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Dying Trees do Tell Tales:
Implications of Biological Agentsin Prunus Replant Disease.
February12th, 2009
Southern San Joaquin Valley Almond Day
David DollUniversity of California Cooperative Extension
Merced County
G. Browne1, B. Holtz2, B. Lampinen3
CPGRU USDA-ARS, Department of Plant Pathology, UC Davis1,UCCE Madera2, UC Davis Plant Sciences3
David Doll
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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Replant Disease of Almond
CP-fumigated plot Non-fumigated plot
Healthy (L) and
PRD-affected almond trees
(R) in Butte County, 2003
Symptoms onalmond:
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UCCE Merced County
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Responses to spot, strip, and
broadcast fumigation treatments(Location: Firebaugh, pre-plant fumigated Oct 2006, planted Jan 2007)
Tr
t.
Fumigant, rate per treated
areaa
Treated area in tree
row
(and % of total area)
Fum.
per
orch.
acre
(lbs)
Disease
severity
rating
6/20/07
Trunk
diameter
February
2008 (mm)
1 Control None 0 1.8 202 Methyl bromide, 400 lb/a 8-ft strip (38%) 152 0.8 24
3 Telone II, 350 lb/a 8-ft strip (38%) 133 1.0 27
4 Chloropicrin (CP), 400 lb/a 8-ft strip (38%) 152 0.1 38
5 CP, 300 lb/a 8-ft strip (38%) 114 0.4 37
6 CP, 200 lb/a 8-ft strip (38%) 76 0.1 39
7 CP, 400 lb/a 8x8-ft tree sites (17%) 68 0.5 348
Midas (IM:CP. 50:50), 300
lb/a8-ft row strip (38%) 152 0.3 36
9 Telone C35, 550 lb/ac 8-ft row strip (38%) 209 0.1 36
10 Pic-clor 60, 550 lb/ac 8-ft row strip (38%) 209 0.0 39
11 Pic-clor 60, 400 lb/ac 8-ft row strip (38%) 152 0.3 35
12 Telone C35, 550 lb/ac 8x8-ft tree sites (17%) 93 0.3 3313 Telone C35, 550 lb/ac Broadcast (100%) 550 0.1 37
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UC Agricultural and Natural Resources
UCCE Merced County
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Replant Disease of Almond
Healthy RD-affected
Healthy (L) and replant disease-affected (R) almond trees,Madera County 2007
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UC Agricultural and Natural Resources
UCCE Merced County
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Effects of replant disease on root system
0
1000
2000
3000
4000
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Root diameter (mm)
Control
Pre-plant chloropcirin
0
1000
2000
3000
4000
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Root diameter (mm)
Control
Pre-plant chloropcirin
Marianna 2624 rootstocLovell peach rootstock
Totalrootlengthpersample
(cm)
Root length densities at 0 to 2 ft depth; determined by root
excavation and digital imaging
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UCCE Merced County
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What causes replant disease?Probesting, E.L., and Gilmore, A.E. 1941. The relation ofpeach root toxicity to
re-establishing of peach orchards. Proc. Am. Soc. Hort. Sci. 38:21-26.Probesting, E.L. 1949. The peach replant problem. Hort. News 30:2213-2214.
Probesting, E.L. 1950. A case history of a "peach replant" situation. Proc. Amer. Soc.Hort. Sci. 56:46-48.
Patrick, Z. A. (1955). "The peach replant problem in Ontario. II. Toxic substancesfrom the microbial decomposition products of peach root residues."Canadian Journal of Botany 33: 461-486.
Wensley, R. N. (1956). "The peach replant problem in Ontario. IV. Fungiassociated with replant failure and their importance in fumigated andnonfumigated soils." Canadian Journal of Botany 34: 967-982.
Mountain, W. B. and H. R. Boyce (1958). "The peach replant problem in Ontario.V. The relationship ofparasitic nematodes to regional differences inseverity of peach replant failure." Canadian Journal of Botany 36: 125-134.
Gilmore, A.E. 1959. Growth of replanted peach trees. Proc. Am. Soc. Hort. Sci.73:99-111.
Hine, R.B. 1961. The role ofamygdalin breakdown in the peach replant problem.Phytopathology51:10-13.
Hine, R.B. 1961. The role offungi in the peach replant problem. Plant DiseaseReporter45:462-466.
Gur, A., Cohen, Y. 1989. The peach replant problem- some causal agents. Soil Biol.Biochem. 21:829-834.
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UCCE Merced County
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What causes replant disease?
Peach Root Toxicity:
-Allelopathy
Nematodes:-Ring, Rootknot, etc.
Microbial involvement:
-Bacteria
-Fungi
No such thing:
Just a growth response to
fumigation
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UC Agricultural and Natural Resources
UCCE Merced County
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What causes replant disease?
