O16 Geoffrey
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Transcript of O16 Geoffrey
Phytophthora diversity in UK gardens
Geoff DentonPlant Pathologist
The Royal Horticultural Society
Detection Methods
Apple Baiting
Immunoassay
Nested PCR
Comparison of positive results from 2006 and 2007 from apple baiting, nested PCR and immunoassay
0
10
20
30
40
50
60
70
80
90
Apple baiting Nested PCR Immunoassay
Posi
tive
resu
lts (%
)
StemRootSoil
n=
145n=
413
n=
401
n=
144
n=
380
n=
320n=92
Positive results for the last 10 years from apple baiting, nested PCR and immunoassay
0
50
100
150
200
250
300
350
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Num
ber o
f Enq
uirie
s
Total testedPositive apple baiting resultsPositive nested PCR resultsPositive immunoassay results
Phytophthora species identified through sequencing ITS
0 20 40 60 80 100 120 140 160
P. tropicalis/capsiciP. syringae
P. sp.510P. ramorumP. quercinaP. primulae
P. porriP. pgchlamydo
P. niederhauseriiP. nicotianae
P. megaspermaP. inundata
P. ilicisP. ideai
P. hibernalisP. gonapodyides
P. fragariaeP. drechsleriP. cryptogea
P. citrophthoraP. citricola
P. cinnamomiP. cambivoraP. cactorum
P. alni
Occurrence of species (n=489)
P. citricolaP. cinnamomi
P. cryptogea
P. niederhauserii
P. tropicalis/capsici
P. ramorum
Phytophthora diversity
• In total 25 Phytophthora species have been recorded in UK gardens
• During 2006 and 2007 alone we recorded 87 different host genera
• Top hosts are; Taxus (19%), Rhododendron(5.6%), Rubus (4.2%) and Viburnum (4.2%)
1---Phytophthora sp.
---2P. syringae
1---P. nicotianae
---1P. megasperma
2--3P. gonapodydies
--3-P. fragariae
-227P. cryptogea
---6P. citrophthora
24920P. citricola
22-32P. cinnamomi
--1-P. cactorum
ViburnumRhododendronRubusTaxus
Following the identification of the Phytophthora species, potential new hosts for the following species have been found:
• P. cactorum: Phylliopsis• P. cambivora: Prunus laurocerasus• P. citricola: Abutilon, Aesculus, Buddleja, Ceanothus, Convolvulus,
Cornus, Enkianthus, Fothergilla, Fremontodendron, Helleborus, Lavendula, Pieris, Sorbus, Santolina, Symphoricarpus, Taxus, Trachelospermum, Wisteria
• P. citrophthora: Ceanothus, Daphne, Heuchera• P. cryptogea: Anemone, Araucaria, Calluna, Caryopteris, Choisya,
Cistus, Delphinum, Heliopsis, Heuchera, Prunus laurocerasus, Tilia, Polemonium, Ribes, Rosmarinus, Ruta, Taxus, Thuja
• P. gonapodyides: Rubus, Sorbus, Taxus• P. hibernalis: Hebe• P. megasperma: Hedera
Proportion of Pythium and Phytophthora identified by sequencing of ITS region, through
all detection methods
0
50
100
150
200
250
300
2006 2007
Year
Num
ber o
f Enq
uirie
s
Pythium
Phytophthora & Pythium
Phytophthora
61%9%30%
57%
5%
38%
Comparison of total Phytophthora and Pythium identified, by method and sample
0
50
100
150
200
250
Stem (PCR) Roots (PCR) Soil (PCR) Stem (Bait) Roots (Bait) Soil (Bait)
Num
ber o
f Enq
uirie
s
PythiumPhytophthora
Pythium species identified through sequencing ITS
0 5 10 15 20 25 30 35 40 45
Py violaePy vexans
Py vanterpooliiPy ultimum
Py sylvaticumPythium sp.Py parvum
Py oligandrumPy montanum
Py monospermumPy minus
Py macrosporumPy irregulare
Py intermediumPy helicoides
Py heterothallicumPy chamaehyphonPy attrantheridium
Occurrence of species (n=160)
Py attrantheridium
Py intermedium
Py sylvaticum
Pythium diversity
• In total 17 Pythium species have been recorded in UK gardens
• During 2006 and 2007 alone we recorded 72 different host genera
• Top hosts are; Taxus (12.6%), Prunus (4.9%), Rubus (4.2%) and Cornus (3.5%)
--47Pythium sp.
1---Py vexans
2-13Py sylvaticum
-1--Py oligandrum
---1Py montanum
---1Py monospernum
---1Py macrosporum
---1Py irregulare
-132Py intermedium
-212Py heterothallicum
2213Py attrantheridium
CornusRubusPrunusTaxus