I hate collar rot! Help! How do you prevent it?

[Maru777]

Hello everyone! I need a bit of advice because I am currently having a meltdown because of this blasted collar rot. 6th time it happens to me (over 4 years, bit still). There must be something that I am messing up here because there is a pattern. Every time a plant got this is was a new plant that I repotted after purchasing. Various media - bark for some, lecca and SH for some others. I never got this on a plant that I had for a while and also it only seems to happen after I repot them because for ex 2 of the 6 I repotted about 2-3 weeks after buying and that was when they got hit. It’s so weird. Out of the 6, 3 I saved (though set back significantly because I had to cut pseudobulbs out before the thing spread), 2 I lost and one I am currently struggling with. It’s always the sympodials - though blessedly not all of them that I bought and repotted that had issues. I do live in a highly humid and very warm place but that seems fine for the ones that make it past the first repot. I’ve repotted the others dozens of times and they are fine and so are the new ones that do not get it on that first repot. Sigh! What do more experienced growers do? Anything that does not involve very heavy chemical use I would be wiling to do - I have a couple of tiny frogs that came from God knows where and live in some of my pots so I am careful with the chemicals I use to not kill them. They are cute Is there any hope that I can avoid this happening again? When I see that unholy buttery color I want to cry

[estación seca]

I'm not clear on what you mean by collar rot. Usually I've seen this term used for rot around the base of monopodial orchids like Phals. Could you explain more, and perhaps show photos?

[Maru777]

Originally Posted by estación seca

I'm not clear on what you mean by collar rot. Usually I've seen this term used for rot around the base of monopodial orchids like Phals. Could you explain more, and perhaps show photos?

This is the best description I found Orchid Diseases and they called it collar rot or southern blight. I just call it the bane of my existence they only show pictures of phals but the description they have is spot on “ The main symptom of Southern blight or Collar Rot is a rapid collapse and rotting of the roots, pseudobulbs and lower parts of the leaves. Roots, pseudobulbs, leaf bases and the lower part of stems turn creamy yellow. The affected tissue becomes brown (resulting from invasion by secondary pathogens), collapses and rots very rapidly. The disease eventually girdles and destroys the entire basal portion of the plant. Affected leaves yellow, wilt and die.
Small yellow or tan sclerotia resembling mustard seeds form on the affected tissue”. Looking for some pictures that I took of them and will post in a bit. I hate this thing sooo much

[Ray]

You may have it in your environment. There are several hundred host plants that can “seed” your local growing area.

Heat and humidity favor the stuff, so you might want to spray the entire area with a disinfectant. Even a 1% bleach solution will help.

[estación seca]

If that's what you have and it's only happening after repotting, my guess is that organisms are entering small wounds occurring during repotting. This situation is common among cactus and succulent growers living in much more humid climates than the plants have in habitat.

I would suggest rethinking your repotting practices to minimize the risk of pathogens attacking your plants.

Wait for a day with lower humidity. This might mean not repotting plants during entire wet seasons, but waiting for dry seasons.

Make sure the plant is in completely dry medium before proceeding.

Then repot the plant into completely dry new medium, but do not water. Wait to water for a few days, so scratches may heal and not provide a means for organisms entering.

If available to you, at the first watering after repotting, use a mycorrhizal preparation at the dilution recommended on the label. Spray the entire plant as well, so it is covered with the solution. These contain beneficial soil organisms that can inhibit pathogens. I started using these when repotting all plants, and when removing orchid seedlings from flasks. I have had excellent results in preventing various rots.

It is always important to have a clean repotting bench. However, organisms causing various rots are common in the humid tropics. Spores are wafting around in the air. Try the suggestions I've given and see what happens, especially if you can get a mycorrhizal supplement. Ray sells one on his Web site.

[Maru777]

Thank you both for the advice! I disinfected everything again, but I think you’re right that it’s just in the environment, just so weird how it only affects them on the first repot. I do my best but absolutely sure I damage some roots in subsequent repots too. Maybe they build immunity after a while or maybe they are less stressed since the ones I buy are usually pretty traumatized by the import to the island. I will give the dry repot a shot too. I had never considered it but it does make sense. Might also keep them in the house where temps are a little cooler and humidity is much lower for a few days after repot. I have 2 new ones I’ve been afraid to repot but will try with these suggestions. Thank you very much!

[SouthPark]

Maru ----- you could maybe even try once - when you see signs of it occurring ----- a copper spray for plants/orchids ..... or even (if you have it) monterey garden-phos spray.

[Ray]

You might a plant probiotic, as they are known to kill and protect against several pathogens.

On the assumption they might be hard to find locally, try brewing up a little colony of Brewer's Yeast (Saccharomyces cerevisiae), and apply the solution monthly.

I'm not sure of the mixing ratio, but some instructions I have read suggest 5 ml yeast + 10 ml sugar or molasses in 1 liter of non-chlorinated, acidic (pH ~ 4.5 using vinegar) water, can provide the decent dose in 24 hours.

[Bamanana]

NOW this all makes sense to me. Ray is right about the probiotics. Here is my evidence: I add Repotme's Quantum probiotics to my fertilizing brew. After flushing week before last, I refilled my reservoirs with plain water only (saw that crap presented on youtube and thought it a good idea for some reason). And what do you know, about a week later 5 phals are going down so fast that I can't keep up. 2 Beallara beginning to show effects. Brassidium too. I just finally identified the fungus this morning, treated it, hacked the living daylights out of my beloved orchids (2 on death's doorstep), and come here to our orchid board to see what else I can learn.

After everything I've read on this board, I believe it does live in my environment (Alabama) and that the Quantum probiotics has been keeping it at bay. Won't be skipping that supplement again. Ever.

[Shadeflower]

This is something I have found I tend to need to do about 50% of times with new purchases.

1. Repot
2. Repot again 3 months later.

You might ask yourself, why would I repot a new puchase twice and it's not something I started off doing or hearing anybody mention but if you have old broken roots that were potted in decomposing bark then chances of bark dust having entered the cuts is very likely. I am a heavy waterer so when decomposing bark dust settles in the root cracks, the old roots tend to rot.

So 3 months down the line I check on the roots. Sometimes there is no issue ans it goes straight back, other times I will need to remove roots that have rotted since repotting it. I would not say that roots need to transition or anything, I have had roots not die from switching substrates cmpletely but if they are damaged and have a brown discoloration to them then chances they have absorbed bark dust is high so if you keep roots like these wet like I do then they rot.

If there are too many broken roots and the plant loses too many of its roots in the first week after a repot then the plant can become so weak it will rot.

So what to do to prevent it happening. Well you could not repot but that is just avoiding the problem which will not go away by itself.

That's like patching up a hole in a dam but if the hole isn't repaired properly it will just burst shortly afterwards anyway. So better not to avoid the problem even if dealing with the problem triggers the problem to occur.

To me the problem is the brown looking roots and cracks in the roots that bark dust can enter into the plant tissue. This is what causes the problems for me at least.
Maybe there is a good way of dealing with it but I just rip off the bandaid and get it over with.

Carefully of course to minimise damaging roots any more so soaking the roots well first but if the plant dies after that then it had an underlying issue in the pot already that subsequently attacked it.