Category: Vineyard Info

By:  Alyssa L. Ochs

As many vineyards take a sustainable and eco-friendly approach to grape growing, habitat destruction has become a topic worth learning more about. Delicate ecosystems depend upon agricultural biodiversity to help the land and native species thrive, yet at the same time, vineyards must safeguard their crops to stay in business and turn a profit.

From experts in the field of wildlife control, here are some ideas about how to maintain a healthy vineyard without unnecessarily impacting the environment and the animals that live nearby.

The Importance of Agricultural Biodiversity

  Stephen McCracken, the marketing operator at Trident Enterprises, told The Grapevine Magazine that winemakers are increasingly turning to biodiversity to mitigate the effects of climate change on their vineyards. Based in Waynesboro, Pennsylvania, Trident is a leading fence supply distributor that serves customers throughout North America.

  “Biodiverse vineyards can help improve soil health, reduce the need for pesticides and fertilizers and provide natural pest control,” McCracken said. “Additionally, a diverse ecosystem can help to regulate temperature and moisture levels, making the vineyard more resilient to extreme weather events. By promoting biodiversity in their vineyards, winemakers can improve the quality of their wine and contribute to the planet’s health.”

  McCracken described how biodiversity could protect against diseases and drastic climate fluctuations.

  “For example, incorporating a variety of cover crops amidst the vine rows attracts a diverse insect population to the vineyard,” McCracken said. “This practice replenishes soil nutrients and maintains cooler ground-level temperatures during daylight hours. Additionally, the preservation of surrounding forests serves as a reservoir of cool air. This process aids in preserving acidity and aromatic compounds in maturing grapes. Moreover, the vineyard benefits from the genetic diversity among the individual vines. Instead of planting identical genetic clones in consecutive rows, growers can safeguard against extensive losses caused by pests and severe weather conditions through Massal Selection.”

  However, McCracken said that biodiversity also presents challenges for vineyards, such as increased labor expenses and unwelcome visitors like birds and deer. But by actively promoting a net positive approach to biodiversity, McCracken said that vineyard owners can cultivate resilience in their vines and ensure the long-term success of their businesses.

  Kevin Adams from the Sisters, Oregon-based company Bird Gard, told The Grapevine that as the world moves toward preferring more natural practices in producing their food, biodiversity has become an important consideration for many growers. Bird Gard has been the world leader in electronic bird control for over 30 years.

  “For them, the balance lies in producing a reliable yield while utilizing affordable natural and organic systems,” Adams said. “The goal is to work with nature to enhance the ecosystem in which the vineyard is raised. We used to think of the vineyard as a standalone plot, with attributes distinct from its nearby neighbors. For many attributes of the vineyard, that is still true. However, birds, in particular, flow from vineyard to vineyard, and growing vines amidst their various homes requires a perspective that reaches beyond a single vineyard.”

Sustainable Wildlife Control Methods

  Fortunately, there are conservation-friendly approaches to vineyard wildlife control that have minimal environmental impacts and do not promote habitat destruction. One example is a deer fence to deter these herbivorous animals from eating grape leaves and fruits.

  “Installing a DeerBusters deer fence is an effective deterrent, preventing deer from accessing the vineyard and causing destruction,” said McCracken from Trident. “The fence is a barrier that blocks deer entry, safeguarding the vineyard and ensuring the vines’ undisturbed growth and development. At DeerBusters, our best fence for large areas is the Fixed Knot Deer Fence. It is the strongest metal deer fence type for deer exclusion on today’s market.”

  “A deer fence should typically be at least eight feet tall, as deer are skilled jumpers and can effortlessly clear shorter barriers,” said McCracken. “Additionally, the material used for the fence must be sturdy and resistant to damage for long-term functionality. Professional installation is often recommended to ensure the fence is properly anchored and secure.”

  Allen Hurlburt from H&M Gopher Control in Tulelake, California told The Grapevine about some of the concerns vineyard growers approach his company regarding burrowing rodents.

  “Our equipment, the PERC (Pressurized Exhaust Rodent Control), collects the exhaust produced by a gas motor that drives a compressor and routes that exhaust gas through a set of cooling coils into the intake ports of a compressor,” Hurlburt explained. “The gas is pressurized in a pressure tank and injected into rodent burrows. While the exhaust gas is 2.5 percent carbon monoxide, initially the purging of the air out of the burrow, replacing it with exhaust gas causes asphyxiation and then death via CO poisoning.”

