What is this? virus, pest or disease?

[BeeJam]

My Miltassia has developed brown marks on the leaves. Any ideas as to what it is and what is causing it?
Thanks!

[Cynthia, Prescott, AZ]

If this is only on one side of the plant, it could be recent sunburn. How long have the leaves been this way? Is it spreading up the leaf towards the plant? I would leave it alone for a while to see how it developes. If it were a form of bacterial infection, you would want to cut off the leaf before it reaches the bulb, with about an inch of clearence between the cut and the discoloration. Sterilized tool only for cutting into live tissue. If it is sun burn, it may enlarge just a little as the perifery tissue, which was also damaged, but less so, shows its nature. If it is sun burn, expect the spots to go black or a dry brown. Cynthia

[BeeJam]

Thank you. Sunburn that could be it. The damaged leaves are only on one side of the plant. I have only had this orchid for about 1 month. It did not have it when I received it. Would it take that long to show damage if it was burned before I received the orchid. I had it on the center of the kithen table and then moved it into the den. Since I have owned it, it was not close enough to a window to get sunburn.

[Cynthia, Prescott, AZ]

A responder of this equivalent post on the garden web forum suggested cold burn. This is also a posibility. But if this plant has not been up against a cold window, or had direct sun on the leaves in the last month, I think it may be bacterial. Especially since I see the discoloration going over a bend in the leaf, and the damage from burns should only be on the surfaces facing the sun or window. You seem to have enough leaves so that the plant won't miss the loss, so I would recommend cutting of the worst leaf completely, down to the top of the bulb, and trim the others to an inch into clean tissue. Use a sterilized tool. Use heat, 10% bleach soak, or saturated solution of real trisodium phosphate soak for 20 minutes or longer if the tool is only questionably clean.

If this is bacterial, you need to think about your culture. Poor culture weakens a plant, and makes it sussepatable to infection. Is the plant getting enough sun? Indirect light might be enough, but it has to be very bright indirect light. Sitting in the center of a room on a table is not enough light. Since it has some Brassia in it that requires more light than Miltonias and Oncidiums, I would suggest you try direct sun light shaded with venetian blinds or a filmy curtain. Feel the leaves when the sun is shinning on it. They can be luke warm or a little warmer, but not hot to the touch. Also, keep the mix from drying out completely if you are going with the partial sun, as it will need the moisture to cool itself. Good luck with this guy.

[Daniel S. Barrett]

i completely agree with Cynthia!
You go girl!

[Daniel S. Barrett]

I'd recommend the simple approach, remove the damaged leaves, & move to a sun sheltered place, and monitor to see if more damage apears later. If none, then chalk it up to sun or cold damage, if more apears, the it coulh be bacterial or even viral, do you smoke?

[Cynthia, Prescott, AZ]

Daniel, I've been testing my plants for virus, and have come up with probably a hundred virused plants so far, and this does not look like anything I have seen on virused plants so far. If it isn't cold or sun burn, then I really think it is bacterial.