United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-88/024 August 1988
Project Summary
of
Sludge on Soilborne Plant
Pathogens
H,A. J, Hoitink and A, F. Schmitthenner
Efficacy of composted municipal
sludge (CMS) for suppression of
Phytophthora root rot of soybean In
field soil and for suppression of
Rhizoctonta and Pythium diseases of
ornamental plants produced In
container was investigated
over a 3-year period.
CMS increased yields of soybean
by Improving soil fertility and/or by
partial control of Phytophthora root
rot {PRR). Disease-enhancing
effects of salt in the CMS were
controlled with a selective fungicide.
In the absence of the fungicide,
beneficial effects were obtained only
by application of CMS at least 3
months prior to planting with
cultivars tolerant to PRR, Increased
yields of soybeans were observed
when high rates of CMS were applied
to corn crops and soybeans were
grown in the next year without further
CMS application. No residual effects
were observed from high rates of
CMS applied to soybeans.
All container media prepared
with CMS cured 4 months or more
and stored 4 weeks after formulation
became consistently suppressive to
Rhizoctonia and Pythium diseases of
ornamentals at levels adequate to
avoid losses under commercial
conditions. An unknown beneficial
microflora involved In suppression, if
present, survived in the outer low-
temperature layer of curing piles
only.
Several bacterial and fungal
isolates were identified that ef-
fectively induced suppression to
Rhizoctonia and Pythium "damping-
off" in CMS media. The relative
contributions of these microbes to
the overall suppressive effects
remain to be determined. Most
bacterial strains were more ef-
ficacious in combination with an
isolate of Trichoderma. A synergistic
interaction was found among an
isolate of Trichoderma ham a turn and
of flavobacterium balustinum for
suppression of Rhizoctonia damp-
ing-off. These isolates, if added to
conducive CMS media, consistently
rendered them suppressive in the
absence of the 4-week incubation
period required for development of
natural suppression.
This Project Summary was
developed by EPA's Water Engineering
Research Laboratory, Cincinnati, OH,
to announce key findings of the
research project that is fully doc-
umented in a separate report of the
same title (see Project Report order-
ing Information at back}.
Introduction
A significant number of munici-
palities in the United States are using the
composting process for further treatment
of municipal sewage sludge. Composted
municipal sludge (CMS) has been utilized
effectively as a source of piant nutrients,
and the organic matter in CMS may
improve physical and biological
properties of soils.
Severity of a number of plant
diseases can be affected by CMS. Some
-------
are decreased in severity, whereas
others are increased as a result of field
soil amendments. The mechanism of this
variability is not understood. However,
suppression of disease has been
associated with increased microbial
activity of treated soil. Severa! micro-
organisms have been isolated from
composts that are involved in the
suppression of soilborne diseases in
soils or container media amended with
composts. Their fate during composting
of municipal sludges is unknown.
Phytophthora Hoot Rot of
Soybeans
Phytophthora root rot of soybean is
one of the most severe diseases of this
crop in the northern soybean growing
region. Approximately 10 million acres
are infected and can be severely
damaged in wet years. Presently, control
of root rot is based on resistance of
cultivars which has been overcome by
new Phytophthora races; application of
the fungicide metalaxyt (a potential
ground-water pollutant) to soil; or a
combination of good drainage, complete
soil tillage, rotation, and metalaxyl seed
treatment of highly tolerant {least
susceptible) cuitivars. The latter inte-
grated control package is not available to
farmers who wish to reduce soil erosion
through conservation tillage,
Additional durable and nonpolluting
options are needed for control of this
important disease. Phytophthora
diseases can be controlled by adding
certain organic amendments to the sotl.
One way to rapidly increase soil organic
matter is with manures and CMS.
Manure is not readity available to farmers
that focus on cash cropping. On the
other hand, CMS, derived from municipal
sludge, is available in many areas of the
United States where soybeans are
produced, CMS can be spread on fields
with a conventional manure spreader,
thus making widespread utilization
possible. However, CMS may have a
high salt content, which can create
adverse effects. Both high fertilizer
application rates and high chloride
concentrations increase PRR of soybean.
