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Re: mold

Richard Grazzini wrote:
> 
> Diana,
> Loren Russell has been handling this pretty well at the list level.
> 
> But ...
> ----------
> > From: Diana L. Politika <diana@olympus.net>
> > To: seeds-list@eskimo.com
> > Subject: Re: mold
> > Date: Monday, November 03, 1997 11:46 PM
> >
> > >
> > > Rick,
> > > I did use *brand new* soilless mix, and *brand new* 1 gallon ZipLocks.
> No, I
> > > did not sterilize the cuttings. ( By this, I assume you mean a dip in a
> > > slight bleach solution.)
> > If you had done this, you'd also have had NO cuttings to speak of.  Be
> > very careful with bleach and cuttings.  Even trays that have been soaked
> > in a 10% solution to sterilize MUST be rinsed well.  I had suspected
> > this thru past experience, but have also seen it discussed in recent
> > trade publications.
> > Aside from using a laminar flow hood, as is used in TC, a sterile
> > environment is impossible.  The mold came, most likely, as a result of
> > no air circulation and warm temps.  A light mist of a broad spectrum
> > fungicide prior to sealing the Zip-Lock should help.
> 
> Diana, I do indeed surface-sterilize any cuttings I root, especially those
> that go into a closed environment (the plastic bag trick).  The cuttings
> get dipped in a 1 to 2% Chlorox solution, rinsed throughly,
When you rinse it throughly again, you've just lost your sterile feild. 
Your hormone dip is also not sterile.  My point here is that STERILE is
just that, STERILE.  The subject we are discussing is STERILIZATION,
rather than cleaning, or degrees of.  I oftentimes speak literally, and
perhaps have taken this subject beyond its' point.  But again, sterile
is sterile.  No ifs, ands or buts.  And I do not beleive that chlorine,
followed by dipping in water, sterilizes anything.  A basic class in
microbiology teaches that.  Not to mention the cross contamination,
chlorine has to remain on the surface for 20 minutes or so to be
effective.

 re-cut, and a
> hormone treatment applied (if needed) before sticking.  I also routinely
> dip all re-used pots and trays in 1 to 2% Chlorox.  These then get rinsed
> extremely well, and allowed to air-dry for many days before use.  I have no
> problems.
Once again, this is a degree of cleaning.

> 
> But the key is to rinse THOROUGHLY.  No, I don't use sterile water.  The
> point is not to get absolute sterilization and to maintain that sterility,
> the point is to knock down the populations of fungal spores (in particular,
> Botrytis) that are going to be on the plant surface.  Obviously, infections
> that already exist are not going to be controlled by the bleach, but might
> be controlled by a systemic fungicide.
> 
> I agree that the fungicide is a good idea.  I have used benomyl and
> chlorothalonil successfullly in these circumstances, too, but feel that the
> bleach treatment is generally sufficient.
> 
> Diana, I also have successfully done TC without a laminar flow hood.  If
> you can control drafts and work within a box that minimizes vertical
> contamination (falling spores), there's not much contamination that occurs.
>  I've seen people use large aquaria turned on the side.  I've seen
> plexiglas and plywood boxes built and used.  I do my work in a chemical
> fume hood with the fan off, and the sash partially closed (I manage a
> commercial research lab --- the hoods are available to me).  Are these
> systems contamination-free?  No.  Are they good enough?  Unless you want
> absolute zero contamination, yes.  The success rates that I have seen and
> experienced are quite high.  Maybe not good enough for a commercial TC lab,
> but for someone dabbling in TC, it works just fine.  Surface sterilize all
> surfaces with 70% alcohol, and go for it.
After my experience with flasking orchids, which included 10 months from
pollination to seed pod, $35 for nutrient agar, an entire morning spent
boiling agar, readying flasks, cooling, cleaning the pod, maintaining a
sterile field, and finally the sowing of the seed, all done in an
aquarium tipped as you stated above.....I saw mold and fungus infect
every last flask.  Once again. sterile is sterile.  No middle ground.
I see no advantage to trying Mickey-Mouse techniques for serious
business.  If its a hobby, that's one thing,  but the time and effort we
put into the orchids taught me that it wasn't worth it.
> 
> Rick Grazzini
> Centre Analytical Laboratories
> rickg@centrelab.com
> USDA 5 or 6 // Sunset 43
References:
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