  Customers often ask Hurlburt if the PERC effectively eliminates gophers and squirrels, and the answer is yes. Dr. Roger Baldwin from the University of California, Davis conducted a study on two acres of almond orchard with a heavy infestation of ground squirrels and reported a 100 percent kill rate after one treatment.

  Yet potential H&M Gopher customers are also concerned about the eco-friendly aspects of PERC units and whether non-targeted wildlife are at risk when treating rodent burrows.

  “While analyzing what is actually going on in the burrow during the injection of exhaust gas is difficult, we have not had one report of a non-targeted animal negatively affected by treatment,” Hurlburt said.

  Jon Stone from Avian Enterprises, LLC in Sylvan Lake, Michigan shared, “Avian Control® Bird Repellent provides the vigneron with a bird control technology that repels feathered pests, that is easy to apply and economical, is not phytotoxic and has no impact on the fine wines produced from the treated grapes. Due to M.A.’s simple chemical structure, its rapid biodegradability and the extremely low level of dosing, Avian Control® does not interfere with or alter the natural progress of the fermentation process.” 

  Stone said that all of the ingredients in Avian Control® are found in food products designed for human consumption. The U.S. Food and Drug Administration has classified all ingredients in the Avian Control® formula as “Generally Regarded As Safe.” Also, the U.S. EPA has determined that the active ingredient of Avian Control®, methyl anthranilate (M.A.), is free from any residual tolerance requirements. M.A. is entirely biodegradable, occurs naturally and is found in bergamot, black locust, gardenia, jasmine, lemon, mandarin oranges and strawberries.

  He also said that several vintners’ side-by-side tests of Avian Control® treated and untreated grapes from the same field showed no difference in taste, aroma, bouquet, complexity or color.

  “The first reason is that the active and inert ingredients in Avian Control® do not penetrate the skin of the fruit,” Stone said. “Avian Control® will not translocate into the treated crop. Translocation is the tendency of a compound to move through the tissues of a plant. This effect is particularly troubling when repellents translocate from the outer skin of a fruit through the skin and into the fruit body. When this occurs, a distinct change in taste can be noticed. Due to its unique formulation, Avian Control® remains on the surface of the plant and its fruit where it is available to repel birds and does not translocate into the plant or its fruit, preserving the natural taste of the crop. This is an important difference between Avian Control® and other bird repellent products currently available.”

  “The second is the very low rate of application of Avian Control and its positive biodegradability profile,” said Stone. “When applied to your grapes at the highest recommended rate of 32 ounce per acre, based upon a yield of three tons of grapes per acre, the level of active ingredient is only 0.6 parts per million. For a yield of 6,000 pounds of grapes per acre, only 6.4 ounces of M.A. is applied. Given the biodegradability of M.A., after several days the amount is even lower. When MA biodegrades, it breaks down into the simple elements of carbon, hydrogen, nitrogen and oxygen, all found naturally in grapes. Other bird repellants with M.A. require application rates of six to 10 times higher than Avian Control®.

  Adams from Bird Gard shared that his company’s systems create a natural fear and flee response in birds through bioacoustics.

  “The systems do not harm the birds or impact their health in any way,” he said. “We don’t just speak their language telling birds to leave. We mimic the frequency ranges of each species to deliver a high quality and realistic sound – something that matters to birds. These distress calls also bring in predator birds looking for a perceived easy meal. This results in a natural falconry occurring in a grower’s field. Unlike lasers, or other devices, our calls target only the birds most likely to be damaging the crop. Other beneficial birds remain active.”

Wildlife Control Innovations

  In vineyard wildlife control, there are some exciting innovations on the horizon. McCracken from Trident told us about the newest deer fence on the market, a seven-foot, graduated welded wire fence that can stop deer and other animals away from grapes.

  “Featuring a tighter mesh on the lower three feet, it keeps smaller unwanted animals out with 2″x1″ wire spacing,” McCracken said. “The upper section consists of a 2″x2″ mesh. This new fence product is an excellent choice for restricting small or large wildlife around the vineyard.”

  Adams from Bird Gard said that through constant innovation, Bird Gard has come a long way from the old squawk box.

  “Today’s Bird Gard utilizes software systems to specifically target the bird’s natural ability to habituate to stimuli that is repetitive,” he said. “With our newest innovation, IntelliGard OS, we have specifically addressed habituation through a substantially increased call library, differing time-off intervals and a more realistic playback experience. The scope of calls allows for greater randomization, causing the targeted species to struggle to detect a pattern in the stimuli. Bird Gard is the only company that utilizes a realistic bioacoustic that can constantly change to address specific species habituation.”

