, and it never spreads. I don't think is is anything to get too worried about.

Doug

Lin,
Thanks for the additional information, I wrote all the "symptoms" to make sure I don't leave anything out. We will call today and see if we can get someone to help. Problem is the school is out for summer they only have the summer classes but hopefully, I'll let you know.

podster,
in my case I'm sure it is not sunburn. And it seams that neither it is for Lin and Doug.

Doug,
you described it perfect that is what happens to mine, the plant will put on a spurt of new growth, which will look totally healthy, but after that growth spurt slows more leaves will become affected.If I'm able to have smeon from the university figure it out, I'll pass the information.

Lourdes

Lourdes...when you call, ask for the Ag. Extension Service. They are attached to the school but like any other state department...someone will probably ask you for a sample and you may have to pay some $$$.

HEY...just thought of something. If someone will send a picture to my email address, carol@bigislandgrowers.com, I will print it out and take it in to our Plant Pathologist on my way to town this morning. Dumb me...don't know why I didn't think of it before!!! Actually, even better, send me some leaves and I will take the leaves in and that will be more effective! Seems the problem(?) is wide enough spread.... Send the leaves to me Priority Mail and I should have them next week to take them in.....

Carol

Cancel that last post until I hear back from Dr. Scott Nelson. He is the chief plant pathologist at the Extension Service here and has a wonderful website...but also welcomes mysteries... So I sent him Lins picture. If he wants samples I will post it here.

carol

PS Lourdes, sorry I didn't do this before but my small bear brain didn't click into gear!!!

Carol

Thank you Carol, don't worry I really appreciate.

I'll call later the Ag. Extension Service and let you know what they say.

If Dr. Nelson needs a leaf, I'll send it to you. Another thing that I noticed is that my leaves have curving, didn't realized until I saw Lin's picture, and it has not put out new growth for a while.
I also have the same spots it in two of the three leaves of the H.juannguoiana that I recently got, but was like that when I received it so I have them together separated from the others.
Thank you and let me know if you need a leaf.
Lourdes

Hmmmm This is interesting. Dr. Scott is out of the office until the 12th. I sent the picture to another researcher who can get to it next week... Is that OK.???

Let's find a commonality here. Of the folks who have it on their hoyas, which hoyas are they? Can you send me a D-mail and tell me where you all got your original plant? plants?

Carol

Just got a reply from Dr. Scott. Wanted a larger photo. Can anyone send me as large as you can get photos to my BIG email of the tops, too?

I have to go to town, but will be bakc..

C

This message was edited Jun 2, 2009 9:02 AM

About to serve lunch, I'll post a big close up pic in a bit and D-mail you the info.
Thank you very much

I called A&M and after bouncing my call all over the place, I got to the diagnosis dept. but it's closed for the day, I'll call back tomorrow. =(

Carol I sent the pics, thank you!

Carol: I sent you an e-mail with a couple of pictures. I hope they are large enough and clearer so you can maybe see this scaly stuff better.

Thanks so much for your help!

Before I am able to send Scot the photos you two ladies sent, he sent me this....

"To me it looks like a slime mold, dried out and partially flaked off the leaves. Slime molds usually are not pathogenic, but reside on the surface of things in wet conditions."

By pathogenic he means that it isn't contagious ... Perhaps spraying the backs of the leaves with alcohol, and putting the plants in an area with more air circulation would help...

In the meantime, I will send him some of the other photos and see what he says...

Thanks...will get to the bottom of this!

Carol

Thank you Carol, I'll apply the alcohol until we know for sure what it is.
I really appreciate you taking the time. And I’ll call tomorrow again Texas A&M University.

It may change, as I sent Scot the photos of the distortions...

Thank you Carol! If it is slime mold, that wouldn't surprise me with all the rain we had for 8 or 9 straight days! Very humid and this hoya was stuck back in a corner behind a bunch of other plants ... very moist conditions out on my deck!

I will try the alcohol and see what happens ... will be interested to hear more about this ugly stuff.

I called the university and left a message; as soon as they call back I'll let you know.

Found the same stuff on the back of obovata leaf today.

I have a question - can you scratch this stuff off with a fingernail or is it actually part of the epidermis of the leaf. I can't really tell from the photos?

KK.


(edited for spelling)

This message was edited Jun 7, 2009 10:34 AM

I'm still waiting for them to call me back. If I don't hear from them by Monday, I call again.
Sorry Lin, I hope those are the only two that have it. =(
In the meantime, I'm cleaning them with alcohol.
Lourdes

I can't without hurting the plant.

Second question then, Lourdes
did the alcohol swab remove any of it?