Soil from old peach
orchard
Pre-plant fumigation
treatments applied to
microplots before
planting with Nemaguard
Control MBr 400 lb/A MBr 2700 lb/A
Chloropicrin 400 lb/A Chloropicrin 2700 lb/A
At end of first growing season, Nemaguard peach seedlings
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UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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What causes replant disease?
Peach Root Toxicity:
-Allelopathy
Nematodes:-Ring, Rootknot, etc.
Microbial involvement:
-Bacteria
-Fungi
No such thing:
Just a growth response to
fumigation
David Doll
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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What causes replant disease?
Nemaguard Seedlings planted in soils that have been previously cropped inpeaches or grapes for 15 years. Microplot trials.
0
10
2030
40
50
60
70
80
90
Peach Soil Grape Soil
Control
Methyl Bromide
Chloropicrin
Telone II
Telone C35
Maximu
mS
hootLength(cm)
Min. sig. dif. = 24 Min. sig. dif. = 15
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UC Agricultural and Natural Resources
UCCE Merced County
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What causes replant disease?
Nematodes:-Ring, Rootknot, etc.
Microbial involvement:
-Bacteria
-Fungi
No such thing:
Just a growth response to
fumigation
David Doll
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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Butte County orchard RD trials (2001-2004):No significant counts of plant parasitic nematodes (3 orchards)
Sugar floatation and mist chamber extractions
Parlier microplot trials (2002-2005):Only pin nematode (Paratylenchus sp.) present in significant number
(3 repeated trials); not correlated with RD incidence
Madera County orchard trials (2003- ):
To date, minor or no nematode involvement; sampling continuing
Conclusion:RD and nematode parasitism not the same, they are distinct replant
problemswith biological agent(s) other than plant parasitic nematodes
What causes replant disease?
Nematode Involvement in PRD:
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What causes replant disease?
Nematodes:-Ring, Rootknot, etc.
Microbial involvement:
-Bacteria
-Fungi
David Doll
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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Hypotheses, Prunus replant disease (PRD):
PRD is induced by unfavorable shifts in soilborne microbialcommunities associated with previous cultivation of thehost
The shifts can be detected by complementary culture-basedand culture-independent sampling of fine roots and therhizosphere
Community members contributing to (or suppressing)
incidence of PRD can be cultured and tested forpathogenicity (or disease suppression)
Effects of semi-selective soil treatments on incidence andseverity of PRD will provide additional evidence formicrobial roles in the disease
What causes replant disease?
David Doll
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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Roots from healthy tree Roots from RD-affected tree
Roots and soil from healthy and RD-affected trees
Whole-organism assays
Direct quantification (nematodes)
Isolation and quantification in culture
(fungi, bacteria)
Molecular assays
DNA fingerprinting (PCR of
rDNA; fungi, bacteria,
cloning of fragments, DNA-
sequence-based id)
Soil treatments
Semi-selective
chemicals or
treatments in
Microplot, GH
tests
What causes replant disease?
David Doll
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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What causes replant disease?
0
10
20
30
40
50
Discoloredroots
(%)
Control
Divide
nd
Maxim
Rido
mil
Stre
pt.+Ch
loram
.
Nem
acur
No heat Autoclaved
Effects of semi-selective soil treatmentsGreenhouse trial:
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UCCE Merced County
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Effects of semi-selective soil treatments
Microplot trial:
What causes replant disease?UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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d
a
bc
d
cd
d
bc
ab
Top fresh wt. of plants per plot (g)
Effects of semi-selective treatments on severity of PRD,microplots
What causes replant disease?
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UCCE Merced County
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Hypotheses, Prunus replant disease (PRD):
PRD is induced by unfavorable shifts in soilborne microbialcommunities associated with previous cultivation of thehost
The shifts can be detected by complementary culture-basedand culture-independent sampling of fine roots and therhizosphere
Community members contributing to (or suppressing)
incidence of PRD can be cultured and tested forpathogenicity (or disease suppression)
Effects of semi-selective soil treatments on incidence andseverity of PRD will provide additional evidence formicrobial roles in the disease
What causes replant disease?
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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Roots from healthy tree Roots from RD-affected tree
Roots and soil from healthy and RD-affected trees
Whole-organism assays
Direct quantification (nematodes)
Isolation and quantification in culture
(fungi, bacteria)
Molecular assays
DNA fingerprinting (PCR of
rDNA; fungi, bacteria,
cloning of fragments, DNA-
sequence-based id)
Soil treatments
Semi-selective
chemicals or
treatments in
Microplot, GH
tests
What causes replant disease?
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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2003 Trial Year
What causes replant disease?