The experiments reported here were
designed to investigate three areas. First,
effects of various CMS rates on root rot
severity and yield of soybean in
Phytophthora-infested soil were exam-
ined. Second, the effect of application
timing was determined. Finally, the
residua! effects of CMS applied during
the previous season were evaluated.
Suppression of Rhizoctonia and
Pythium D/seases of
Ornamenfa/s Produced in
Container Media
Composts prepared from a variety of
tree barks are utilized successfully for
suppression of soilborne diseases of
ornamental plants produced in container
media. These composts are particularly
effective for control of Rhizoctonia and
Pythium diseases when microbial an-
tagonists have recolonized the compost
after peak heating has occurred. The
mechanisms of suppression involved
vary with the pathogen, the source or
type of compost used, and the level of
decomposition achieved during the
composting process. This portion of the
study shows that container media
amended with CMS can be used ef-
fectively for suppression of Thizoctonia
and Prrthjum diseases of greenhouse and
nursery crops if certain precautions are
taken to overcome the detrimental
effects imposed on microbial antagonists
by the long-term high temperature
treatment (>55°C) necessary to ensure
fecal pathogen and parasite destruction.
In addition, beneficial microorganisms
involved in the suppression of Rhizoc-
tonia and Pythium diseases were
identified,
Objectives
The objectives of research reported
here were: 1} to determine the effects of
CMS on soybean PRR severity in the
field; 2) to develop procedures for the
formulation of container media with CMS
that consistently suppress diseases
caused by soilborne plant pathogens of
ornamental plants; and 3) to determine
the nature of the beneficial microflora
involved in suppression of these dis-
eases,
Methods
Cftaracferisf/cs of the Compost
Composted municipal sludge was
obtained from the Columbus Southerly
Composting Facility where the aerated
static pile composting process has been
used on a daily basis since 1980. Raw
sludge cake, consisting of a 1:1 ratio (dry
wt basis) of primary sludge and waste
activated sludge, was dewatered with
centrifuges aided by polymer as a
coagulant. Sludge cake, averaging 16%
to 17% total solids, was mixed with
hardwood chips (1 in. to 2 in. chips) at a
ratio of 5 volumes of chips to 1 volume of
sludge. Mixing was accomplished with
front-end loaders in a covered mixing
area. The composting process generally
was complete after 21 days. Piles were
then processed and stacked with or
without aeration for a 60-day curing
period. Thereafter, the mixture was dried
by passive solar drying on a concrete
pad. Wood chips were recovered by
screening with a 3'8-in. rotary screen
Screened compost was then stored in
bays in a covered shed- A weekly
composited compost analysis was
associated with each bay of compost.
Compost thus prepared was used
throughout this work A summary of the
chemical properties of the CMS is
presented in Table 1.
Soybean Phytophthora Root
Rot
Field experiments were conducted
for 3 years at the Northwest Branch of
Ohio Agricultural Research and
Development Center (OARDC) of The
Ohio State University located at Custar,
OH, in a Hoytville clay loam containing
50% clay, 40% si it, and 10% sand The
plot area used during the first 2 years
was tiled, but gates located at the tile
exits were closed to reduce drainage In
the third year, the location was changed
so that the plots could be irrigated 3 days
after planting to provide optimum
conditions (or Phytophthora infection
This field was tiled, but the tiles were old
and nonfunctional
Plots consisted of 8 rows, each 26 m
long and spaced 76 mm. Each plot was
split into two treatments of four rows
each. In the first year the split treatments
were the cultivars Sloan (some tolerance
to PRR) and OX 20-1 (no tolerance to
PRR). In the second and third years the
split treatments consisted of the cultivar
Sloan, with and without 280 g
metalaxyl/ha (5.6 kg/ha of Ridomil 5G").
