Compost tea: a brewable
food web for disease
control
Martha Rosemeyer
June 25, 2003
rosemeym@evergreen.edu
Outline
Background- what is compost tea?
Organisms involved
Does it work?
How does it work?
Future research
Resources
How to make it- David Bell
Photo: Seth Book
What is compost tea?
Water extract of compost that is brewed, ie
fermented (Ingham, E. 2001)
Specifically the organisms are released
from the compost and increase in number
Nutrients may be added to further increase
organisms
Used for disease control, as well as a plant
nutrient source
Not to be
confused with:
Manure tea made as a
nutrient source
Plant extracts or
herbal teas for disease
control or plant health,
for example
biodynamic
preparations
Photos: Eliot Coleman’s European tour (Diver 2001)
What does compost tea contain?
plant nutrients and humic acids
active bacteria (1 billion to 10 trillion
cfu/ml)
active fungi
protozoa
nematodes
products of microbes that can have
antibiotic properties
Photo from: Compost Food Web slide show
Why compost tea? Why now?
Increasing societal concern for health and
environment and organic production
Lack of disease control mechanisms for
organic farmers and gardeners
– Restricting agrochemicals due to recognized
toxicity, for example FQPA
Organic farmers need control methods that
work within a holistic system
Organic sales increasing at 20+% per year
Worldwatch Institute. 2000. Why Poison Ourselves.
Used extensively due to
perceived benefits
Homeowners
Without tea
Nurseries
Organic crop growers
Golf courses
Organic landscape management
With Tea
Ingham 2001
– municipal parks and recreation dept
BUT LITTLE RESEARCH HAS BEEN DONE
Background
Since 1920’s compost water used to soak
seeds for nutrients, prevent disease
Two main approaches
– compost extracts = watery fermented compost
extract= steepages =non-aerated compost tea
(Scheuerell and Mahaffee 2002)
•
•
•
•
fermented but not aerated, stirred occasionally
lower costs, lower energy
much research
disease control has been documented
– aerated compost tea
• fermented, aerated
• higher costs, energy
• little research, some disease control reports
Diver 2001
Benefits of compost tea
Nutrient application, lesser
Disease control
– Foliar disease
– Root disease
Inoculation of functioning soil food web
How to make non-aerobic
compost tea
Mix ratio of compost to water-1:4-1:10
compost to water in an open container, stir
occasionally
At least 3 days at 15-25°C (50-70 °F)
How to make Aerobic Compost Tea
Choose compost- well aged
– plant based or worm compost
In water (remove chlorine from water)
Ratio 1 compost:10 water to 1:50
Add nutrients (optional) like molasses,
humic acids, kelp
Aerate and mix solution for 12 - 24 - 48
hours
Commercial aerobic compost tea
brewers
Soil Soup: www.soilsoup.com
Microb Brewer: www.microbbrewer.com
Growing Solutions:
www.growingsolutions.com
Earth Tea Brewer: www.composttea.com
Xtractor: compara.nl/compost_tea_systems.
Soil Soup
www.soilsoup.com
Microb Brewer
www. microbbrewer.com
Growing Solutions
www.growingsolutions.com
bubbling
aeration
What happens in the compost tea
while brewing?
?
?
TESC Student expts:
Scott Chichester and Seth Book
•Changes in compost tea
during brewing
•Preventing damping off
of marjoram
Photos: Seth Book
Dissolved Oxygen >5.5 ppm
DO(ppm)
Dissolved Oxygen
10
9
8
7
6
5
4
3
2
1
0
ppm
48 hrs
24 hrs
0
20000
40000
60000
80000 100000 120000 140000 160000 180000
time(seconds)
ppm
NO3
Nitrate
3.6
3.55
3.5
3.45
3.4
3.35
3.3
3.25
3.2
0
10000
20000
30000
40000
Tim e(se con ds)
50000
60000
70000
20 hrs
From: Book and Chichester
pH > 7.2
pH
7.4
pH
7.35
7.3
7.25
7.2
7.15
0
10000
20000
30000
40000
50000
60000
70000
Tim e(second s)
Temp erature(C)
Temperature(compost tea s olution)
°C
26
25.9
25.8
25.7
25.6
25.5
25.4
25.3
0
10000
20000
30000
40000
Tim e(se con ds)
50000
60000
70000
Food web concept
”Everything eats, everything excretes, and
everything is food for something"
– Elaine Ingham, 2001
A great resource:
SWCS/NRCS,
Soil Biology Primer
A functioning food web is
desirable in a compost tea
From: Soil Biology Primer
Most bacteria (99%) cannot be cultured
Direct counts and genetic diversity assessment
Activity of bacteria important
Nutrients can help to “wake up” to active state
A ton of microscopic bacteria may
be active in each acre of soil.
Bacteria dot the surface of strands
of fungal hyphae.
