Big Brown soft spot on Encyclia Rioclarense
 

I bought this Encyclia in the fall. I have been growing it on my windowsill. I hope this spot is sunburn, but if it is Erwinia soft rot I do not really know what to do. Please let me know if you can help!

I would first question how the plant could have gotten a sunburn on only this spot/leaf. If the window lighting somehow fell more strongly here, I would think sunburn. If I had a few other leaves with some irregular brown spots that were more dry than wet, I would think sunburn. If I had splashed water which may have heated up, I would think burn again.
If this is kinda outta the blue...I would think Erwinia.
Regardless, if I have a single bad looking leaf, I get rid of it. :twocents:
Cut this leaf off with a sterile blade at least one inch into good tissue. Consider treatment with an anti-baterial like Phyton 27; but most importantly, increase your circulation around your plants.

This a good cut of should be enough.

Although anti-bacterial treatments on plants? Normally the only ingredients that work on plants are antibiotics or desinfectants the later would also kill plant tissue.

I was referring to the Phyton 27 which kills both Erwinia and Pseudomonas ... both bacteria
I've used it for years.
If I am mistaken, please let me know.

The damage is too regular to be sunburn (it's too circular). And it's too localized to be sunburn (there's only one spot, sunburn doesn't behave like that).

The only thing that I would think that causes that kind of damage is fungus (ever heard of "fairy rings"?).

My :twocents:.

Solution:

As everyone has said - remove that part of the leaf.

I'm in horticulture professionally and I've always learned there is no propper treatment against bacteria. Besides hygene and removing infected parts. On another forum I found that copper is the active ingredient. After doing some searches it seems that there is some effect of copper against certain bacteria (Xanthomonas amongst others). Well learned something again.

Where I have some stronger doubts is that they claim it be systemic. One can also find that copper is toxic in plants. Of course it could be depening on which form of copper they use if the plant takes up the "copper" and if it's toxic or not.

Still think that just cutting the leaf should be enough though.

It's safe to assume that any toxic product on plants has a stressing effect on the plant. I typically only use chemical products against wooly and scaly aphids.

sorry for offtopic

to Rob:

Not at all off topic!
I found your research very informative as these issues of different infections are important to many of us including me ;)
It's one thing to read what the bottle says it does and another to realize what will result.
But I do agree with both you and King in that cutting the leaf off should suffice in this instance.