Wildlife Control Methods to Reconsider

  However, there are specific wildlife control methods that vineyards may choose to limit or avoid to protect and preserve native animals, such as lethal traps and poisoning.

  “These methods harm targeted wildlife and can have unintended consequences by harming non-targeted animals and disrupting the ecological balance,” McCracken from Trident said. “Instead, vineyards should consider implementing alternative control methods, such as habitat modification, which involves creating favorable conditions for desired wildlife species and encouraging them to stay away from areas where they might cause damage.”

  “Pesticides pose a significant risk to wildlife health, contaminate water sources and negatively impact the surrounding environment,” McCracken added. “Alternative methods are available, such as integrated pest management, which utilizes a combination of cultural, biological and chemical controls to minimize pesticide use. This comprehensive approach allows vineyards to control pests effectively while safeguarding the well-being of wildlife species and maintaining the ecological balance necessary for a healthy ecosystem.”

  Adams from Bird Gard said, “When it comes to bird deterrents, pesticides, poisons and shooting of birds should be avoided at all costs. There are plenty of other deterrents that won’t harm animals, the grapes or the soil. While we do not discourage the use of other deterrents in conjunction with Bird Gard’s bioacoustics systems, ours is the only one that targets individual species and can be randomized to reduce habituation. Although no bird deterrent can guarantee to get rid of 100 percent of your birds, unless you are growing indoors, we will guarantee a customer’s satisfaction. If a customer isn’t happy with the results, we will buy back our systems at full price at any point within a year. No other bird deterrent company can tell you that!”

Final Thoughts on Controlling Wildlife

  With deer overpopulation becoming a pressing issue in many regions, many vineyards face degraded habitats, crop damage and an increased risk of vehicle collisions. Yet McCracken from Trident maintains that integrating a strong deer fence is a surefire way to ensure the prosperity of vineyard harvest for years to come and help wildlife coexist harmoniously with human settlements. 

  “In vineyards, it is essential to be mindful of the various wildlife control methods used,” McCracken said. “Avoiding or limiting those that could harm wild animals or disrupt the delicate ecological balance should be considered. By choosing alternative methods, such as deer fencing, vineyards can effectively manage wildlife while protecting biodiversity and ensuring the long-term sustainability of their operations.”

  Regarding burrowing rodents, Hurlburt said the fundamental questions that need answers are these pests’ positive and negative aspects in a vineyard.

  “There is opinion that gophers help loosen and aerate the soil,” Hurlburt said. “I doubt that there are any vineyard operators that subscribe to this philosophy. Gophers love young grapevine roots. They can devastate a new vineyard. Drip irrigation lines can be damaged by gophers, and the mounds made by gophers, as well as the open burrows made by ground squirrels, are very detrimental in vineyard operations. However, the injection of exhaust gas does not have any negative effect on the crop and its root structure.”

  “Much like taking vitamins during flu season, humane bird control needs to start before the birds show up,” said Adams from Bird Gard. “Bird pressure in a vineyard can vary from year to year, and you must always be ready for the flock of 10,000 starlings to show up on your doorstep. Utilizing bird deterrent to reduce bird pressure should be part of your growing protocol and considered as a best practice when dealing with a hungry wild animal.”

Arming Vineyards with the Best Weapons Against Their Worst Enemies

By: Cheryl Gray

Left unchecked, an army of an invasive species as tiny as an eighth of an inch can destroy acres upon acres of vineyard grapes. We are talking about the dreaded mealybug.

  There are multiple species of this unwelcome guest, and the potential for each to wreck a grape crop is all too real. Some experts say that among the worst of the bunch is the vine mealybug. In the United States, some of the worst infestations are found in California and, more recently, in Oregon. However, this pest is a globe-trotter. According to the University of California Division of Agriculture and Natural Resources, the vine mealybug is found in grape-growing regions of the Mediterranean, Europe, Africa, the Middle East, South Africa, Pakistan, and Argentina. Researchers explain that the vine mealybug can infect every part of the grapevine, producing massive quantities of a clear, sugary secretion called honeydew, which destroys the grapes and the foliage all around it.

