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Pierce's Disease (PD)

PD Vectors
How to Trap
PD Symptoms
BGSS top page
PD Crop report 2020
A Quick Guide to Pierce's Disease
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Click here to see the full 2020 Napa County Crop Report

Pierce's Disease Management 

Inspect incoming grapevine nursery stock

Buy certified plants to reduce pest introductions

Revegetate riparian areas to reduce BGSS host plants

Monitor vectors using yellow panel traps

Avoid severe pruning: infected vines can't be rehabilitated

Identify symptoms and Rogue diseased vines

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PD vectors, breeding habitat and monitoring

Click on the image to learn more!





PD Vectors
BGSS can be confused with a common leafhopper

compare and contrast insect characteristics

Bluegreen sharpshooters  (in green)​ 

  •   blue to green head and thorax

  •   yellow legs and underside

  •   distinct head and face markings

Blue Green sharpshooter UCCE Napa County

Photos by Malcolm Hobbs

Thamnotettix zelleri (in red)

  •   no distinct facial markings

  •   wider bodies

  •   muted green color


T. zelleri is in the same insect family as BGSS, but does not transmit PD

leafhopper 2.jpg

Photos by Malcolm Hobbs

leafhopper 1.jpg

These are leafhoppers NOT blue-green sharpshooters.

Supplies for BGSS monitoring

Binder clips (3-4 per trap) secure trap to mount

Trellis post to mount trap support

Zip ties (11") to secure trap support to post

Plastic trap support 6.5"x9.5"

Materials List

Yellow panel (sticky) traps

[optimal size: 5.5 x 9 in.]

Trellis or end posts: to mount traps Or can be mounted on trellis wires using twist ties

"Trap supports" built using plastic sheet boards (i.e; HDPE M/M Opaque Sheets from TAP plastics, Santa Rosa, CA).

Cut the plastic slightly larger than the trap. For a 5.5x9 in. trap, build sheet to 6.5x9.5 in.

Binder clips (3-4 per trap) to secure the trap to the support

Zip ties (11 in.; 3-4 per trap) to secure the trap support to trellis posts along vineyard edge

Yellow panel trap 5.5"x9"

BGSS how to trap
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Trapping guidelines for BGSS

Trap quantity is based on block size. Place a few traps for small blocks (less than two acres); up to one trap for every two to three acres for larger blocks. 


Before budbreak, place yellow sticky traps on trellis wires or posts above the canopy. Keep traps 100- 200 feet apart (~30-60m) along vector sources (riparian or ornamental habitat) or areas with historically high PD prevalence.

There are two flights per year, in spring (Mar-May) and mid-summer (Jun- Aug). During these periods, check traps as frequently as 2-3 days, but once a week at minimum. If BGSS are found, record the number of insects and remove them from the trap. Depending on trap counts, follow UC IPM guidelines for management.

Change traps as needed, such as when they are dirty, faded or no longer sticky. Note: The purpose of monitoring is to quantify insect populations, not reduce them.

Figure at left displays sample configuration of trap locations for BGSS monitoring

Adapted from:

L. Varela,  R. Smith, M. Cooper. 2016. Pierce’s Disease Vectors, their Habitat and Monitoring Methods.


M.P. Daugherty, M. Cooper, R. Smith, L. Varela, R. Almeida. "Has Climate Contributed to a Pierce’s Disease Resurgence in North Coast Vineyards?" Wine Business Monthly. Dec. 2019.

Bettiga et al. 2013. Grape Pest Management. Third edition. University of California, Agriculture and Natural Resources, Richmond, CA, USA.

Pierce's disease monitoring example
PD Symptoms
Pierce's Disease Symptoms

Photos by M. Hobbs, ML Cooepr, & S. Vengco

Disclaimer: these photos are not exhaustive of what PD looks like on all vines. 

Leaf scorch on a red cultivar

Leaf scorch on a white cultivar 

Cluster shrivel

Stunted growth in chronically diseased vine 

Uneven lignification

Matchstick petiole: leaf blade falls and petiole remains attached 

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