Prosthechea cochleata black spots on leaves

[MJG]

This is Prosthechea cochleata, formerly Encyclia cochleata. It's developed some black circles on the upper parts of the leaves. At first it was just a couple of leaves. Now it's starting to show up on more and more leaves.

The circles aren't indented or mushy. It's tested negative for CyMV and ORSV. Any idea what this could be? What should I do about it?

Thanks.

[estación seca]

When a bug takes a bite the tissue surrounding may die. That is likely what's happening here.

[MJG]

Originally Posted by estación seca

When a bug takes a bite the tissue surrounding may die. That is likely what's happening here.

I don't think it's bugs. This and all of my other orchids are grown indoors year-round. I've seen no signs of bugs on anything.

The reason I'm worried about this is because of what is going on with my Onc. Twinkle. It developed a bad fungus several years ago. All of its leaves are covered in spots. I finally learned what it was from this Board. I tried sprayed it with copper fungicide multiple times. I tried another fungicide. It has not improved and new growths all exhibit the same symptoms. I read today that when a fungus sets in like that you really can't cure it. My source said that the fungicide just helps control spread. I this correct?

I decided today that I am going to have to dispose of the Twinkle.

The reason for this long story is that I am afraid that the cochleata might have contracted the same fungus, or at least a fungus. I would hate to part with the cochleata. I am looking for some perspective on this all.

[Roberta]

A systemic fungicide perhaps? Others are more familiar with specific products since I fortunately haven't had the need.

[estación seca]

A systemic fungicide will eliminate a fungus if the fungus is susceptible to it.

[MJG]

Originally Posted by estación seca

A systemic fungicide will eliminate a fungus if the fungus is susceptible to it.

Do you have any product recommendations? Thanks

[katsucats]

I've been having spots like that on a few of my orchids as well. It's not a virus. It's either fungal or bacterial. I usually just cut them off when I find them. I have a bottle of thiomyl, which I think works for leaf spots, but I haven't tried it.

[estación seca]

You need to know which fungus it is. Not all fungicides are effective against all fungi. Perhaps take a piece to your local agricultural extension office, or a university agriculture or microbiology department.

[SouthPark]

Originally Posted by MJG

The reason I'm worried about this is because of what is going on with my Onc. Twinkle.

MJG ------ Twinkles, and I think Sharry Babys are known to (and people don't even worry about it) have some kind of leaf markings that just develop like that - either heriditary or some non-life-threatening fungus). My Twinkles gets some spots too like that. If they don't spread through-out the whole leaf and whole plant, then no need to worry about it. This kind of thing is really seen by a lot of growers.

If the growing area has some gentle air movement - which yours does I think - then that should be ok.

If there appears to be significant spreading, then I agree with Roberta ----- could just apply some systematic fungicide.

Also - some patches on orchids can be due to not a disease or fungus ...... but due to some deficiency in elements or something. So every once in a while - eg. once a month, some weak mag-cal will help some orchids stop black coloured patching due to mag or cal deficiency. But maybe you use mag-cal already.

[MJG]

Originally Posted by SouthPark

MJG ------ Twinkles, and I think Sharry Babys are known to (and people don't even worry about it) have some kind of leaf markings that just develop like that - either heriditary or some non-life-threatening fungus). My Twinkles gets some spots too like that. If they don't spread through-out the whole leaf and whole plant, then no need to worry about it. This kind of thing is really seen by a lot of growers.

If the growing area has some gentle air movement - which yours does I think - then that should be ok.

If there appears to be significant spreading, then I agree with Roberta ----- could just apply some systematic fungicide.

Also - some patches on orchids can be due to not a disease or fungus ...... but due to some deficiency in elements or something. So every once in a while - eg. once a month, some weak mag-cal will help some orchids stop black coloured patching due to mag or cal deficiency. But maybe you use mag-cal already.

I do have some other Oncidiums and am familiar with the normal leaf spots. My Twinkle has a problem that goes way beyond that. Here's a picture of the Twinkle. (You have to click on the picture to see how bad it is.) It's really sick and I'm not sure anything will safe it. A systemic would be the last resort.





I showed the cochleata at the top of this thread. I'm worried (not sure though) it's getting what the Twinkle has. You mention Cal-Mag, and I've been wondering whether I need to use that or not. I use MSU fertilizer, which has calcium and magnesium in it. I always assumed that was enough. Would a person need to supplement more than what's in a calcium/magnesium-containing fertilizer?

Thanks for all of your help.