  Fortunately, there are companies who have the expertise in equipping vineyards with biological weapons to combat this threat. Pacific Biocontrol Corporation, headquartered in Vancouver, Washington, manufactures ISOMATE VMB for grape growers who are ready to upgrade their arsenal. The company, in business for nearly 40 years, considers itself one of the original pheromone corporations and a global leader in the science of manipulating naturally occurring chemicals known as pheromones. Pheromones are emitted by organisms that allow them to talk to each other within their own species. The chemicals serve multiple functions, such as locating sources of food, detecting likely dangers – and finding a potential mate. Pacific Biocontrol Corporation zeroes in on the latter.

  Jeannine Lowrimore is a technical sales representative for Pacific Biocontrol in the company’s Northern California sales region. She holds a Bachelor of Science degree in entomology from UC Davis and has more than 20 years of pheromone experience.

  Lowrimore breaks down the details of how treacherous the vine mealy bug can be to vineyards and how ISOMATE VMB works to virtually eliminate this pest.

  “This key pest is the most prolific in having more generations in a season, more eggs per female and producing copious amounts of honeydew. Not only do they reduce fruit quality and marketability, but, more importantly, they transmit devasting viruses, including grapevine leafroll-associated virus 3 (GLRaV-3). They are efficient vectors and can transmit viruses within one hour of feeding. VMB can be easily spread within blocks and moved by birds, crews, and equipment to neighboring vineyards.

  Once VMB is established in a vineyard, it is nearly impossible to eradicate due to its ability to live under bark and in the roots where insecticide treatments cannot always reach. For this reason, it’s best to take preventative measures to reduce VMB infestations from the start.”

  Lowrimore describes how ISOMATE VMB uses biochemistry to disrupt mating among the vine mealybugs, which is key, she says, to eradicating this cryptic pest from vineyards.

  “Pheromone mating disruption is a key component of IPM programs and fits with sustainability models and certifications. Pheromone mating disruption works best in low-moderate populations by preventing male VMB flyers from finding the females for mating. Growers are now open to incorporating pheromones in new plantings to implement this prevention program to ‘stay clean.’ Growers with light VMB pressure are also excellent candidates and should consider adding pheromone to their management program to maintain and reduce populations from spreading.”

  Lowrimore recommends that vineyards under attack from a high concentration of vine mealy bugs, should consider using ISOMATE VMB in combination with an aggressive insecticide program that will help in reducing VMB populations over multiple seasons.

  “Pheromones should be considered an additional tool to an insecticide program. ISOMATE VMB dispensers have proven longevity to last 200 plus days in cooler growing regions and fill in the ‘gaps’ between insecticide treatments. Having pheromone coverage into the large and critical fall flight is imperative and this is where ISOMATE VMB has excelled. When growers deploy dispensers in March or April, they can have a ‘set it and forget it’ pheromone program that covers them into November and won’t hinder harvest activities.”

  She explains how the product is dispensed throughout the typical vineyard and how it has earned a global reputation for its effectiveness.

  “ISOMATE VMB is deployed at a rate of 120 to 200 dispensers per acre depending upon VMB pressure. This variable rate allows growers to economically address VMB populations without compromising on efficacy.

  ISOMATE dispensers have been used for numerous pests worldwide for over 30 years. They are known for their consistent release of pheromones and ease of deployment. ISOMATE VMB longevity is supported by trap data, in-season gravimetric weighing and gas chromatography ionization detection (GC-FID). Understanding and monitoring the release rates of the dispenser is imperative in having a reliable product year after year.”

  Lowrimore says that the mission of Pacific Biocontrol is to increase the use of its products designed to disrupt the mating of vine mealy bugs by educating grape growers on how a pheromone program can impact production. Lowrimore adds that the company partners with academia, industry, and growers, establishing regional pest management programs where pheromone mating disruption can benefit whole communities.

  Clients of Pacific Biocontrol include fruit and nut growers ranging from small operations to large-capacity production farms.

Another company with expertise in deploying biological solutions to combat vineyard pests is BioSafe Systems, a family-owned and operated firm headquartered in East Hartford, Connecticut. The company has worked over 25 years innovating sustainable chemistry designed to supplement conventional methods in fighting vineyard organisms that threaten crops. 

  BioSafe Systems also considers itself a steward of the environment. Its line of products includes Oxidate 5.0 and PerCarb. Both focus on improving wine grape production. The GreenClean Alkaline Cleaner and Sanidate 5.0 are used in winery facilities.

