yellow spots on a friend’s Phragmipedium Cardinale (?) leaves

[BrucherT]

Second problem post of the day!

my friend sent these photos from her greenhouse. After4 years, her Phragmipedium at last rewarded her with abundant, ongoing flowers from a plant that had grown lushly in a tray of water but never bloomed. I think it’s P. Cardinale.

Now, she’s seeing these leaf spots. My guess is mineral issue but I don’t know.

Thoughts and suggestions please? Greenhouse grower. Uses well water but it’s very pure. Infrequent feeding.

 

[CarlG]

What's underneath the yellow spots?

 

[BrucherT]

Sorry, do you mean the leaf underside?

 

[CarlG]

Yes. Often something chewing on the bottom of the leaf is reflected in yellow spots on the top.

 

[NYEric]

scale?

 

[BrucherT]

Yes. Often something chewing on the bottom of the leaf is reflected in yellow spots on the top.

Ok thank you, let me try to find out.

 

[Greg Barnes]

What fertiliser and dosage is she using?

 

[tamwi66]

It appears to be scale.

 

[BrucherT]

scale?

She couldn’t find any scale anywhere on it.

 

[BrucherT]

It appears to be scale.

She’s telling me no but she cut off all the marred leaves.

 

[BrucherT]

What fertiliser and dosage is she using?

Well water (shockingly very pure/low mineral) and very occasional dilute Jacks.

 

[BrucherT]

Ok thank you, let me try to find out.

She couldn’t find anything chewing underneath. She cut the marred leaves off.

 

[awesomei]

I have dozens of phrags.. I find this same sort of thing on many of my phrags. It never seems to kill the plants. But, it does look nasty. I think that it is a bacterial or fungal problem. So, I treat it as such with; excision of the affected tissue and peroxide, bensole peroxide, fungicides or a combination of both. I have found Ridomil Gold to be very effective. I am experimenting with cinnamon green leaf extract. Dragons blood seems to help a lot also.
George

 

[richgarrison]

ditto on the cutting, but also second the 'starving the plant' thing in terms of nutrients and pure water leaching the small amount of nutrients available.. at least with the parts of the leaves excised, she can track progression...

 

[Hardwood]

I would repot the orchid and give it more water. The leaf tips should not be dying.
It could also be hungry. The new leave look small. Dust the cut surfaces of the leaves with cinnamon or bordeux mix.