sterilization question

[Denver]

I am about to get a new flask and am wondering people's opinions on if it is necessary to sterilize the medium before I deflask into it? From my reading it doesn't seem to have a definitive answer, just trying to get opinions. For those who say it is necessary, what is the best method? I will be potting into a bark, sphagnum, charcoal, sponge rock mix.
thanks in advance!

 

[Ozpaph]

I use new, clean mix and deflask with Mancozeb.
The world is full of germ so the mix will be sterile for a very short time anyway.

 

[Bjorn]

I put the mix in the microwave and heats it until its scaldingly hot. Does not kill everything, but at least keeps some of the "competition" at bay. I am making my own mixes based on bark, sand, and moss etc.

 

[naoki]

I use a pressure cooker for 20 min. I put the mix in some other container, and put it in the pressure cooker with a little bit of water, so the water doesn't directly touch the mix. It is basically pressure steaming. It is somewhat similar to autoclaving in the lab. The kitchen does smell like wet forest floor after this. Some people may not like it, but I think it could be considered refreshing (experience of camping without dealing with cold rain). I haven't tried without sterilizing, so I don't know if it helps or not. For the plastic pots, I just spray Physan-20. I spray/drench seedlings with aspirin water (they haven't used the immune pathway in the flask, so I'm trying to kick start it), and don't use fungicide at first.

 

[PaphMadMan]

If you sterilize a potting mix you eliminate the healthy normal microflora that would result from the natural materials in the mix. This actually leaves it wide open for an aggressive unhealthy microorganism to move in and take over catastrophically. Established normal microflora would inhibit at least some undesirable types. I'm not saying it happens often, usually a healthy microflora develops as spores etc. come in contact with the sterile medium. And I'm not saying I would never sterilize, just be aware of a potential down side. And it doesn't stay sterile for long unless you are taking extreme isolation measures.

If I did want to sterilize potting mix I would use a pressure cooker for 20 minutes, as suggested by noaki. The forest floor smell is mostly from a compound called geosmin, produced primarily by Streoptomyces bacteria, part of that healthy microflora I mentioned.

 

[Stone]

If you sterilize a potting mix you eliminate the healthy normal microflora that would result from the natural materials in the mix. This actually leaves it wide open for an aggressive unhealthy microorganism to move in and take over catastrophically.

Couldn't have put it better! Sterilization is risky and not necessary.
On the other hand, ''Solarization'' is very effective at destroying most fungal pathogens and leaving the beneficial types thriving. If its still reasonably hot there you could try that. Keep moist mix about 5-10cm deep in closed, clear plastic in the sun for a week or so.
Having said that, I don't bother and don't get damping off troubles but I do drench in banrot WP after potting to make sure. If you use a clean fresh mix as Ozpaph suggests you are unlikely to have trouble with pathogens.

 

[Ozpaph]

Mike, do you like Banrot? Where do you get it? Thanks

 

[Denver]

thanks for the replies. I went ahead and potted up my Paph adductum flasks from Chuck Acker last night into a fresh but unsterilized mix of bark, sphagnum, perlite, and charcoal.

I'll post pictures sometime this weekend

 

[polyantha]

There is another factor that could eventually be interesting in the future: especially inline breeding can produce weak plants which are not adapted to germs. But these germs will come in contact with the plant sooner or later. So probably you could think about deflasking without fungicides whatsoever if you have enough plants and if you are willing to take the risk to lose a big part of them.

 

[AdamD]

Survival of the fittest. I look at it this way, I don't have room for all of them to survive! Just those best adapted to my conditions.

 

[Stone]

Mike, do you like Banrot? Where do you get it? Thanks

I love it. I still have some left over from years ago when I was in the biz.
I either soak or drench the flasklings and have never had any damage at all. Even really delicate things like tiny immature kovachii which should have been replated.
You need an ABN or a nursery person who can order it for you. But make sure you get the wettable powder not the liquid. Brett M told me he had damage from the liquid.

 

[Paul]

Hello,

To me: no sterilizing at all when deflasking. Be sure to have a fresh compost
I use both Orchiata classic or sphagnum moss + perlite

 

[Ozpaph]

I love it. I still have some left over from years ago when I was in the biz.
I either soak or drench the flasklings and have never had any damage at all. Even really delicate things like tiny immature kovachii which should have been replated.
You need an ABN or a nursery person who can order it for you. But make sure you get the wettable powder not the liquid. Brett M told me he had damage from the liquid.

Thanks for the info.

 

[PaphMadMan]

There is another factor that could eventually be interesting in the future: especially inline breeding can produce weak plants which are not adapted to germs. But these germs will come in contact with the plant sooner or later. So probably you could think about deflasking without fungicides whatsoever if you have enough plants and if you are willing to take the risk to lose a big part of them.

While it is true that inbred plants can be weak, there is no basis to imply they won't be adapted to germs. All plants are exposed to germs from the moment they come out of flask, sometimes even before they come out of flask. They must survive to maturity before they can be used for breeding. There is no way to accidentally select for germ intolerance except in a germ free environment.