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Did I over-fertilize my Lepanthopsis?

Discussion in 'Issues, Disease and Pests' started by harpspiel, Apr 25, 2015.

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  1. harpspiel

    harpspiel New Member

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    I posted this question on another forum but am not getting any response, maybe someone here will have some advice:
    The Lepanthopsis on April 3rd:
    [​IMG]

    Today:
    [​IMG]
    [​IMG]

    My Lepanthopsis astrophora 'Stalky' recently went into a rapid decline and is probably dying. The only thing I can think is that I fertilized using Schultz Orchid Food 19.31.17. My fault, I didn't measure the amount - I put a few granules into a 1 cup spray bottle. I usually fertilize around once a month, and I thoroughly wet first with pure distilled water. I fertilized all the orchids in my terrarium this way, including a number of pleurothallids, and the rest are all fine.

    The Lepanthopsis was thriving, had just grown around 10 new leaves and 4 or 5 spikes. It started dropping the new leaves first and the spikes have all blasted. Also, all the moss growing in the pot with it has turned gray - I believe moss is pretty sensitive to fertilizer.

    Other condition considerations: good ventilation and air movement, 65-90% humidity, potted in sphagnum and never allowed to dry out, temps between 55 and 80, and no other conditions have changed since it was thriving. The black spotting on the old leaves has been there for months, although it may have gotten worse.

    In the same terrarium, I have a Masdevallia coccinea 'Dwarf Pink' that occasionally develops brown, sunken patches on an older leaf. I suspected something fungal and have been removing affected leaves and spraying Physan. The Masdie is constantly putting out new leaves and has three buds, so otherwise it is very healthy. I also just removed two leaves from a Dendrobium cuthbertsonii that had suddenly developed two perfectly circular, sunken yellow rings. Hoping that isn't viral. I have no idea if all these problems could be related - they don't look similar.

    Is there anything else likely to have caused this? Fortunately if it was the fertilizer, that is easy to remedy next time around.
     
    Last edited: Apr 25, 2015
  2. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Without knowing the concentration of the fertilizer it is hard to say that it was the cause. When did you fertilize it? Also, if the other masdevallias are fine, too much fertilizer probably isn't the problem. It is a pretty rapid decline. The spotting on the Masdevallia coccinea could be a result of bacteria and pleurothallids are prone to that on older leaves sometimes. If the spots turn soft/watery then you need to remove them and treat it (I wouldn't bother with Physan). If the spots remain dry and aren't increasing you can leave them on the plant as the leave is still contributing to the nourishment of the plant. The spotting on this plant is a bit reminiscent of false spider mite which will attack both pleurothallids and Dendrobium cuthbertsonii and can devastate a collection in pretty short order. If you want to treat for them you will need to find a product that specifically says false spider mite as most miticides don't kill these. You may want let the Lepanthopsis astrophora approach dryness between waterings rather than staying wet all the time. They do best mounted where the keikis can hang out in the air.

    Perhaps others have some thoughts on this too.
     
  3. harpspiel

    harpspiel New Member

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    Thanks for your response!

    I fertilized a few days before it started dropping leaves. The fertilizer can only have been around double strength at most, based on my calculation after the fact. There are two Pleurothallis plants and a Masdie that all were fertilized at the same time and are fine.

    Would false spider mites cause apparently healthy new leaves to drop suddenly? The black spotting was only on the plant's older leaves, which are now the only ones left.

    I can certainly let it dry out a bit between waterings, but I was on a consistent schedule of twice weekly watering for months, which in my humid environment allowed the sphagnum moss to go from wet to damp. It was apparently thriving with that watering regimen.
     
  4. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    No, false spider mite would not cause healthy new leaves to drop.
     
  5. KellyW

    KellyW Orchid wonk Staff Member Supporting Member

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    Harpspiel, my plant of this species declined similarly to yours, although perhaps not as severely. I mounted it and it has improved. I suspect I was keeping it too wet. Good luck.
     
  6. harpspiel

    harpspiel New Member

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    Well, the general consensus seems to be that I was overwatering it, which makes more sense with the sudden leaf drop than over-fertilizing, I think. I took it out of the pot today and the roots weren't rotten, but they were light brown and a bit soft, and I did see some green stuff that looked like mold. I trimmed off all the dead stems, pulled off most of the sphagnum, and mounted it to the coco fiber/great stuff back of the tank. Hopefully it can recover with the four leaves it has left.
     
