Pierce's Disease (PD)
PD Vectors
How to Trap
PD Symptoms
A Quick Guide to Pierce's Disease
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
Important concepts of Pierce's disease ecology inform management decisions
PD vectors, breeding habitat and monitoring
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BGSS can be confused with a common leafhopper
compare and contrast insect characteristics
Bluegreen sharpshooters (in green)
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blue to green head and thorax
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yellow legs and underside
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distinct head and face markings
Photos by Malcolm Hobbs
Thamnotettix zelleri (in red)
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no distinct facial markings
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wider bodies
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muted green color
T. zelleri is in the same insect family as BGSS, but does not transmit PD
Photos by Malcolm Hobbs
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"
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. https://www.winebusiness.com/wbm/?go=getArticleSignIn&dataId=222327
Bettiga et al. 2013. Grape Pest Management. Third edition. University of California, Agriculture and Natural Resources, Richmond, CA, USA.
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