Loss of roots of phalaenopsis when there is change of substrate

[Ray]

You do not need to treat the fungus on rotting roots. That's what's decomposing them, and healthy, living tissue does not rot.

[Merita]

Hello everyone, again with my doubts, I would like to know how you treat the crown rot and roots, and if watering by immersion is the right thing. I have read in many internet forums and I see that they differ widely opinions, I would like to hear your own criteria on this to put them into practice, thank you all, greetings

[estación seca]

I reread your original post. I don't know how much orchid experience you have. Please forgive me if what I write is too basic.

Are you asking about roots dead when you first unpot them from sphagnum, or roots dying after you repot them? If the second, how do you know the roots are dying after you repot them?

Many beginners think living orchid roots are dead, because living roots don't always look the same. Living roots are white when very young, and age to light or dark tan. They are slightly rough to touch when dry. They turn dark green when completely wet. It is easier to soak older tan roots than younger white roots. Roots may be bent or broken and still viable. Roots can have the outer, spongy or papery velamen coat stripped off, leaving just the threadlike roots normally hidden inside the velamen, and still be alive. A plant can have a root system of mostly stripped roots and they can still function fine. The surest sign of a viable root is a bright green growing tip. These may be absent if conditions for root growth have been poor for some time, but the roots nevertheless can remain able to grow again. You cannot tell whether a root with the velamen stripped off is living or dead without high-power magnification.

Dead Phal roots are dark brown or black. They are squishy or slimy. They take a very long time to dry, much longer than living roots. They do not turn tan or white when dry.

Crown rot rarely occurs in healthy Phals in good growing conditions. They like warm temperatures, warmer than many people keep their houses in winter. They like moderately high relative humidity: 50%-60% is good, 90% tolerable but encourages fungus. They like bright shade but not any direct sun. They like plenty of air circulation. They require air at the roots. The commonest cause of various rots in Phals is insufficient air at the roots. Orlando has appropriate temperature and humidity this time of year. Unless your crown rot started during your recent extremely humid hurricane weather, your problem is likely insufficient air at the roots. Crown rot (usually caused by fungus) often ascends from rotten roots.

A bacterial disease called Erwinia begins on leaves but quickly progresses to kill the crown. Leaves have dark, wet spots that liquefy when touched. There is a bad smell. Fungicides will not kill Erwinia. It tends to occur when humidity is very high, air circulation is poor and plants are crowded together. It spreads rapidly from plant to plant, and the liquid is teeming with infectious bacteria. This is not crown rot.

Some people treat crown rot by adding a few drops of 3% hydrogen peroxide to the crown. This is sold in drug stores as an antiseptic, usually in a brown bottle. Leave the peroxide until it stops bubbling, then pour out, and dry with a paper towel or cotton swab. Do this every day for only 2-3 days. If the plant survives, it may eventually grow a new leaf from the crown, and peroxide may burn the tiny leaf. Keep peroxide off roots. It may kill them.

Others use cinnamon powder, which has pronounced antimicrobial properties against many organisms. The cinnamon must be fresh. Sprinkle a little into the crown. Keep it dry. You shouldn't need to re-treat. You can put cinnamon on the cut surfaces of roots but do not put it on entire roots. It may damage them. I don't treat cut roots, but some here do.

Others use a commercial fungicide. But many fungi can cause crown rot; unless you know which fungus, you might pick a fungicide that doesn't kill that fungus.

I would not immerse the leaves and crown of a plant with a rot problem. It should be fine if they dry rapidly, but sometimes they don't dry as rapidly as we might think. See below for immersing roots.

Many here treat a Phal with root rot by unpotting, drying completely in warm shade, and potting it into large chunky medium. Then we water thoroughly, place it someplace with 60%-75% relative humidity, and water only when the medium is completely dry. A viable Phal like this will begin developing new roots from the stem quickly. It may retain leaf wrinkling a long time. So long as new roots are forming all should be well.

Others set rerooting Phals on top of barely damp sphagnum moss in a mostly closed container. This is often known as "sphag and bag." If the moss is too wet the plant will rot. The high humidity is what is important, not water from the moss.

Others here treat root-damaged Phals by suspending them in a vase or jar with the leaves at the mouth of the vase. Put the plant someplace very humid. Water by filling the vase, letting the roots get completely wet for minutes to some hours, then dumping the water. You may water again as soon as all the roots have dried. In proper humidity you might water once every few days. Some people will leave just enough water in the vase between waterings that a few healthy roots are just touching it. Others leave water in the vase, but not touching any roots, to increase humidity in the vase. Still others drain the vase completely between waterings. Some people grow Phals like this all the time.

Sometimes the fungus kills the growing point (meristem) in the crown, but the plant survives. If there are leaves down stem above which flower spikes have not formed, there are reserve meristems, and the plant may make new growth from down the stem. It may take a long time for this to happen, sometimes over a year. Don't give up if the plant survives, but doesn't grow a new leaf from the crown.

[Merita]

Thank you very much, Estacion seca, I have learned a lot with your explanation, now I know that the roots are only damaged by moss and that they can recover or take new ones. Some years ago I practice this hobby and I have had a plague of mites, I also had crown rot but I was able to save the plant and now it gave me a keiki. All my orchids are outside, in a small greenhouse and in the trees the cattleyas and the dendros, I had them inside the house but they did not prosper, in the yard they go very well, taking out new spikes and others recovering from the sequels of the mites and the burns that I made accidentally, cleaning them with alcohol, again thank you for your time. Greetings.