-1.0 1.0
Arthro-2Bacill-4
Bacill-6
Entero
Flav-4Microb-1
Microb-3
Pseud-1RhizA-2
Pseud-2
Pseud-3
Rhiz-1RhizA-1
Vario-1
Control
Chloropicrin
Methyl Bromide
Control*Bleach
Control*Rinse
Chloropicrin*Rinse
Chloropicrin*Bleach
Methyl Bromide*Bleach
Methyl Bromide*Rinse N=266
Ordination significant
at P=0.008 for axis 1
and P=0.002 for axis 2.
Ordination of bacterial incidence, Parlier trial, 2004
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What causes replant disease?Ordination of cultured fungal incidence, Firebaugh replant trial, 2007
N=150
Ordination
significant at
P=0.002 for eachaxis -1.0 1.0
.
Cylind
Fusoxy1
Fus1
Fus3 Fus4Unk-C
Tricho-2
Acremon
Asper
Control CP
Control*Rinse
Control*Bleach
CP*Rinse
CP*Bleach
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UCCE Merced County
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UC A i l l d N l R
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What causes replant disease?Testing pathogenicity of bacteria and fungi on
Nemaguard peach
UC Agricultural and Natural Resources
UCCE Merced County
6-23-10
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UC A i l l d N l R
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What causes replant disease?Pathogenicity of bacteria associated with replant disease on NG peach
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UCCE Merced County
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UC A i lt l d N t l R
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What causes replant disease?
Pathogenicity of fungi associated with replant disease on NG peach
Disea
seserveritysco
re
(0=healthy,5=dead
)
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What causes replant disease?
Microbial involvement:
-Bacteria
-Fungi
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Non-Fumigant Management of
Replant DiseaseApplication of pre-plant cropping and fallow treatments.Microplot experiments.
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0
200
400
600
800
Responses of Nemaguard peach seedlings to short-termfallow, rotation treatments. Microplot Experiments.
Topfreshwt.endoffirst
year(grams)
Non-Fumigant Management of
Replant Disease
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Non-Fumigant Management of
Replant DiseaseThe affects of Piper-Sudan on replant disease of peach. FieldTrials. Planting: OHenry Peach on Nemaguard following 20
yr old Santa Rosa Plums on Marianna 2624
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Non-Fumigant Management ofReplant Disease
Responses to spot, strip, and broadcast fumigation treatments, Firebaugh(pre-plant fumigated Oct 2006, planted Jan 2007)
Fumigation treatment
(Oct 2007)
Fumigant
per
treated
acre
(lbs)
Fumigant
per
orchard
acre
(lbs)
Sudan grass rotation
(Jul-Sep 2007)
Disease severity
rating
(0 to 5 scale)
(7 Jul 2008)
Increase
in trunk
diameter
by 30 Aug
2008
(mm)
Control 0 --
no 1.5 7.9
yes 0.9 14.1
MB, by conventional
shanks to 8-wide row
strips
400 168no 0.9 22.6
yes 0.5 20.4
Telone C35, by
conventional shanks to 8-
wide row strips
540 227no 0.3 28.3
yes 0.3 31.9
Telone C35, by GPS-
controlled shanks to 5x 6
tree spots
540 81no 0.7 21.4
yes 0.5 24.2
Inline, by single drip
emitters
to 4-dia. tree spots
540 43no 0.8 20.8
yes 0.6 21.3
Chloropicrin, by GPS-
controlled shanks to 5x6
tree spots
400 60no 0.6 24.2
yes 0.2 26.5
None, yeast extract root
spray and drench at
planting
0 --no 1.2 10.4
yes 1.0 14.0
Minimum significant difference (according to 95% confidence intervals): 8.9
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18
18.5
19
19.5
20
20.5
21
21.5
22
Control Sudan
TreeDiamter
(mm)
a
b
P=0.048
Non-Fumigant Management of
Replant Disease
g
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6-23-10
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Conclusions:
Replant disease (RD) of almond is a biologically induceddisease showing poor growth or survival in almondplanted after Prunus. Prevented by pre-plant fumigation with fumigants containing
Chloropicrin.
Some fungi and bacteria are being implicated, multipleapproaches are being used to determine causal agentsand developing greenhouse assays.
An unfavorable microbial community may beresponsible for the disease: Shifting the microbial community in favor of the newly planted
Prunus sp. tree may provide some level of disease control.
Pre-plant application of treatments or cover cropping mayprovide alternative control reducing the use of fumigants
g
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6-23-10
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Thank you!
Almond Board of California
USDA-ARS Pest Mgt. Program for Integrated
Alternatives to Methyl Bromide
TriCal, Inc.
Commercial almond and peach growers of CA
Multiple scientific personnel involved
g
UCCE Merced County
6-23-10