Severe Root Burn - Orchid Board

qze · #1 06-06-2009, 07:50 PM

I have had my lc in Prime-Agra for about a year now and fertilized it with MSU (pure water) at 100 ppm twice a month. In the past few months, it hasn't been able to put out new roots without the tips turning black and shriveling up, which is evident from the visible shiny salt build-up at the surface of the pellets and brown residue at sides of the pot. I read in another thread that the salts were alkaline, so I tried soaking the plant in distilled water mixed with vinegar and lemon juice everyday for a few hours. But that didn't make a significant difference. Is there any way to purge the salt from the pellets and the pot?

Des · #2 06-06-2009, 08:35 PM

It can be quite difficult to remove salt build up in the clay pellets also if you are using a clay pot this will aggravate the build up of salts. I would suggest repotting into fresh media and a new pot.
A 100 ppm of fertilizer does not sound that strong to me, although i must admit that I am not sure about this as I measure my fertilzer strength in micro siemens. Are you sure about your water source as this sounds more like a buildup of calcium carbonate not fertilizer salts
I have also noticed in the past that if the plant is not anchored firmly in the pot the new root tips will rub against the pellets which are very abrasive, especially if they are dry, damaging the sensitive root tip which will turn black and stop growing
Hope this helps

Ray · #3 06-07-2009, 04:04 PM

1) PrimeAgra, because it was designed to absorb and release well, has a fair amount of manufacturing residues in it that require pretty thorough cleaning before use.

2) If you are allowing the LECA to dry out between waterings (especially at the surface), you are forcing the concentration of the dissolved minerals.

3) Read this, you might find it informative:
Phrag. Roots In S/H Culture - The Orchid Source - Orchid Forum

4) It is PrimeAgra, huh? I am the sole source of supply, and have never shipped any to Malaysia.

khozmo · #4 08-16-2009, 01:45 PM

Ray so you are saying that misting the top of the pot in the morning will help. I have a similar issue. When the roots his the PA they generally dry up or go black.

Ray · #5 08-16-2009, 04:45 PM

I don't ever have that issue, as I grow in a very humid greenhouse.

If your conditions result in excessively fast evaporation of the liquid from the pots, as indicated by the apparent "dry line" being well below the surface, then misting the top of the medium as roots first start to come in contact with it can help. Once they penetrate the surface, they grow deeper and deeper with no issue.

I have absolutely no idea if a morning mist will help. If your environment is really dry, it may take a couple of times a day. Then again, if it's THAT dry, you really should do something to raise the humidity, as that's bad for the plants in general.

Sun rm.N.E. · #6 08-16-2009, 06:16 PM

First, I think thorough soaking many times, in a large quantity of water, of the original material is essential and it depends on the type of leca you have and how much toxic salts it contains. This involves more than just cleaning off the visible junk.

It is ironic that that those of us with low humidity and most salt build-up benefit the most by passive hydro once we deal with the side-effects. My humidity is low in the Winter and had experienced extensive loss of new roots with some type of leca even after a lot of soaking, followed by boiling out most of the original toxic material several times in a huge pot, which I did as an experiment. I have not found a practical way to eliminate long-term build-up, however, even though I first wet the surface to dissolve salts and wait before I flush. Different plants also have different sensitivity to salt.

Since now I start with well leached leca, I do not find it necessary to repot the entire plant. If I see new roots developing I just dump the top 1/2-1 inch or so of leca, if it shows salt crystals, I replace with freshly leached material (you can see the crystals glistening in high light, the chalky calcium deposits do not seem to be as toxic).

I hope this helps.

orchids3 · #7 08-19-2009, 05:39 PM

Dose anyone check the pH of the water the pot holds to determine pH of the media? (Besides me) I flush the ports every 4 to 5 waterings to wash out residue - anyone else? Understand the only way to get salt out of media is to flush - no chemical additives will help.

Jerry Delaney · #8 08-19-2009, 11:14 PM

Those of you that are using RO water, this may not be even applicable to you. I use only tap water which here has a pH in the mid 7 range. I flush once a month using tap water adjusted to a pH of 5.0 to 5.5. I know that the water really has no buffering capacity but in the media with residual salts, I really don't know if that changes anything. Does anyone think that the pH of the flush water makes any difference?

Becca · #9 08-20-2009, 12:43 AM

Here are my thoughts....and mostly it is what I have learned from Ray....and I must admit...I light bulb came on in my head the other day with a problem I was having...so I hope my words will help. I have had a few orchids established in Prime Agra. I didn't start them at the right time (no new root growth) so it took them a while to adjust. One constant problem I had been having was the residue build up on the roots on just a few particular orchids. I have been keeping them in good humidity in the orchidariums so I couldn't figure out why in one orchidarium I had no problems but the other I was having problems...both had great humidity. Then it occurred to me that the ones I moved back into the orchidarium where I struggled more with humidity but was still able to keep it up, I was having the residue build up. Some of the pots seemed to dry out a little quickly as well. Then the other day it occured to me....I think what was keeping my humidity up in that orchidarium was the evaporation of the water in the s/h pots....thus I was seeing the residue build up...not just on the roots....but on the rhizome and base of the p-bulbs! I don't know why it took me so long to figure this out....but perhaps this might be something that is going on with others having the residue build up problem?

Ray · #10 08-20-2009, 12:08 PM

Once you have thoroughly cleaned the LECA, the only sources of the "residues" or "buildup" are what's in your water supply, what you add to your water (fertilizers, additives), and waste products from the plants' biological processes.

It is more easily observed in S/H culture, because those residues get transported up to the top of the medium, where all of the evaporation is occurring. In "regular" media, the transport to the top is not as great, so the entire pot full builds up residues more-or-less evenly.

Assuming you're watering properly to flush the pot, the amount of buildup in an s/h pot is actually considerably less than with traditional culture.

Addressing orchids3's question: the clay particles are inert and pH neutral. I stored some cleaned PrimeAgra in a container of RO water for almost a year, and a water analysis showed no increase in the dissolved solids. The pH was down very slightly, most likely from CO2 in the air.

On the other hand, the pH in the reservoir will change drastically as a result of the plants' biological processes. A few years ago, several of us tried measuring the pH, and found it to be as low as 3 or 4, especially first thing in the morning, after the respiratory processes dumped all that CO2 into the root zone. THAT'S why I insist that folks fill pots rapidly to the top and let it drain, so the reservoir gets flushed and the chemistry returns to normal. Topping up just dilutes the bad stuff a little, and plugging the holes for a while just mixes it with new solution.