david appel cdfa - epidemiology of pierce’s disease in texas vineyards - 2008 symposium
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Epidemiology of Pierce’s Disease in Texas Vineyards
2008 Pierce’s Disease Research Symposium
Session 5: Crop Biology and Disease Epidemiology
Dr. David N. Appel, ProfessorDept. of Plant Pathology and Microbiology
Texas A&M UniversityCollege Station, TX
December 17, 2008
Objective
Compare rates of Pierce’s Disease development amongcommon grape varieties in Texas vineyards
• Locations of inoculum sources,- primary (outside vineyard) vs. secondary (within vineyard),
• Influence of varietal selections, • Vector behavior,• Success of cultural and control practices.
“Historically, mapping the incidence and vine locations of PD and tracking spread over a few consecutive years has led to key conclusions regarding the sources of PD spread (Hill, Hashim and Purcell, 2002, PD Research Symposium, San Diego, CA)
Vineyard Surveys Methodology
• Rating of vine health (1 = healthy, 5 = dead),– based on composite of all symptoms,– recognize limitations!
• Incorporate into a Geographic Information System (GIS),• Conduct analyses of data,• Create georeferenced maps and analyze disease incidence
and severity in relation to site characteristics and vector behavior,
• Collect isolates for strain diversity analyses.
“Gulf Coast”Vineyard
“Hill Country”Vineyard
Disease Progress in Gulf Coast Vineyard
2001 2005 2006 2007
Chambourcin, n = 1071
Survey maps
Rating scale: 1 = healthy , 2 = incipient symptoms , 3 = advanced symptoms , 4 = advanced symptoms/deiback , 5 = dead .
Logistic rate of disease increase (r) = 2.02
Ü 0 40 8020 Meters
Gulf CoastVineyard
12,342 vines
8 vine varieties
Variety No. of Vines Year Planted Rootstock
Chambourcin 1071 2001 own
Shiraz (4) 1270 2001 101-14
Primitivo (4) 1270 2001 SO4
Primitivo (3) 1280 2000 101-14
Shiraz (3) 1280 2000 101-14
Ruby Cab 1152 2000 101-14
Blanc du Bois 1071 2001 own
Disease Progress – Gulf Coast Vineyard
2005 2007
P
P
S
S
M
M
Mb C
BdbRcÜ
0 10 20 30 405Meters
Disease Progress in the Gulf Coast Vineyard
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
2000 2001 2002 2003 2004 2005 2006 2007
Year
Pro
po
rtio
n D
ead
Vin
es
Chambourcin
Shiraz 3
Shiraz 4
Primitivo 3
Primitivo 4
Rub Cab 5
Blanc du Bois
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
2000 2001 2002 2003 2004 2005 2006 2007
Year
Pro
po
rtio
n D
ead
Vin
es
Chambourcin
Shiraz 3
Shiraz 4
Primitivo 3
Primitivo 4
Rub Cab 5
Blanc du Bois
Disease Progress in Hill Country Vineyard
Cabernet sauvignon
Pinot grigio
Cabernet sauvignon
Charadonnay
MerlotCab franc
Melbec
Ü
Disease Progress in the Hill Country Vineyard
Year
Spatial PerspectivesOrdinary Runs Analysis
Variety Year Prop.
Within
Prop.
Across
Cab Sauv. 1 TXH
03 .105 .101
05 .210 .16
06 .316 .16
Merlot PAL 05 .40 0.0
06 .70 .023
Merlot TXH 05 .44 .127
06 .61 .222
HILL Country VineyardVarietal responses
Variety n rm rdEdge
Effect?
