Die-off of active new roots in S/H - Orchid Board

slide1475 · #1 02-05-2009, 03:49 PM

Hi,

I have quite a few plants in S/H and things had been going well for weeks, but now I see that some of my S/H repotted plants may be starting to fail. The roots that were growing so well have died, blackened, and are starting to slime. A few of my Bulbophyllums look to be the hardest hit (particularly a Bulb ramosii and a Bulb liliacinium). The ramosii still has older roots that are green and viable, but the new roots that were actively growing have been lost.

Could this be from an overdose of fertilizer? superthrive? K-L-N? I feel like I saw this problem after misting on superthrive... Is overdose or burn a common problem in S/H?

Ray · #2 02-05-2009, 05:40 PM

Temperature too cool?

slide1475 · #3 02-05-2009, 05:45 PM

Hi Ray,

I dont think the temperature could have been too cool - I forgot to add that I keep my collection in an orchidarium and have been keeping the temps on the higher side even in the evening (high 60s to low 70s for night, up to low 80s during the day) to promote root growth.

Since these two are the hardest hit, I have moved them into an even shadier spot - not hard to find a shady corner of the orchidarium since I live in NYC and my windows are all north/northwest.

Becca · #4 02-05-2009, 07:36 PM

Are the roots that are rotting previously established but active roots that they had before you transferred them to s/h?

slide1475 · #5 02-05-2009, 08:03 PM

Hey Becca!

OK, on the Bulb. lilacinium was growing roots for a while before being transplanted to S/H, but they were stunted and not too enthusiastic. Then, when I transferred to S/H, the roots were very happy and growing like mad. Now they are at least 50% if not more dead and rotting.

The Bulb. ramosii had just started putting out new roots from the newest growth when I replanted to S/H. They were looking really good and growing strong for at least a week and then died off at the same time (or very nearly) as the Bulb. lilacinium.

s.kallima · #6 02-05-2009, 09:22 PM

I have a Bulbo wendlendianum in S/H since august 08. At the time I put it in S/H, it had a lot of roots growing, but not many new ones.
It lost most of the roots after the transfer, and a few psb dried. I then trimmed the dying roots and kept 1 or 2 cm of the remaining green roots.
As the plant in general was still alive and lots of roots still green (at least the part above the pellets), I decided to keep it in S/H.
Only at the end of November it started to grow new roots from the 2 last psb on the rhizome, the existing roots were actually branching into new ones. A few of these died when they came into contact with the top layer of pellets, and I think it is because of salt deposit.
I noticed the same thing with other plants in S/H : the top layer of pellets dries up quickly, and if i don't spray everyday, the roots touching them die.
But the roots that manage to go down under this top layer are fine, I guess because the pellets stay moist all the time and the salts are not as concentrated at their surface. (BTW I use hydroton pellets)

Right now my Bulbo is growing a few new roots and a brand new psb

I hope yours get better !

Becca · #7 02-05-2009, 11:31 PM

Quote:

Originally Posted by slide1475

Hey Becca!

OK, on the Bulb. lilacinium was growing roots for a while before being transplanted to S/H, but they were stunted and not too enthusiastic. Then, when I transferred to S/H, the roots were very happy and growing like mad. Now they are at least 50% if not more dead and rotting.

The Bulb. ramosii had just started putting out new roots from the newest growth when I replanted to S/H. They were looking really good and growing strong for at least a week and then died off at the same time (or very nearly) as the Bulb. lilacinium.

They may have seemed happy, but if they aren't tailored to growing in s/h culture then more then likely they will die off and the new roots will come in and adapt. Transferring to s/h takes a lot of patients. If you have new roots growing you should be ok once they take over. My other thought is if you are growing in low humidity you will have problems with high evaporation rates which would cause the roots to stay cool and rot (I learned this from experience and figured it out with the help of Ray).

Sun rm.N.E. · #8 02-06-2009, 03:47 PM

Just like to mention my experience. Perfectly beautiful brand new roots blackened as soon as they hit the media. No spreading rot observed since immediately above the damage new clean root branches formed quickly. Right next to it in other S/H pots, similar plants with media that was slightly different, no visible mineral deposit, new root tips did well with same humidity, nearly the same temperature and light. My problem seemed to be mineral deposit forming on top of this particular media that was clearly visible with magnification.

What seemed to help is changing out the top of the media to very well soaked and rinsed new ones and also spray/flush with tap water any new root tip at least daily until it passes this chemically toxic deposit layer that seem to concentrate on the top layers of the media. Once roots develop a cover of velamen they seem to tolerate this toxic zone better than the naked growing tips.

slide1475 · #9 02-06-2009, 06:41 PM

Hi Becca, Hi Sun rm,

The humidity is quite high in my orchidarium (generally over 60% day and night and the temps are nice and warm) so I am inclined to believe that Sun rm's experience is a bit more in line with what is going on. I have been noticing some white filming on the medium so I will flush the pots with tap water and mist religiously in the mornings (give it time to evaporate off the leaves and not open myself up to rot, etc). Also, I believe I will add a bit more medium and top off the pots to bring the medium level above the level of the roots.

Has anyone else had this experience of a "toxic layer" deposited on top of the medium?

Ray · #10 02-07-2009, 05:54 PM

Slide - your post suggests to me that you did not clean the LECA sufficiently before use.

In the manufacturing process, there are "binders" added to the clay to stick it into balls before firing, and usually, non-potable water is used to quell the dust and cool them rapidly after firing. The better the grade of LECA you use, the more absorbent they are, and the more of those residues will be present when you first get the stuff, so a very thorough cleaning and soaking is necessary.

I'd like to throw another possibility into the mix: As you live in NYC, your water is probably as close to pure as any municipal water supply in the country. As such, you are pretty much forced to use a fertilizer designed for RO, or your pH could be damagingly low.