  BioSafe Systems officials stress that the company conducts perpetual vineyard crop protection research throughout the nation to demonstrate the efficacy of its products. Its vineyard protection brands are formulated to guard and improve soil quality by creating an optimal ground environment in which grape plants can thrive. The company was recently awarded U.S. Patent Number 11439151 B2, entitled “Process for Treating an Agricultural Medium.” The patent acknowledges the company’s Restorative Soils Program™ (RSP) as a vital tool for the future of the industry.

  Company officials explain that the process begins with a soil treatment of aqueous peroxyacetic acid (PAA) to diminish the levels of soilborne plant pathogenic organisms. The next step is to apply complementary beneficial rhizobacteria and biostimulants to the soil to fortify a diverse soil ecosystem that supports and promotes optimal plant health.  The BioSafe Systems’ Restorative Soils Program™ is designed to rebalance and enhance soil’s microbiome to deliver a solid foundation to protect the investment that vineyards in planting grapes.

  Sarah Budde Rodriguez, Ph.D., is a field development specialist for BioSafe Systems. Her expertise is in plant pathology. Dr. Rodriguez explains why the Restorative Soils ProgramTM works to achieve optimal grape production.

  “The Restorative Soils Program is the ideal footing to build upon when replanting and establishing new vines. It begins with a soil treatment using TerraStart® HC or OxiDate® 5.0 to diminish soilborne plant pathogenic organisms. Next, an application TerraGrow® Liquid, a blend of beneficial rhizobacteria and biostimulants, is introduced to promote optimal plant health. The process is especially important in the first few seasons following new plantings to support the establishment of healthy new vines, while it can also be repeated during the vines’ lifespan, to bolster the health and quality of the vineyard through the years. The Restorative Soils Program™ (RSP) is the foundation of a comprehensive integrated pest management plan providing the tools needed to fight soilborne pathogens, improve rhizosphere dynamics and reinforce plant health.”

  One more company with an organic approach to helping growers is Live Earth Products, Inc., based in Utah. The family-run business mines and manufactures humic acid and fulvic acid-based products. Humate is a mined mineral that experts say is used to help improve nutrient retention and water conservation. Humates are used to reduce fertilizer loss and add organic matter to improve water conservation. 

  Live Earth Products started as a small operation but now has clients all over the world. Russell Taylor, whose father launched the company shortly after a deadly mining accident in 1984, is the company’s vice president. Taylor was recently awarded the 2023 CCA Conservationist of the Year Award. 

  “In the late ’80s and ’90s, promoting soil health and fertilizer reduction was not a common item discussed by farmers,” he said. “My father was a visionary far ahead of his time, and I can assure you that selling humate was not extremely profitable at the time. The good news is that we persevered. Our products are now sold internationally.”

  Taylor explains that Live Earth Products has three core offerings: Humate Soil Conditioner, Liquid 6 (humic acid) and LM-32 AG (fulvic acid). While all three products are used by conventional growers, they are also OMRI-listed for use in organic agriculture. Liquid 6 is popular among growers because humic acid helps to improve micronutrient availability. LM-32 is a liquid fulvic acid that is naturally pH 3.0 and is used not only in agriculture but also in other industries, such as cosmetics.

  The science of biochemistry plays a vital role in fighting on multiple fronts to protect grapes from harm. At the same time, there are companies that also focus on protecting the environment around vineyards and beyond.

By: Kirk Williams, Lecturer-Texas Tech University

While there are many methods to control weeds, weed control with herbicides remains a viable option due to its lower cost versus other options such as mechanical cultivation.  When herbicide applications are done efficiently it can be a much faster process when compared to mechanical cultivation. 

  Application of herbicides through nozzles is important for correct herbicide distribution and dosage over the target.  The target could be existing weeds in the case of post emergent herbicides or the soil surface with pre-emergent herbicides or a combination of both existing weeds and the soil surface in the case of tank mixing post emergent and pre-emergent herbicides.  Coverage is critical for herbicides to work effectively.  Hydraulic spray nozzles create a wide range of droplet sizes.   These droplets are measured in microns with droplets from 200 to 400 microns considered the most appropriate size for herbicide applications.   Larger droplet sizes may bounce or roll off leaves while very fine droplets are more prone to drift.

  To provide satisfactory results, recommendations from Syngenta, one of the manufacturers of water sensitive cards, is to have 20 to 30 droplets per square centimeter for pre-emergent herbicides. For post emergent herbicide applications, it is recommended to have 30 to 40 droplets per square centimeter.   A square centimeter is about 1/6 of a square inch. 