Rows With clusters
Cab sauv 2 1627 0.79 0.56 Yes n/a
Pinot grigio 3477 0.59 0.46 No n/a
Merlot 1419 0.56 0.50 No Yes
Chardonnay 3267 0.27 0.22 Yes n/a
Cab franc 557 0.18 0.13 Yes n/a
Cab sauv 1 1111 0.06 0.05 Yes Yes
Fates/Recovery Rates of Diseased Vines
Majority of Chambourcin, even healthy,were dead after 2 years
Small number vines with incipientsymptoms rated healthy after 3 years
No Chambourcin with advancedsymptoms recovered after 2 years
Fates/Recovery Rates of Diseased Vines
Majority of Shiraz healthy,After 2 years
Large number vines with incipientsymptoms rated healthy after 2 years
One Shiraz vine with advancedsymptoms recovered after 2 years
Results of Attempted Isolations From Chambourcin
= positive = negative
• 33 attempted isolations ,• vines selected on symptoms,
• Vines sampled in June,
• Health ratings made in August,
• Vines selected on basis of suspected symptoms,
• 24 positive, 9 negative.
Positive for Isolation
Negative for Isolation
Health Rating (no.) (no.)
1 2 3
Chambourcin 2 1 2
3 9 3
4 2 1
Health Ratings of Vines Sampled for Isolation
Gulf Coast Vineyard (Six Blocks)
Numbers of Positive Vines
Numbers of Negative
Vines
YearRating =
1Rating =
2Rating =
3
Rating = 4-6
Rating = 1
Rating = 2
Rating = 3
Rating = 4-6
2005 30 33 2 1 24 10 0 1
2006 13 24 21 8 26 5 3 1
2007 12 6 20 28 19 7 3 6
Culture attempts = 101Positive isolations = 66 (6 blocks only)
Strain Analysis at Gulf Coast VineyardMultiplex PCR Assay Primers
Primer Sequence (5'-3')
XF1968-L GGAGGTTTACCGAAGACAGAT
XF1968-R ATCCACAGTAAAACCACATGC
XF 2542-L TTGATCGAGCTGATGATCG
XF 2542-R CAGTACAGCCTGCTGGAGTTA
ALM-1 CTGCAGAAATTGGAAACTTCAG
ALM-2 GCCACACGTGATCTATGAA
Hernandez-Martinez et al. 2006. Plant Dis. 90: 1382-1388
*C.P. TORRES, D.N. Appel, and L. Morano. 2008. Phytopathology (Abstr.).
Multiplex PCR Assay used to differentiation subspecies of Almond strain I, Almond strain II, Pierce’s Disease strain, and Oleandar*
Step 1.
Simple Sequence Repeat Markers
Primer Forward Sequence Reverse SequenceType of repeat
motif
OSSR-9 TAGGAATCGTCTTCAAACTG TTACTATCGGCAGCAGAC (TTTCCGT)13
GSSR-4 GCGTTACTGGCGACAAAC GCTCGTTCCTGACCTGTG (ATCC)7
GSSR-7 ATCATGTCGTGTCGTTTC CAATAAAGCACCGAATTAGC (GGCAAC)24
GSSR-14 TTGATGTGCTTTTGCGGTAAG GACAGGTCCTCTCATTGCG (TCCCGTA)24
GSSR-19 GCCGATGCAGAACAAGAAC TCAACTTCGCCACACCTG (GAAAAACAAG)19
Lin et al. 2005. Applied and Environmental Microbiology 71(8): 4888-4892
Step 2. Differentiation of Xylella fastidiosa subspecies piercei isolates into strain groups utilizing simple sequence repeat markers
OSSR# 9 OSSR# 4
OSSR# 14 OSSR# 19
OSSR# 7
• 102 Isolates– 7 Varieties– 5 Blocks
• 3 Major groups– Red
• 44 Isolates• 7 Varieties• 5 Blocks
– Blue • 39 Isolates• 6 Varieties• 5 Blocks
– Green • 14 Isolates• 4 Varieties• 3 Blocks• Temecula
– Black• Non-Grape and Dixon Strain
Hierarchical Cluster Analysis -Between-Group Linkages
Observations/Conclusions
• Secondary spread within vineyards prevalent,• Different varieties respond to infection with
great variability,• Variability goes beyond varietal differences,• Grape strain (subsp. fastidiosa) dominates
population,• Consequences for growers,
– recommended varieties,– roguing practices.
Questions?
Thanks to:
Cruz TorresTom KurdylaKelly Bryan
TX PD Research Group
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