Leaf spot on Aerangis

[shakkai]

Hi everyone, While soaking the mounted plants today, I noticed a problem with my Aerangis mystacidii x modesta. One of the top leaves has this 'spot' where the leaf itself has gone very translucent and the back of the leaf is turning brown. I've never seen this before - but then, I think I've been lucky so far with my plants!

Can anyone tell me what this is? And most importantly, what do I do about it?!

Here is the front view:


And here is the underneath:


Apart from the orangy-brown inside the box I've drawn on the photo, the base of the new leaves and the tips of the roots have what appears to be a natural, orangey tint to them. So far, the 'damage' is confined to that one spot on that one leaf.

[Neverend]

I have very little experience with aerangis, (just got myself a biloba today in fact!), but based on my experience with phalaenopsis, it seems to be bacterial rot.

I would treat that as soon as possible before it spreads.

[shakkai]

Thanks for that! I don't grow many Phals... so I've never seen this before. So, do I cut the whole leaf off, then?

I didn't know what it was, so it was difficult to search for a solution to what I had to do... I'll go and look up recommendations now.

Thanks again! And good luck with your biloba! That's one I don't grow, as it likes those Phal conditions that I struggle to provide...

[cb977]

I'd give that one a good squirt of Listerine. It should stop it from going any further.

[shakkai]

Thanks, Sue! I'll give that a go, and see if I can't stop it from spreading without losing the entire leaf.

[Neverend]

Thanks, I'll also suggest trying methods to save the leaf, cutting off a new leaf like that one should be a last resort, though I do not hesitate to cut off older leaves...

[FinnBar]

i'm also grateful for all the answers, i noticed very similar spots on my Aerangis mooreana.

what are the odds for this one spreading?

[shakkai]

So far, the size of the area affected has not increased on my plant. Though the brown is spreading out to fill that area that was showing as dark green in the photo. I'm keeping a close eye on mine, just to make sure. This was just one spot showing on mine, so, would this have been caused by some mechanical/physical damage that then got infected?

I hope all goes well with your mooreana! Have you got Listerine that you can use?

[Barbara]

Hi, I agree with Neverend, it looks like Bacterial Brown Spot as mentioned on this website:

http://www.ionopsis.com/Pests_and_Diseases.html

Here's the info:

Bacterial Bacterial Brown Spot This disease is most prevalent in phalaenopsis, and is as deadly as black rot is with cattleyas. It is especially active under wet and coot [cool] conditions.

Symptoms: Infection by Pseudomonas cattleyas, the bacterium involved, starts as a brown, watery blister on a leaf and quickly spreads, engulfing whole leaves. If it reaches the growing center (the crown), then the plant is essentially gone.

What to do: Act immediately. Remove infected leaves with a sterile cutting edge. Spray immediately with Physan at the rate Of '12 tablespoon per gallon of water. Repeat in a few days.


I've seen it on some of my phals, couple Onc. types and now a new Aerangis which we just added to the collection. I've read that they like warmer conditions and moisture which amounts to needing good air circulation. That can be a tall order during the cool damp days of autumn.

Hope this was helpful.

[Barbara]

[QUOTE=shakkai;66563] This was just one spot showing on mine, so, would this have been caused by some mechanical/physical damage that then got infected?

Most likely. Insects can also transfer diseases and/or create punctures where pathnogens can enter and go crazy if the conditions are right. I took a few of my orchids outdoors this summer to see how they would do, and now I'm noticing more problems like this showing up then what's normal. They also got tossed around in some wind storms and some were damaged. Needless to say, I won't be taking anything outdoors next year, just to much bug action, and inclement weather around here. Of coarse having worked in horticulture for awhile, I should have known that.