From: Soil Biology Primer
Fungus beginning to decompose leaf veins in grass clippings.
Soil Microbiology and Biochemistry Slide Set.
1976. J.P. Martin, et al.,eds. SSSA, Madison WI.
From: Soil Biology Primer
bacteria
Protozoa: Flagellates have one or two flagella which
they use to propel or pull their way through soil. A
flagellum can be seen extending from the protozoan
on the left. The tiny specks are bacteria.
Credit: Elaine R. Ingham, Oregon State University
From: Soil Biology Primer
Protozoa: Ciliates are the largest of the protozoa and the least
numerous. They consume up to ten thousand bacteria per day,
and release plant available nitrogen. Ciliates use the fine cilia along
their bodies like oars to move rapidly through soil Credit: Elaine R.
Ingham, Oregon State University, Corvallis From: Soil Biology Primer
Interaction
Vampyrellidae attack
fungus “take all” of
wheat
From: Soil Biology Primer
cysts
Most nematodes in the soil are not plant parasites.
Beneficial nematodes help control disease and cycle nutrients.
Credit: Elaine R. Ingham, Oregon State University, Corvallis
From: Soil Biology Primer
Interactions:
Nematode trapping fungi
From: Soil Biology Primer
Total population of active
microbes
Bacteria minimum 107-1010 (Scheurell and
Mahaffee)
But may not be associated with disease
control, if appropriate agent not present!
Do we know what the diversity or quantity
of microbes means with respect to disease?
Not entirely
Most soil organisms are unknown!
Does microbial diversity increase microbial
function?
If we are mainly interested in disease
prevention then do we know what
mechanism and whether that organism is
involved?
In general more diversity means better
change that have the appropriate organism
Does it work?
NCT- Good evidence under
certain circumstances
Much research with
– grey mold
(Botrytis cineraria)
Downy mildew of grape
(Plasmopara viticola)
Evidence of NCT disease suppression
Late blight of potato, tomato
Phytopthora infestans
Gray mold on beans, strawberries
Botrytis cinerea
Fusarium wilt
Fusarium oxysporum
Downy & Powdery mildew-grapes
Plasmopara viticola
Uncinula necator
Powdery mildew on cucumbers
Sphaerotheca fuliginea
Gray mold on tomato, pepper
Apple scab
Venturia conidia
Horse compost extract
Weltzein (1990)
Cattle compost extract
Weltzein (1990)
Bark-compost extract
Kai, et al (1990)
Animal manure-straw compost
extract
Weltzein (1989)
Animal manure-straw compost
extract
Weltzein (1989)
Cattle & chicken manure compost
extract
Grape marc compost extract
Elad, Shtienberg (1994)
Spent mushroom compost extract
Cronin, Andrews (1996)
Diver, 1998
Is ACT better than NCT?
Both ferment well-characterized compost in
water for a period of time, with or without
nutrients
Few studies have actually compared the two
NCT has been suggested to cause plant
problems and potentially an environment for
human pathogen growth (Ingham)
According to Scheuerell and Mahaffee, there is
no evidence that phytotoxic symptoms
Apple scab control using NCT but not
ACT manure-based spent mushroom
compost (Cronin et al. 1996)
ACT (7 d) vs. NCT (7d)
In vitro effect on germination
of conidia of Venturia inaequalis,
pathogen of apple scab
NCT reduced conidia germination, not
ACT unless let sit for another 7 days
Apple scab on leaf and fruit
Powdery mildew of rose
(Scheurell and Mahaffee 2000)
Three sources of compost
ACT commercial preparation vs.
7-day NCT
All equal results on powdery mildew of
rose (Sphaerotheca pannosa) within source
of compost
Authors concluded that source of compost
more important than ACT or NCT
Tests for Disease control of ACT
Control of:
Brown rot blossom
blight of sweet
cherry (Monilinia
laxa)
Lettuce drop, post
harvest fruit of
blueberry
Powdery mildew of
rose (Sphaerotheca
pannosa var. rosae)
No control:
PM of apple,
grape, apple and
pear scab, brown
rot of peach,
peach leaf curl,
cherry leaf spot
Early blight of
tomato
Reference:
Pscheidt and
Wittig 1996
Granatstein 1999
Scheuerell and
Mahaffee 2000
Disease control with ACT
Granatstein 1999
ACT had effects on yield and disease
control
No effect on early blight of tomato
Lettuce drop incidence decrease in summer
not spring
Post harvest rot of blueberries significantly
reduced, but reduced yields
Spinach yield decreased, but broccoli
spring and summer increased
No general pattern
Disease control with ACT
Presidio golf greens
Decreased
Microdochium
No effect
Anthracnose
Conforti et al. 2002
Bacterial vs. fungal dominated
teas can be determined by added
nutrients (Ingham 2001)
Bacterial- use simple sugars to fulvic acids
Fungal- use humic acids
Have been difficult for some to produce fungal
dominated teas (Scheuerell and Mahaffee 2002)
Reports on reduction of suppression due to
nutrient competition?
