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Old 09-01-2013, 11:01 PM
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What is this???

Hoo, boy - just had to throw out a Catt with black rot and now this on one of my phals. (See the big black spot at the top of the torn leaf in the top middle of pic. Looks gross, almost like a gunshot wound!!) I don't think it's black rot as I had sequestered that Catt quickly and this looks very different. It's on an older leaf, happened VERY suddenly and is wet. I punched my finger right through it. Do any of you Geeksters know what it might be? How I may treat it? Should I sequester it immediately? I would hate to lose it. It's the pretty yellow flowering one that's my profile pic!
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Old 09-02-2013, 12:47 AM
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"Hoo boy" is right: it has not been your month, has it?

It may be bacterial brown spot (Acidovorax; = Pseudomonas). Like the black rot, cut out the affected tissue with a sterile blade. If you have a bactericide (like Physan), treat the remainder of the infected plant, and adjacent plants, too.

I have read that Ca and Mg supplements tend to help plants resist diseases, and I notice fewer problems now that my plants receive regular Ca and Mg. I've posted before, I use gypsum and Epsom salts, but Cal-mag or similar supplements are fine too.

Excess water and humidity help fungal and bacterial infections, hurt your plants. Try not to water from above if you can. I use a small pump sprayer to get water to the medium under the leaves, avoiding water on the leaves. Increase air circulation if possible.
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Old 09-02-2013, 01:02 AM
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Thanks, Catt. Getting the Cal-Mag, STAT, now. How do you water with a pump sprayer, though?? I like to drench them when I water. Doesn't a sprayer just mist? I had thought of getting something like a gas container (the kind you fill your mower up with) so I could drench, but direct the water directly to the medium. I've been using milk cartons which are a bit unwieldy to get into the racks where my orchids are, hence, watering from above, out of necessity. I do have 2 windows in the room wide open, so I thought they were getting enough air.
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Old 09-02-2013, 02:00 AM
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If you have the pump sprayer "wide open" in terms of spray volume, you can get quite a bit of water to flow into and through the medium. I always spray enough to get flow-through. Just don't over-pressurize the sprayer or you could blow small plants and media out of the pots!

A note on water quality and leaching - I had forgotten you are up in Illinois. Your water is probably harder, has more TDS than mine. The good side: you may already have good Ca and Mg in your water (ask the local water company for their test results; it is publicly-available, free information). The bad side: you may need to run a lot more water through your pots to battle mineral build-up. Not sure how many plants you have but it may be more practical to take them to the sink to water - in which case you can use the sink sprayer (on low pressure) to get water on the medium and not the leaves. I mostly use collected and saved rain water, and when using tap water is needed, my tap water is really good. Even running small volumes of water in and out of my pots is sufficient to keep mineral build-up from happening.
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Old 09-02-2013, 09:34 AM
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Oh no! you had to throw out your cattleya? It didn't stop when you cut the area? Cut generously to make sure you get it all, good luck!!
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Old 09-02-2013, 11:53 AM
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Quote:
Originally Posted by Catt Mandu View Post
If you have the pump sprayer "wide open" in terms of spray volume, you can get quite a bit of water to flow into and through the medium. I always spray enough to get flow-through. Just don't over-pressurize the sprayer or you could blow small plants and media out of the pots!
Catt, yeah, it's really getting annoying trying to water these guys on 4 shelves with a milk carton. I'm such a "re-use, recycle" nut (and a cheapskate to boot!) that I have been avoiding getting something more useful. Will check into these pump sprayers.

Quote:
Originally Posted by Catt Mandu View Post
A note on water quality and leaching - I had forgotten you are up in Illinois. Your water is probably harder, has more TDS than mine. The good side: you may already have good Ca and Mg in your water (ask the local water company for their test results; it is publicly-available, free information). The bad side: you may need to run a lot more water through your pots to battle mineral build-up. Not sure how many plants you have but it may be more practical to take them to the sink to water - in which case you can use the sink sprayer (on low pressure) to get water on the medium and not the leaves. I mostly use collected and saved rain water, and when using tap water is needed, my tap water is really good. Even running small volumes of water in and out of my pots is sufficient to keep mineral build-up from happening.
I actually had forgotten about our super mineralized water, too! I'll bet there is cal-mag in this water. If anything, I probably need to acidify the water. I think minerals raise the Ph?? Not sure. I need to check the Ph of this water because I believe orchids like a slightly acid Ph. Anyway, we get our water from Chicago and the report really only lists contaminants. The mineral data is probably out there somewhere. Catt, I've been meaning to get rain barrels and just haven't. What I think I'll start doing, though, is flushing with distilled water - to remove the mineral salt buildup.

Anyway, thanks again, Catt, for the very detailed response and good advice. I always appreciate it!
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Old 09-02-2013, 12:07 PM
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Oh no! you had to throw out your cattleya? It didn't stop when you cut the area? Cut generously to make sure you get it all, good luck!!
Love Phals - yes, I had to dispose. I cut as deeply as possible, but the black spread. This Cattleya was not in good shape to begin with. Got it bareroot in June with terribly shriveled pbulbs, but two new leads. You can see in the first pic it already showed the black rot on the base of that new pbulb when I potted, but I had no idea what it was. When I cut off the shriveled pbulbs and repotted a few weeks ago, became concerned about that black base - and black was spreading. I cut and snipped and it just kept spreading. So - she is now in Catt heaven! The weird thing is that it was watered and splashing all my other orchids on the shelves around and below for several weeks and NONE of my other orchids got it! That Phal is way on the other side of the room, so I don't think it's the same thing. Strange, huh??
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Old 09-02-2013, 01:06 PM
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I hope this will be the end of the infections.
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