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What to do and when to worry?

This is a discussion on What to do and when to worry? within the General Orchid Culture forums, part of the Orchid Culture category; In my short life I have learned that sometimes imperfections on leaves happen without there ...

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  1. #1
    dahlia_guy is offline Member
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    Default What to do and when to worry?

    In my short life I have learned that sometimes imperfections on leaves happen without there being a problem. Some of my orchids get blackened tips on a few leaves or tiny black dots on a leaf or two. My question is, how does you tell the difference between the "normal" spots on leaves due to sunburn, or whatever and an infection or disease? Some of my orchids get blackened tips on a few leaves or tiny black dots on a leaf or two.

    I don't like to use sprays, etc... but how many of you regualry spray your orchids with a fungicide, algicide, or similar product as a preventative measure?

  2. #2
    LJA's Avatar
    LJA
    LJA is offline OrchidTalk Tech Admin
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    dahlia_guy, that's a really good question. Oncidiinae are typically the worst for having brown spots. A haze of them, all tiny, will pepper the ends of the leaves, especially if the plant is given enough light to bloom well and profusely. The ends of the leaves will also turn slightly yellow. There's not a whole lot you can do about that, so most people have just learned to live with it, and to cut off the ends of the leaves into a V-shape when they become an eyesore. If you grow those under dimmer conditions, you might avoid the spotting somewhat, but the blooms won't be anywhere near as fantastic.

    As far as leaf tips turning brown, that's usually caused by an over-application of fertilizer. If you haven't fertilized in a while and then do so suddenly, the salts in the fertilizer will literally rush to the ends of the leaves and burn them. So the key to avoiding that is to fertilize more often, at a weaker strength. (That's a tough one for a lot of folks to follow; we can't help but think that "just a little more" fertilizer will make the plant grow bigger / stronger / healthier, but that just isn't the case.)

    Brown spots on leaves that indicate infection or disease are usually a lot larger, and they usually spread pretty quickly. The centers of those spots can get wet, mushy, and runny (indicating, more often than not, a bacterial infection), and, if left unchecked, such an infection spreading to the center of the plant can very easily kill it.

    Nobody I know of "likes" to apply poison of any kind to their plants, so many home growers usually wait until there's a problem before doing any kind of spraying. We were the same way. But ever since we went commercial, we just can't afford to allow a problem to occur because invariably, putting a stop to a bacterial or fungal infection that's run rampant often involves cutting away the problem areas. It doesn't look so bad on Oncidiinae, but do that to a Phal and the plant will end up looking marred and disfigured. So we now use pesticides and fungicides on a regular basis as preventative measures. That's still not a guarantee that nothing will come up; we still get the occasional spot of fungus, (and I don't know any grower who doesn't) but we're pretty vigilant, so it happens infrequently. A regular spraying schedule (every three months or so) is something you might try if you're concerned.

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    dahlia_guy is offline Member
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    Great reply, that awnsered my questions. Thanks. I think I need to do some reading on this subject, any suggestions for a good book?

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    The one I read when I got started is called Orchid Growing Illustrated, by Brian and Wilma Ritterhausen. This was written in 85 or 86, so I'm sure there's either an updated edition or that they have come out with a new book altogether. You can check out the AOS website's Online Shop to see if it's there; they also have a pretty good selection of a lot of current things in print that might be more appropriate and up-to-date.

  5. #5
    dahlia_guy is offline Member
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    I have several general orchid care books, I was wondering if anyone knows of a book that is specific to orchid pests/diseases. Thanks for all your help.

    Travis

  6. #6
    dosal is offline Member
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    Trav is, the AOS has a booklet on Pests and diseases. You can get it from their website. It has color photos and very good descriptions.

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