Useful to know nutrients that support
antagonists
How might compost teas work?
Mechanisms from NCT
Prevention of pathogen colonization
– due to competition of space or nutrients
– direct destruction of pathogen
Antibiosis
– Release of antimicrobial compounds
Induced resistance
Colonization of phylloplane
If 70% of leaf covered by organisms
reduction of disease (Ingham)
60-70% active bacteria and 2-5% active
fungi
Various authors
Pseudomonads,
aerobic Bacillus,
aerobic spore forming
bacteria with reduction
in powdery mildew
of grape
Predation NCT: Fusarium
spore rupture
Root drench for Fusarium diseases of
pepper and cucumber
Direct destruction on disease-causing
spores
Ascospores of Fusarium solani
Antibiosis: what organisms and
metabolites may be involved?
Bacteria- Bacillus, Pseudomonas, Serrantia
Yeast- Sporobolomyces, Cryptococcus
Fungi- Trichoderma, Gliocladium and
Penicillium
Chemicals involved - phenols, amino acids,
low molecular weight non-protein
(sometimes produced by fermentation and
other times already within compost)
NCT induced resistance to plant
pathogens
Powdery mildew of cucurbits
(Sphaerotheca fuliginea)
NCT changed host response to pathogen
– papillae (bumps)
– necrotic reaction
– leaf toughens
(lignification)
Standards for compost tea
So far only one proposed minimum standards
(Ingham 2001)
– oxygen concentration remain above 5.5 ppm or
60% DO [but there is disease suppression in
NCT]
– in vitro pathogen inhibition [but question as to
whether this reflects field conditions]
Minimum standards for compost
tea/mL (Ingham 2001)
10-150 g active bacteria,150-300 g total
bacteria
2-10 g active fungi, 5-20 total fungi
1000 flagellated protozoa
1000 amoeba-type protozoa
20-50 ciliates protozoa
2-10 beneficial nematodes (soil drench)
How to test?
Send compost tea to Soil Food Web (direct
counts)
BBC Labs, Vicki Bess
Need to correlate counts to field
performance
Potential to support human pathogens
Appears that despite popular conception, ACT
can support human pathogens if fermented with
sugars (2 papers)
If no sugars, including molasses, are used then
neither ACT and NCT appear to be able to
maintain human enteric pathogens (Escherichia,
Salmonella, Shigella, Yersinia) even if contain
low levels of pathogens
If use worm compost as source appears that can
avoid pathogens
Needs more research
Summary
Jury still out on NCT vs ACT, bacterial vs.
fungal composts and tea, human pathogen
tests
Good testimonials but variable results
– May be due to variability in the compost tea
due to compost quality, fermentation nutrients,
fermentation time and specific microbial
antagonists
Variability may also be due to previous use
of pesticides and fertilizers
Important to understand how compost tea
production and application interact with the
pathogen’s biology, put your plan into
practice and carefully observe results
Not a panacea but a great tool!
Future research
We are all experimenters!
– If possible send sample in for testing: BBC labs
(www.bbclabs.com), Soil Food Web Inc.
Need to understand connection between
quantity, specific organisms, food web for
disease suppression
How to support the suppressive organisms
and mechanisms that suppress disease, add
biocontrol agents
Effect of cropping system-- organic vs.
conventional --Duff Wilson, Fateful Harvest
Resources
Diver, S. 1998. 2001. www.attra.org
Ingham, E. 2001. Compost Tea Brewing
Manual. Available through: www.soilfoodweb.com
Soil and Water Conservation Society and
NRCS. 2001. Soil Biology Primer. www.swcs.org
Scheurell and Mahaffee. 2002. Literature
Review: Compost tea: Principles and Prospects
for Disease Control. Compost Science and
Utilization 10(4):313-338
Brinton, W.F. et al. 1996. Investigations into
liquid compost extracts. Biocycle 37:68-70
PNW research experiences
Granatstein, D. 1999. Foliar disease control
using compost teas. Compost Connection
for Western Agriculture 8:1-4
Pscheidt and Wittig. 1996. Fruit and
ornamental disease management testing
program. Ext. Plant Path. OSU
Scheuerell, S. 2003.Understanding How
Compost Tea Can Control Disease. Biocycle
44: 20-25
Photo credits not listed above
Bacteria Credit: Michael T. Holmes,
Oregon State University, Corvallis. From:
Soil Biology Primer
Fungus Credit: R. Campbell. In R.
Campbell. 1985. Plant Microbiology.
Edward Arnold; London. P149. From: Soil
Biology Primer
From: Growing Solutions website