This is a list of plants in which Pierce's disease (PD) strains of Xylella fastidiosacan multiply. Hosts of other strains of Xylella fastidiosa (abbreviated as Xf) follow the PD list. The lists are alphabetically ordered by the scientific (Latin) name. We used the scientific and common names that appeared in the original references, with limited attempts to reconcile older names with more contemporary ones.
What does a plant's rating as a "host of Xylella" mean?
This list includes plants from which Xylellahas been recovered using a variety of detection methods. The plants posing the greatest risk in the development of Pierce's disease are those that·
Allow systemic movement of Xylella
Are preferred feeding hosts of important vector species
Most of the plant species were selected because they are preferred by important insect vectors or because they commonly occur in habitats where those insects live. Not all possible host plants have been tested. The plants that insect vectors feed on most frequently are probably the most important reservoirs of Xf. Most of this research has been done in California using plants from areas that have had ongoing problems with Pierce's disease. Some plants were selected arbitrarily or because investigators were curious about plants that belonged to certain botanical families.
Why are there so many hosts?
PD strains of Xf can multiply to some degree within the great majority of plants that are inoculated with the bacterium. However, relatively few plants support moderate to high bacterial populations, and fewer still allow movement of Xf beyond the inoculation point. It is easier for an insect vector to pick up Xylellafrom plants that have high bacterial populations. Plants ranked "high" can support between 10 million and 1 billion live bacteria per each gram of tissue. "Low" category plants support less than 100,000 live bacteria per gram of plant. Vector acquisition of Xffrom plants in the "low" category is very inefficient. The ability of Xylellato move systemically throughout the plant, beyond the inoculation (insect feeding) point, is an important host attribute. Systemic movement enables the bacteria to spread on its own to a much larger volume of plant tissue, making it easier for feeding insects to pick it up.
What factors influence the growth of Xylellain a plant?
The growth of Xylella in plants depends on the bacterial strain (genetic variation), the plant's physiology and the temperature. Other factors not yet understood may also influence the fate of Xylella. The methods used to study Xf in plants also determine how well we observe what really happens to the bacteria. Each detection method reveals different kinds of information and has its own level of sensitivity and reliability.
Key to List Categories
** Plants which were tested and came out negative are indicated by asterisks**.
A blank cell indicates the data was not available.
FIELD ISOLATED: Xylellawas isolated from field-collected material after mechanical (needle) inoculation
GH ISOLATED: Xylellawas isolated from greenhouse-grown material after vector inoculation or needle inoculation. Greenhouse conditions can result in populations of bacteria that are several times higher than for the same plant species in the field.
POPULATIONS of Xf are expressed as:
High = 10 million to one billion live cells per gram of plant material
Medium = 100,000 to 9 million live cells per gram of plant material
Low = less than 100,000 live cells per gram of plant material
SYSTEMIC: "Y" means Xfwas recovered from tissues beyond the inoculation point. "N" means that the bacteria was not recovered. The bacteria moves from cell to cell in the xylem of the plant. A question mark (?) indicates that Xfwas detected at a long distance from the inoculation site but this may have been due to the xylem vessels in the plant being very long.
XfISOLATION TECHNIQUE: The method used to detect Xylellafrom plant material.
Culture = Assays based on the growth of Xffrom finely ground plant samples plated onto semi-selective microbiological media and incubated. The number of live bacteria in the sample can be determined from the number of colonies that grow on the plate. The advantages of culture-based assays are that they quantitatively detect live cells, are fairly sensitive (down to thousands of Xfper gram) and highly reliable if the cultured bacteria are further confirmed as Xfby other means. Disadvantages are that the method requires at least a week to complete, other bacteria and fungi in plant samples can completely obscure the results, and certain plants (black walnut and coffeeberry, for example) contain substances which inhibit growth of Xfon the Petri dish.
ELISA = Enzyme-Linked ImmunoSorbent Assay uses antibodies against Xylellato detect if Xfoccurs in the sample. The antibodies bind specifically to proteins on the outer wall of Xf, and other reactions allow enzymes to cause a color change in proportion to how many antibodies are bound to Xf cells in the sample. The more intense the resultant color, the more bacteria are present. Advantages of ELISA are it can indicate the quantities of Xf(dead or alive) in the sample and the test is easily run for many samples. Disadvantages are its low sensitivity (lower detection limit 100,000 Xfper sample), failure to distinguish live from dead Xfcells, and occasional false positive readings, especially for plants other than grape.
