November 20, 2003: Microbes are the hottest
topic and yet the least known aspect of organic agriculture.
The U.S. northwest has for years been the epicenter of compost
tea research and use in North America. Below I relate some
of the things I heard at the conference – whether during
hallway discussions, in the dining room, or from speakers
The inimitable Bob “Amigo” Cantisano of Organic
Ag Advisors and Aeolia Organics of North San Juan, California,
presented a design for a compost tea maker that costs just
a few dollars (plus an air compressor), and is yielding compost
teas with microbe counts that are higher than the counts from
expensive compost tea makers. Here is a rough description
of it. (Disclaimer: this description based on Amigo’s
diagram and explanation at the dinner table is limited in
its details. If you want to make one you should contact Amigo
for more details at firstname.lastname@example.org).
Run a hose into the bottom of a barrel (i.e. 55 gallon drum),
and there connect it to a soaker hose. Connect the other end
to an air compressor. Fill the barrel with water to roughly
¾ capacity. Don’t forget to aerate the chlorine
away. Securely attach some shade cloth (cheap and effective
mesh) around the top of the barrel in such a way that when
compost is put into it, the aerated water bubbles up and soaks
the compost but doesn’t submerge it. The water level
should be just below the sagging shade cloth with compost.
That’s it. Amigo uses 10:1 weight to weight of water
to compost, or 30-35 lbs compost per 45 gallons of water (about
what a 55 gallon drum would hold for this setup). The soaker
hose, according to Amigo, makes a fine air bubbler.
Alison Kutz-Troutman of Sound Horticulture in Bellingham,
related her experiences with controlling powdery mildew in
greenhouse-grown plants with compost teas. Alison uses kelp
extracts as a compost tea additive and also side-dresses with
azomite, a rock dust product widely available from organic
product suppliers. She thinks that bi-weekly or even tri-weekly
applications of compost teas are sufficient. Alison related
a story about the effectiveness of her compost teas in controlling
powdery mildew. While she was away on a trip, her greenhouse-grown
sage plants were left unsprayed, and were 90% covered with
powdery mildew when she returned. She applied undiluted compost
tea twice a week and within a couple of weeks mildew was completely
Swearing by kelp
Several veteran organic farmers I talked to swear by kelp
products, whether in compost teas or as a stand-alone foliar
spray. Nearly all of the kelp extracts used in agriculture
come from the common North Atlantic kelp species Ascophyllum
nodosum. Kelp contains some 60 naturally occurring major and
micro nutrients, carbohydrates, and 18 amino acids, vitamins
and naturally occurring growth promoting substances. Mannitol,
a chelating agent that potentiates the transport of cations
like calcium and iron into plant cells, is one of the primary
beneficial compounds in kelp.
A number of companies harvest kelp from the coast of Nova
Scotia where the tides fluctuate by 20-30 feet. Kelp under
these conditions is alternately dried out, frosted, stretched,
and wetted, and therefore contains a number of compounds that
apparently enable plant cells to withstand these stresses.
Lynn Rogers of Microbial Matrix Systems in Oregon (www.microbialmatrix.com),
just this year opened a laboratory for analysis of composts,
compost teas, and soils. Lynn worked for Elaine Ingham before
deciding to go her own route. Lynn says that she has had excellent
results from inoculants containing plant growth promoting
PGPR can be a number of genera, but the most common ones
are the fluorescent pseudomonads (Pseudomonas fluorescens)
and Bacillus subtilis. The inoculant Lynn used is still under
proprietary development, but dozens of companies sell PGPR
inoculants. Lynn adds the PGPR inoculant to her compost tea
after the brewing and uses it as a soil drench. She says she
gets potatoes three weeks earlier and with fewer lesions by
using the PGPR inoculant.
New compost tea organizations
At a round table on compost teas and agricultural microbes,
Cindy Salter of Growing Solutions (compost tea equipment and
additives) in Oregon described two new organizations started
in the northwest. The Compost Tea Industry Association (www.composttea.org),
out of Eugene, Oregon, got going in January, 2003. The CTIA
will provide a forum for information exchange and marketing
opportunities for products and services within the rapidly
growing compost tea industry. The Compost Tea Education and
Research Foundation will, which has not yet been officially
formed, will focus more on research on compost teas. For more
information contact Cindy at email@example.com.
There was talk about the state of the art of vermicomposting.
The word is that Jack Chambers of Sonoma, California, is the
cutting-edge practitioner. Chambers is on the board of directors
of the CTIA. He uses “separated dairy solids”
(dairy manure), plus various carbon sources, and has a pre-worm,
thermal composting stage in which he forces air through the
mix. Then just as the thermal composting rate slows and temperature
begins to decline, it is put into the worm stage.
Insect control using fungi: The amazing Paul Stamets of Fungi
Perfecti in western Washington (www.fungi.com)
gave a keynote speech as well as a packed-to-the-rafters workshop
on the role of fungi in, well, life. Paul related his recent
development of a mycoattractant cum mycopesticide, essentially
a process for growing common entomopathic (insect-lethal)
fungi in such a way that insects are actually attracted to
it. He related the story of how he treated carpenter ants
in his house with it, and they completely disappeared. Then
gave his aunt some, and the carpenter ants completely disappeared
from her house as well.
So apparently huge is the potential of Stamets’ mycopesticide
patent that several billionaires flew into little Shelton
County airport in their private jets, one by one, to meet
with him and try and convince Stamets to let them be the primary
backer of whatever company he starts.
Stamets related how he negotiated with the investors about
necessary ethical principles that would need to be adhered
to by any company he is involved in. This means 1) the company
will not be involved in the eradication of insects by using
plague-like organisms (his invention is not spread like a
plague organism); 2) protocols must exist to make sure that
the product is accessible by low-income communities, 3) some
of the profits go to non-profit organizations, and 4) the
intellectual property rights of native peoples must be respected,
i.e. profits from products derived from traditional native
herbs or organisms must be shared with those peoples.
The core of Stamets’ mycopesticide process is to culture
the entomopathic fungi in their pre-conidial stage. Up until
now, entomopathic fungi have always been used on insects in
their conidial (spore) stage. A number of products and patents
have been developed for such common entomopathic fungal genera
as Metarhizium, Beauveria, and Paecilomyces, names that anyone
working in biological control recognizes. The problem has
been that the conidial stage is highly repellent to insects,
and is the form that up until now, has been used to dispense
What Stamets found was that the pre-conidial, non-sexual,
hyphal stage of the fungus, which has long been ignored by
mycologists because it wasn’t active against the insects,
is highly attractive to insects. “The fungus knows that
the insects know that the conidial stage is lethal, so it
produces a form of itself that is attractive” says Stamets.
Then, when the insect takes the mycelia to its colony, the
mycelia sporulate in the warm, moist conditions of the colony,
and produce the insect-lethal form of itself.
Stamets related how his aunt found the carpenter ant queen
and her worker-ant minions in a swarming pile on the carpet
after the bait fungal mycelia had been taken away by the ants.
The colony had become so toxic that the ants abandoned it
and brought the queen out into the open. After flushing them
down the toilet, they haven’t come back.
Stamets believes that there will be numerous applications
of this process in agriculture.