Napa County UCCE
University of California
Napa County UCCE

Vineyard Views & Events

Latest information on viticulture, UC research and newly released UC publications.

Issue Articles Type Date Added
Vineyard Leafhoppers (242KB)

Three leafhopper species--western grape, variegated and Virginia creeper--are present in Napa vineyards. Both variegated and Virginia creeper are invasive species, whose range has expanded considerably in Napa in the last 10 years. Proper identification of vineyard leafhoppers is critical to development of a successful management strategy. Access the newsletter link below for a "Quick Reference Guide to North Coast Vineyard Leafhoppers".

PDF 6/26/20
Pierce's disease vectors (113KB)

The UCCE-Napa viticulture team has a new resource for Pierce's disease:

On this website you will find:

Blue-green sharpshooter trap counts from county-wide monitoring program

Guidelines for trapping blue-green sharpshooters

Resources for identifying common vectors

Sharpshooters and spittlebugs are vectors of Xylella fastidiosa, the causal agent of Pierce's disease of grapevines. In 2020, the UCCE-Napa viticulture team, with support from the Napa County Wine grape Pest and Disease Control District, launched a county-wide monitoring program for blue-green sharpshooter (BGSS), the most common vector in the north coast region. Trap data are updated in real time and are accessible via the link above. Trap data are viewable by growing region, by date, and by landscape category (riparian, ornamental, other).


PDF 6/22/20
Phenology data request (992KB)

Do you have long-term (10 or more years) phenology data

CU Boulder researchers Chiara Forrester & Eve-Lyn Hinckley are interested in these data (budbreak, bloom, veraison and harvest dates) as part of their investigations into the ability of diverse block-scale vineyard microclimates to buffer the effects of climate change. 

Please direct all questions, comments and data to Chiara: 

PDF 2/11/20
Spotted lanternfly: early detection and identification (3,268KB)

Spotted lanternfly is a newly invasive pest that has been found in several eastern states. Feeding activity and copious honeydew production can damage vines and fruit trees and promote the growth of sooty mold. 

There is great potential for dispersal of this insect from the eastern US to other regions, given that females will lay eggs on a variety of inanimate objects (pallets, outdoor equipment, railway cars) that may be moved large distances.   

UCCE IPM Advisor Cindy Kron developed these resources to support identification and detection efforts:

Vigilance and efforts to identify early invaders are critical to a successful response, should this pest be introduced to California. Report sightings and bring suspicious specimens to your local Agricultural Commissioner's office for confirmation. 

PDF 12/6/19
Monitoring and Detecting DMI Fungicide Resistance in Grape Powdery Mildew (343KB)

Follow the link to the newsletter below for more information on the status of resistance testing for grape powdery mildew for the DMI (FRAC 3) fungicides. 

PDF 4/27/18
Inspecting green-growing vines for VMB (22,933KB)

Vine mealybug has been found on recent nursery shipments of green-growing vines in the North Coast region. 

Follow the newsletter link below to learn more. The newsletter can be used as training tool for crews inspecting vines as they are received. 

In Napa County, staff of the Agricultural Commissioner inspect all incoming shipments of green-growing vines and nursery plants. If you are expecting a shipment, contact the Agricultural Commissioner's office: (707) 253-4357

PDF 8/10/17
Potential benefits of powdery mildew resistant grapevines (201KB)

Recent research from the UC Davis Department of Agricultural and Resource Economics evaluated the potential economic benefits to California of powdery mildew resistant grapevines. (See newsletter link below).

As a follow-up to this study, the research team is collecting information on grower preferences for specific traits. We would appreciate if you could take a few minutes to respond to their survey questions

Please direct questions to Olena Sambucci,

PDF 12/10/15
Walnut Twig Beetle and Thousand Cankers Disease (5,462KB)

In early September 2015, the California Department of Food & Agriculture confirmed the presence of thousand cankers disease of walnut in Napa County. 

Access the newsletter below for additional information on this fungal disease and the beetle that moves it from tree to tree. 

PDF 11/3/15
Monitoring Guide for Western Grapeleaf Skeletonizer (1,370KB)

On June 24, 2015, staff of the Napa County Agricultural Commissioner found one male Western Grapeleaf Skeletonizer in a pheromone-baited trap in a vineyard on Tubbs Lane in Calistoga. 

UCCE Advisors Lucia Varela and Monica Cooper developed a "Monitoring Guide for Western Grapeleaf Skeletonizer" so that vineyard owners, growers and workers could familiarize themselves with the pest's life stages and feeding habits.

Please use the newsletter link below to access the Monitoring Guide (English and Spanish versions). 

If you find this pest or feeding damage in Napa County please contact the office of the Agricultural Commissioner: 707-253-4357, OR contact UC Cooperative Extension: 707-253-4221,

For additional information on biology and management of this pest, access the UC IPM Pest Management Guide for Western Grapeleaf Skeletonizer

PDF 7/8/15
Arboreal Camel Cricket (33,926KB)

In April, we observed leaf symptoms in select vineyards consistent with feeding damage by arboreal camel crickets. 

