brown rot pandemic

[Hera]

Have you cleared out the growing space and sprayed down the benches , walls and floors with a bacteriacide? Spores permeate the growing area and it might be time for a good cleaning. Forgive me if I am repeating someone.

 

[TyroneGenade]

Thanks for the advice. I think I must just keep at it. Around here the weather is hot and windy so plants dry out very fast: plants in stone need almost daily watering, and plants in bark every 3-4 days.

If I don't see any improvement in a months time then I will try the peroxide etc... The whole area is swept out weekly and the area left to dry. I think that perhaps a repot is in order.

 

[keithrs]

H2O2 gos great with repots! Wink wink

 

[TyroneGenade]

Ho Keith,

Thanks for the subtle hint.

I forgot to mention, that I water about 2x a week and the rest I spray/mist. so I'm either watering with the bleach or spraying. I had been bleaching/fertilizing alternatingly but I think I will stick to bleaching for now.

Over the next week I will start repotting and quarantining symptomatic plants (not that I think there are any unaffected plants).

Thanks for all the help.

 

[jtrmd]

This time last year I had the same issue.It took about a month to get it completely under control with a combo of Green Sheild,Bleach,and then Phyton 27.Plus getting on my hands and knees to pick up every last piece of dead leaves,bark,etc off the GH floor that I missed in the Fall.Any of the ''Junk'' plants just got tossed,and didn't bother with trying to save them.

 

[Justin]

i'm sure this has been covered in this thread, but when i was having rot problems it was partially due to mineral deficiencies in my watering & feeding program.

good luck!

 

[Rick]

Ho Keith,
Over the next week I will start repotting and quarantining symptomatic plants (not that I think there are any unaffected plants).

This is a total epidemic that I've never encountered before. How many total plants are effected (or lost) and what percentage of the population is this?

 

[TyroneGenade]

Hi Rick,

It looks like everything is affected. The moment anything starts a new growth the new growth rots from the leaf tips down. This weekend I found that one of the two growths on my Dendrochilum wenzelii had rotted... I suspect the source of the infection was the organic fertilizer I was spraying a while back. It was derived from earth worm cultures...

So far the only plants which are unaffected are:
Masdevallia tovarensis
Paph. insigne
Paph. Leeanum
There are several other Paphs which have not lost growths but also haven't put out any new growths...
I had previously thought my Restrepia were immune but several new growths also rotted. The only plant which lost mature growths was my Phrag bessae which went from 4 mature growths to one (and that one doesn't look happy). My Den. virginalis and Nobile hybrid seems OK but the kingianum and speciosum lost several growths. Both the Den virginalis and Nobile hybrid was far away from the other plants when they were sending out new growth so this does seem to be some sort of contagion. The Neofinetia and Renanthera is also, so far, unscathed. I am not sure if the Phals are resistant. I lost a lot of Phals this last year but I think it was neglect more than anything else.

Affected plants are: Tolumnia, Restrepia, Paphs, Phrags, Catts/Laelia, Dens, Cymbidiums, Dendrochilums, Masdevallia and Stanhopea.

I have started adding Ca/Mg to my water.

Jtrmd, your experiences give me some encouragement. I am now only watering/spraying with the bleach solution and hope this will prove effective.

 

[Rick]

Hi Rick,
I have started adding Ca/Mg to my water.

Is there any way to get Hardness/alkalinity/conductivity values for your water, and points in between when the plants see it?

 

[TyroneGenade]

Hi Rick,

No... Our tap water is generally soft (about 1-2 GH). I'm supplementing now with Ca/Mg up to the levels in the MSU fertilizers.

In the past, soft water hasn't been a problem.

 

[TyroneGenade]

Some photos of the problem:

In the picks you can see a Catt Trick or Treat and Dendrobium kingianum. The new growths had withered back (rotted and then stopped). There is no damage to the pseudobulbs (they are even sending out roots). Since watering with the bleach some new growths have come along better but I am not sure they are viable. The Catt growth has stalled, not growing any more for about a month now. (The L. anceps in the background, I think, is pretty much wasted, having run out of nodes to sprout new growth.) Root tips are green and growing so I don't think this a bleach problem.

 

[Faan]

What I will do is to cut away the rotten pieces as in my experience most of these "attacks" do not like fresh air and will dry up in a few day's time. Leave the wound open and give it lots of fresh air.
My concern is always that if you put something on that is wet it will just make the problem worse, unless it is something that will dry the "wound" fairly quickly.
Sometimes I have experienced that when the air circulation is not that good I could find a small area in the leave that would start a fungal or bacterial rot. I would put a needle or something similar into the area and open it up. In most cases the rotting will stop and become dry in a short period of time.

