Riparian Plants and Pierce's disease

The following table summarizes some key features of selected stream bank plants relative to Pierce's disease (PD). Their attractiveness to the main PD vector (blue-green sharpshooter) and how they support multiplication and spread of Xylella fastidoiosa (Pierce's disease strains) are shown for each species. A question mark (?) indicates more data needed.

Blue-green sharpshooter

X. fastidiosa hosts

Breeding
Feeding
Propagative
Systemic
Comments
Alder, red and white
no
rare
no
no
Non-host
Ash, Oregon
no?
occasional
yes
no

Bay laurel, California
no?
occasional
yes
no

Blackberry, California
major
major
yes
yes
Occurs in riparian habitat in shaded areas. Major propagative and systemic host of the bacteria.
Blackberry, Himalayan
major
major
yes
yes
Major propagative and systemic host of the bacteria. Occurs in riparian habitat and in drier locations such as along fenced rows, ornamental landscapes, along roads and railroads. These drier locations are not as important, because the growth is not very succulent for very long.
Broom, French
no?
rare
yes
yes
Major propagative and systemic host of the bacteria.
Brush, Coyote
no?
rare
yes
no

Buckeye, California
no?
rare
yes
slight

Coffeeberry
major
major
yes
?
Not common near vineyards in Sonoma and Napa Counties, it is only attractive for the BGSS in moist and sunny or partially sunny locations.
Cottonwood
no
no
no
no
Non-host
Elder, Box
no
rare
yes
no data?

Elderberry
major
major
yes
yes
Major propagative and systemic host of the bacteria.
Grape, wild
major
major
yes
yes
No. 1 host for the BGSS and the bacteria. Find high levels of infection in nature, bacteria achieves highest number per gram of tissue, and multiplies and spreads faster than in other hosts.
Hemlock, Poison
no
minor
yes
yes
BGSS winter feeding host, not a significant host in the spring and summer. Very susceptible to Pierce's Disease, gets very severe disease symptoms. Because it is an annual plant it is not a reservoir of the bacteria year round.
Ivy
minor
minor
yes
no

Maple, Big leaf
no
rare
yes
sporadic

Mugwort
major
major
yes
no
Common in the riparian area. It is attractive to BGSS as a feeding host as long as it remains succulent which is well into the summer. Because it is a propagative host of the bacteria but not a systemic host, insects can pick the bacteria only at the site where a previous feeding insect infected the plant.
Nettle, stinging
major
major
no?
no
Under the right conditions an excellent breeding host for the BGSS but a poor host of the bacteria
Oak, Coast live and
Valley
rare
minor
yes
slight

Periwinkle ground cover
minor
major
yes
yes
BGSS breeding and feeding host at the end of winter and occasional feeding and breeding will continue where periwinkle is grown in shade with high moisture, eg. riparian areas. Major propagative and systemic host of the bacteria and it survives the winter
Plums, wild
minor
minor
yes
no?

Poison oak
no
no
yes
no?

Rose, Wild
minor
minor
yes
no data
Major feeding host when the plant is succulent
Snowberry
minor
minor
yes
probably
(no data)

Sedge, Umbrella
no
minor-rare
yes
yes
Green SS feeding host, problem in ditches. Excellent propagative and systemic host of the bacteria, the plant gets a disease from the bacteria evident at the end of the summer.
Spice bush
no
no
no
no
Non-host
Walnut, Black
no
rare
no
no
non-host?
Willows, arroyo (yellow), red and sandbar
minor
minor
yes
No
In the case of red and arroyo (yellow) willows the bacteria multiplies but survives only for a few weeks. Willows when removed will tend to resprout and succulent sprouts are good BGSS feeding sites.
? = insufficient data

Compiled by Lucia Varela, IPM Advisor, University of California Cooperative Extension, Santa Rosa, CA. Data from A. H. Purcell and Stuart Saunders, University of California, Berkeley 1994-96. April 1997.

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	Blue-green sharpshooter		X. fastidiosa hosts
	Breeding	Feeding	Propagative	Systemic	Comments
Alder, red and white	no	rare	no	no	Non-host
Ash, Oregon	no?	occasional	yes	no
Bay laurel, California	no?	occasional	yes	no
Blackberry, California	major	major	yes	yes	Occurs in riparian habitat in shaded areas. Major propagative and systemic host of the bacteria.
Blackberry, Himalayan	major	major	yes	yes	Major propagative and systemic host of the bacteria. Occurs in riparian habitat and in drier locations such as along fenced rows, ornamental landscapes, along roads and railroads. These drier locations are not as important, because the growth is not very succulent for very long.
Broom, French	no?	rare	yes	yes	Major propagative and systemic host of the bacteria.
Brush, Coyote	no?	rare	yes	no
Buckeye, California	no?	rare	yes	slight
Coffeeberry	major	major	yes	?	Not common near vineyards in Sonoma and Napa Counties, it is only attractive for the BGSS in moist and sunny or partially sunny locations.
Cottonwood	no	no	no	no	Non-host
Elder, Box	no	rare	yes	no data?
Elderberry	major	major	yes	yes	Major propagative and systemic host of the bacteria.
Grape, wild	major	major	yes	yes	No. 1 host for the BGSS and the bacteria. Find high levels of infection in nature, bacteria achieves highest number per gram of tissue, and multiplies and spreads faster than in other hosts.
Hemlock, Poison	no	minor	yes	yes	BGSS winter feeding host, not a significant host in the spring and summer. Very susceptible to Pierce's Disease, gets very severe disease symptoms. Because it is an annual plant it is not a reservoir of the bacteria year round.
Ivy	minor	minor	yes	no
Maple, Big leaf	no	rare	yes	sporadic
Mugwort	major	major	yes	no	Common in the riparian area. It is attractive to BGSS as a feeding host as long as it remains succulent which is well into the summer. Because it is a propagative host of the bacteria but not a systemic host, insects can pick the bacteria only at the site where a previous feeding insect infected the plant.
Nettle, stinging	major	major	no?	no	Under the right conditions an excellent breeding host for the BGSS but a poor host of the bacteria
Oak, Coast live and Valley	rare	minor	yes	slight
Periwinkle ground cover	minor	major	yes	yes	BGSS breeding and feeding host at the end of winter and occasional feeding and breeding will continue where periwinkle is grown in shade with high moisture, eg. riparian areas. Major propagative and systemic host of the bacteria and it survives the winter
Plums, wild	minor	minor	yes	no?
Poison oak	no	no	yes	no?
Rose, Wild	minor	minor	yes	no data	Major feeding host when the plant is succulent
Snowberry	minor	minor	yes	probably (no data)
Sedge, Umbrella	no	minor-rare	yes	yes	Green SS feeding host, problem in ditches. Excellent propagative and systemic host of the bacteria, the plant gets a disease from the bacteria evident at the end of the summer.
Spice bush	no	no	no	no	Non-host
Walnut, Black	no	rare	no	no	non-host?
Willows, arroyo (yellow), red and sandbar	minor	minor	yes	No	In the case of red and arroyo (yellow) willows the bacteria multiplies but survives only for a few weeks. Willows when removed will tend to resprout and succulent sprouts are good BGSS feeding sites.