MONDAY, MARCH 31, 2025. BY STEPHANIE BOLTON, PhD, LODI WINEGRAPE COMMISSION.
A rediscovery of the age-old IPM practice of canine detection applied in viticulture offers an opportunity for early identification of mealybugs and virus at the nursery and grower level, protecting our wine industry and reducing the use of high-risk pesticides.
In 2023, the California Department of Pesticide Regulation awarded a small team of us $428,118 for a proof-of-concept study looking at whether canines could detect our state’s most challenging vineyard pest and disease combo: leafroll 3 virus (GLRaV-3) and its main vector, the invasive vine mealybug.
The Proof-of-Concept Project Team
The human part of the interdisciplinary research team included myself, Dr. Stephanie Bolton, as the Principal Investigator and overall project strategist, Lisa Finke MS (Canine Detection Services) as the canine team leader, Dr. Neil McRoberts (UC Davis) as the detection statistician and Dr. Maher Al Rwahnih (Foundation Plant Services, UC Davis) as a provider of verified virus-tested material and grapevine virus knowledge. On the canine side, we welcomed Malbec, Sauvi B, Cab and Zinny (pictured below; photos by Lisa Finke). Success was driven by the amazing noses of the pups and each member’s unique expertise combined with access to an established industry network that is financially invested in discovering sustainable solutions for California agriculture.
As many of our growers know all too well, vine mealybugs and the leafroll virus disease they vector threaten our entire grape industry, spreading at an alarming rate through plant source material, between neighboring vineyards and across entire regions. Virus infections reduce yield and quality, decrease a vineyard’s lifespan and make land less suitable for future plantings. For more insight, see our blog post entitled, “Why Its Particularly Difficult to Protect Your Vineyard from Mealybugs & Viruses in California.”
Mealybugs are spread easily via wind, equipment, people, birds, nursery material and vehicles. Chemical control is challenging because there are few modes of action available, and mealybugs hide underneath bark and on roots where contact insecticides cannot reach (and people cannot see). By the time a mealybug infestation is detected with traditional trapping and scouting in a vineyard, it is far too late for eradication.
Canines have an extraordinary sense of smell due to the 300 million olfactory receptors in their noses which they rely on for survival.
Chris Storm, an active member of the Lodi Mealybug Biocontrol and Virus Research Focus Groups, with his dog Wayland. This canine detection project builds upon years of investigations by the Lodi Focus Groups and several amazing scientists, including Drs. Tim Gottwald and William Schneider.
Canine detection, already used in numerous applications for human health and safety, was recently rediscovered as an integrated pest management (IPM) tool and made popular by Dr. Tim Gottwald (retired USDA). In citrus orchards, dogs are used to locate Asian Citrus Psyllid, an insect that vectors Huanglongbing disease. Applied in viticulture, canine detection offers an opportunity for early, real-time, non-destructive field identification of pests and disease.
What Part of IPM is the Cheapest, Smartest, Most Efficient and Most Logical? Prevention!
Canine detection can help us prevent grapevine pests and diseases, save us money and improve winegrape quality. It’s a win all-around, especially since dogs already play such a valuable role in viticulture and are well-loved by both industry and public.
Growers, nurseries and scientists agree that improved early detection techniques are imperative for inhibiting the spread of the mealybugs and the leafroll virus disease they spread around rapidly.
Where to Start?
Truly alarming shortfalls exist in our ability to quickly and accurately detect mealybugs and viruses, our available methods for mealybug and virus control (especially in organic farming) and in our California Department of Food and Agriculture (CDFA) Grapevine Registration and Certification Program which is meant to help provide clean nursery vines for commercial vineyards.
Below are some of the major challenges we face when it comes to protecting our grapevines from mealybugs and leafroll virus, in addition to the prohibitive cost of management for many farmers.
- Mealybugs and viruses continue to move through our grapevine supply chain (see photo below).
- It takes up to two years before a human notices a mealybug infestation in a vineyard. It may take much longer for leafroll virus to be noticed, depending on the symptom expression. Symptoms of leafroll virus are apparent in red grape varieties, but not in rootstocks or white grape varieties.
- The CDFA grapevine certification program offers a false sense of security due to the very limited – arguably, negligible – amount of virus testing it conducts:
- In 2023, only 0.0297% of registered nursery increase block vines (3,068 out of 10,324,963 vines) were tested by the CDFA for leafroll 3 virus. In comparison, New York State tests 25% of their registered nursery vines annually.
- Neither nurseries nor growers have access to real-time, non-destructive, affordable early detection virus testing that is accurate.
If Canine Detection Works, How Can We Use it in a Way That Brings the Most Value to Our Industry?
Prevention is the core of IPM. By employing canine detection of mealybugs and virus in grapevine source material before it is propagated, at the nursery increase block level, we would drastically reduce the need for future costly mealybug and virus management practices statewide, which include:
- Insecticide and biocontrol applications,
- Scouting and monitoring for mealybugs and diseased vines,
- Sanitation of equipment,
- Testing, mapping and vine-by-vine rogueing of diseased vines,
- Removal of entire vineyards, and
- Forced land fallowing when nearby mealybug infestations and virus infections make the land unsuitable for new vineyard plantings.
Well before we began our project, we hosted several meetings with California’s top nurseries, extension personnel, virus testing laboratories, growers, pest control advisors, consultants and leading mealybug and virus experts from across the globe. It became clear that to offer the most value to our industry, canine detection for leafroll virus should first be applied to the most popular/at risk nursery increase blocks with a focus on rootstocks and white varieties which do not show virus symptoms.
