Disease symptoms on Phalaenopsis- and (upcoming) lab-confirmed diagnosis

[camille1585]

I have been battling against a few diseases on the majority of my Phal collection for the past couple of years. I am in the process of throwing out most of them (due to disease and also a never ending mealybug problem- but that’s an entirely different story).

But before throwing them out, I will, at last, find out what these diseases are. I started a new job in May, and the institut runs one of the main daignostic labs in the country. There is budget for personal projects, and I have greedy colleagues eager to get their hands on my diseased Phals…. I thought I would share this process with you, since having definitive diagnostics to match symptoms could be useful for other people.

I'm hoping that by knowing what pathogens are causing this, I can take steps to change things in my growing setup/conditions to prevent it from happening again once I restart my home collection.

So I have given them samples from 5 plants (photos in this order), representative of the general health status of all my phals :
Phal bastianii
Phal mannii ‘Dark’
Phal gigantea,
Phal Liodoro
Phal equestris x maculata

Before testing I suspected that the black spots were likely to be bacterial- probably Acidovorax cattleyae. I also suspect that my Phal gigantea is virused- on some of the older leaves there were tell-tale ringspots, and in the photo here the ringspot marks eventually got covered by generalized leaf pitting. The biggest mystery however, is what is the pathogen causing the pitting (spots and streaks). That one has by far caused me the biggest headache and spread to nearly all my Phals, even if they were on the other side of the room or a different room!

I’ll have the results in a week or two since private work is low priority, and it’s also going to take some time to run the full battery of tests. For any pathogen not already in their database they might not be able to get a pathogen ID more precise than genus level. (Still good enough for me!)

I’ll update this post once I have new information!

[Orchid Whisperer]

A lot of those leaves look like spider mite damage.

[camille1585]

Originally Posted by Orchid Whisperer

A lot of those leaves look like spider mite damage.

It does look like mite damage but it's not mites. 2 years ago I took a bunch of leaves into work with me and looked at them under a binocular microscope. Absolutely nothing... The symptoms are also very seasonal, generally appearing on new leaves and spreading on others in the winter, when growing conditions are suboptimal.

[dangerouseddy]

does look a bit like cell collapse especially if it happens when its cooler and to new leaves first as they're more tender. I could be wrong though.


Physiological Disorders in Orchids: Mesophyll Cell Collapse1

[jkofferdahl]

To what lab did you send your samples? If it was Critter Creek then I strong urge a second opinion.

[Orchid Whisperer]

Originally Posted by jkofferdahl

To what lab did you send your samples? If it was Critter Creek then I strong urge a second opinion.

Read first post.

[jkofferdahl]

Originally Posted by Orchid Whisperer

Read first post.

Nicely pointed out, ma'am.

[Orchid Whisperer]

Originally Posted by jkofferdahl

Nicely pointed out, ma'am.

Awkward.

Circle with arrow thingie = opposite of ma'am.

[camille1585]

Originally Posted by jkofferdahl

To what lab did you send your samples? If it was Critter Creek then I strong urge a second opinion.

It's the lab at the place where I work, which is pretty much the Dutch equivalent of the USDA. It's the go-to lab for the seed and horticulture industry in the Netherlands, and all samples are tested in duplicate or triplicate. There are so many controls in place when running the tests that false positives/negatives are very rare. My job here is to help develop disease screening tests, so I'm pretty confident in the results.

[Ray]

Originally Posted by Orchid Whisperer

Awkward.

Circle with arrow thingie = opposite of ma'am.

John must have been having a "low biorhythm day". Missed that fact that Camille is in Holland, and your gender.

Relatively speaking, those are minor mental glitches. The REAL faux pas - one I have a avoided, but did get to witness once - is commenting on a woman's pregnancy when it's actually just extra pounds.