Need help with an Onc. leaf issue

[smokinjoe1952]

Hi,

I have several Onc. intergenerics in my grow chamber, and and most of them are starting to get, or already have this brown leaf disease. I have researched many resources, but could not come up with a specific cause. Any identification and treatment help would be most appreciated.

Thanks,

Joe

Specifics:
Indoor grow chamber
68N-79D this time of year
Humidity 60-75%
LED lighting
active air circulation and periodic fresh air intake
K-lite 25ppm
Kelp-max
Innocucor

[aliceinwl]

For what it’s worth I grow most of my Oncidium type intergenerics outside. The older leaves on all of them look similar to yours. Mine are all healthy otherwise. I just assumed it was part of the leaf aging process.

[Dollythehun]

Many of the oncidium tribe have crummy looking leaves. What you're seeing is not out of the ordinary.

[Selmo]

You have guignardia or the Thai crud disease. Oncidiums seem to get this often. Ussally caused by the leaf wetness and not enough air movement. The new growth will not have, but will become infected over time. To control it you need to start a monthly spray program. Spraying a fungicide every 3-4 weeks until all the old infected leaves are gone and only new clean leaves are left. This may take a year or longer. Don’t use the same fungicide more than 3 times in a row or resistance can build up.
Or just live with it, increase air movement, decrease how long leaves stay wet.

[smokinjoe1952]

Thanks for the replies. I do have 3 PC fans running in the chamber, and have reduced air flow volume a couple times because all the air roots were drying up. That seems to be under control now. The plant whose picture I took has 2 fans 1 foot above it moving air away from it. (Up into the top of the chamber) Also, the leaves never get wet except once a month when I flood the pots with RO water and spray the leaves with Innocucor.

Maybe I'll try Physan once a month when I flood the pots.

Joe