November 17, 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 at seminars.
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, WA (www.soundhorticulture.com),
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 rhizobacteria (PGPRs).
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 entomopathic fungi.
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
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
Stamets believes that there will be numerous applications of this
process in agriculture.