Black/Yellow Leaf Tip on Cattleya

[butterfly_muse]

Evening, all!

I noticed this evening that one of my cattleyas has a yellow/black tip on one of its leaves. When I watered them this past Saturday, that was not there, so whatever it is sprung up fast.

I have been running the humidifier by the orchids for the last couple days, and I am wondering if that by chance happened to have something to do with it? (The air has been really dry, but in an effort to raise the humidity I brought our humidifier out to their corner). I have inspected the whole plant and the tip of the leaf is the only part of the plant that is yellow/black. It has very healthy roots and is growing another new growth.

It looks to me as if it's maybe fungal? Should I treat it with fungicide/alcohol, or remove the tip? Is it maybe something else?

Ideas, anyone?

[james mickelso]

Why folks think their orchids need humidity bugs me. They do not need high or even moderate humidity. Moisture at the roots is sufficient. That is a fungal infection. Look it up at staugorchidsociety.org. Cut the part of the leaf off 1 inch below where the yellow starts and dab cinnamon on the cut edge. Reduce your watering as this is sometimes due to too much water at the roots. The media isn't drying quickly enough.

[No-Pro-mwa]

Because I do therefore they do we get very dry and wrinkly in winter in Wyoming. Oh and cracked fingers and static electricity. I really hate to be shocked.

[james mickelso]

I know. But catts don't need as much humidity at their leaves as a lot of folks think. Just keep them well watered and they'll be fine.

[butterfly_muse]

Maybe because every beginner orchid source/book/blog/board/website/etc., mentions the fact that most of the orchids we humans like to have in our homes are native to the tropics and thus to emulate their natural environment require humidity up to and including the use of humidifiers, grouping them to increase respiration, terrariums, greenhouses, misting, humidity trays, blah blah. So the idea of saying, "Hmm, I think I'll leave my tropical plants in my 30% humidity house with the dry hot air blowing on them during the winter time when my skin dries out, cracks, itches and I get insane nosebleeds due to the abnormal dryness" is sort of counter-intuitive.

:P But obviously I'm still a noob since I screwed up, so. I did use the St. Augustine Orchid Society's website (nice PDF they have) to diagnose the fungal thing, I just wanted to be 100% sure before I went and lopped off part of the leaf. Thank you for your help I won't be using the humidifier anymore.

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[Paphman910]

Looks like the leaftip got a bit of a fertilizer burn in combination with it being too dry and possibly a sudden change in light levels could have caused the burnt leaf tip.

Just keep an eye so the black part doesn't progress!

[james mickelso]

Two years ago the fall here in SoCal was abnormally dry. 10% for a few days at a time. But it seemed to go on and on. None of my orchids needed extra humidity and they all flowered just fine. The leaves have stoma and close them up when it gets drier than they are genetically used to. It is correct that many cattleyas come from the tropics but wrong to assume that they always have lots of humidity. There are droughts just like most anywhere else. There are portions of the year that are very dry. It is the roots that we should keep moist enough to keep them nice and vital. Not wet. Not even "moist." Just damp enough to keep them from desiccating. When they are not actively growing their moisture needs are low. I know how dry it gets in many places in the country. In Landers, Ca. where Gublers Orchids has their huge greenhouses it not only gets Hooooottttt, but very dry. And in winter it gets cold. they've been growing orchids there for decades. Theirs do just fine. I'm not saying not to give your orchids the best environment you can, but just understand that it is ok to let them get dry. Cool. Hot. Humid. They are more adaptable than we give them credit for. I'm just sayin.