DIF = Direct ImmunoFluorescence uses antibodies against Xylellato bind a fluorescent indicator dye to Xfcells so they can be seen using a microscope that has ultravolet light illumination.
PCR = Polymerase Chain Reaction amplifies a Xylella-specific piece of DNA millions of times. The amplified DNA is visible as bands on a gel after separation in an electric field. PCR is becoming more widely used to detect Xf.It has the advantage that it is the most sensitive method for detecting Xf(to below 100 cells per sample), and can be used even for frozen or preserved samples. PCR also is unlikely to give false positives or be affected by the presence of other microorganisms. PCR can also be used to quickly distinguish some strains of Xf. Disadvantages are that it is generally not quantitative, it is still not widely available in diagnostic labs, and cannot distinguish DNA from living vs. dead bacteria. Some naturally-occurring chemicals in plants can inhibit PCR, resulting in negative test results even though Xfis present in the plant.
Budding = Xylellawas transmitted when budwood from an infected plant was grafted onto a previously healthy plant. This older method depends on accurate identification of the disease in the indicator (recipient) plants. Successful grafting requires the inclusion of live xylem ("wood") with the scion grafted onto the indicator plant.
BGSS = Blue-Green
Sharpshooter
(Graphocephala atropunctata). See a list of preferred hosts in coastal
California.
GWSS = Glassy-Winged
Sharpshooter
(Homalodisca coagulata). See a list of preferred hosts at the California
Department of Food and Agriculture's web site on GWSS at http://plant.cdfa.ca.gov/gwss/.
RHSS = Red-Headed
Sharpshooter
(Carneocephala fulgida). Primarily found in central California on
pasture grasses, some sedges and reeds in wet spots. Highly prefers water
grass and Bermuda grass in weedy situations.
Plant Host Status
for Pierce's Disease Strains of Xylella fastidiosa
Scientific
Name
Common
Name
Reference
Acacia
longifolia
golden
wattle
Freitag
'51
Acer
macrophyllum
big
leaf maple
P
+ S '99
Acer
negundo
box
elder
P
+ S '99
Aesculus
californica
California
buckeye
P
+ S '99
Aesculus
californica
California
buckeye
Freitag
'51
Aesculus
californica*
California
buckeye*
Raju,
1983
Agropyron
sp.*
crested
wheatgrass*
Raju,
1983
Alnus
rhombifolia
white
alder
P
+ S '99
Ampelopsis
arborea
peppervine
Hopkins
'88
Amsinckia
douglasiana
buckthorn
weed
Freitag
'51
Artemisia
absinthium*
mugwort*
Raju,
1983
Artemisia
douglasiana
mugwort
P
+ S '99
Artemisia
douglasiana
mugwort
Freitag
'51
Artemisia
douglasiana
mugwort
H
+ P '95
Avena
fatua
wild
oat
Freitag
'51
Avena
fatua
wild
oat
Freitag
'51
Baccharis
pilularis
coyote
brush
P
+ S '99
Baccharis
pilularis
coyote
brush
Freitag
'51
Baccharis
salicifolia
mule
fat
P
+ S '99
Beta
vulgaris*
sugar
beet*
Freitag
'51
Bidens
pilosa var. pilosa
beggar-ticks
Freitag
'51
Brassica
rapa*
field
mustard*
Freitag
'51
Bromus
catharticus
rescue
grass
Freitag
'51
Bromus
rigidus
ripgut
grass
Freitag
'51
Bromus
sp.
Russian
brome grass
Freitag
'51
Callicarpa
americana
American
beautyberry
Hopkins
'88
Callistephus
chinensis
China
aster
Freitag
'51
Calycanthus
occidentalis*
spicebush*
P
+ S '99
Calycanthus
occidentalis*
spicebush*
Freitag
'51
Canna
sp.
