Biological control of Pierce’s disease: Influence of grape genotype, plant growth stage, and geographic location
D. L. Hopkins Mid-Florida RECUniversity of Florida
Phil BrannenPlant Pathology Dept.University of Georgia
Biological Control of PD with strain EB92-1
• Grape Genotypes
• Mature, Producing Grapevine
• Different Geographic Areas
• Treatment Methodology
• Colonization
Current tests on new grape plantings of various grape genotypes
Field injections
Greenhouse injection
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60%
Pie
rce
's d
ise
as
e
Cab.Franc Chamb. Cynth.
Grape Genotypes
Untreated
EB92-1
• Effect of strain EB92-1 on PD in various genotypes, V. vinifera (Cabernet Franc), V. aestivalis (Cynthiana), and French/American hybrid (Chambourcin) in the vineyard in Central Florida.
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50%
Pie
rce
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ise
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Chardon. CheninBlanc
GoldenMuscat
RubyCabernet
Grape Genotypes
Untreated
EB92-1
Effect of strain EB92-1 on PD in various cultivars in Central Florida
Additional Genotype Studies
• North Carolina – Mature plants of Vitis labrusca cultivars Canadice, Concord Seedless, Einset, Glenora, Himrod, Interlaken, Jupiter, Lakemont, Marquis, Mars, Reliance, Suffolk Red, Vanessa, and Venus.
• South Carolina – Young transplants of Vitis labrusca cultivars Jupiter, Neptune, Mars, and Venus.
• Georgia – Young transplants of Cabernet Sauvignon, Cabernet Franc, and Vidal Blanc (hybrid).
• California – Young transplants of Cabernet Sauvignon, Orange Muscat, Barbera, Viognier, Reisling, and Chardonnay.
Inoculated approximately 107 cells EB92-1 per plant into 2nd and 3rd internodes.
Mature Plant Treatments
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50%
Ne
w P
D S
ym
pto
ms
2006 2007 2008
Year
Untreated
EB92-1
Effect of EB92-1 on development of PD in mature ‘Mourvedre’ grapevines in North Georgia vineyard with a high incidence of PD
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100
2006 2007 2008
Year
% S
urv
ivin
g V
ine
s
Untreated
EB92-1
Untreated
EB92-1
Effect of EB92-1 on survival of symptomatic, mature ‘Mourvedre’ grapevines in North Georgia vineyard
29 36 10 6
0
2
4
6
8
10
12
14
16%
P
ierc
e's
dis
ea
se
2006 2007 2008
Year
Untreated
EB92-1
Effect of EB92-1 on development of PD in mature ‘Mourvedre’ grapevines in North Georgia vineyard with a low incidence of PD
0102030405060708090
100
2006 2007 2008
Year
% S
urv
ivin
g V
ine
s
UntreatedEB92-1
Effect of EB92-1 on survival of symptomatic, mature ‘Mourvedre’ grapevines in a North Georgia vineyard
3 4
(2)
Planned Mature Plant Study for 2009
Inject EB92-1 into the main trunk of the vines to get more systemic affect
North Georgia
Central Florida North Carolina
South Carolina
Different Locations (Climates)
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30
35
40%
P
ierc
e's
dis
ea
se
Florida Georgia S. Carolina
State
Untreated
EB92-1
Effect of EB92-1 on development of PD in new plantings in Florida (4 years - Cabernet Franc, Chardonnay, Chenin Blanc, Golden Muscat, Ruby Cabernet), Georgia (1 year – Cabernet Sauvignon, Cab. Franc, Vidal Blanc), S. Carolina (1 year – Neptune)
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0.5
1
1.5
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2.5
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3.5
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4.5
5P
ierc
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Chardonnay Chambourcin
Cultivar
RC Untreated
EB92-1 RC
RC injected EB92-1
Comparison of treatment method with EB92-1 on control of Pierce’s disease in rooted cuttings in the greenhouse.
b b
a
b
aa
EB92-1 Treatment Methodology
Effect of EB92-1 on host colonization by the virulent Pierce’s disease strain
• Rooted cuttings of Carignane grapevine with >18 inches of new growth were used.
• Plants were inoculated with a suspension of EB92-1 (108 cells/ml). One drop was inoculated into the 1st and 2nd internodes (total 107 cells/plant).
• Three weeks later, plants were inoculated with a suspension of PD92-9, a virulent PD strain (106 cells/ml). One drop was inoculated into opposite sides of the 3rd internode (105 cells/plant).
• The 3rd internode (0, pathogen-inoculated internode) and the 13th internode were sampled for grinding and dilution plating.
• EB92-1 and PD92-9 were labeled with different colored fluorescent proteins for differentiation on culture plates.
Growth curves of strains in grape stem internode 10
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0 1 2 3 4 5 6
Weeks after inoculation
Bac
teri
a pe
r g
stem
tis
sue
(Log
10)
Virulent
Combo Virulent
Comb Biocontrol
105 PD92-9 cells
Colonization of host plant by EB92-1 and pathogen (PD92-9
Growth curves of strains in inoculated grape stem internode (0)
01234567
0 1 2 3 4 5 6
Weeks after inoculation
Bac
teri
a pe
r g
stem
tis
sue
(Log
10)
Virulent
Combo Virulent
Comb Biocontrol
105 PD92-9 cells
Summary
• Grape Genotypes – In Florida, EB92-1 was effective in Vitis vinifera cultivars, V. aestivalis, and American hybrids. Tests are in progress on other cultivars in other locations.
• Mature, Producing Grapevine - Treatment of mature grapevines did not reduce new cases of PD in the first year, but may have had a slight benefit in year 2 and 3. Treated vines that developed PD symptoms had a better survival rate in year 2 and 3 than the untreated.
• Different Geographic Areas – Biological control has been very effective on transplants in Florida. Preliminary data is positive in Georgia and South Carolina.
• Treatment Methodology - Propagating rooted cuttings from mother vines infected with EB92-1 was inconsistent in biological control of Pierce’s disease, providing control in Chambourcin and not in Chardonnay.
• Colonization - In greenhouse inoculations, EB92-1 prevented the pathogenic Pierce’s disease strain from reaching a threshold population in the plant needed to produce disease.
Thanks!