Help! am I loosing my whole orchid collection? Fungus? Bacterial? Rot? Pt. 1

[paytyn2flex]

Hello, I'm not sure if I'm posting this in the correct way, so pls advise if that is the case. My issue is, I have all my orchids under a pergola (approximately 13ft x 34 feet)for the past 2 years. All Phalaenopsis are on the patio table. My Vandas hang together where the sprinklers can water the roots almost daily and I have 2 orchids (I think 1 is an oncidium, and 1 is a brassica) that where given as a gift).. then I have some dendrobium on shelves up top... I water the phalaenopsis maybe every 8 days, they are planted in orchid bark mix) The Vandas and oncidium and brassica get watered daily, and the dendrobium maybe every week. I don't know if I have a bacterial infection or fungus or the dreaded black rot. I have tried spraying with hydrogen peroxide. I'm going to try to attach pics. The phalaenopsis with the all yellow leaves actually had the top,new growth, leaf fall right out. Pls help!! only allowed 4 photos, pls see following posts
I live near Clearwater Florida

[paytyn2flex]

continued photos from previous post

[paytyn2flex]

continued photos from previous post

[raybark]

To me, the issue does not seem to be a dire as you have expressed.

I suspect that the spots are simply fungal damage from water droplets left standing on the leaves at night. Watering only early in the day can help reduce that, but a disinfectant spray cannot hurt, either. Don't bother with hydrogen peroxide, it simply decomposes and leaves water standing on the plant. Chlorine bleach, Physan (not Phyton), or Biosafe Systems Disease Control is the way to go - especially the last.

The second phalaenopsis looks fine - the loss of bottom leaves is normal. That first one may have had water sit in the leaf axils leading to rot - hence the loss of the growing crown.

As a general comment, I'd bet the plants, especially phals, are not getting enough water. In your heat - despite the humidity - I'll bet the bark dried out pretty rapidly. I also suggest you check the root systems, especially if they have not been repotted in two years. That bark will decompose. (FWIW, a lot of Florida growers use lightweight expanded clay aggregate as a potting medium, so they can water frequently with impunity.)

How about fertilizer? What formula, mixing concentration, and application frequency?

[Mike H]

Yes, and that dendrobium might be trying to have it's winter rest.

[JDT]

A lot of the yellowing is from not enough water, if you only water your phals every 8 days that is a problem, being in Florida I water my phals every day, they love moisture, the vandas unless the roots are a darkish green color need water when I had mine they got water twice a day year round. Now you being in Tampa is a little different as you have cooler temps then we get down here in south Florida. Did you bring any of your orchids indoors when we got had all the recent cold? When it gets below 50 you need to protect them as if they get too cold they will loose leaves. I would agree with Ray on the phal leave loss in the crown, sounds to me like water got into the crown, that is when you would pour peroxide in that area but do it early so that it will dry out, or use a straw to blow any water out of that area. Not sure if that is a dendrobium that needs a winter rest, not all of them do, probably from the cold if they were left outside.

[Dorsetman]

I can agree with most of what is said above ( have no nowledge of how to grow plants in Florida - its a long way from me ! ).
But in general, I cannot see any sign of root activity on the vandaceous stuff. I expect and want to see green leaf tips. Almost certainly more water is the answer there . In Thailand they water their big vandas twice a day !