Browning and blackening of leaves

[Zoren]

:: Good day members, it's been awhile since I visited the Board, I will try to keep better contact.
Now the problem at hand, I've been having browning and blackening of a number of my plants. The problem is not restricted to any one type of plant, it is happening to my Maxillaria, Paphs, Phrags and 2 of my Zygos. Not all my plants are having this problem (I have about 85 plants). I've moved them around my Florida room thinking maybe there might be to much or to little light. I would appreciate if one of my esteemed members could give me some suggestions or know what is wrong. See attached pictures. Waiting for an answer, Zoren......

[OrchidBro]

What is your fertilizing routine? How often, how much, method (slow release/mixed with water)

[SouthPark]

Definitely a possibility of fertilizer issue.... eg. too concentrated .... or even accumulated fertilizer residual contents in the potting media over time.

[Ray]

Looks like erwinia and/or anthracnose to me...

[Zoren]

I want to thank the both of you for a quick reply to my thread.My fertilizing routine is every watering at 1/4 tsp/gallon of either K-Lite or 20/20/20 (I usually use K-Lite). I flush my plants usually once a month to every 6 weeks. And, once a month (or longer), I add KelpMax, K-Lite and Inocucor-Garden Solution to my 4th watering (I got this Root growth, microbe stimulant and fertilizer routine from Ray of 'First Ray'((he is aklso a Senior Member of the Board)). As I said it seem to be happening to only a few plants. Like all of us I've lost a number of plants. I try to replace the ones I've lost with the same plants, if I can find them and I liked them in the first place. I've started collecting species plants and I'm always looking for fragrant ones. I usually buy my species and hard to get plants from Andy's Orchids in California. He's recommendations for the plants I like has been very good. I also buy from Elegant Orchids here in Florida, they have changed owners and Melissa is trying hard to purchase plants for the orchid collector (they have a large commercial floral business). Again thank you for your suggestions, let's see if anyone can come up with more ideas. As always, Zoren!!!

---------- Post added at 05:40 PM ---------- Previous post was at 05:32 PM ----------

Hello again Ray, hope everything is Ok. I knew you would come up with an answer I would have to look up and you didn't fail me. I will look into your analysis ASAP. Zoren...........

[SouthPark]

Zoren .... if it really is fungal, then better isolate those plants and pop some systematic fungicide on them.

Or maybe put fungicide on all of them. Do you have good air circulation in your growing area?

[Zoren]

South Park, I'm going to use Physan20 directly on the effected plants and spray the rest of them, starting tomorrow. Thank you again. Zoren...

[Ray]

"1/4 teaspoon per gallon K-Lite or 20-20-20 at every watering" tells us little. How often do you water?

Also, 1/4 teaspoon K-Lite is about 40 ppm N, while for a 20%N formulation it's more like 66 ppm N. That's a big difference, and coupled with the frequency, will tall us a lot more info.

How long since the affected plants were repotted? Despite periodic flushing, residue accumulation can also be toxic.

Am I correct to assume you're still growing in super-hot conditions? That would suggest rapid drying, which accelerates residue buildup.

If you're dealing with a systemic infection, Physan isn't going to do a damned thing to help. If you've been using the Garden Solution properly (3 TBSP/gal, monthly), I find it hard to believe you've contracted a disease. If, on the other hand, you have used Physan or any disinfectant, itnhas killed all of the beneficial microbes.

[Zoren]

Ray good morning. I water one to two times per week (Yes I'm still dealing with hot conditions--I have put in a 14M-BTU portable air conditioner (not a swamp cooler). Since it is summer I usually turn the AC on when it gets to 88F in the room, some times lower--I set it at 80F which all the orchids I have will tolerate well. I also run a Humidifier to compensate for lose by running AC. I also run the AC and humidifier from 10pm to about 7-8AM, in this heat I can bring the temperature down to about 70F (in autumn and winter it will go down to about 64F). As for re-potting generally 1 to 2 years depending on the type of orchid and the medium it is planted in. I have some orchids that are re-potted over the 2 year time frame. As I wrote before I flush every 4-6 weeks. As to fertilizing, I use K-Lite mostly (I don't combine fertilizers), at less once/week (I don't fertilize plants at every watering if more then once/week). I might use 20/20/20 maybe once every 3-6 months. As to how much Pysan20 I use, I only use it if I detect a problem. And I usually spray all my plants at the same time if I see what I think is a problem. As to my use of K-Lite, Kelp Max and InocucorGS (1.5oz/Gallon), I do this every 4-6 weeks as per all directions. I don't feel that my occasional use of Physan20 would destroy the healthy microbes of the InocucorGS based on my routine of 4-6 week application. Ray I'm not quite sure I can put my finger on the problem, because I feel if the problem was fungal or bacterial it would have effected all my plants. Because I water all my plants communally, in the same water and fertilizer water. I see no problems with my other plants (they are flourishing beautifully). The problem is with about 10 plants out of 85, I've had the problem of a while, I came to the Board to see if We could solve the problem. As always you give me 'food for thought', if you or anyone else can come up with suggestions I would appreciate them. As always Zoren.... P.S., I didn't realize how much I missed the Board, I will try to come on-line to the Board more offten.

[aliceinwl]

I can’t offer any advice on what’s ailing your plants, but I used to water communally to until I lost one plant and almost lost a second to some type of fungal disease. Since most of my plants stayed healthy or at least asymtomatic, I don’t think susceptibility is uniform. I also don’t know if continued exposure would have eventually resulted in infection of the rest of my plants. I wouldn’t completely dismiss the idea of a pathogen and maybe err on the safe side and at least exclude the affected plants from communal watering.