Canna
Freitag
'51
Chenopodium
ambrosioides
Mexican
tea
P
+ S '99
Chenopodium
ambrosioides
Mexican
tea
Freitag
'51
Citrus
limon
lemon
'Meyer'
Freitag
'51
Citrus
reticulata
tangerine
Freitag
'51
Citrus
sinensis
sweet
orange
Hopkins
Î91b
Claytonia
perfoliata
miner's
lettuce
Raju,
1983
Conium
maculatum
poison
hemlock
P
+ S '99
Coprosma
baueri
Coprosma
Freitag
'51
Cotoneaster
francheti
Cotoneaster
Freitag
'51
Cotoneaster
rotundifolia
cotoneaster
Freitag
'51
Cynodon
dactylon
Bermuda
grass
Freitag
'51
Cynodon
dactylon
Bermuda
grass*
H
+ P '95
Cynodon
dactylon*
Bermuda
grass*
Raju,
1983
Cyperus
acuminatus*
sedge*
P
+ S '99
Cyperus
eragrostis
purple
nutsedge
P
+ S '99
Cyperus
esculentus
yellow
nutsedge
Freitag
'51
Cytisus
scoparius
Scotch
broom
Freitag
'51
Daucus
carota var. sativa
short
white carrot
Freitag
'51
Daucus
carota*
wild
carrot*
Raju,
1983
Digitaria
sanguinalis
hairy
crabgrass
Freitag
'51
Digitaria
sanguinalis
hairy
crabgrass
Freitag
'51
Distichlis
spicata*
saltgrass*
Freitag
'51
Duranta
repens
pigeon-berry
Freitag
'51
Echinochloa
crus-galli
water
grass
H
+ P '95
Echinochloa
crus-galli
water
grass
Freitag
'51
Elymus
sp.*
wild
rye*
Raju,
1983
Epilobium
californicum
willow-herb
Freitag
'51
Epilobium
paniculatum
panicled
willow-herb
Freitag
'51
Eragrostis
diffusa
diffuse
love grass
Freitag
'51
Erodium
cicutarium
red
stem filaree
Freitag
'51
Escallonia
montevidensis
Escallonia
Freitag
'51
Eschscholzia
californica*
California
poppy*
Raju,
1983
Eugenia
myrtifolia
Aust.
brush-cherry
Freitag
'51
Fragaria
californica
wild
strawberry
Raju,
1983
Franseria
acanthicarpa
annual
bur-sage
Freitag
'51
Fraxinus
dipetala
California
ash
Freitag
'51
Fraxinus
latifolia
Oregon
ash
P
+ S '99
Fritillaria
sp.*
fritillary*
Raju,
1983
Fuchsia
magellanica
Fuchsia
Freitag
'51
Genista
monspessulana
French
broom
P
+ S '99
Hedera
helix
English
ivy
P
+ S '99
Hedera
helix
English
ivy
Freitag
'51
Hedera
helix*
English
ivy*
Raju,
1983
Helianthus
sp.
wild
sunflower
Freitag
'51
Heteromeles
arbutifolia*
toyon*
P
+ S '99
Heteromeles
arbutifolia
toyon
Freitag
'51
Hordeum
murinum
common
foxtail
Freitag
'51
Hordeum
nodosum*
wild
barley*
Raju,
1983
Hordeum
vulgare
barley
Freitag
'51
Hydrangea
paniculata
Hydrangea
Freitag
'51
Juglans
californica
Calif.
black walnut
P
+ S '99
Lactuca
serriola
prickly
lettuce
Freitag
'51
Lactuca
serriola*
prickly
lettuce*
Raju,
1983
Lathyrus
cicera
Lathyrus
Freitag
'51
Lathyrus
clymenium
Lathyrus
Freitag
'51
Lathyrus
sativa
grass
pea
Freitag
'51
Lolium
multiflorum
Italian
ryegrass
Freitag
'51
Lolium
temulentum
darnel
Freitag
'51
Lonicera
japonica
Japanese
honeysuckle
Freitag
'51
Majorana
hortensis
sweet
majoram
Freitag
'51
Malus
sylvestris
apple
Freitag
'51
Malva
parvifolia
cheeseweed
Freitag
'51
Matricaria
suaveolens
pineapple
weed
Freitag
'51
Medicago
hispida
bur
clover
Freitag
'51
Melilotus
alba
white
meliot
Freitag
'51
Melilotus
indica
hubam
clover
Freitag
'51
Melilotus
officinalis
yellow
sweet clover
Freitag
'51
Melilotus
sp.
