My Orchids got SPOTS!!

[Tanya]

Thanks for "Peaches and Cream" thread, Louis. It prompted me to post these photos of my "spotted" orchids.

Pic one. is Den amethystoglossum. Spots are not spreading so I'm not really worried.

Pic two. Phal hybrid. The spot started last Jan. I cut out the spot when it was still small, but then it progresses. I didn't bother to cut again and now its spreading.

Pic three. Phal hybrid (White Cloud). I think this is going to be OK, its not progressing, but I wonder if its caused by too much fertilizer.

Next page.......

[Tanya]

I'm not sure if could I cram all the pics in one post so, here are the rests...

Pic four. Another Phal (NOID). Now this one is scary. The yellow spots weren't there yesterday. I am thinking sun burn, but the other Phals next to it doesn't show any sign of burns. Please tell me its only sunburn (the plant will recover) not that dreadful "yellow plague" (the plant will surely die !!!).

The next pic is the underside of the leaves, its really more yellow than it appears in the pic. I need help specially for this plant. Help please.

Diagnoses, tips, comments, welcome. Thanks.

[RSJ]

Tanya,

Don't know about the dend, but the phal ones look to me like:

#2 fungal spot.
#3 Looks like old sun or heat burn to me. I think fertilizer burn always affects the tips where it builds up, not isolated on the side of the leaf like that, doesn't it?
#4 Looks like overheating to me. I have a phal that experienced the yellowing like that. The yellow areas eventually collapsed and caused dry spots and the leaf grew old and dropped off.

I could be wrong, I'm in no way an expert, but the only one that freaks me out upon first look is the #2 that is growing in the center of the leaf. I'd cut out the whole leaf if it was mine.

What is the dreaded "yellow plague" you referred to? Specific to phals?

RSJ

[Tanya]

RSJ, thanks for the suggestions. The "yellow plague" I referred to is the sudden yellowing of the Phal leaves. It seems to happen overnight and spread very quickly. No amount of fugicide or cinnamon can stop it. No one seems to know what it is, it killed few of my Phals in the past and I think one of the members, Liza, if I'm not mistaken also experienced it.

I am still more worried of #4 than #2.

[LJA]

Pic 1 are those fungal lesions, same as in my pic 1.

But 2, 3, and 4 look like sunburn to me, with a secondary fungal infection setting in. I say that because our shadecloth out here got a hole in it from hail damage, and a ray of direct sun came in and burned the out of some Phals. and a Cattleya. Localised burn looks just like that, an irregular lesion in the center of the leaf, which then can get infected and start spreading. It's almost as if someone took a magnifing glass over just one area of the leaf, since too much light in general would have yellowed the entire plant.

Tanya, I don't know where you're growing these, but I would check for holes or gaps in your shadecloth if you're growing them outside, places where direct sun can come in as it tracks across the sky, possibly while you're not home to see it. Each of those dots in #4's leaf look like too much light just in that spot, getting ready to burn.

RSJ, you're right. Fertilizer burn on leaves occurs at their tips, not randomly at the center.

[LJA]

Here's a pic of one of my burned Phals, front and back. Most of the burned area just died away, leaving a transparent skeleton of leaf veins. I used Captan powder on my fingertip and rubbed it all around the area. This happened two years ago, when that leaf was the newest one at the top, and the spot hasn't spread. Just a permanent blister.

[Tanya]

Thanks you both for the diagnosis. I feel much better now that #4 don't got the plague.

Louis, #4 is growing with the other Phals on a window sill.http://www.rv-orchidworks.com/orchid...ead.php?t=2348. In winter, no direct sunlight, but come late spring and summer and that window get the full force of the afternoon sun. I use a double layer of sheer curtain to filter the afternoon sun. But there are times that I neglect to pull down the curtain before going to work, especially when its raining. Weather here is sometime crazy. Raining now, and then suddenly it stop and out comes the sun in full force.

Anyway, I feel relieved that the plant got sunburn, not the "yellow plague". At least now it got a chance to survive. It is now in one of the bedroom window, one that get early morning sun for only few minutes, its also cooler.

The spreading of the yellow in #2 seems to have slowed down. And the dark spot had sunk and appears to be drying. So you maybe right about it being sunburn, although I couldn't think of any reason how did this happen because the dark spot started last January.

[OrchidTraci]

Here's a pic of one of my burned Phals, front and back. Most of the burned area just died away, leaving a transparent skeleton of leaf veins. I used Captan powder on my fingertip and rubbed it all around the area. This happened two years ago, when that leaf was the newest one at the top, and the spot hasn't spread. Just a permanent blister.

Many of the orchids I put out now have lovedly blisters. The shadecloth came off of my mini greenhouses. I promptly went out and bought velcro to hold it more securely until I can sew it.