Category: Archived Articles

By: Tracey L. Kelley

In the May-June issue of The Grapevine Magazine, a savvy group of experts provided detailed information about irrigation system maintenance. That article outlined seasonal start-up and troubleshooting tips. For part two of this topic, we’ll move on to ongoing system checks, typical problems often overlooked, monitoring water flow and quality and critter control.

Once again, our experts are:

• Guy Fipps, Ph.D., P.E., professor and extension specialist of irrigation and water management at Texas A&M University, College Station, Texas; in collaboration with Charles Swanson, extension program specialist, Texas A&M University.
• Jacob Hernandez, CCA, owner, JH Ag Consulting, Santa Margarita, California; in collaboration with James Anshutz, AGH20, irrigation engineer with Netafim USA in Fresno, California; and the Cal Poly SLO Irrigation Training and Resource Center, San Luis Obispo, California.
• Mark Hewitt, district sales manager, Rain Bird Corporation Ag Products Division, in Azusa, California.
• Steve Purvins, owner, The Vineyard at Lawton Hall in Bushwood, Maryland, which produces Vidal Blanc and Chambourcin grapes.

Checks and Balances

Continual process management is the key to a fine-tuned irrigation system. During the rush of season preparation, however, some aspects might inadvertently go by the wayside.

Hewitt pointed out numerous required fixes this time of year. For example, field zone valves might have broken or damaged wires because of animals, or as a result of “tractor blight”—nicks and punctures caused by machinery, which happens to vines, too.

“There might also be stuck plungers in the solenoids,” he said. “Pull coils and plungers. If the coils are swollen, replace them. Use emery cloth on plungers if they’re only slightly rusted.”

If you’ve noticed a torn or deformed diaphragm, Hewitt said, sometimes simply turning it around works, depending on the valve type, or replacing it. “Same with any springs located in the bonnet of a valve. Springs and diaphragms wear out or develop a new ‘memory,’ especially pressure-reducing valves that are always partially open throughout irrigation season,” he said.

For growers with low-volume micro sprinklers, which are similar to drip emitters, Hewitt advised clearing nozzles of debris and “checking that any fixed spray plates or rotating spinners are providing the correct patterns, distance of throw, and uniform coverage.” LFS and LFX high-performance sprinklers often don’t require much maintenance, he said, but it’s still important to check periodically for proper rotation, nozzle clogs and “insects building in deflectors.”

Hernandez offered a reminder about flushing mainlines, submains and laterals. “This isn’t done enough by growers. Most growers flush once or twice a year—either at the beginning or end of the season,” he said. “In-season flushing should be done after fertigation events with thick materials. Flushing velocities should be greater than two fps. Have your irrigation professional develop a proper flushing routine.”

What is lurking in your system? “The moist, dark interiors of drip hoses and emission devices can be ideal environments for biological slimes and chemical precipitates to form,” Hernandez said. “Various chemical solutions exist to shock and treat these issues. Irrigation professionals should test water quality throughout the season and provide treatment plans to rehabilitate dirty lines and emitters and implement continuous treatment to maintain the lines after cleaning up.”

Fipps added that if growers don’t already have flow meters and pressure gauges, now’s the time to install them.

“Monitoring system pressure and flow rate are crucial for managing operation and scheduling. Unfortunately, many vineyard drip systems lack either a flow meter or pressure gauge—or both—on their system,” Fipps said. “Observing situations of increased flow or decreased pressure can often be signs of leaks in the system, whereas situations of decreased flow and increased pressure can be signs of clogging of the drip emitters.”

Pay Attention to Pumps

“Attention to pump controls should always be given,” Fipps told The Grapevine Magazine. “Pump controls should be in manufacturer-recommended housings that prevent moisture accumulation, or pests like ants and wasps from building nests in or above the components.” He added that “if injection pumps are used for fertilizers or chemicals, hoses should be inspected and replaced if there are any signs of cracking or dry rotting to prevent chemical spills and waste.”

