Problem with Asconcenda

[Don Perusse]

I didn't know whether to post here or the Vanda alliance as my problem is with one of my ascocendas. A couple weeks ago I noticed white spots on the leaves. It looked like something ate the tissue on the top and bottom leaving a white membrane in the middle. Then they turned to brown and almost black. Can use help in determining the cause? Is is bugs, a fungus or bacteria?
Maybe someone else has had the same problem.

[kiki-do]

I don't have a clue Don, but bumping this back to the top. It sounds like some type of bug, though.

[cneos]

Is this only occurring on the upper leaves? There appears to be a pattern of the spots that suggest sunburn.

The whitened tissue is like a blister. If too much damage occurs, the tissue dessicates and turns brown or black.

Vandas aren't as susceptible to insects as other genera, but sucking insects - mealy bug or scale - can cause similar damage. Inspect your plants and treat appropriately. (We've managed to keep insects under control with alcohol and Safer insecticidal Soap)

Incidentally, a friend reported similar damage to her cattleya collection that is 'enjoying' the summer outdoors. All of a sudden, the catts had small puncture wounds on the upper side of the leaves. The tissue surrounding the wounds seemed faded and soft; ultimately the spots turned brown. Turns out, the culprit was a hailstorm.

[JennS]

I am not positive, but I have similar looking black marks on one of my vandas. Mine looks like the marks that are on the lower leaves of yours, not really the top leave that is shown close up. I have determined the small black spots on mine as sun spots. I wouldn't really call them sunburn though, but it is a result of over exposure. I just kept adjusting mine until I didn't see any more spots. There are a few larger spots on mine also like the large black on you have and it is the same thing. I would check for mushiness. If they are still as hard as the rest of the leaf it is probably fine. If they seem at all mushy I would assume it is a fungus of some sort. You might want to treat with Physan or somethign (not sure if this is the correct thing for fungus but someone else might know for sure) similar. If the top leave that had the white spot appears to have spreading then I would get worried. If is seems to stay in one spot you are probably fine.