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