Hewitt said you might have to check impellers if pressure is lower than before, indicating they might need replacing. Packing leaks might mean replacement, but also a need to refill oil cups and install mechanical seals.

Also, Hernandez suggested adding a variable frequency drive (VFD). “Adding a VFD to your pumping station allows for a soft start of pumping motors, reducing wear and tear. If growers have multiple irrigation methods, various plant and row spacings, different size irrigation sets or sets on slopes, VFDs allow for one pump to operate on a number of different pressure and flow settings. This permits a grower only to use the amount of energy they need for the particular set they’re irrigating,” he said.

Managing Water Effectively

Fipps said one aspect often overlooked by growers is monitoring water quality. “Annual analysis of water quality, whether it’s from groundwater or surface water, should be conducted to check salinity and mineral composition, which can affect both the irrigation system as well as plant health,” he said. “Knowing the water quality helps guide growers on how much water to apply at irrigation, as well as prevent any negative reactions from injecting chemicals or fertilizers into the system.”

He also strongly recommends soil moisture sensors—a technological tool that works to your advantage. Soil moisture sensors might initially seem expensive, averaging $300-$500 per unit, plus the cost of telemetry devices for data transmission across the vineyard, but, Fipps said, “they take the guesswork out of deciding when it’s time to irrigate.” If you can’t afford to populate the vineyard with multiple sensors, some experts recommend having one or two in an irrigation block representative of the overall field profile.

Hernandez also recommends expert analysis. His consultancy tries to bridge the gap.

“Certified crop advisors and other irrigation professionals can help vineyard managers maintain and service their irrigation systems with analysis, implementation and ongoing monitoring to aid in the reduction of energy use; and improving crop performance through better distribution uniformity (DU).”

As a method of irrigation application efficiency, Hernandez offered two tips.

The first is setting up proper scheduling for both duration and amount of water to replace soil moisture used by the vines. “Improper scheduling can result in runoff, deep percolation, crop stress and even crop damage,” he said.

His second tip is to “use monitoring technologies to give virtual pump test and DU evaluation data every 15 minutes. These sensors give insight into the impact of changes in practice and hardware,” Hernandez said. “For example, if a DU evaluation finds extensive plugging, we’ll want to rehabilitate the lines with chemical treatment and flushing. Pressure sensors installed at strategic locations in the field can tell us almost immediately if we’ve improved the pressure in the drip hoses and provide a ‘heads-up’ during the irrigation season that we’re beginning to have a problem that can be addressed before it becomes serious.”

Purvins suggested growers ease inadequate volume issues with proper emitter spacing. “During extreme drought conditions, my system doesn’t supply enough water. Fortunately, I’ve only experienced one such year out of 20. I would spec the next system with twice the number of emitters—48” spacing vs. 96”—and adjust zones accordingly.”

He also pointed out the value of developing partnerships with equipment vendors who understand what you’re trying to accomplish. “When I purchased my system, the rep was knowledgeable about sizing the system but had no experience with vineyards. Such experience would have been useful.”

Hewitt said his company is trying to assist vineyard operators with water management through technology products, such as Rain Bird IQ Water. “Real-time sensors and remote web-access allow growers to monitor every aspect of their irrigation system from the water source to the emission device. They can focus in on a single irrigation system part, or see the big picture across every system they manage,” he said.

What About Those Critters?

Since we don’t grow in a biosphere, there will always be wildlife control issues. Often, our experts said, it’s easier to anticipate their actions with some preventative measures.

Purvins of The Vineyard at Lawton Hall has had a critter or two chew tubing, but since that damage is easy to spot and repair—and the vines and grapes aren’t bothered—he feels he doesn’t need to control wildlife.

Hernandez of JH Ag Consulting said, “As we install more sensors and monitoring technology, we’re seeing that animals like to chew on sensor wire and electronic cables. Wrap monitoring systems with a wire screen to protect them from animals and passing farming equipment.”

