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Re: mold

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, 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.  

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.  

Rick Grazzini
Centre Analytical Laboratories
rickg@centrelab.com
USDA 5 or 6 // Sunset 43
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