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Re: Regulation of compost teas (was: NOSB loses its head)



Hi Joel, jeff and Greg,

Joel wrote:
> I do not doubt that increasing the community of beneficial
> microorganisms on
> leaf surfaces will often improve plant performance...

Compost and manure are complex and diverse materials and they are
beneficial in many ways.  But people who use compost "tea" to control
diseases are probably getting benefit by altering leaf surface flora.

> What I am skeptical about is the benefit of increasing microbial
> populations in compost teas using sugar, molasses, nutrient
> solutions, or aeration...

Well, if you add sugar and aerate compost leak water, SOMETHING is
going to grow like wildfire, and it will probably be some sort of
bacteria or yeast.  Maybe positive responses from these "teas" are
non-specific reactions to large amounts of sub-pathogenic microbial
pressure on the plant.  Maybe there are antibiotics involved.  It is
probably a very hit-or-miss game.

> As I wrote earlier (but perhaps obscured my meaning with a typo),
> the great **majority** of soil microorganisms (>95%) are unculturable
> using all known types of media (let alone something very simple like
> glucose). Why does selective enhancement of the "greedy"/r selected
> species improve the performance of a compost tea ?

What is going on may be very simple.  Probably there is some abundant,
culturable yeast or bacteria in many composts, and this is what takes
off on when they add sugar and air.  There must be some literature on
the manipulation of leaf surface flora using biocontrol agents.  I
don't have time to search right now.

> As Dale implied with his question about applying cultures of known
> biocontrol species, the # of bacteria or fungi applied per square
> inch of crop leaf surfaces should be less important than the species
> composition of compost teas.

I don't know, maybe it is a mass-action kind of thing.  It would be
very valuable to take samples of successfully brewed compost tea and
perform dilution plating to see what is in there.  Someone must have
done this.

> I want to know if people have found that compost teas work better
> after they
> have been supplemented (with sugar, nutrients, oxygen...).

Yeah, It would be nice to get comments from someone with hands-on
experience with compost tea.

Dale

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