This systemic soil fungicide provides
good control of Phytophthora when
applied in the seed furrow at planting
time.
CMS application rates were 0, 10,
20, arid 40 tonne,ha. Application times
were preplant, applied within 1 week
before planting to maximize salinity
effects; and early, applied at least 3
months before planting, either in
February or November, to minimize
salinity. To determine the fertility effects
of trade names or cornrnercidl products
does not constitute endorsement of recom-
mendation (of use
-------
Table ! Characteristics of Municipal Sludge and
from the Columbus Southwesterly Compost
Sludge"
Composted Municipal Sludge
Facility
Composted Sludge
Volatile Solids %
Conductivity (mmhoS'Cmff
Cl (ng-mi
pH
W (°.'o, total Kjetdahl)
P (°A)t
K (%)
Ca (%}
Mg (%>
Cd (fflQtkrj)
Cr fmg.kg)
Cu (fflQ-kg)
Pb (mg-kg)
Ni (mg.kg)
Zn fmgftgj
Na Cmg'ht?;
Mean
71
5.8
6.5
3,2
? 5
8.8
131
218
170
45
1,057
flange
57-79
5.4-6.3
3.2-8,4
1, 6-5.8
0.2-2.2
2,7-26
72-290
1 30-270
92-560
18-74
550-1,900
Mean
59
10,5
370
7.5
4.5
3.3
1.6
3.6
0.86
20
262
255
274
65
1,664
776
Range
43-74
7.5-15,0
245-360
6.2-8.4
3.2-5.3
2.5-4.7
0.9-1.9
3.4-3.8
O.S4-0.8?
73-24
750-325
1 90-640
760-320
54-111
1.000-1,971
699-827
"The sludge was a 1:1 mixture of raw and waste activated sludges. Means are based on
64 samples. Analyses performed by City of Columbus Central Surveillance Laboratory.
tDetermined in a saturated pasts extract.
tAtt metal concentrations were determined after nitric perchloric ecid digestion.
of CMS, plot soil was brought into the
laboratory, mixed with the equivalent of
0, 10, 20, and 40 tonne dry wt CMS/ha,
planted with soybeans under conditions
that promote maximum Phytophthora
tosses, and, after 2 weeks, submitted to
the Research Extension Analytical
Laboratory (REAL), QSU, for fertility
analysis {Table 2). Based on this
analysis, a fertility control preptant
treatment was applied consisting of
superphosphate (200 kg PgOs/ha) and
NaCI (327 kg/ha) which was the soluble
salt equivalent of 20 tonne/ha CMS.
Disease analysis consisted of counts
of healthy and diseased plants 5 weeks
after planting in late October, the
weights and percentage moisture of the
seed from the two center rows of each
pfot were taken to determine effects of
Tatjie 2,
treatments on yield. Ail treatments were
replicated four times. Data were
subjected to an analysis of variance with
application times and CMS rates as
whole plots and cultivars of metalaxyl
soil fungicide treatment as split pfots.
Preparation of Container Media
A CMS container medium was
prepared by mixing CMS with Canadian
sphagnum peat and perlite (1;2:1,v/v, pH
5.5), This medium was not amended with
fertilizer since sludge compost media
release adequate amounts of plant
nutrients for at least 6 weeks after
potting. A peat container medium was
prepared from Canadian sphagnum peat
and perlite (1:1, v/v) and adjusted to pH
5.5 with a 2;1 (w/w) mixture of cfolomitic
and hydrated lime. It was fertilized to
adjust fertility to levels identical to that in
the CMS medium. The peat medium is
conducive to Rhizoctonia and Phthiurn
dam ping-off and, therefore, served as a
control in this work.