Can the Robust Olfactory Senses of Canines Detect Vine Mealybugs and Leafroll Virus in a Scalable and Economically Feasible Way to Help Protect Our Vineyards? Yes, They Can!
Our main goal was to have trained canines available to work at the end of the grant project. The study included proof-of-concept trials, the development of an economic feasibility and scalability strategy, plus industry outreach.
The vine mealybug detector canines (Malbec and Sauvi B) were imprinted using tennis balls paired with target odors. The target odor of vine mealybug crawlers was used during this phase and tested later to ensure that canines were able to detect vine mealybugs even in the presence of pheromone mating disruption, since this is a crucial tool in our vineyards that we want to be able to employ simultaneously. For leafroll 3 virus, canines Cab and Zinny were imprinted on a target odor of viral protein.
Following odor imprinting, behavior exercises and detection training with a skilled Canine Handler named Miguel Encinas (pictured above with Zinny in a Lodi AVA vineyard), three sets of trials using mealybug-infested and virus-infected vine material – indoor, outdoor and field experiments – led to calculations for sensitivity and specificity.
Sensitivity can be described as how good the dogs are at determining if a vine has vine mealybugs or leafroll 3 virus. Specificity is how good the dogs are at determining if a vine does not have vine mealybugs or leafroll 3 virus.
As the results above show, our canines performed outstandingly well. Anything above 90% is considered exceptional, and detection only improves with more time and experience. The canines even outcompeted our averaged California commercial laboratories for accuracy of leafroll 3 virus detection (private testing conducted by the Lodi Winegrape Commission in October 2023).
In Conclusion
The robust olfactory senses of canines can detect vine mealybugs and leafroll 3 virus in vineyards at a level which contributes to IPM and is both economically feasible and scalable. Canine detection offers a promising opportunity to enhance our industry’s sustainability and long-term viability, all while elevating the quality of California wine.
Gratitude
A very sincere thank you to the many growers and nursery professionals who took time to provide real-world numbers which greatly contributed to the usefulness and accuracy of this article. We look forward to continued collaboration for a brighter future for us all.
The author would especially like to thank: Zinny, Cab, Malbec, Sauvi B, Dolcetto, the California Department of Pesticide Regulation, the Lodi Winegrape Commission, Lisa Finke MS, Miguel Encinas and the rest of the Canine Detection Services team, Wonderful Nurseries, Sunridge Nurseries, Dr. Maher Al Rwahnih and Foundation Plant Services, Dr. Neil McRoberts and his lab, Charlie Starr IV, Emma Canepa, Dr. Kent Daane, Dr. Mark Sisterson, Dr. Marc Fuchs, Dr. Ying Ying Zhai, James Brown, Sean Uchima, Dr. Bill Schneider and Dr. Bill Turechek.
The project team would also like to express sincere thanks to the following people who wrote generous letters of support for the grant proposal: Dr. Nick Dokoozlian (E&J Gallo Winery), Dr. Marc Fuchs (Cornell University), Dan Martinez (Martinez Orchards), Nicholas Podsakoff (Sunridge Nurseries), Eric Pooler (Nuveen Natural Capitol) and Jason Saling (Sonoma County Winegrape Pest and Disease Coalition and Rodney Strong Vineyards).
Our proof-of-concept canine detection project (DPR GRANT 23-PMG-R003) was funded by the California Department of Pesticide Regulation with in-kind donations from nurseries, growers, scientists, industry, Foundation Plant Services, Canine Detection Services and the Lodi Winegrape Commission. The contents may not necessarily reflect the official views or policies of the State of California.
Interested growers and nurseries may contact Stephanie Bolton (209.367.4727) or Lisa Finke (lisa@canine-detection.com) to learn more. For more information on mealybugs and grapevine viruses, click HERE.
In the Press
- Pollard, C. “How dogs could save wine production threatened by disease.” January 12, 2025. Daily Mail UK.
- Bird, S. “Dogs could be the saviour of global wine production threatened by disease.” January 11, 2025. The Telegraph.
- Mercer, C. “Dogs sniff out vineyard diseases and pests in trials.” January 9, 2025. Decanter.
- “Dogs Prove Their Nose for Vine Diseases.” January 8, 2025. Falstaff.
- “Dogs Can Sniff Out Vine Diseases.” January 7, 2025. Wein.plus.
- Cardoso, C. “Combating Vineyard Pests Goes to the Dogs.” January 7, 2025 (online) and April 2025 (print). Wine Spectator Magazine.
- Feilden, E. “Detector dogs are sniffing out grapevine disease.” January 6, 2025. The Drinks Business.
- Boyd, V. “A Nose for Pests Trained detector dogs prove their worth in identifying VMB-and leafroll-infested grapevines.” December 12, 2024. Grape and Wine Magazine.
- Todorov, K. “Pilot Program Brings in Detector Dogs to Hunt For Vine Mealybugs, Grapevine Leafroll-associated Virus 3.” December 2, 2024. WineBusiness.com.
- Shakespeare, M. “Going to the Dogs.” October 24, 2023. Comstock’s Magazine.
- Press Release. “Lodi Winegrape Commission Awarded $400,000+ Grant to Study Canine Detection of Mealybugs and Leafroll Virus in Vineyards.” June 8, 2023. Wine Industry Advisor.
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