He also recommended that growers “bury five-gallon buckets at the downstream ends of some of the hoses and allow water from emitters to keep the buckets full during the summer to provide an easy water source.”

Hewitt told The Grapevine Magazine that setting out water is a good idea, plus using more natural control methods. “For larger animals—such as coyotes and foxes—simply put a large 2” high pan under your drip tubing. The water will overflow and still get water to your plants, and the critters can get the drink of water they want without chewing on the drip tubing.”

“It’s a bit tougher to combat gophers and ground squirrels, especially with buried hose systems,” Hewitt said. “One grower I know uses trained falcons that he releases into the area to help control these pesky critters.”

By: Judit Monis, Ph.D., Plant Health Consultant

After writing about the presentations at the Unified Symposium last January I promised I would write an article that focuses on the control of the spread of leafroll viruses in the vineyard.  Transmission and spread of leafroll viruses have been documented in all grape growing areas worldwide.  Specifically, leafroll disease has been reported spread in Australia, Argentina, Europe, New Zealand, South Africa, USA, and other important viticulture areas in the world. Different types of mealybugs and soft scale insects can transmit some species of leafroll virus and Vitiviruses. However, long distance dispersion of viruses (as well as other pathogens) is most effective by producing cuttings and grafting.  If you follow my work, you know that I recommend that you plant healthy vines to prevent virus infection in the vineyard.

Grapevine Leafroll Disease

The most important effect of leafroll disease is the production of small grape clusters with uneven ripeness.  The grapes have lower sugar content (reduced brix values). Foliar symptoms include downward rolling, reddening or yellowing of leaves and vary depending on the grapevine variety or winegrowing area. The leaf veins may remain green or take many other colors (yellow, purple, red, etc.).   Sadly, some wine and tourist magazines use photos of infected vineyards to promote their wine regions.  Although all leafroll associated viruses belong to the Closteroviridae (Greek, clostero: thread-like) family, the only species known to be transmitted by insects are found in the Ampelovirus genus (Greek, ampelos: grapevine). Ampeloviruses include the majority of Grapevine leafroll associated viruses (GLRaV-1, -3, and -4). So far, no vector has been reported for GLRaV -2 or GLRaV-7 (but as other viruses are propagated by cuttings). Research has shown that leafroll viruses are able to recombine in mixed infections, generating many variants of similar viruses that scientists define as a quasispecies (i.e., almost a species). These genomic changes have serious implications on virus detection as standard methods may miss infection. Transmission by mealybug and soft scale insects has been reported for GLRaV-1, -3, and -4. Different mealibugs such as the grape (Pseudococcus maritimus), citrus (Planococcus citri), long-tailed (Pseudococcus longispinus), obscure (Pseudococcus viburni) and vine (Planococcus ficus) are able to transmit Ampeloviruses and Vitiviruses non-specifically. Furthermore, work in South Africa has shown that a single individual of vine or long-tailed mealybug is capable of starting a GLRaV-3 infection.

Sampling in The Vineyard:

The correct identification of the disease causal agent is critical for devising a control strategy. Regular visual inspections and sampling of grapevines should be performed to monitor the disease status of a vineyard. It might not always be possible to correlate the presence of virus infection with symptoms, especially with new viral infections. Complicating matters, other viruses, fungi, or nutritional deficiencies can cause similar symptoms in grapevines. Furthermore, vines planted on their own roots do not develop typical symptoms. Symptoms may appear two or more years after top-working a vineyard with a new variety. Viruses associated with leafroll move slowly in the vine and may remain undetected by laboratory testing, unless sampling is done correctly. Collection of representative samples will allow the laboratory to detect the presence of viruses associated with leafroll. The season for testing is important and samples should be collected from vines late in the summer throughout dormancy.