Suppression of Pythium and
Rhizoctonia damptng-off was deter-
mined with cucumber and radish
bioassays, respectively. Inoeuta of
Rhizoctonia so/an/ and of Pytftium
ultimum were added at rates of 0.5 g/L
container medium. This amount of
inoculum kilted 50% of the plants in a
suppresstve medium and all plants in a
totally conducive peat medium. Mean
disease severity ratings were determined
for various sludge compost and peat
media to compare efficacy of CMS for
suppression of these diseases.
Fertility Factors in HoyM/te Stity Clay Affected by Applications of
Composted Municipal Sludge
Rate
(dry tonngfha)
0
10
20
40
LSD (0.05)
P
134
214
353
575
93
K
498
501
545
642
55
kg/ha
Mn
19
20
28
39
8
Zn
96
105
139
222
58
8
1.8
2.1
2.4
3.1
0,26
WO3
340
370
532
S78
120
-------
Tafile 3. Effect of Composted Municipal Sludge on Yield
(kgltia) of Soybeans Under MM Phytophlhora Root
Rot Pressure in 1984
Variety
Rate
(dry tonn&iba)
Application Time
Sloan
(susc)
OX 20-8
(very
suscj
Means
Yield (kg/ha)
0
?0
F0584
2651
2590
7959 230S
1953 2272
20
40
0
10
20
40
Salt Control"
LSD =0.05
Feb84
Feb84
May 84
May 84
May 84
May 84
May 84
2849
3345
2779
2657
2923
308?
2583
499
1853
215?
2235
2076
1581
IS58
1612
2356
2751
2507
2366
2252
2322
2087
256
'200 kg of P^Os and 327 kg NaCtha, the soluble salt equivalent of
20 tortna CMS-ha
Interactions Among Beneficial
Microorganisms in Container
Media
Bacteria and fungi were isolated by
baiting with radish and cucumber roots
produced in CMS media or with
Rhizoctonia and Pythium soit propagules
incubated in sandwiches in the
suppressive media. Pure cultures of 650
bacterial isolates and 30 fungal isolates
were then tested for their abilities to
induce suppression to Rhizoctonia and
Pythium damping-off using the
bioassays described above. Spontane-
ous rifampicin-resistant mutants were
isolated from the most effective bacterial
strains. The root colonizing potential of
these mutants was then tested. Finally.
various mixtures of bacterial antagonists
with strain 382 of Trichoderma hamatum
were examined to reveal synergistic
interactions among antagonists in CMS
media.
Results
Soybean PRR
In 1984, the 40 tonne dry wt CMS/ha
treatment applied in early February
significantly increased the yield of the
moderately susceptible cultivar Sloan
(Table 3), Yield differences were not
found in the highly susceptible cultivar,
OX 20-8. There were no differences in
stand or plant death among any of the
variety-treatment combinations. The
lack of yield response in the highly
susceptible OX 20-8 could be explained
by greater hidden root rot damage
offsetting a potential fertility response.
High rates of CMS applied preplant
(May) did not increase yield of the
moderately susceptible cultivar Sloan
and also significantly reduced the yield
of highly susceptible OX 20-8. These
results were not accompanied by
significant differences in stand or plant
death from PRR. The salt-phosphate
treatment significantly reduced the yields
of both cultivars. This agrees with
previous findings for effects of chloride
on soybean PRR severity. The salt
content of CMS applied preplant
probably increased hidden root rot,
which prevented a yield response in
Sloan and decreased yield in OX 20-8.
The yield of Sloan in the high CMS
treatment was significantly better than
that in the salt-phosphate treatment,
indicating a response to organic matter
even in the presence of high salts.
Cultivar OX 20-8 did not respond to
organic matter in the presence of sait.
Thus, the response of cultivars to organic
matter may have been associated with
their level of susceptibility to
Phytophthora.
