Mold growing in S/H. - Orchid Board

Bruno Ville · #1 11-17-2010, 08:02 AM

Hello everyone,

About a week ago I decided to test a few plants in S/H.

It is still early to tell how they are doing, but one of the Cattleyas started to mold. I really don't know why. There were also a few new growing root shoots, that died.

Why is this happening to this plant?

The others seem to be fine.

And one more thing. I had to adapt the fertilizer to a brand available in my country. It is orchid specific and liquid/soluble. But I tested the Ph of the solution and it is around 6,2. Is that too bad?? Im using RO water.

Thanks.

Cattleya sp.:

Ray · #2 11-17-2010, 08:19 AM

The pH is probably close to perfect. I always shoot for the 5.5-6.5 range. What is the formula and concentration of fertilizer you are mixing?

When moving plants into new media, it is important to do so just as new growths with new roots are forming. Those new roots will grow to be "tailored" to that new environment, and we expect the old roots to die and decompose.

Right off the top, I can think of three potential reasons that the new root growth might fail - too cold (don't disregard evaporative cooling from that very coarse medium [personally, I think it's too coarse]), too dry (sometimes more frequent watering or misting is needed to keep the top surface moist and "root friendly"), or there is some sort of contaminant that is chemically poisoning them.

It is also possible that the particular plant was just weak and/or infected to start with and has succumbed to the stress of repotting.

Bruno Ville · #3 11-17-2010, 09:26 AM

Thanks for the reply, Ray.

Im using 6-8-6, it also has the other nutrients on the label, showing concentrantions.

As for the humidity, I see condensation up to around an inch from the surface.
I don't believe the temperature is that cold. The minimum is around 70F at night.

As for the medium, this is the hardest to correct. Would be quite expensive to import the PrimeAgra to Brazil, I believe. Shipping costs would probably be quite high due to size and weight, and my country charges 60% over importations, including shipping costs.

Medium was my main concern when I started.

As for misting, Im not doing any. How do I know if the roots need misting? Should I use plain RO water or the same nutrient solution?
Should I use folliar feeding or the roots are able to get everything the plant needs?

Ray · #4 11-17-2010, 05:24 PM

Hi Bruno.

I was not going to recommend shipping PrimeAgra into Brazil - surely you can get Aliflor of different sizes.

At what concentration are you mixing the fertilizer?

I don't think using RO is necessary, nor desired with that fertilizer, I'll bet.

I agree with your temperature assessment.

Bruno Ville · #5 11-17-2010, 06:33 PM

Im using 0,8 ml per litre, (I tried to calculate 1 teaspoon/galoon and converted to ml/l).
I also added 6 drops/litre o B vitamin complex, which I read could help in root growth.

The fertilizer Im using is this one:
Biofert - Planta é bom demais!
Could you take a look and see if it is fine? Scroll down the page a bit and you will find the composition, under a pink word: "Composição".

Also, I googled for Aliflor and didn't find anything in Brazil. Do you have a link for it??

Thanks very much for the help! I really want to make S/H work down here.

Anisa · #6 11-18-2010, 12:24 PM

I dont see mold in your picture. It rather looks like fungal infection. Mold and fungal infection can be killed spraying fungicide or diluted household disinfectant. I dont know what is available to you, but you can search forum for recipes.

Bruno Ville · #7 11-18-2010, 03:34 PM

There is mold in there, maybe the picture doesnt show well but I see a lot of white hairs. It doesn't seem to be growing more, thou.

Anisa · #8 11-18-2010, 03:50 PM

Either way fungicide and increasing your air flow should help.

Ray · #9 11-18-2010, 04:39 PM

1) At 0.8 ml/L of that formula, you are applying at a concentration of about 65-70 ppm N, which is fine. I might go stronger, but it's not critical.

If the "white hairs" are in a web form, it's definitely a mold. If they stand up more like whiskers, it's probably manufacturing residues coming from the LECA.

Bruno Ville · #10 11-19-2010, 08:51 AM

What would you reccomend to achieve 100-150 ppm??

Also, how do I know if they need some misting?

What about the Aliflor LECA, where is it manufactured?