Erwinia, Fungus, Sunburn or Mineral damage?

[orchid junky]

Hi all,

I have noticed some brown "rot" along the tips and edges of some of my paph Michael Koopowitz and another hybrid I have. The pictures are below..

Pretty much this edge effect has been on these paphs for months.. I think the newest ones developed last summer. This paph has 1 or 2 edges like this that I know have been on it for 2-3 years now. Usually the tip or edge of the paph starts to get brown.. it's soft at first but after a couple of months it gets kinda hard/crispy.. although sometimes it just stays soft and brown too.

Mind you this plant has had this issue for at least 3 years and otherwise the fans look healthy even the ones with this weird brown edge on them My other paph has even flowered last month! At first I thought it could be Erwinia but doesn't Erwinia wipe out the plant or at least the whole leaf within days or at most within 2 weeks? Can Erwinia just be kept at bay if the plant is pretty much healthy?

The other thing I can think of is that it's some kind of mineral buildup issue since this mainly occurs on the edges and on 1-2 leaves its on the tip. The 2 plants that have this problem are in s/h??

I also have them in a window that receives lots of afternoon light so could this also be sun damage??

Any thoughts would be great.

 

[Rick]

It's not erwinia, but I would suspect more along the lines of "leaf tip burn" (salt buildup).

Go back through some of the threads on K-lite fertilization. "Salt buildup" includes the potassium in fertilizer. So without knowing all the ins and outs of your SH program, I'd still just be guessing.

Otherwise consider general low humidity and sun burn.

Erwinia is discussed in a lot of other threads for reference (with some good pics), but erwinia is a red/brown soft rot that typically starts at the base of outer basal leaves (at the plant axial). It also smells like fermenting sweet things. It can go fast, but in healthier plants it can be slower and stop on its own.

 

[orchid junky]

It's not erwinia, but I would suspect more along the lines of "leaf tip burn" (salt buildup).

Go back through some of the threads on K-lite fertilization. "Salt buildup" includes the potassium in fertilizer. So without knowing all the ins and outs of your SH program, I'd still just be guessing.

Otherwise consider general low humidity and sun burn.

Well there have been points in the time that I had this that I got lazy n topped off the reservoir... I figure that could be it... Like I said the plant has been fine otherwise... N Ive had erwinia with other orchids... N usually the whole plant is gone within a week to two..

 

[Ozpaph]

Looks like direct trauma or burn to that area given the edge only is affected and the rest of the leaf looks fine.

 

[SlipperKing]

As Rick has mentioned, salt build up is possible but typically that starts at the tip and burns its way down the leaf. This side damage is most likely as OZ suggests, sun or cold damage. Feel the leaves of your plants when the sun is at its strongest. Do they feel "hot" if so too much sun and burn is likely. The leaves must feel cool to the touch to be happy. Cold damage, the leaf edge would have to be the closest to a window/ winter time.

 

[Erythrone]

Looks like direct trauma or burn to that area given the edge only is affected and the rest of the leaf looks fine.

I am with Ozpaph and Slipperking. It looks like direct trauma or burn.

 

[NYEric]

Actually looks like physical damage. were those leaves lying against something?

 

[eggshells]

Must be the leaves that are affected were leaning on the hot glass as you stated that they are in a windows that gets afternoon sun.

 

[John M]

Welcome to SlipperTalk from Southern Ontario, Canada!

It's either sunburn or frost burn IMO. Frost burn would occure if the leaf edges were touching a frozen window. I'm leaning towards most likely sunburn. Just use a new exacto knife and cut out the damaged portions. The leaves will look better and they'll continue to function normally after that. Also, do a better job of protecting them from direct sun. Even in winter, the sun can be too strong for a Paph.; especially if the window area they are growing in has no air movement and the ambient air temperature in that area rises due to the sunshine streaming in through the window glass.

Edit: Ooops, I answered your quesiton while assuming that you were in the Northern Hemisphere, probably North America and not much further North than Southern Canada. Would you please update your profile information to give us some sort of idea where in the world you live? That makes a big difference to the culutral advice you get. It puts everything into context. Thanks very much.

 

[Paphluvr]

Looks like sunburn to me. I also am a window grower and all of my orchids are at south facing windows. I have to be particularly careful in spring and fall to make sure they don't get too much sun. In summer the sun is high enough and they're back away from the window enough that they don't get direct sun. In winter the light intensity isn't enough to burn them even though it's direct.

How good is your air circulation? With adequate circulation and humidity you should be able to keep the leaf temperatures down.

 

[Stone]

I also see possible mite damage on the leaf tip