  7. TheKellylove

    TheKellylove Active Member

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    How is the air circulation in your grow space? I have heard that those sunken brown spots can be caused by low air circulation. As for the lepanthopsis, I agree it should be mounted. I grow mine with live moss all over it, and water it when the moss is looking a little droopy, but not quite dry. I also have a computer fan in my terrarium that allows for enough air to move the leaves slightly. I also fertilize it VERY lightly when it's not blooming. Good luck! When this guy gets happy, he's really amazing.
     
  8. harpspiel

    harpspiel New Member

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    There is a circulation fan on 24/7, and a ventilation fan that turns on and off during the day to bring the humidity down to 65% (alternating with a humidifier that brings it back up). I have a Begonia pavonina in the bottom of the tank which is notorious for having leaves that spot and "melt" with poor air circulation, and its leaves are fine, so I don't think circulation could be the problem.

    I'm going to leave it mounted and just hold off on fertilizing entirely for the time being, and see what happens.
     
  9. orcoholic

    orcoholic Member

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    It's really hard to tell.

    Overfertiizing, or even fertilizing at higher levels safe for orchids will kill moss. I don't think overwatering will - at least not real fast. If you have soft brown roots, they may be dead but just not long enough to look real bad. I don't know anything about this genera, but lepanthes are really susceptible to overfertilizing.

    If your terrarium has good humidity, you probably should keep watering to a minimum to encourage new root growth.

    I wouldn't use distilled water. The pH of it can drop drastically when fertilizer is added. Mix the distilled with some regular (tap or well ) water and fertilize really lightly until the orchid improves. Do fertilize, as distilled water has nothing in it to help the orchid - except it's wet.
     
  10. Boytjie

    Boytjie Out hiking Supporting Member

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    Not meaning to hijack the post, but if you use an MSU-type fertilizer designed for RO water, would that still make the pH drop with distilled water?
    - Stephen
     
  11. orcoholic

    orcoholic Member

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    I don't know about MSU, but Jack's RO can and does. You need to add a buffer to the water and then the fertilizer.
     
  12. orcoholic

    orcoholic Member

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    Another thought, the black spotting looks like my Masd. used to when it got hot out.
     
  13. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I use MSU with my RO and it must have a buffer, because the pH doesn't fluctuate in the hose end product. That is one of the things I like about it.
     
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  14. naoki

    naoki Well-Known Member

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    Orcoholic, I thought that you use fairly high fertilizer concentration (EC of 800-1000 microS/cm from ST discussion). Does the "buffer" of tap/well water really influence at that concentration? I would think that the pH of the solution would be dominated by fertilizer.

    Also with regard to pH and nutrient availability, as Ray frequently mentions, the optimum pH for epiphytes appears to be quite different from the frequently mentioned pH6-7.

    You might be interested in this:
    http://hortsci.ashspublications.org/content/46/7/1022.full.pdf
    They use 100-200ppmN fertilizer (pH raised to 6.0), but the pour-through measurement indicates the pH which roots experience can be 3-5 (Fig. 1) depending on the type of potting media. Also the final concluding remark of the paper is interesting (I added comments in []):

    "The results of this study show that the roots of Phalaenopsis may be the main cause of substrate acidification [this is talking about the long-term decline in pH], which may have something to do with how originally the epiphytic roots absorb mineral nutrients in their natural habitat. Growth of Phalaenopsis is normal in a substrate with low pH [around pH of 3]; therefore, raising substrate pH may not be needed in the production of Phalaenopsis."

    The punch line is that the potting media can be a big "buffer", and it could have a larger influence on the pH which roots experience than the pH of fertigation water and low pH may be ok for some orchids.
     
  15. Dave The Scientist

    Dave The Scientist Active Member

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    I had an Lepanthopsis I got from Kelly got through a similar decline(sorry Kelly), if a bit more slower. It stopped putting out new leads and slowly dropped its old one. I also thought it was false spider mites(or some other type of mites, I never made a firm ID) eating all the leads but i may have been keeping it too wet also or mostly like a combination of the two. Its down to two leaves and a keiki. I moved it and it is finally sending up a new lead.