When it is like in your pictures I think you do not have much of a choice to cut the bad pieces away. The bad news is that by the time you remove those affected pieces the "sickness" could have been into the rest of the plant although you cannot see it.

 

[dodidoki]

Some photos of the problem:

In the picks you can see a Catt Trick or Treat and Dendrobium kingianum. The new growths had withered back (rotted and then stopped). There is no damage to the pseudobulbs (they are even sending out roots). Since watering with the bleach some new growths have come along better but I am not sure they are viable. The Catt growth has stalled, not growing any more for about a month now. (The L. anceps in the background, I think, is pretty much wasted, having run out of nodes to sprout new growth.) Root tips are green and growing so I don't think this a bleach problem.

Yes, I had exactly the same disease. It is pseudomonas cattleyae. But as I can see, potting media is not right. You should use only bark for catts, 2-2,5 cm size. I usually put in the bottom of pot some clay for draining water.

 

[TyroneGenade]

Hello dodidoki, and thank for confirming. Why I hadn't posted photos before I don't know... But at least know I can be a bit more confident in my bleaching the plants.

Faan, your advice about pricking the infected tissue is what I have been doing, more or less. I think once the tissue is open to the air the bacteria can't progress---kind of like gangrene.

 

[Rick]

Hi Rick,

No... Our tap water is generally soft (about 1-2 GH). I'm supplementing now with Ca/Mg up to the levels in the MSU fertilizers.

In the past, soft water hasn't been a problem.

However, it can take years for plants to build up excess K in their tissues that ultimately make them sensitive to disease. This is especially the case if you are adding true calcareous materials to your potting mix at intervals while having your soft water wash it away in between. It's a push-pull based on rates of fertilizing, pot amending/repotting, and watering.

I converted your German Hardness values to mg/L CaCO3 which comes out to (~) 18 to 36 mg/L CaCO3) which is indeed considered soft (low Ca/Mg water). Note that even though the units are expressed as Calcium Carbonate, there doesn't have to be any carbonate in the system at all. In European convention, carbonate is often labeled as KH hardness, but I know it as Alkalinity (also expressed as a CaCO3 unit). For plants/animals, the need for Ca/Mg (as US hardness values) is distinct from the need for carbonate/bicarbonate buffer (as US alkalinity).

What forms of Ca and Mg are you adding to your MSU? When I first came up with the low K system I cut the amount of MSU and "diluted" it with Calcium nitrate and MgSO4 (Epsom salt).


This feeding regime cannot "cure" infected plants, but makes all the subsequent new growth tougher and disease resistant.

 

[TyroneGenade]

Hi Rick,

If I recall correctly, I it is a solution of calcium chloride and magnesium sulfate. For some odd reason I didn't list the contents (and concentrations) on the bottle, only the dose (2 mL to 1 L). When it is done I will need to rethink the mix.

I have lots of new growth coming and I am hopeful that some of these will make it.

I have an expert visiting me this coming Friday to have a look and give some advice.

Thanks for your advice.

 

[Rick]

Hi Rick,

If I recall correctly, I it is a solution of calcium chloride and magnesium sulfate. For some odd reason I didn't list the contents (and concentrations) on the bottle, only the dose (2 mL to 1 L). When it is done I will need to rethink the mix.

I have lots of new growth coming and I am hopeful that some of these will make it.

I have an expert visiting me this coming Friday to have a look and give some advice.

Thanks for your advice.

You might consider some basic hardness and alkalinty test kits from an aqurium supply (or on-line). It sounds like you are flying blind on your water conditions.

 

[TyroneGenade]

Ah, found it. The mix would give 56 ppm Ca and 48 ppm Mg in the fertilizer solution (given the soft tap water, I haven't bothered to factor it into the formulation). The salts were both chlorides. This would give 2 mol Ca per mol Mg.

 

[Bjorn]

Tyrone,
Has there been any progress?
B

 

[TyroneGenade]

Hello,

I'm glad you asked! At the end of Feb I stopped bleaching the plants and there hasn't been any more casualties or than a Paph godefroudae "dwarf" which wasn't looking good. I am not sure if it was the bleach, the Ca/Mg added to the fertilizer or moving the plants into a more sunny spot but my Trick or Treat has managed to get two growths up and there haven't been any more casualties. Of course, I will go home to day and find another... In any case, I have now given up and what must die must die.

The bleach (and I used a higher concentration than suggested!) did not seem to hurt the plants at all. I haven't noticed any improvement in leaf color due to the Ca/Mg or move into the sun. It does look like the growths are a bit stiffer though.

Hope that helps.