Seedlings dying off

[SelectOrchids]

A bit busy as of now... But for the seedlings, the problem is to keep the conditions even. If they dry out/get wet in cycles, it eventually damages the base, and result in rot. However there is more to that, and the symptoms are typical of an infection.

For the seedlings death on the photos, the only treatment is an anti-pythium/phytophthora such as mefenofam, fosetyl-al and similar as a drench. It will stop overnight. Afterwards, it is worth to check the EC of the potting mix and its pH. A lot of problems are related to those two parameter, though oomycete death can occur even if all the paramteres are fine. Simply because it is an infection...

Regarding the copper/Kocide that is copper hydroxide, it is still use by some large nurseries, and it is definitely not damaging to Paphiopedilum. It is especially efficient for wet rots types. But in that compot case, it will not help.

 

[swamprad]

For the seedlings death on the photos, the only treatment is an anti-pythium/phytophthora such as mefenofam, fosetyl-al and similar as a drench. It will stop overnight.

Regarding the copper/Kocide that is copper hydroxide, it is still use by some large nurseries, and it is definitely not damaging to Paphiopedilum. It is especially efficient for wet rots types.

Xavier, thanks for your input. As I looked at the photos, I thought it was erwinia. Please tell me how to distinguish pythium/phytophthora from erwinia.

 

[SelectOrchids]

Xavier, thanks for your input. As I looked at the photos, I thought it was erwinia. Please tell me how to distinguish pythium/phytophthora from erwinia.

Erwinia is a great rarity in Paphiopedilum. In fact pretty much all pictures of 'erwinia' or 'pseudomonas' I have seen on Paphiopedilum turned out to be oomycetes, not bacteria. I have to know because we had to run diagnosis by PCR and earlier cultures, and erwinia turned out to be very rare. There is one strain of wetter brown rot that induces a chlorosis in the plants, this is the true erwinia cypripedii, very rare. And another one that makes slow progress as soon as the plants are watered/humid enough, to stop until next time. That's pretty much all about erwinia and Paphiopedilum.

You will find out as well that mefenoxam would stop those 'bacterial rots' absolutely overnight... which is an indirect confirmation of the PCR tests...

That's one of the common problems in the orchid world, wrong information passed from generation to generation. Some of the pythium/phytophthora can induce overnight collapse with watery tissues. They are actually oomycetes, in their own family as of now, they proliferate very quickly.

 

[swamprad]

Erwinia is a great rarity in Paphiopedilum. In fact pretty much all pictures of 'erwinia' or 'pseudomonas' I have seen on Paphiopedilum turned out to be oomycetes, not bacteria. I have to know because we had to run diagnosis by PCR and earlier cultures, and erwinia turned out to be very rare. There is one strain of wetter brown rot that induces a chlorosis in the plants, this is the true erwinia cypripedii, very rare. And another one that makes slow progress as soon as the plants are watered/humid enough, to stop until next time. That's pretty much all about erwinia and Paphiopedilum.

You will find out as well that mefenoxam would stop those 'bacterial rots' absolutely overnight... which is an indirect confirmation of the PCR tests...

That's one of the common problems in the orchid world, wrong information passed from generation to generation. Some of the pythium/phytophthora can induce overnight collapse with watery tissues. They are actually oomycetes, in their own family as of now, they proliferate very quickly.

Xavier, thank you very much. One more question. I have had periodic problems with rot similar to the photos. Would it be a good idea to drench with mefenoxam periodically as a preventative? If so, how often would you suggest?

 

[DKkenn]

I’m seeing moldy substrate. It sounds like you’re fertilizing too much and already causing “salt” buildup. I would promptly and thoroughly soak each pot in pure RO or distilled water and then flush through with more pure water to clear that salt buildup. Then I would water twice in a row with KelPak/RO solution. Going forward, do not fertilize every watering; tiny seedlings are not able to process all that and your fertilizing to date has likely burned their roots already; the KelPak will hopefully help stimulate new root growth as well as replacement leaves for what’s dying. When you do fertilize, water first thoroughly with distilled or RO water, wait a bit, then fertilize. Your plants will be safely hydrated and more easily able to take up nutrients they need while avoiding overfeeding that results in what you’re seeing.

Regarding the comment about how rain in nature means it’s ok to get water in plant crowns, I dissent; most none of these plants grow upright-facing in nature. They’re inevitably on a tree-trunk or slope and the leaves tend to hang downward to shed water. I am very careful to avoid getting water in crowns, ever; when I do, I blow it out or use the corner of a paper towel to wick it up. A fan blowing across the grow area is a must if you’re one to spray water all over.

As others have noted, dragon’s blood is the bomb. You have to be sure you get the good stuff; there’s at least one other thread where it’s extensively discussed. I’m attaching a photo of my bottle. You need the product to declare that it contains 100% Croton lechleri extract and no additives.

Thanks. I will try to work on my fertilizing a bit. I was probably a bit too lazy to read up on it and go all the way.
I am not sure if the moldy substrate is because of that. It was more like when soil has been too wet and there is algae growth.
But I will try a different way.
And yes, your thoughts on the rain in nature seems valid also.

A bit busy as of now... But for the seedlings, the problem is to keep the conditions even. If they dry out/get wet in cycles, it eventually damages the base, and result in rot. However there is more to that, and the symptoms are typical of an infection.

For the seedlings death on the photos, the only treatment is an anti-pythium/phytophthora such as mefenofam, fosetyl-al and similar as a drench. It will stop overnight. Afterwards, it is worth to check the EC of the potting mix and its pH. A lot of problems are related to those two parameter, though oomycete death can occur even if all the paramteres are fine. Simply because it is an infection...

Regarding the copper/Kocide that is copper hydroxide, it is still use by some large nurseries, and it is definitely not damaging to Paphiopedilum. It is especially efficient for wet rots types. But in that compot case, it will not help.

Thanks for that. I must find a better way to water. I am not able/willing to use fungicides, as they are in my livingroom.

It seems the problem is because of incorrect watering or the wrong/bad kind of substrate. I must think on this..

Thanks

 

[CharlesD]

Xavier, thank you very much. One more question. I have had periodic problems with rot similar to the photos. Would it be a good idea to drench with mefenoxam periodically as a preventative? If so, how often would you suggest?

I’ve heard that Sunset valley orchids does subdue (menoxofam) and heritage (azoxystrobin) twice annually as a preventative


This thread has been super helpful. Thank you Xavier!