In conclusion, the 1984 season
demonstrated that the yield response of
soybeans may depend on susceptibility
to PRR and application time. Possible
negative effects of high salt in CMS could
be eliminated by early application. To
separate the fertility and disease seventy
effects, experiments for 1985 and 1986
were changed to incorporate control of
Phytophthora with Ridomil, a specific
fungicide, Ridomil applied in the furrow
with the seed at planting time controls
PRR damage in all but the most
susceptible cultivars,
In 1985 there were no differences
between Rrdomil-treated and untreated
plots The salt-phosphate treatment had
no effect on yield, Thus, in 1985, PRR
did not occur Both the 20 tonne ha and
40 tonne ha rates of CMS significantly
increased yield (Table 4), The beneficial
fertility effects of CMS were clearly
evident in this year in the absence of
Phytophthora dam age.
Residual effects of CMS applied in
1984 were evaluated in 1985. There were
no differences among any of the CMS
rates in soybean-soybean plots (Table
4), All yield levels were low. In the corn-
soybean sequence, the high rale of CMS
(40 tonne'ha) applied to corn in 1984
significantly increased the yield of
soybean in 1985 Thus, the residual
effects of CMS were only evident if
applied to corn, which is the logical time
to apply CMS in a cropping system.
In 1986, only two rates of CMS, 0
and 40 tonne dry wt'ha, were compared.
Ridomil, application time, and salt-
phosphate treatments also were included.
-------
Table 4. Effect of Composted Municipal Sludge on Yield (kg/ha) of
Soybean Under Phytophthora-Free Conditions in 19B5
Crop and Time of Application
Sludge
(tonne/ha)
0
10
20
40
Salt Control'
LSD(O.Q5} = 270 Kg
Feb 94
Soybean
3073
3086
3060
3154
-
May 84
Soybean
2893
2965
2979
3113
2979
May 84
Corn
3370
3423
3423
3558
3370
Nov 84
Soybean
3208
3235
3504
3693
May 85
Soybean
3208
3316
3693
3706
3383
'200 kg of P2O5 and 327 kg NaCUha, the soluble salt equivalent of 20
tonne CMSiha.
The crop was irrigated with tO cm water
over a 2-day period approximately 3
days after planting when the seedling tap
roots were about 5 cm long Flooding
induced conditions favoring PRR. Yield
levels were not high in this experiment
because of a 9-week drought between
July and September and fertility benefits
were not evident. However, a significant
disease response to treatments was
evident.
Preemergence and postemergence
damping-off occurred in plots not
treated with Ridomif (Table 5), Stands
were poorest in plots with CMS applied
preplan! and best in plots treated with
CMS early, Ridomit controlled damping-
off and resulted in good stands and
improved yields in all sludge treatments.
In plots not treated with Ridomil, only the
early CMS application significantly
increased yields compared to the
preplant application and the controls,
Under this severe disease pressure,
early application of CMS increased
yields over the control as much as
treatment with Ridomil. Response from
CMS and Ridomil was not additive,
possibly because the late season
Table 5.
drought prevented a fsrtiiity response.
The 1986 data confirm the importance of
time of application of CMS.
The following conclusions on PRR in
soybeans can be drawn from these data.
1. CMS applied just prior to planting
may increase Phytophthora damage.
Yields will be increased or
decreased depending upon severity
of Phytophthora.
2. A salt-phosphate mixture equivalent
to fertility in CMS, has the same
erfect as CMS applied immediately
before planting,
3. CMS appfied 3 to 6 months before
planting reduced Phytophthora and
increased yield.
4. CMS applied in the absence of
Phytophthora increases yields even
in very susceptible cultivars.
5 Response to 40 tonne dry wt
CMS ha is better than to 20 or 10
tonne dry wt ha.
6. Ridomil applied at recommended
rates reverses the negative effects of
CMS applied immediately before
planting.
Effect of Compost Curing Time
on Suppressiveness of CMS
All batches of CMS stored in curing
piles with temperatures in the center of
the pile higher than 60°C and formulated
into a CMS medium, were consistently
suppressive to Pythium damping-off.
However, these CMS media varied in
their effects on Rhizoctonia damping-
off- CMS cured 4 months or more in piles
and formulated into media, became
consistently suppressive to Rhizoetonia
damping-off within an additional 4
weeks of storage.