  One way to increase and improve coverage in herbicide applications is to use a double nozzle body.  This allows two nozzles to occupy the same space as one nozzle.  The double nozzle body allows you to easily increase the volume of coverage no matter what kind of nozzle you using. This is especially true when you have to use a relatively large spray nozzle to apply higher volumes.  Larger sprayer nozzles tend to produce coarser droplets.  Splitting the required flow into two nozzles can produce an efficiency gain by decreasing the number of coarse droplets.  The double nozzle body also helps with increasing droplet coverage of target.  (See the double nozzle body set up in Image 1).

  It was found in a study with water sensitive cards that coverage was increased by 20% when double nozzle bodies were used when compared to single nozzle bodies.   The study used regular flat fan off center 03 nozzles, calibrated to deliver 47 gallons per treated acre and the water sensitive cards were placed on the berm underneath the grape vines.   While the double nozzle body had higher coverage the droplets per square centimeter went down due to the droplets running together versus the single nozzle body.  The single body nozzle had 43 droplets per square centimeter while the double body nozzle had 17 droplets per square centimeter but the droplets are much bigger.  (See the water sensitive cards in image 2).   While the droplets per square centimeter are out of the recommended range for droplets per square centimeter for herbicides with the double nozzle body the better coverage should result in similar or better weed control with both pre-emergent herbicides and post emergent herbicides. 

  Herbicide application technology has improved with a wider selection of nozzles available.  Adoption of these newer type of nozzles has been widely adopted in row crops but may be not as widely adopted for vineyard herbicide applications.  These newer type nozzles reduce drift but still deliver good weed control. 

  Air Induction nozzles are a newer type of nozzle that are available in a wide range of spray tips.  The air-induction nozzle is noted for producing large drops through the use of a venturi air aspirator. The venturi draws air into the nozzle through holes in the side of the nozzle and then the air is mixed with the solution to create larger spray droplets, which reduces drift potential.   These larger droplets are filled with air bubbles and explode on impact with the target surface and produce coverage that is similar to other nozzle types. 

  Many sustainable grape growing standards include drift management as a component of their plans.  The incorporation of air induction nozzles that reduce drift by reducing the number of fine, drift prone droplets could be a part of meeting the requirements of these standards.  Drift reduction is important during the growing season to reduce phytotoxicity due to herbicides.  When herbicide applications take place in the in dormant season, phytotoxicity to the grapevines is not an issue but with the wide spread adoption of cover crops, herbicide applications need to stay where they are intended to be, so they don’t impact the cover crops.     

  In a study, double nozzle bodies were equipped with air induction under banding nozzles (AIUB8503), calibrated to deliver 44 gallons per treated acre.  Water sensitive cards were placed on the berm underneath the grape vines.  This nozzle configuration delivered 56% coverage of the water sensitive cards and produced 26 droplets per square centimeter.  As you can see, in the water sensitive cards in (image 3) the droplets produced are large with few small droplets.  The droplets per square centimeter are in the recommended range for droplets per square centimeter for pre-emergent herbicides but outside of the recommended range for post emergent herbicides.  The coverage produced should result in similar or better weed control with both pre-emergent herbicides and post emergent herbicides when compared to the regular nozzle set up.  The air induction nozzles will also produce a minimum of drift prone fine droplets.  

  Adoption of double nozzles bodies into your herbicide application program will increase coverage for both pre-emergent and post emergent herbicides.   Switching to air induction nozzles is one way to make sure the herbicides that you are using stay where they are intended to.   

  In addition to coverage and nozzle selection, don’t forget about integrated weed management principles.  These principles include knowing and correctly identifying your weed problems so that appropriate herbicides can be chosen.  Controlling weeds when they are small when they are more susceptible to herbicides and easier to have better spray coverage.  Another integrated weed management principle is to keep annual weeds from going to seed which reduces the weed seed bank in the soil.   Other principles include rotating among herbicides with different modes or action or tank mixing herbicides with different modes of action together which helps manage weed population shifts as well as herbicide resistance.  Staying clean is easier than trying to clean up a mess, so pre-emergent herbicides may help to keep the vineyard berms clean.  

