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-   -   Help! oncidium roots with black spots... (https://www.orchidboard.com/community/beginner-discussion/107851-help-oncidium-roots-black-spots.html)

Zekeyflower 09-22-2021 03:01 AM

Help! oncidium roots with black spots...
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I have an oncidium orchid that might be dying. A little over a month ago I repotted it in spaghnum moss/bark mixture- it used to just be in bark. Then I started noticing little gnats flying around the plant so I bought some of those sticky traps and I haven't seen them since. But just today I noticed a couple of the leaves from the newest pseudobulbs are turning yellow at the tips. I freaked out thinking that they are infected and maybe the gnats are still in there. I unpotted it and did not find any evidence of pests but the roots look bad. Most of them are brown and the ones that are green/white have black spots on them. The roots are not mushy- even the brown ones feel firm. So my question is, do I cut the roots off or leave them? Are the black ones infected? Im planning on repotting it in just bark again because I think there was too much moisture with the sphagnum moss.... I just don't know how many roots I should be cutting off. Any help would be greatly appreciated cuz I'm clueless.

YetAnotherOrchidNut 09-22-2021 04:06 AM

Fungus gnats are generally harmless (even if annoying as heck) as long as there is organic food for them to eat in the pot that isn't your plant. :-) They thrive on wet media like wet sphagnum. As long as you have spahagnum in the pot they will eat it and not your plant.

You can treat gnats with the yellow sticky paper, or you can use various pesticides, or even diluted hydrogen peroxide or you can just let your pots dry out in between watering.

To me your roots look fine. Maybe a little nutrient burned. Do you use chemical fertilizers based on urea? Do you pre-wet your roots when you water? If the answer is yes and no, then that is your problem. Switch to a softer fertilizer or preflush your roots before you fertilize.

For now I would recommend you just repot, *with* the roots, be less stressful about the gnats, and wait until you see more pseudobulbs ("pups") start to grow, and when they do repot again, and remove any dead roots. I have found that oncidums respond really well to fine-bark, it stays wet for a long time while not being /too/ wet. Your plant seems to have fatter roots so usually that indicates a coarser bark, but IMO with oncidiums you can ratchet it down one level, they usually like a fairly moist root zone.

BTW, a general rule of thumb with sympodial orchids is do NOT repot them unless there is a new pup growing. They pretty much only grow new roots from the new psuedopods, so given you said you have pups growing then you are likely to come out of this ok.

PS, last time i had a plant in t he situation you are in I divided it and ended up with 4 new plants. (And then regretted it because I have no space...) Ive been giving them away to friends, although my wife insists of "vetting" them for suitability before I do (the friends I mean). :-)

Zekeyflower 09-22-2021 12:16 PM

1 Attachment(s)
I don't use fertilizer at all and I usually water about once a week with tap water. Perhaps it's something in my tap water that's affecting the roots. Any suggestions for bark brand? I was using some stuff that I got from Lowes and it was a larger bark that tended to dry out quickly- that's why I tried to mix in the moss. I've had this plant for over two years now and although it grows bulbs, it never flowers so I'm definitely doing something wrong. I think it comes down to the watering because the bulbs always wrinkle so that indicates not watering enough BUT then when I put in moss I get fungus gnats and leaves start turning yellow.... So yea I'm switching back to bark and watering more. Also, any idea why the leaves began to yellow? I cut the yellow tips off and sealed with some cinnamon and when I unpotted the plant I sprayed down the roots with hydrogen peroxide - left it to dry out all night and this morning the roots look less scary.

Zekeyflower 09-22-2021 12:26 PM

Oh and side note- one of my bulbs is connected to the rest literally by one root lol but I'm too scared to separate it. Maybe down the line if I can ever get this plant happy!!!

rbarata 09-22-2021 12:32 PM

I would turn to repot the plant in your original large bark mix, even if you need to water it a little more.
As a side note, peroxide applied on the roots will kill them (and cinnamon also).

YetAnotherOrchidNut 09-22-2021 12:35 PM

You gotta fertilize. Bark has almost nothing in terms of nutrients. The rule of thumb is water weakly weekly. That is, water at very low strength fertilizer (compared to the typical for non-specialist orchid fertilizer), 3 weeks out 4, then on the 4th flush it big time with unfertilized water. Ideally get yourself a quality brand of organic/bio liquid orchid fertilizer online. Follow the instructions. If its good quality they will include instructions for weekly watering. Flush your roots regularly with LOTS of tap water. Use finer bark to increase the surface area that gets wet without introducing stuff like sphagnum. You can also use perlite to increase water retention without attracting gnats.

But seriously, you gotta fertilize. Your yellowing leaves and no flowers are likely directly because the plant is not getting the nutrients it needs. I mean think about what would happen if you lived off of bread and water for 6 months, you would get all kinds of nutrient deficiency diseases. Your orchid looks surprising healthy to me given you aren't fertilizing, but it is probably sacrificing old growth to produce new growth, hence the yellowing leaves. And since it doesnt have the raw materials it cant construct a flower, and for all we know it isnt getting the minerals it needs so the roots aren't as healthy as they should be.

estación seca 09-22-2021 01:25 PM

You're fussing too much. Fussing too much is a primary cause of orchid death. Most YouTube videos are dramatic in order to get people so excited they watch more, and make money for the creator. Most are not primarily oriented to giving good advice. There is no drama in good gardening.

Orchids grow slowly, so the gardener has to be patient. Oncidiums are easy to grow for other people, so they should be easy to grow for you, too.

Continually pulling plants out of the pot to check roots kills them quickly. Don't do it. Would you pull a sick tomato plant out of the ground to examine its roots? Why should orchids be any different?

Pot the plant in any of the media discussed above. Leave it in that pot until it outgrows the pot. Keep it always moist, but not so wet there is no air at the roots. Fertilize regularly with small quantities of almost any fertilizer with micronutrients. If you use tap water you probably don't need to supplement calcium and magnesium. Give it bright light. A little direct sun through a window is good so long as it isn't hot enough to burn leaves.

Do this and your plant will probably flower next spring.

Shadeflower 09-22-2021 03:03 PM

good, diagnosis performed so this is no diagnosis just my personal observation (which nobody will agree with - note) that the older roots have died. The only functional roots are on the latest Pseudobulb.
This will cause the bulbs to wrinkle because the plant hasn't got enough roots. One will notice that the new roots are also thinner than the previous roots. A sign of stress.

Moss can hold 18 times its weight in water. I persnally cannot use the stuff correctly myself, I always end up soaking the moss too much. This leads to soggy roots.

Zekeyflower 09-23-2021 01:26 AM

Thank you everyone for the input. I repotted in bark and did not cut the roots. I'll just keep watering regularly and hope for the best!

Shadeflower 09-23-2021 02:05 AM

zekey I feel a bit bad because I don't think you have received very good advice from anyone yet.

But you have to realize growing orchids is challenging for lots of people, even the people that think they know what they are doing.

You can use bark but this was drying too much for you before so you have to be prepared to water a bit more regularly.

Personally I love adding a little bit of perlite to my bark if it dries too much. Perlite plugs the holes a bit and keeps the bark a bit more moist.

You will need to water more than before when using only bark, aim for a "just humid" state where it never fully dries out but is not soaking wet either.

It's a fine balance between success and failure. You newest bulb has completely detached from the other bulbs, this will make it even more challenging. If they are only connected by one root then they are no longer physically connected anymore.

Good luck.

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