Rescue! Vandas roots black and leafs drop

[kaarthiik]

Hi All,

I have found some black area around the roots(at there start) on my few big Vandas.
When I noticed on a fat root, I have used a dab of peroxide on it thinking of fungal infection.
Now all 3 fat roots became lean and dry and black. Please see the pics and guide me.
I see similar things it 2 huge vandas and one medium vanada.

And another big worry is they are dropping leafs fast!

I was watering around 3 times in the morning (between 7 AM to 10 AM) and the weather is very hot around 43 degrees centigrade outside, and in the Vanda's area I was able to maintain 30-32 Degrees centigrade.
Humidity on average of 50 to 60

Please help!

[RJSquirrel]

my 1st thought would be over-watered. if the roots arent dry and you continue to water them between 7 am and 10 am then your drowning the root system and it cant breathe. watering 3 times a day would be fine IMO but only if the roots have sufficiently dried out.

I only have 1 vanda. its very hot here with very low humidity. I dont have any dew in the AM on anything, only dried up dust on the leaves of everything. I water at 7 am when the sun comes up and I water again in the early afternoon when the sun moves off the plants or I wake up whichever comes 1st. you dont want to water anything in the full afternoon sun unless you like salad. .

I think its just being over watered

[Blueszz]

The way the leafs yellow let me think it's stem rot :-(
Is it possible that during watering water could accumulate in the leaf axles? Do the roots get bad close to the stem at first?

Currently we have 30C during the day and humidity 20%. I water twice a day with a high pressure pump sprayer for about 20-25 minutes and that seems to be enough. If the weather stays like this I'll dunk the root system twice a week, always carefully avoiding water between the leafs.
Nicole

[kaarthiik]

Hi,
Bluezz
Thanks for the inputs. I too think of stem rot after your say. Is there any way to stop it?
RJSSqurriel,
I understand your point, and from today I reduced watering to twice, and doing only when roots are totally dry.
Is there any way to stop?

I am having only Neem oil and Chloropyriphos (insectiside never used on Orchids, but for other plants effective in controlling GNats).
I can try for Physan, but not sure if they are avilable in my country.

[Blueszz]

I'm afraid there isn't much you can do. I succesfully stopped it once in Vanda (Trudelia) cristata but it was has just begun. I removed the leaf, scratched away soft/hard brown spots and covered the wound I left with cinamon (it helps it dry out). The waiting began from that point and now 1.5 years later the plant is growing well, didn't lose leafs anymore, didn't develop leaf loss... putting out lots of new roots, also above that critical point.
You could try the same but I've seen pictures from Vanda's that were decapitated for that reason and the rot was wide spread in the stem. The inner from the stems looked brown but still felt hard to the touch.
A drastic method would be decapitating it and try to reroot the healthy top part... if you succeed in this at all.
I'm sorry, wish I had better news for you.