sweet
clover
Freitag
'51
Melissa
offcinalis
garden
balm
Freitag
'51
Mentha
sp.
mint
Freitag
'51
Mimulus
aurantiacus
bush
monkeyflower
Freitag
'51
Nasturtium
officinale*
water
cress*
Raju,
1983
Nerium
oleander*
oleander*
Raju,
1983
Nerium
oleander*
oleander*
Purcell
Î99
Oeanthe
sarmetosa
water
parsley
Freitag
'51
Oenothera
hookeri
evening
primrose
Freitag
'51
Parthenocissus
quinquefolia
Virginia
creeper
Hopkins
'88
Parthenocissus
tricuspidata
Boston
ivy
Freitag
'51
Paspalum
dilatatum
Dallisgrass
Freitag
'51
Pelargonium
hortorum
fish
geranium
Freitag
'51
Pennisetum
clandestimun
Kikuyugrass
Freitag
'51
Phalaris
minor
Mediter.
canary grass
Freitag
'51
Phalaris
paradoxa
gnawed
canary grass
Freitag
'51
Philadelphus
lewisii
syringa
Freitag
'51
Phleum
pratense
Timothy
grass
Freitag
'51
Pittosporum
crassifolium
karo
Freitag
'51
Plantago
lanceolata
English
plantain
Freitag
'51
Plantago
lanceolata*
English
plantain*
Raju,
1983
Platanus
occidentalis
sycamore
Hopkins
'88
Poa
annua
annual
bluegrass
Freitag
'51
Poa
pratensis*
Kentucky
bluegrass*
Freitag
'51
Polygonum
convolvulus
black
bindweed
Freitag
'51
Polygonum
persicaria
ladys
thumb
Freitag
'51
Polygonum
ramosissimum*
knot
weed*
Raju,
1983
Polypogon
monspelensis*
rabbit
foot grass*
Freitag
'51
Populus
fremontii
Fremont
cottonwood
P
+ S '99
Populus
sp.*
cottonwood*
Freitag
'51
Portulaca
oleracea*
common
purslane*
Freitag
'51
Prunus
armeniaca*
apricot*
Raju,
1983
Prunus
demissa
western
chokecherry
Freitag
'51
Prunus
mume
Japanese
apricot
Freitag
'51
Prunus
sp.
wild
plum
P
+ S '99
Pseudotsuga
menziesii*
Douglas-fir*
Freitag
'51
Pyracantha
augustifolia
firethorn
Freitag
'51
Quercus
agrifolia
coast
live oak
P
+ S '99
Quercus
domosa*
scrub
oak*
Raju,
1983
Quercus
lobata
valley
oak
P
+ S '99
Reseda
odorata
common
migonette
Freitag
'51
Rhamnus
californica*
Calif.
coffeeberry*
P
+ S '99
Rheum
rhaponticum
rhubarb
Freitag
'51
Rosa
californica
California
wild rose
P
+ S '99
Rosa
californica
California
wild rose
Freitag
'51
Rosa
californica*
California
wild rose*
Raju,
1983
Rosmarinus
offcinalis
rosemary
Freitag
'51
Rubus
discolor
Himalayan
blackberry
H
+ P '95
Rubus
discolor
Himalayan
blackberry
Raju,
1983
Rubus
sp.
