Black identations on pseudobulbs?

[Fredmax]

Hi, sorry for the stream of questions but hopefully I can assist others when I get the hang of this.

I'm encountering these black marks across some of my plants bulbs and would love to understand the cause? Do the pictures look like mite or insect damage, or a result of fungus?

I'd like to apply a treatment promptly but don't want to use a blanket approach without knowing what's occurring, I'm hoping someone here has seen this before.

Thanks

[SouthPark]

Fred - hard to say what's causing that right now. It could be due to any one of those things you mentioned. Or one of those things could lead to another.

Does your growing area have a little natural air-movement most of the time? That can often help cut down on that sort of thing ----- as in cuts down on fungal and/or bacterial activity - on the outside.

Do you keep any yates anti-rot phosacid ? If it is fungal related - then that's one product to try out - making sure to mix with the recommended dosage (with water).

Also - maintain suitable ranges of growing temperature, which you're probably doing already.

[Fredmax]

I have the anti rot, but thought I'd try mancozeb first in case it was bug related - mancozeb seems to cover both?
Is that a good approach? If it continues to spread I'll know it's not working.

Speaking to a commercial grower I understand a fan is needed 24 hours even in winter, maybe this is something I have to look at (but my heating bills are hurting me already).

The bulbs are zygonesia, neogyna and lycomormium, the last two should be cold tolerant so don't believe it could be caused by the temperature in their case. The Zygonesia never transitioned from Qld to SA successfully but keeps trying to put out growths (which decay).

Is there an all round treatment I should apply periodically, I've only applied Confidor spray/tablets once I discovered what mealies could do to my paphs and phals but don't have any more hygiene routines, which may be my downfall.


Thanks again.

[Fredmax]

Zaleton and Algaecide look to be next on my cleaning list, apparently the same active ingredient as Physan20 is present in Alganox or Hy Clor from Bunnings so will give this a go.

[SouthPark]

Originally Posted by Fredmax

I have the anti rot, but thought I'd try mancozeb first in case it was bug related - mancozeb seems to cover both?

Is that a good approach? If it continues to spread I'll know it's not working.

You could try it that way. If the situation isn't critical, as in that region doesn't appear to be spreading much or quickly, then trying the non-systematic fungicide mancozeb is quite ok. Yates anti-rot phosacid is a systematic fungicide.

Definitely - the treatment will be effective if the target is what the treatment is meant to handle. If the issue is bacterial, then a treatment that doesn't harm the particular type of orchid will be needed (eg. maybe copper spray, which they say can handle some sorts of fungal and bacterial issues).

Confidor will likely handle mealies. Suitable dosage of imidacloprid can handle mealies (but keeping in mind that substance is nasty on bees).

[Ray]

To me, at least the first two photos appear to be the work of insects or rodents.

[Fredmax]

Originally Posted by Ray

To me, at least the first two photos appear to be the work of insects or rodents.

Hmm rodents, I have caught half a dozen tiny mice in recent weeks, I hadn't thought of that. I'm more equipped to deal with them than Fungus, thanks.

@SouthPark, I will stick with the systematic option in that case as you've suggested as a precaution for fungus.