The environment in which the
compost was cured affected
Suppressiveness. CMS stored next to
piles of bark compost suppressive to
Rhizoctonia damping-off, became sup-
pressive earlier than CMS stored in
isolated locations. Microorganisms iso-
lated from the suppressive CMS that
could cause this effect were Trichoderma
spp. and a number of bacterial
antagonists. Without this recolonization of
CMS with antagonists of R. solani,
Suppressiveness did not develop.
Effect of Composted Municipal Sludge on Stands (ptants.26 m of
Row Spaced 76 cm) and Yields (kgtha) of Sloan Soybean Under
Severs Phytophthora Root Hot Pressure in 1986
Stand (plants 26 m rows)
Yield (kg ha)
Sludge
(tonne; ha)
0
40
0
40
Salt Control"
Time of
Application
Feb 86
Feb 86
May 86
May 86
May 86
No
Rid omit
211
226
176
105
207
Ridomil
352
318
346
312
354
Mean
281
272
261
209
280
No
Ridomil
984
2056
627
512
815
Ridomil
2420
2615
2251
2736
2440
Mean
1705
2332
1442
1624
1624
LSD (0.05)
89
607
337
"200 kg of P2&5 and 327 kg NaCl^ha, the soluble salt equivalent of 20 tonne
CMS'ha
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Table 6 Suppress we ness of a Nursery Sludge Compost and a Conducive Peat Container
Medium to Pythium and Thizoctoma Damping-Off Over a 2-year Period
Disease Seventy Rating?
Medium
Sludge
Compost
Peat
Control
Treatment
Chech
Infested
Check
infested
May
7.7
1.8
1.2
3.9
July
1.0
2.6
1.1
4.0
Nov
1.0
23
17
3.5
LSD (P =0.05)
Oct
1
2.
1
3.
0.8
7
7
2
a
May
1.5
3.7
r.3
3.9
July
1
2
7.
3
2
6
3
9
0.3
Nov
12
23
1 7
36
Oct
1 r
29
! 1
38
"Infested with 0.5 g Rhizoctonia solan! or Pythium ulttmum soil inoculum per L container medium.
fOisease seventy ratings: 1 = symptomless; 2 ^diseased but not damped-off.
3 =postemergence damp/rrg-otf; 4 =pre emergence damping-off, based on five pots each
planted with 32 radish seed. May, July and November represent 1984. October represents
1985 values.
Suppression on Diseases During
the Production of Potted Crops
Pythium diseases caused by P.
ultimum or P. aphanidermatum in
floricultural pot crops were suppressed in
CMS media throughout a 5-month
production period. Similarly, Pythium
root rot caused by P. irregulare in
nursery crops was suppressed over a
2-year production period (Table 6),
Diseases caused by R. solani were also
suppressed in both floricultural (Figure 1}
and nursery crops (Table 6), but only
consistently if the formulated container
medium was stored 4 weeks before
utilization.
It was concluded that CMS becomes
naturally suppressive to Pythium damp-
ing-off but that 4 months of curing is
required followed by an additional 4-
week storage period of the formulated
medium required to ensure suppres-
siveness to Rhizoctonia dampmg-off
Efficacy of Microbial
Antagonists
T. hamatum 382 added as an
antagonist by ttself to a conducive CMS
medium did not induce a significant level
of suppression to Rhizoctoma dampmg-
off (Table 7). However, a combination of
Table 7.