  Kirk Williams is a lecturer in Viticulture at Texas Tech University and teaches the Texas Tech Viticulture Certificate program.  He is also a commercial grape grower on the Texas High Plains.  He can be contacted at kirk.w.williams@ttu.edu

By:  Judit Monis, Ph.D. – Vineyard and Plant Health Consultant

New methods are being applied for the testing of imported plants and the certified foundation mother blocks at the University of California at Davis that manages the foundation blocks for the California (CDFA) certification program.  After so many years of considering the biological indexing technique a gold standard, the methodology has been replaced with modern technology that is able to detect any virus in the propagation material.  Furthermore, due to the infection and spread of Grapevine red blotch virus (GRBV) in the former CDFA (Russell Ranch) certified foundation block, new measures are being applied to avoid that the problem occurs again. 

Plant Quarantine Programs

  Plant quarantine programs have been developed worldwide to reduce the risk of introducing foreign plant pests and/or pathogens not found in a particular state, country, or region.  My expertise is plant pathology and throughout my career I have specialized in the application and development of methods for the detection of bacteria, fungi, and viruses that cause diseases in vineyards and fruit orchards.  In spite of the current existence of plant quarantine programs, most grapevine pathogens with rare exceptions occur in all grape growing areas in the world.  The reason is that in most cases, quarantine programs were implemented after the introduction of the infected plant material.  In addition, modern techniques for the detection of these pathogens were not available at the time of plant introduction. In other words, the majority of grapevine pests and pathogens were moved unknowingly.  The advancement of science and the use of sophisticated detection methods for grapevine pathogens and isolation has helped keep certain viruses outside of Australia.  For example, Grapevine fanleaf (GFLV) has not been reported in Australia as of yet.  Presently, with the use of advanced methodologies, new pathogens continue to be discovered. As science progresses with the development of more refined technology (e.g., next generation sequencing also known as high throughput sequencing), it is expected that new (or unknown and established) pathogens will be discovered. In practice, most grapevine pathogens have originated at the centers of origin of Vitis species (a plant genus that includes both table, wine, and rootstock grapevine varieties) and moved to many grapevine growing areas of the world during plant introduction. 

  In the United States, the United States Department of Agriculture (USDA) Animal and Plant Inspection Services (APHIS) Plant Pest Quarantine (PPQ) unit regulates the introduction of plant material for planting from foreign countries.  However, the USDA does not have a centralized government plant quarantine center.  Instead, the APHIS PPQ  issues permits to specific clean plant centers with proper containment facilities and approved protocols to manage the quarantine of specific crops. For grapevines, two importation centers are available for introducing quarantined planting material: The Foundation Plant Services (FPS) at the UC at Davis and the Clean Plant Center at Cornell University in Geneva, New York.  

Grapevine Certification Programs

  Grapevine certification programs are needed to produce tested plant material that is free of important known pathogens.  These plants are then distributed to nurseries that propagate and sell these plants to growers.   In the United States, certification programs are voluntary and are managed by individual states.  I will describe the California certification program as many US grapevine growing regions purchase planting material from California nurseries. 

  The Grapevine California Registration and Certification (R&C) Program was first written into law in the 1980’s.   The Grapevine R&C Program is administered by the California Department of Agriculture (CDFA) and provides for the testing of source vines for grapevine viruses that cause important diseases. Registered sources and certified nursery stock are periodically inspected by the CDFA staff and are maintained by the participant nurseries.   Starting in 1996, I participated and provided input at the industry meetings that lead to the revision of the California Grapevine R&C program many years later.   In 2010 the Grapevine R&C program was revised to include testing of foundation mother vines for the presence of a comprehensive list of viruses.

  The California Grapevine R&C Program rules can be found in CDFA’s website:  https://www.cdfa.ca.gov/plant/pe/nsc/nursery/regcert.html

  With funding from the National Clean Plant Network, a new of foundation block named Russel Ranch was planted at the UC Davis in 2009.   The planting material (both scion and rootstock varieties) included in the new foundation block had to pass a rigorous testing program and have been propagated using the “apical micro-shoot tip culture” technique.   The apical micro-shoot tip culture process is a plant tissue culture technique that is used to eliminate pathogens from vegetative propagated plant material.  The testing program at UC Davis is known as Protocol 2010.  The maintenance and testing of the scion and rootstock mother blocks are performed by UC Davis FPS personnel.  Shortly after the update of the California Grapevine R&C Program, GRBV, a virus of significant importance for the vineyard industry, was discovered.  Consequently, the California Grapevine R&C Program was revised to include the testing of foundation and nursery increase blocks for the presence of GRBV.  Sadly, the Russell Ranch foundation block became progressively infected with GRBV.  The infection status was so high that FPS had to suspend the sale of plant material to nurseries. 