For photos and additional information, access the newsletter using the link provided below. 

PDF 6/1/15
Vine mealybug management and FAQs (10,329KB)

The Napa County Wine grape Pest & Disease Control District sponsored a seminar on vine mealybug (VMB) on February 25. We discussed VMB detection, biology and management. As a follow-up, this article summarizes significant points from the day, focusing on issues that are of particular concern for management of VMB, and also addresses FAQs

PDF 3/16/15
Water limiting (drought) conditions (23KB)

Resources for water management of grapevines under drought conditions (courtesy of our colleagues in Australia) are available in the Irrigation section of the UC Cooperative Extension-Napa County website:

Considerations for managing vine growth & yield under water-limiting conditions include:

1. Managing crop size through reductions in bud numbers and/or thinning after set. Adjust crop size to predicted water availability. 

2. If possible, target supplementary irrigation to critical physiological periods: (a) budburst to flowering, (b) flowering to fruit set, (c) veraison to harvest, (d) harvest to leaf fall--hopefully will be raining by then!

3. Organic residues (from cover crops or weeds) and mulches may moderate soil surface temperatures.  

PDF 1/20/14
Virginia creeper leafhopper (1,847KB)

Update on Virginia creeper leafhopper (VCLH) populations:

Populations of Virginia creeper leafhopper (VCLH) have been identified in Napa County, in Pope Valley.

Follow the newsletter link below for additional information on VCLH and variegated leafhopper populations in Napa, including photos and links to additional training tools. Early detection and identification can be critical to avoiding economic injury. 


PDF 7/30/15
Video demonstration (in Spanish): Measuring grapevine leaf water potential (21KB)

Dr. Arturo Calderon, Postdoctoral scholar, USDA and UC Davis has released an instructional video (in Spanish) on the use of the pressure bomb to measure grapevine leaf water potential. 

We hope you will find this video to be a useful training tool.

PDF 2/7/13
Brown Marmorated Stink Bug (2,022KB)

Since its introduction to the United States from Asia in the 1990's, the brown marmorated stink bug has become established in the mid-Atlantic states, as well as Portland, OR and Los Angeles, CA. 

You can support pest prevention efforts by being aware, recognizing the pest, and reporting suspicious specimens. 

The UC IPM Pest Alert Card for BMSB provides information on identification and damage. Consider printing and displaying it to increase awareness.  

PDF 6/27/12
Phylloxera Populations on Resistant Rootstocks (630KB)

We have updated our newsletter addressing phylloxera on resistant rootstocks.

Follow the newsletter link below to read our updated report.  

PDF 6/20/12
Is it a trunk disease? The case of the missing pathogen (515KB)

In January, Dr. Gubler and I visited a vineyard that seemed to have very clear symptoms of a trunk disease (Eutypa or Botryosphaeria). Yet when we looked closer, we determined the symptoms were not caused by a to the newsletter below to see photographs and read our full report. 

PDF 3/5/12
Gopher Control Workshop (110KB)

Workshop Flyer
Thursday, May 26, 2011
9:00 am - 11:00 am
UC Davis Oakville Experimental Vineyard
1380 Oakville Grade Road

Speaker:  Dr. Roger Baldwin, UC IPM, Statewide Vertebrate Control Advisor

Dr. Baldwin will provide an overview of pocket gophers and discuss the use of baiting and trapping.  He will also provide demonstrations on baiting and trapping techniques.

Attendance is limited to 50 participants (3 maximum per company).
Pre-registration is required.
1.5 CE hours have been approved for this workshop.

Register at

PDF 5/4/11
Berry shrivel

It's that time of year: shriveled berries on ripening clusters. See the attached article by Krasnow et al. in California Agriculture. The authors describe the distinctive symptoms of 4 common types of berry shrivel disorder in grape in California.

PDF 8/26/10
October 2008 Vineyard Views

Leafroll Spread and Plant Material information and survey form; Planting Material Workshop flyer and registration form; Napa County UCCE Viticulture Farm Advisor position, more..

PDF 10/31/08
April 2008 Vineyard Views

Viticulture Program Representative, View from Below the Vine, Weed Field Meeting

PDF 4/1/08
May 2007 Vineyard Views

New Weed Advisor in Napa Light Brown Apple Moth Herbicide Resistant Weeds ... More

PDF 5/27/07
September 2004 Vineyard Views

Vine Mealybug - Little Good News Berry Shrivel Napa Valley Viticultural Fair ...More

PDF 9/30/04
January 2004 Vineyard views

Vine Mealybug Update UC Budget Woes Continue Olive Fly Hits Hard PP Research Symposium New Publications

PDF 1/6/04
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