I didn't see any stuff coming off or any difference after cleaning them with it.
Lourdes

OK,
This LOOKS to me like the kind of age related corkiness you sometime see on the old part of cacti stems. If I have read the earlier posts correctly no-one has seen this on new growth, only on mature leaves. It may be that these particular leaves are just OLD, and the plant hasn't shed them for some reason, possibly because it is growing under cultivated conditions.

For those who have affected plants, could you estimate what percentage of the leaves are marked in this way. If there are only a few, the solution might be as simple as picking them off to encourage new growth.

Here is a photo of one of my Opuntias, showing the discolouration at the base.

Ciao, KK.

I honestly don't think it is age related. My two affected plants are young cuttings, One has all the leaves affected, the other two out of the three leaves. But thank you anyway.
Lourdes

KK:

My H. blashernaezii is a small plant and 5 out of the 12 leaves have this scab on them. The Hoya obovata only has two leaves affected on the entire plant. It seems to be older leaves and looks very much like what is showing on your Opuntia's. I just went out and took a paring knife to one leaf of blashernaezii, scraping the stuff off. It doesn't seem to be very thick and I gouged the leaf a bit. I have wiped the leaves with isopropyl alcohol a few times but the scabs/corkiness is still there, it doesn't come off. It seems very smooth, no bumps or raised area's ... just something like a scab growing and covering the reverse side of some of the leaves. I think these are all old leaves, I've not had any new growth lately on either of the hoya's that I've found this stuff on. Maybe, as with your cactus it is a normal growth. I was just worried that if it completely covered the leaves, they wouldn't be able to breathe. It will be interesting to watch and see what happens with it.

edited to correct spelling.

This message was edited Aug 15, 2010 3:57 PM

In my mind I keep referring to it as a scab, rather than corkiness. I guess I think of cork as having raised areas, but I'm not sure. I don't know a thing about maladies or diseases of plants but have never seen anything like this on plants and am just curious. I'm not real concerned (yet) but will keep watch because I sure wouldn't want it to spread to other plants.

I keep looking at our 150 gal. marine aquarium and this stuff reminds me of the hard coralline (coraline) algae that grows on the rocks and glass in the aquarium. I don't know if there is any sort of hard algae that affects plants, or if so whether it would be harmful. My husband says the coraline algae in the tank is calcium based and not like green or slimy algae that grows in stagnant water.


edited to correct spelling!


This message was edited Jun 7, 2009 11:12 AM

Hi All,
Thanks for the extra information guys. I shall summarise here -

lourdes49 H. blashernaezii - all leaves.
lourdes49 H. juannguoiana - 2 leaves out of 3

plantladylin H. blashernaezii - 5 leaves out of 12
plantladylin H. obovata - 2 old leaves only.

tropicbreeze H. ? - plant in habitat, similarity not confirmable

ceedub H. 'Krimson Queen' a few old leaves, removed; apparently "cured"

Hoya_24 "species like H. blashernaezii" - old leaves only; apparently NOT spreading to other plants

I think I have got it all together. If you have any other information to add, DMail me and I will edit this post as needed.

For my part, I think it would be wise for plantladylin to remove the 2 affected leaves from the H. obovata. The plant seems mature enough that it won't miss them. If you want to keep them for later testing you can put them in a paper bag in your fridge crisper - they should keep for quite a while.

The species in the biggest trouble appears to be H. blashernaezii. Would it be possible to ask around and see who else has this species, and if so, do they have symptoms? I am wondering if all specimens of this plant in cultivation can be traced back to one source collection - if so the original plant may have been genetically weak or unhealthy in some way, and this is the result. (By the way, my spell checker hates "blashernaezii"! - actually, to be fair it hates most plant names, I have little red underlines all over this post!)

Well that's all I have to contribute, except for one stray thought - would it be worth emailing David Liddle and asking him if he has seen this on wild plants, and what he thinks about it?

Ciao, KK.

My H. blashernaezii came in a trade from someone here on DG a year ago. I don't think she is a subscriber anymore, haven't seen her post in a long time so I don't know where she got the original plant, whether in trade or a purchase.

Earlier today I put this Peperomia plant out in the rain because it was quite dry. Just now as I was returning it to it's place on the porch I noticed the undersides of a couple of leaves have a similar scabby, scaly growth, only dark brown in color. I've had this plant for @ 10 years but I don't know which are new leaves and which are old leaves!

The plants affected don't seem to be suffering in any sense, no yellowing leaves, distorted growth, dying stems etc. I'm wondering if it is just something happening to the plants as they age ... Maybe they are just getting it from me, I'm getting a little scalier and crustier as I get older! ^_^