  The testing of the foundation mother plants includes a list of well characterized viruses, Xylella fastidiosa, and phytoplasmas using biological, serological, and molecular testing techniques (https://fps.ucdavis.edu/fgr2010.cfm).  The nursery increase blocks are inspected and tested by CDFA personnel with a reduced number of pathogens.  The updated Grapevine R&C added the testing for the detection of GRBV using the polymerase chain reaction (PCR) to vines in the foundation and nursery increase blocks.  Related to nursery certified plants, the rules are vague and state that certified plants may be tested (particularly if after inspection suspected symptoms are observed).  According to CDFA, the goal is to test a statistical sample with a 95% confidence level assuming a 1 % disease incidence.  It is disappointing that in spite of the importance of the decline and canker diseases caused by fungal pathogens (and how easily the pathogens can be transmitted by activities carried out at the nursery), the regulations do not include inspection or testing for fungal pathogens in foundation or increase blocks. 

  The use of certified material is expected to be less risky than planting field selections of unknown infection status.  However, it is always prudent to consult with me to assure that the planting material meets the expected cleanliness standards. An important piece of advice when working on the procurement of clean planting stock is to plan in advance.  Most nurseries in California collect cuttings for budwood as soon as the vines are dormant.  However, grafting activities are performed during the spring of the following year.  Planning with time will allow for inspection of the increase blocks early in the fall before a freeze.   Being familiar with the nursery’s operations and their staff is important.  Good communication will help with scheduling inspections and testing of the increase blocks from which bud wood and rootstock cuttings will be collected. 

Changes in the Testing and Management of UC Davis Grapevine Foundation Block and Introduce Quarantine Plant Material

  The FPS laboratory at UC Davis performed comparative studies between the traditional biological indexing technique and the high throughput sequencing (HTS) methodology.  To refresh my readers, the biological indexing technique or commonly known as woody indexing is an ancient method that relies on the grafting of grapevine (or other woody species) material onto an indicator host.  An indicator host, is a plant variety that is very susceptible to the disease we wish to detect.  For example, the indicator host for grapevine leafroll disease is  Cabernet Franc.  To perform the assay, buds from quarantine or foundation plants are grafted onto the indicator plants.  After a period of time (generally two years) the symptoms of the grafted plants are recorded. If the  buds of the grapevine plants that we wish to test for are infected with a virus that causes red leaf discoloration, and successfully transmits the virus to the indicator plant, it is concluded that the test vine is infected with a Grapevine leafroll associated virus (GLRaV). 

  However,  GRBV also causes red leaf symptoms in Cabernet Franc and other red grape varieties, therefore the test vines could be infected with GRBV.  In more simple words, the biological indexing technique is able to detect disease symptoms and not a particular pathogen that causes it. As long as there is a detection, there is no problem.  The problem occurs when a vine is infected but no symptoms are visible in the indicator plants.  In this case, the vines would be considered healthy and will spread a disease-causing agent.  After a series of experiments and discussions with regulators at USDA APHIS PPQ and CDFA, UC Davis FPS personnel have been able to implement the use of HTS instead of the woody indexing assay. This is a welcomed change I sincerely never expected to happen during my professional life! Another important needed change in the management of the UC Davis foundation plants is the construction of an insect-proof greenhouse that will host the CDFA certified mother vines.  The greenhouse is expected to be finished by the end of 2023.

Conclusions

  Diseases, pathogens, and/or their vectors do not know or respect the borders between blocks (at the nursery, foundation block, or your vineyard).  Even if the planting material came from a reputable certification program, paying attention to the surrounding vineyards as well as having knowledge of the potential presence of disease prior to planting is important.  The planning of a new vineyard is not trivial and requires specialized knowledge.  I am available to help look for suspicious symptoms (inspect scion and rootstock source blocks), evaluate the planting site, develop a testing plan based on science and statistics, and review nursery and vineyard disease testing history.  

  Judit Monis, Ph.D. provides specialized services to help growers, vineyard managers, and nursery personnel avoid the propagation and transmission of disease caused by bacteria, fungi, and viruses in the vineyard.   Judit (based in California) is fluent in Spanish and is available to consult in all wine grape growing regions of the word.  Please visit juditmonis.com for information or contact juditmonis@yahoo.com to request a consulting session at your vineyard.