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Yellow patches and yellow pseudobulbs

Discussion in 'Issues, Disease and Pests' started by fernbrook, Apr 14, 2014.

  1. fernbrook

    fernbrook Member

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    Hi, I went into my shade house this morning and was alarmed at yellow patches and yellow pseudobulbs! Any ideas what this could be? We have had a bit of rain lately and I switched to a new fertiliser that I bought at an orchid show about a month ago that I mist all over the plant as opposed to the previous kind that I always applied with a watering can to the medium. The only other thing that I did was wipe some black off them with milk which was recommended to me as I get some black from trees that are nearby.
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  2. lepetitmartien

    lepetitmartien Active Member

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    I'd go for spidermites for the yellowin parts on leaves, but a close up would help.

    If you changed the fertilizing mode/method, I'd investigate, it may be this too for the chlorosis.
    What do you mean by "black"?
     
  3. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I don't think that cattleyas are going to get enough fertilizer just by misting.
     
  4. fernbrook

    fernbrook Member

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    The black that I mentioned is possibly residue or something similar from some very big gum trees that hang over a part of the shade house. They are far too big to cut down even if I wanted to and we also have a "preservation order" on our property which means we can not cut down anything (is fine by me but does make it hard to have flowers when you have very limited full sun positions).

    I do think I have spider mites and have begun to attack them with White Oil and will do so weekly now. I have one other question (for now anyway) as suggested, I may have some fungus but Phisan is not available in Australis that I can see anyway, what else can I put through the potting medium to kill fungus? I am repotting a large number that are in big pots to try to ensure they get to dry out and also get enough air movement so that there is no root rot.

    Sorry for so many questions but I seemed to encounter several issues all at once! ImageUploadedByOrchidsForum.com1398672777.668309.jpg
     
  5. lepetitmartien

    lepetitmartien Active Member

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    Careful with the oil, it should be hydrolyzed well (with safer soap), else it'll clog the stomates.

    For physan, check the algicides for swimming pools. (hint hint) Now it won't clear everything depending of what's the issue especially as it's not systemic.

    I can't help you much in the chemicals as the available in Oz are not the same as where I am. But Bordeaux mixture can help, and should be available.
     
  6. fernbrook

    fernbrook Member

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    Ok thanks. One last question, after repotting and getting rid of any rotten roots, should I hold off on watering, fertilising and also when would it be safe to use a systemic fungicide?
     
  7. KellyW

    KellyW Orchid wonk Staff Member Supporting Member

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    Cindy, that last photo is blurry but it looks like you may have a scale insect of some sort. If it is scale you need to take some immediate action because it spreads quickly.
     
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  8. fernbrook

    fernbrook Member

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    Marni - I agree, I think Cattleya need more fertilising than a spray (ignore the sales pitch even though I bought it at an orchid show) back to the old ways for me.

    KellyW -I definitely agree with the scale spreading quickly - I see it with my own eyes!

    Lepetitmartien - With regard to caution on White Oil, I certainly will, I now have neem oil that I will mix with soap and I think I will alternate with Eco oil to hopefully stop them from becoming tolerant. I bought algaecide the other day as it was recommended in a locally produced orchid society book that I have now misplaced as well as by someone that let me get in their ear at a recent orchid show, but I need to find the dilution before I try it.

    Are then any rules with fertilising and watering following repotting? It was not the perfect time to repot so I would like to minimise any added stress?

    Thanks all.
     
  9. Daethen

    Daethen Orchid Mom

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    I agree with the scale diagnosis. Any oil can be dangerous to the plant when added to sunlight. It can burn the leaves. I have seen some growers who never fertilize catts or if they do it is like once a year so I don't think that has anything to do with your troubles. Easiest way to rid yourself of spidermites is to spray off the plants regularly. They like very dry conditions. Most suggest soaking the new medium in water overnight before repotting then letting the plants stay on the dryer side for a while before resuming normal watering. I do not follow this and I have no trouble.
     
  10. fernbrook

    fernbrook Member

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    I think I have success, I am certain I had spider mite and scale, not sure if I had mealy bug as well but I certainly had some root rot. I have repotted about 30 of my cattleya's and I have got rid of all signs of any pests which I will continue to monitor. I also will continue with my 3 in 1 spray.

    Once I am confident I have everything under control, is it ok to put orchids on a lower shelf under all of my others in the shade house? I would love to start filling the lower shelf too but I have read that you shouldn't. As I have learned the hard way that a few things that I had thought were a bit pedantic actually have a lot of merit I wonder if this is another of those things!

    Thanks again for your help!
     
  11. Daethen

    Daethen Orchid Mom

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    If you are worried about the water from the plants above getting onto the lower ones, then attach a piece of plastic sheeting to the bottom of the upper shelf.
     
  12. fernbrook

    fernbrook Member

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    Ok, I will do but if you have no pests or disease, does it really hurt if water drop below onto other orchids?
     
  13. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Well, if you have no pests or diseases (as opposed to having none that you are aware of) it isn't a problem. Pests probably aren't so much the problem as they move on their own and can be treated easily. Virus is a different story and I don't really know if water spreads that, but bacterial and fungal issues I think do spread with water. That said, my mounted plants are on vertical racks and I do have plants in baskets and pots hanging over some of the benches so things do get water from other plants above.
     
  14. fernbrook

    fernbrook Member

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    Thanks Marni
     
  15. Daethen

    Daethen Orchid Mom

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    I think the main worries are virus and getting water in the crown of the lower plants that could create rot. If you have good air circulation this may not be a concern either.
     
  16. fernbrook

    fernbrook Member

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    Ok, yes I hadn't thought about crown rot, will keep an eye on that. Thanks