Hoya Problem

Hello,

I'm trying to help out a fellow DG member who is also fond of hoyas, but she is not a registered member of DG. The bottom picture attached is her Hoya australis and this is the message she has sent me:

I received it from the supplier with some spots on leaves as you can see on the photos.
It appears on more leaves now, seems like it's spreading.
Spots on leaves look like washed-out. They quickly appear on the edges of the leaves and become more yellow. I took some cuttings from this pant and potted.
It looks like new grows get similar spots on leafs.

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I cannot pin point out the exact illness of her plant: not sure if this is overwatering or too much sun. I did remember that one of my hoya plants had similar yellow specks too...just wondering if this is from a deficiency of some sort...

Any suggestions?

Eliz

Could it be a fungus?

My first thought was chlorosis but the more I look at the photo, I agree with ThreeG that it might be a fungal infection of some sort. I'd spray the plant with a fungicide for houseplants to see if it improves.

Here's some info I found about troubleshooting plant problems: http://www.thegardenhelper.com/troubleshooting.html

This looks like it could be edema to me, but it is hard to tell without a closer look. Are the spots sunken at all or whitish on the surface? My second suspicion based on the pattern and color is potassium deficiency. Neither of these is harmful and you should be able to get the cutting to root. Edema is typically caused by excess uptake of water for whatever reason- often a sudden change in environment or weather. Potassium deficiency is rather common in many plants and tends to be small circular dots of yellow or black with yellow halo dots throughout the leaf. You want to correct it of course, and as soon the cutting roots I would begin regular light feeding.

The reason I don't suspect fungus in this case is there is no irrregular shape to the affected area or orange to brown or black discoloration or necrosis. You could carefully wipe down the leaves with a light alcohol solution just to be sure.

I have the same problem with H. crassipes.It has those yellow dots on just about all the leaves. This leaf is very bad. Lots of yellow. I have to un-wind the plant and see if I can find new leaves without the yellow, so I can take cuttings.

Imadigger, are the backs of the leaves pitted too? Insect bites?

I, too, have the same problem with two of mine! Would love to know what it is! With mine there is no pitting and I'm pretty sure no insect bites.

Hi Carol. Yes, let's not rule out pests!

KK- can you get a picture of yours, too? Anyone willing to mail some leaves to me to submit to a pathologist?

On the leaf back, there are some little black spots. The spots are also on healty leaves. The plant was treated with BATS back in Nov. A few new leaves are OK and others are starting with the yellow spots. There are other hoya close to it, and they are not showing any yellow spots.
Lynnae, I've sent you two leaves. They will go out in tomorrow's mail. Hopefully someone can figure what's happening.
Eileen

I would hit it with an all purpose fungicide...like Daconil. Just in case.

I've got the same thing on a few of mine too...almost looks like it's caused by something I have been misting them with?

Joni

Carol, now that you mention fungicide, you may have 'hit the nail on the head'. I never thought it might be a fungus problem. Years ago my friend gave me a large yucca plant. I ended up getting rid of it because the lower leaves always ended up with black spots on them. I had it in the house and at the time I was afraid it had some disease. I didn't want to lose any of my plants, so it got tossed. I have a fungicide and will spray it and see what happens. First I'll find a good section to see if I can root it. Thanks.

Eileen, I get fungus on my plants sometimes too ... guess with all the moisture/humidity here in Florida it's a given that at some point our plants get fungal infections. I use a product called Garden Safe Fungicide ... seems to work well.

By the way, how did your area fare with those severe storms yesterday afternoon? I was watching the news and saw there were a couple of tornado's in your county! I never got our lawn mowed yesterday because of all the rain ... can't complain though, we sure need it. I got all the mowing, edging and trimming done today and repotted a few plants. It's getting real cloudy out now, sky looks nasty in the west ... I better get a shower before it hits! There were tornado watches and warnings just north of us earlier but I didn't think we were supposed to get bad weather today. We can use more rain!

Lin, all we got was a light rainfall. It seems that we are in a 'vortex'. I tell my kids that whenever there are warnings of tornados or severe thunderstorms. LOL. It seems to happen all around us. There is a small 'bridge' over a culvert, about four blocks north of us that seems to be the 'rain stopping spot'. There are days when we pray for rain, and we get in car and drive around the neighborhood, and it's all around us except for a few block radius. We call it 'our vortex'. My kids didn't belive it , until they were here visiting and saw with their own eyes.

Make sure it is a good fungicide. Garden Safe products often simply 'coat' the fungus so it kills off the spores. Cinnamon in alchol works for some of the fungi. Daconil is a broad spectrum and gets Cercosphora which is pretty common.

The very circular black spots on yucca is likely one of the "shotgun" fungi, this species being Coniothyrium concentricum. It is specific to yucca and I am not aware of it's occurence on any other plant. Also, I believe in most cases, esp. in landscape, it isn't prescribed as being worth treating since it is species specific and it doesn't kill the yucca.

I agree that all purpose fungicide isn't going to hurt, but I am not yet convinced this is fungal, especially the symptoms in the first photo. I would keep a watch for the formation of spores- some pathogenic fungal spores are visible and some are not.

Hi guys,

Sorry it took a while to catch up to this thread, thought it would be much simpler solving this kind of stuff..

So main suspects could be:

1. Fungus
2. Chlorosis
3. Edema
4. Potassium deficiency

It looks like she's been keeping her hoya in water to root, so would it be safe to say that the cutting should be taken out of the water to cure and take out edema from the list? While also at the same time, would it be safe to apply fungicide on a cutting to rule out/take out the fungal infection if the cutting did have it?

Then if none of the treatment works, can she treat it for potassium deficiency?

Eliz

I would certainly spray with a fungicide, put it in a good media to root and continue to spray 1/2 strength fertilizer as it roots. If it has been sitting in city water...it could be a reaction to the chemicals in the water? I think so. City water is not good for tropicals.

I completely agree with Carol. In fact- you are so on to something about the city water! I forgot about that. Furthermore, the kind of chlorosis spotting cause by excess chlorine looks exactly like potassium deficiency becuase of the 2 ions that regulate the opening and closing of the stomae. Same symptom, different cause.......

Iamdigger- I got your sample today. The symptoms in your plant and evr's look a little different- maybe some sort of mesophyll disruption. Will let you know!

Imadigger, sorry I've had your results sitting here, but have been really swamped last few weeks. Your nutritient levels in the leaves are telling- they are very low in nitrogen and potassium, 2 of the 3 macronutrients (the ones that are always given on a fertilizer formulation.) Your secondary nutrients and micronutrients were average, so you may want to evaluate the fertilizer you are using. There was Gleosporium present in your sample, but the pathologist felt that the levels were low and not the primary problem.

f4f Interesting . Thanks for that.

Hi Carol. Hope you are having a Happy Sunday! :-)

I'm sorry it took so long to get back to you. Thanks for the information. My children were visiting from NY until Monday and I haven't been on line too much. I'm glad it's not a disease. It's a nice size plant. Thanks again.

YES...my Sunday was exquisite: I was in SF, staying with Mark and Sunday we had killer chilaquiles at a tiny rest. and then walked all over ... it was wonderful!!!

Carol

:-) My weekends have been very busy as well. Packed with good stuff! It's summertime..........