Virus Testing

Two methods can be used for the detection of leafroll-associated viruses: ELISA and RT-PCR.  Each method is designed to detect different portions of the virus. ELISA detects the capsid protein (coat or protective cover), and RT-PCR detects the viral genomic RNA (genetic information).  Therefore, ELISA and RT-PCR complement each other on the detection of virus and virus variants. ELISA stands for enzyme-linked immuno-sorbent assay, and consists of trapping the virus protective protein on a plastic test plate containing specific viral antibodies.  The detection is done through a colorimetric enzymatic reaction (positive samples yield a yellow color). The method is limited to the amount of virus present in the sample (i.e., there is not amplification or danger of laboratory contamination). RT-PCR, is the abbreviation for reverse transcription-polymerase chain reaction.  The method involves the amplification or multiplication of viral RNA present in the vine. The process is specific, and utilizes a couple of primers to start the amplification process.  Primers are essentially artificial copies of a portion of the viral genome. The amplification is repeated many times, each step or cycle continues to makes more copies of the viral segment. Consequently, RT-PCR is a sensitive technique for the detection of plant viruses.

As mentioned above, the sensitivity and specificity of the detection of viruses associated with leafroll is dependent on the method used for diagnostics.  However, detection it is also influenced by the season and part of the vine from which samples were collected as well as the quality of reagents used. While ELISA is known to be less sensitive than RT-PCR, the ELISA has a broader spectrum of detection (i.e., it detects virus variants). On the other hand, RT-PCR (especially Taqman PCR) may be too specific, and could miss the detection of a virus with small changes due to mutation or recombination (e.g., variant species). Lately, fewer quality ELISA reagents are being developed as designing PCR primers is less time consuming. My recommendation is to use ELISA initially (commercial reagents work well for GLRaV-1 to -4) and RT-PCR to confirm infection (or lack of infection).  When mapping infection in a white fruited grape block such as Chardonnay or Sauvignon Blanc, ELISA may be the only economical way of determining the leafroll disease status of specific vines as many samples must be tested in a yearly basis.

Leafroll Disease Management and Control Strategies

To manage leafroll disease, it is important to develop a map of virus infected vines. The map will provide information of virus spread and determine the pattern of infection.  A random distribution of symptomatic vines would generally be associated with planting infected vines. While symptomatic vines aggregated or clustered in one area of the vineyard block is an indication of virus spread.  The initial assessment must be done using a testing lab to determine the presence of a virus species capable of being transmitted.  Once the vineyard manager is familiar with symptoms, the mapping could be done by visual observation.  It is much easier to determine the characteristic leaf roll disease symptoms in red fruited varieties.  In white varieties it may be possible to train eyes to determine the presence of infection but likely will rely on the confirmation of the presence of virus by testing vines.

Effective disease control requires the availability of clean planting stock (i.e., certified disease-free tested). However, to ensure that the vineyard remains disease free, the grower must be aware of the presence of virus infection in neighboring vineyards. It is important to devise procedures to protect a healthy vineyard from potential disease introduction. The presence of insect vectors and ants should be routinely monitored and controlled. Unfortunately, mealybugs are not always easy to observe in the vineyard, however the presence of ants are usually associated with the presence of mealybugs. Special traps (including pheromone traps) are available to monitor the presence of mealybug infestation. The dispersal of mealybugs by birds, wind, field equipment, and/or workers are responsible for long distance spread of virus. Sanitary practices such as fallow periods, sanitation of equipment, and sanitation of field worker’s clothing are recommended to avoid moving disease vectors from one vineyard block to another.  I always recommend to start work in the non-infected blocks and move workers to infected blocks at the later part of the day.

Controlling the spread of viruses requires strict protocols for handling vines and performing cultural practices in the vineyard and nursery. Hot water treatment of vine cuttings and grafted vines are effective controlling the movement of mealybugs from one site to another. Other recommended practices include establishing wind traps, planting insecticidal cover or border crops, using site dedicated clothing and/or shoes for workers, and avoiding the use of potentially contaminated equipment in the vineyard.

