The Orchid Forum, for the UK and Europe (previously known as The UK Orchid Forum) • View topic - Fredclerkeara/Cycnodes black spot infection?
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PostPosted: Wed Aug 16, 2017 5:19 pm 
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I have been trying for some months to kill a nasty looking black spot infection all over my Fred.After Dark, and now its starting to spread to my Cyc.Taiwan Gold.

I'm assuming it is bacterial, rather than a virus, so I've already done on bleach bath a few weeks back (seemingly no effect) and covered it in cinnamon and some mite powder as well in case there are critters too. Seems to always start as a new leaf emerges, which then develops a few light brown wet spots that quickly go dry and black.

The plants are growing outside, so plenty of fresh air BTW.

I'm new to Catasetum types, so any advice (even if its bin them) would be appreciated. I've been trying to salvage in the hope the problem may at least get shed along with the leaves in autumn if I cant eradicate it!

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PostPosted: Thu Aug 17, 2017 10:02 am 
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If you're growing them outside, I'm inclined to say they are probably getting a bit too chilly at night as I'm sure Catasetums are warm growers. They are known for leaf spotting and being mite magnets. Bear in mind that the foliage is deciduous so as long as diseases don't get into the pseudobulbs all should be well.

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PostPosted: Thu Aug 17, 2017 1:51 pm 
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Telipogon wrote:
If you're growing them outside, I'm inclined to say they are probably getting a bit too chilly at night as I'm sure Catasetums are warm growers. They are known for leaf spotting and being mite magnets. Bear in mind that the foliage is deciduous so as long as diseases don't get into the pseudobulbs all should be well.


Thanks for the advice. Yes, I wondered if all this rubbish weather lately isn't helping. I will give them a final disinfect and then move them indoors and see if it makes a difference.
Chris


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PostPosted: Fri Aug 18, 2017 7:25 am 
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Hi Chris,

Sorry I can't be of any help whatsoever for the main reason I've stated before in that I have no confidence in accurately identifying whether a blemish is a bacterial, virus or fungal infection :confusion-scratchheadyellow:

I've quickly looked on one Website (the American Orchid Society) and they have helpful photos but some of the ailments look much like the other leaving me none the wiser :confusion-scratchheadyellow: :confusion-shrug:
As Teli has pointed out, with a deciduous plant, at least you'll get a second chance for a brand spanking new, blemish-free plant next year :dance:
But with an evergreen like my Aerangis articulata, no chance. I gave it the bleach treatment a few weeks back which hasn't killed the plant but it doesn't appear to have killed off what ever was causing its leaf-blotches either.
It has a still-maturing 30cm flower spike which thankfully doesn't seem to be affected, I've removed the affected top pairs of leaves and after the spike has gone over, will remove the top half of the plant leaving a lower stump of 4 pairs of unaffected leaves then play the waiting game to see that the lower leaves don't become affected, and that the plant will have to put out a new side-growth to continue its flowering.

Otherwise I can see a trip to the local dump.

Its very frustrating and disheartening when these marks appear, its a shame some-one hasn't invented a "cure-all and everything in one go" solution.

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PostPosted: Fri Aug 18, 2017 7:31 am 
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I've done better preventing leaf spotting and diseases by dropping the humidity and being vigilant for sap suckers which spread diseases around. I use soft soap flakes made into a spray or dunking solution in a bucket.

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PostPosted: Fri Aug 18, 2017 8:15 am 
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Hi Teli !

Not sure but I don't think my humidity is that high?, on average mostly around 50% rising to 60/70% after spraying/watering and I always have a fan going but I can try just opening the windows and leaving the door open to create a through-draught (until winter! so thanks for that, I will certainly give anything a try.

Steve


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PostPosted: Fri Aug 18, 2017 8:36 am 
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I've always been taught by other growers that I should keep humidity up, but when I do I get problems even with fans running so now I don't worry about it (windows open, door open, etc) and i'm having fewer problems.

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PostPosted: Fri Aug 18, 2017 10:42 am 
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Telipogon wrote:
I've always been taught by other growers that I should keep humidity up

Me too, no wonder (some of us) are confused ! :crazy:

Of course, there are a number of factors which could contribute to problems, mine could be the use of rainwater from the dirty old roof even though I filter it through aquarium filter wool and carbon before use?

Have tried bleach, but today I am trying "Dettol" surface cleaner, but only on a single plant, an off-shoot of Dend. Victoria-reginae.
It states it kills 99.9% of bacteria & viruses (but if anything, I've probably got the 00.01% which it doesn't kill! :roll: )....well let's just see !

An added bonus, it contains Lime & Mint so I could knock myself up a quick cocktail while I'm using it?

Steve


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PostPosted: Fri Aug 18, 2017 10:44 am 
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I think it'll only kill on contact, though. There'll be no systemic action inside the plant. I was surprised at the bleach thing at first but then you put bleach in the water with cut flowers to stop them rotting and it doesn't damage them at all.

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PostPosted: Fri Aug 18, 2017 1:15 pm 
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Telipogon wrote:
I think it'll only kill on contact, though.

That's okay, the aim is to use it as a preventative measure maybe spraying once a week.
I'll see what it does to my "trial" plant over a couple of months.

Steve


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