blackberry
Hopkins
'88
Rubus
ursinus
California
blackberry
P
+ S '99
Rubus
ursinus
California
blackberry
Freitag
'51
Rumex
crispus
curly
dock
Freitag
'51
Salix
bebbiana*
willow*
Raju,
1983
Salix
laevigata
red
willow
P
+ S '99
Salix
lasiolepis
arroyo
willow
P
+ S '99
Salix
sessilifolia*
sandbar
willow*
P
+ S '99
Sambucus
canadensis
American
elder
Hopkins
'88
Sambucus
mexicana*
blue
elderberry*
Raju,
1983
Sambucus
mexicana
blue
elderberry
Freitag
'51
Sambucus
mexicana
blue
elderberry
P
+ S '99
Setaria
lutescens
yellow
bristle grass
Freitag
'51
Sonchus
asper
prickly
sowthistle
Freitag
'51
Sorghum
halepense
Johnson
grass
Freitag
'51
Sorghum
halepense*
Johnson
grass*
Raju,
1983
Sorghum
vulgare
Sudangrass
Freitag
'51
Sorghum
vulgare*
Sudangrass*
Raju,
1983
Symphoricarpos
albus
snowberry
P
+ S '99
Symphoricarpos
albus
snowberry
Freitag
'51
Syringa
vulgaris
lilac
Freitag
'51
Tatragonia
expansa*
New
Zealand spinach*
Freitag
'51
Toxicodendron
diversilobum*
poison
oak*
Raju,
1983
Toxicodendron
diversilobum
poison
oak
P
+ S '99
Toxicodendron
diversilobum
poison
oak
Freitag
'51
Trifolium
fragarium
strawberry
clover
Freitag
'51
Trifolium
hybridum
Aliske
clover
Freitag
'51
Trifolium
incarnatum
crimson
clover
Freitag
'51
Trifolium
pratense
red
clover
Freitag
'51
Trifolium
repens
white
clover
Freitag
'51
Trifolium
repens var. latum
Ladino
clover
Freitag
'51
Umbellularia
californica
California
bay or laurel
P
+ S '99
Uritca
dioica ssp.gracilis
stinging
nettle
Freitag
'51
Urtica
dioica ssp.gracilis
stinging
nettle
P
+ S '99
Veronica
sp.
speedwell
Freitag
'51
Vicia
monathus
vetch
Freitag
'51
Vinca
major
greater
periwinkle
P
+ S '99
Vinca
major
greater
periwinkle
Freitag
'51
Vinca
minor
periwinkle
Raju,
1983
Vitis
californica
Calif.
wild grape
Freitag
'51
Vitis
californica*
Calif.
wild grape*
Raju,
1983
Vitis
rupestris
St.
George
P
+ S '99
Vitis
vinifera
grape
'Pinot Noir'
H
+ P '95
Vulpia
myuros var. hirsuta
foxtail
fescue
Freitag
'51
Xanthium
strumarium
cocklebur
Freitag
'51
Plant Host Status
for Non-PD Strains of Xylella fastidiosa
| Scientific Name | Common Name |
|
|
|
|
|
Reference |
| Baccharis halimifolia | eastern baccharis |
|
|
Hopkins '88 | |||
| Bidens leucantha* | beggarticks* |
|
|
Hopkins '88 | |||
| Chenopodium ambroisoides* | Mexicantea* |
|
|
Hopkins '88 | |||
| Citrus sinensis | sweet orange (Florida) |
|
|
|
Hopkins '91b | ||
| Citrus sinensis | sweet orange (California) |
|
|
|
Purcell (unpublished) | ||
| Commelina sp.* | Commelina* |
|
|
Hopkins '88 | |||
| Cotoneaster pyracantha* | Cotoneaster* |
|
|
Hopkins '88 | |||
| Cynodon dactylon* | Bermuda grass* |
|
|
Hopkins '88 | |||
| Diospyros sp.* | persimmon* |
|
|
Hopkins '88 | |||
| Eupatorium capillifolium* | small (dog) fennel* |
|
|
Hopkins '88 | |||
| Koelreuteria paniculata* | golden raintree* |
|
|
Hopkins '88 | |||
| Lantana camara* | lantana* |
|
|
Hopkins '88 | |||
| Ludwigia peruviana* | primrose willow* |
|
|
Hopkins '88 | |||
| Morus rubra* | mulberry* |
|
|
Hopkins '88 | |||
| Myrica cyrifera* | southern waxmyrtle* |
|
|
Hopkins '88 | |||
| Nerium oleander | oleander |
|
|
|
Grebus 1996 | ||
| Nicotiana tabacum | tobacco |
|
|
|
Lopes '00 | ||
| Panicum sp.* | Panicum* |
|
|
Hopkins '88 | |||
| Paspalum sp.* | Paspalum* |
|
|
Hopkins '88 | |||
| Platanus occidentalis | sycamore |
|
|
Hartman '92 | |||
| Prunus persica | peach |
|
|
Hopkins '88 | |||
| Prunus persica | peach |
|
|
Boyhan '97 | |||
| Prunus persica | peach |
|
|
|
Raju, 1982 | ||
| Prunus salicana | plum |
|
|
Boyhan '97 | |||
| Prunus salicana | plum |
|
|
|
Raju, 1982 | ||
| Prunus serotina* | black cherry* |
|
|
Hopkins '88 | |||
| Quercus falcata | southern red oak |
|
|
Hopkins '88 | |||
| Quercus imbricaria | shingle oak |
|
|
Hartman '92 | |||
| Quercus laurifolia | laurel oak |
|
|
Hopkins '88 | |||
| Quercus nigra | water oak |
|
|
Hopkins '88 | |||
| Quercus palustris | pin oak |
|
|
Hartman '91 | |||
| Quercus rubra | northern red oak |
|
|
Hartman '91 | |||
| Quercussp. | oak |
|
|
Blake '93. | |||
| Rhus sp. | sumac |
|
|
Hopkins '88 | |||
| Solidago fistulosa | goldenrod |
|
|
Hopkins '88 | |||
| Ulmus alata* | winged elm* |
|
|
Hopkins '88 | |||
| Ulmus americana | American elm |
|
|
Wester '59 | |||
| Vaccinium pennsylvanicum* | blueberry* |
|
|
Hopkins '88 |
Reference
Blake '93: Blake, J.H., 1993. Distribution of Xylella fastidiosain oak, maple, and sycamore in South Carolina. Plant Disease 77:1262.