Suppression of Rhizoctonia Damping-Off Induced by Bacterial Antagonists Alone and in
Combination with Tnchoderma hamatum in a Sludge Compost Container Medium
Disease Severity Patmgt
Bacterial Antagonist"
LSD 005
Bacterial Antagonist
Alone
Bacterial Antagonist
with T, hamatum
Wone
Bacillus cereus 106
Enterobacter cloacae 127
0. cloacae 3)3
Flavobacterium balustinum 299 (ATCC53198)
Janthinobactenum livid urn 275
Pseudomonas ftuorescens biovar til, A9i
P. (lucrescens biovar V, Ai
P. fluorescons biovar V, A498
P. putida 305
P. putida 375
P. putida 37J
P. stut2ert280
Xanthomonas maltophilia 76 (ATC53199)
2.9
3.0
2.6
21
3.1
2.7
2.9
2.4
2.7
22
23
23
24
30
26
20
2.6
2 J
2.1
25
2.4
26
23
1 3
2 1
25
27
2.4
04
"Bacterial antagonists were adcfed to the heated (60"C, 5 days) sludge compost container medium at
initial population levels of 10SCFU g dry wt T. hamatum was added af TO4 CFUg dry wt.
flnfested with 0.5 g Rriizoctonia solatu soil inoculum:L container medium. Mean disease seventy rating
determined 7 days after incubation at 26"C from Five pots planted with 32 radish seeds each.
1 -symptomless^ 2 -diseased but not damped-off: 3 -postemergence damping-off; and
4 -preemergence damping-off Mean disease severity in the container medium not infested with R.
solani was 1.2
-------
8.O-
Aug Sept Oct Nov Dec
Sampling Date
Figure 1. Suppresstveness of s peat and
a sludge compost medium
{CMS} to Rhizoctonia damping-
off during production of poin-
settta plants. Disease severity
rating: 1 ~symptomtess; 2-dis-
eased but not damped-ofl,
3=post-emergence damping-
off; and 4-^preemergence damp-
ing-olf. Infested with 0.5 g
Rtzoctonia inoculum per liter
container medium. ISOoos for
all sampling times com-
b/t-ied-0.4.
Flavobacterium balustinum strain 299
with T. hamatum 382 significantly
(P = 005) reduced damping-off, even
though each bacterial antagonist by ttseif
was not effective. This bacterial antag-
onist significantly enhanced population
development of the T. hamatum strain
early after its addition to the compost-
amended medium (Figure 2). A syner-
gistic effect was established, therefore.
This effect occurred in compost cured 4
months that was conducive if not infested
with the antagonists Several other
combinations of bacterial antagonists and
T. hamatum 382 were identified that had
similar synergistic interactions in sup-
pression of Pythium damping-off in the
CMS medium.
It was concluded that microbial
antagonists can be utilized to develop
predictable levels of suppression to
Rhizoctonta damping-off in container
media amended with conducive CMS.
This process eliminates the need for
storage of formulated CMS media.
Tho full report was submitted in
fulfillment of Cooperative Agreement No,
CR-810581 by the Ohio State
University under the sponsorship of the
U.S. Environmental Protection Agency.
4.0 z.
0 ? 8 15
Days After Inoculation with Antagonists
Figure 2. Population development of Fia-
vobactenum balustinum 299ft
f— ) and T. hamstum 382
( I in a container medium
planted with cucumber and
amended with compost F.
baiustinum and T. hamatum
were inoculated individually in
a container medium amended
with (1) conducive compost from
the high temperature center of
the curing pile { 01; (2) svppres-
stve edge compost { B I; of 13)
were introduced as a combina-
tion (reaiment in the conducive
center compost medium ( © )
Vertical bars indicate standard
error.
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H.AJ. Hoitink, and A.F Schmrtthenner are with the Ohio State University, Ohio
Agricultural Research and Development Center, Woosier, OH 44891
James A. Ryan is the EPA Project Officer (see below).
The complete report, entitled "Effects of Composted Municipal Sludge on
Soiihorne Plant Pathogens," (Order No. PB 88 195 714-AS; Cost
$14.95, subject to cfhange) will be avtitabte only from:
National Technical Information Service
5?85 Port Hoya/ Road
Spring field, VA22161
Telephone: 703-4S7-4SSO
The EPA Project Officer can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH
Official
Penalty for Private Use $300
EPA/6QO/S2-88/024
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