Help identify some leaves problems - Orchid Board

drosera · #1 12-11-2011, 06:43 PM

Hello, I need your help!

Does anyone have an idea what disease is?
1 to 4 are Cattleya percivaliana and Vanda hybrid with brown sunken spots, but not watery.
5 and 6 are a strange patching in underside leaves of Vanda suavis and some Cattleya, although don't have relief.

Thanks in advance!
Arnau

drosera · #2 12-20-2011, 05:16 PM

Hello! Nobody can help me?
Thanks

Olivia · #3 12-20-2011, 05:45 PM

Sorry no one has been able to help. I'm not really an expert with pests and diseases but there are some basic things which could help others diagnose what's going on.

1) How long have the plants been in your collection and did they already have the leaf problems or develop them shortly thereafter?

2) Have you observed any type of insect?

3) Has there been any spread since your last post?

The fist four photos look to me like it could be mechanical bruising or some kind of bug. I have no idea whats going on in the last two photos.

Bud · #4 12-20-2011, 06:03 PM

Cold water on leaves particularly in winter, can cause black spotting - new leaves that sprout in spring will have no spots. Some black leaf tips are sign of build up in mineral salts from fertilizer. Flush the roots with water so the crystal deposits are washed away. It can be trimmed off so as not to look unsightly.
Not all marks on orchid leaves are a sign of disease...some are sun scorch that will remain in the leaf until it is shed off.
but check with a magnifying glass if you can find any crawling tiny insects on any part of the leaf...
as for the vanda: that is also one of my oldest concern...its like a banana with black spots...its caused by cold water and the sun burning through the water drop...if it doesnt have direct contact with the sun then it is just the cold water the plant is reacting to...I just water in the sink with tepid warm water and let it dry by the oscillating electric fan

drosera · #5 12-20-2011, 06:26 PM

HELLO Olivia, thank you for your reply.

I have these plants for about 2 years, and I observed the disease for the first time 1 month ago. I put the plants in quarantine and it seems that the disease has spread, and since I have not seen insects on these plants, I think they are not the cause. However I have a few plants in my collection with mealybugs.
I'm not sure, but the Cattleya seems to have a virus because the injuries are becoming more elongated. The last 2 pictures are really mysterious...

silken · #6 12-20-2011, 06:31 PM

Sorry, I really can't say I have seen exactly the problem you have. But if you are sure there are no insects (using a magnifying glass) then I would use an anti-fungal spray. it seems odd that a number of your plants would all become spotted recently if it is virus as it seems too coincidental, so I am thinking more a bacterial thing. Hopefully someone else will chime in as I have not dealt with a lot of bacterial issues to date.

drosera · #7 12-20-2011, 06:59 PM

Hello Bud, thank you very much too.
I have a rain system that maybe worked in a too cold temps... I hope it all. Anyway, I moved the plants to a warmer place and the disease seems to have progressed. Is it normal?

---------- Post added at 11:59 PM ---------- Previous post was at 11:44 PM ----------

Hello Silken,
I used Alliete a couple of weeks ago, but I don't see any improvment. I just hope it is not a virus!
Thanks a lot!

silken · #8 12-20-2011, 07:12 PM

Maybe a repeat treatment should be done. I don't know what Alliete is but am assuming its an anti-fungal? Good luck with it.

#9 12-20-2011, 07:44 PM

I can second Bud on vandas, those black spots are from sun. I noticed them appearing on one side of my vanda, the side that is facing the window with midday sun. The side that is facing the room is free of those spots. I don't think they affect the plant much though.

Merlyn · #10 12-20-2011, 10:54 PM

I will give you this = virus CANNOT be diagnosed by sight !!! The ONLY way to tell if you have a virus is by a virus test, either send a piece away to a lab that does testing or buy some home tests !!!!! I have been involved for 3 years testing and disposing of 30 gallon garbage cans full of virused orchids and less than 1% LOOKED sickly !!!! And ones we tested that DID look sickly tested negative !!!! So stop passing ignorant gossip like suggestions around about viruses ! THE BOTTOM LINE IS, YOU CAN'T TELL BY LOOKING !!!!!