Boyhan '97: Boyhan, G.E., Tangsukkasemsan, J.D., Norton, J.D., and Himelrick, D.G. 1997. Incidence of Xylella fastidiosaon plum and peach in Alabama. Fruit Varieties Journal 51: 31-35.
Freitag '51: Freitag, J.H. 1951. Host range of the Pierce's disease virus of grapes as determined by insect transmission. Phytopathology 41:920-932.
Grebus 1996: Grebus, M.E., Henry, J.M., Hartin, J.E., and Wilen, C.A. 1996. Bacterial leaf scorch of oleander: A new disease in southern California. Phytopathology 86: S110.
Hartman '92: Hartman, J.R., Eshenaur, B.C., Jarlfors, U.E. 1992. Shingle oak, a new host for bacterial leaf scorch caused by Xylella fastidiosa. Phytopathology 82: 498.
Hartman '91: Hartman, J.R., Kaiser, C.A., Jarlfors, U.E., and Eshenaur, B.C. 1991. Occurrence of bacterial leaf scorch caused by Xylellafastidiosain Kentucky. Plant Disease 75: 862.
H + P '95: Hill, B.L. and Purcell, A.P. 1995. Multiplication and movement of Xylella fastidiosawithin grapevine and four other plants. Phytopathology 85: 1368-1372.
Hopkins '88: Hopkins D.L. and Adlerz, W.C. 1988. Natural hosts of Xylella fastidiosain Florida. Plant Disease 72: 429-431.
Hopkins '91a:Hopkins, D. L., Bistline, F. W. Russo, L. W. Thompson, C. M. 1991. Seasonal fluctuation in the occurrence of Xylellafastidiosain root and stem extracts from citrus with blight. Plant Disease 75: 145-147.
Hopkins '91b:Hopkins, D. L., Bistline, L. W. Thompson, F. W. Russo, C. M. 1991. Relationship between xylem-limited bacteria and citrus blight. Proceedings of the Florida State Horticultural Society 102:21-22.
Lopes '00: Lopes, S.A., Ribeiro, D.M., Roberto, P.G., França, S.C., and Santos, J.M. 2000. Nicotiana tabacumas an experimental host for the study of plant-Xylella fastidiosainteractions. Plant Disease 84:827-830.
P + S '99: Purcell, A.H., and Saunders, S.R. 1999. Fate of Pierce's disease strains of Xylella fastidiosain common riparian plants in California. Plant Disease 83: 825-830.
Purcell, Unpublished: Purcell, A.H. 2000. Repeated attempts to isolate two California PD strains of Xffrom sweet orange ('Valencia', 'Washington navel'), 'Lisbon' lemon, and grapefruit after mechanical and vector inoculation were unsuccessful.
Raju, 1983: Raju, B.C., Goheen, A.C., and Frazier, N.W. 1983. Occurrence of Pierce's disease bacteria in plants and vectors in California. Phytopathology 73:1309-1313.
Wester '59: Wester, H.V., and Jylkka, E.W. 1959. Elm scorch, graft transmissible virus of American elm. Plant Disease Reporter 43: 519.
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