Ultimately, the removal of infected vines or entire blocks will be key to reducing the source of infection.  Guidelines call for rouging (removal of individual infected vines) if there is less than 25% disease incidence and entire blocks (greater than 25% disease incidence). A common mistake is the removal of a portion of the infected vineyard block (see photo 2).  This decision is made to avoid production losses at the vineyard. However, in no time, the newly planted vines will become infected by the same virus present in the other portion of the vineyard.

The control of leafroll spread needs to be based on a concerted effort among growers. In California the development of a network of neighboring growers has allowed open discussion of infection status of blocks and applied control measures. The use of cultural practices (especially sanitation and insect control applications) should be coordinated and scheduled to include area-wide treatments as grapevine viruses and their vectors do not know or respect neighboring borders.

  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 their vineyard blocks.   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.

By: Dr. Richard E Smart and Amaya Atucha

We wrote this article to promote the use of the Scott Henry training system in vineyard regions of North America; for reasons which we do not completely understand the system has been overlooked,  under-researched and also under-promoted. For those growers who use this system, mostly overseas, the benefits are substantial. They might be summarised as improved yield and fruit composition and reduced disease incidence. Wine quality is also improved. The system is not difficult to manage, contrary to some rumours in this regard. It is a matter of learning new tricks, mostly about timing, so not too difficult for commercial grape growers.

For those growers prepared to try new ideas, you will be rewarded, and the winemakers (and bank managers) will smile.

Why the Scott Henry?

Canopy Management 101

The basic aim of canopy management is to train grapevines in in such a way that yields are promoted, as is desirable fruit composition and disease avoidance. It follows a few basic principles, which follow:

• Maximise sunlight interception, remember it is Sunlight into Wine. Preferably use north-south rows, spaced about as far apart as they are tall. If you are in a hot, sunny region, you might avoid N-S rows and the heat caused by afternoon sun on west-facing canopies. Taller canopies are of course more efficient than shorter ones.
• Maintain a sufficiently wide spacing between shoots to avoid dense canopies, around 5 shoots per foot of canopy length, or 2.5, 2-bud spurs per foot of canopy. Most canopies are more crowded than this. Shading of bunches has serious effects on wine quality, and shading of the base of shoots reduces bud fruitfulness.
• Fruit exposure will generally be sufficient in such low density canopies as above; perhaps if very leafy there may be a need for some leaf or lateral removal.
• Vine balance is very important, and this is largely determined by winter pruning level; the bud count should be matched to the vineyard vigor. The best way to assess this is by weighing prunings on a few average vines. To obtain vines of moderate vigour, the rule of thumb is retain about 14 buds per pound pruning weight. This is often more buds than are normally left. Ideally the vines should be spaced 5-6 ft apart in the row.

These general rules apply to any vineyard trained to any system, not just the Scott Henry. The Scott Henry (SH) is like the Smart Dyson (SD) and Geneva Double Curtain (GDC) systems. All three have two feet of canopy per ft of row, in other words they are a “divided canopy” system. The Scott Henry and Smart Dyson are called vertically divided. One canopy grows upwards, one downwards from mid height  (3 ½ ft) fruiting zones. The GDC on the other hand is horizontally divided, with two pendant curtains about 3 ft apart.

Managing the Scott Henry

The Scott Henry is a cane pruned system, using two or four canes. The Smart Dyson is spur pruned, with spurs pointing upwards and downwards from a mid-height cordon. We will discuss the management of the Scott Henry only here.

Normally, for vigorous vines we prune to four canes, two on a lower fruiting wire at around 40”, two on an upper fruiting wire at about 46”, on the opposite side of the post and on the upwind side. An extra wire is used for the SH, a moveable foliage wire to help downwards shoot positioning.  At winter pruning, this rests about opposite the top fruiting wire, and at early flowering it is placed on top of the shoots from the bottom canes after they are separated from those growing upwards; subsequently, after fruit set it is moved downwards and attached, so positioning the shoots downwards. When pruning remember not to wrap the bottom canes too tightly, one or two wraps is best, and secure the ends of the canes.

At the beginning of flowering, and before the tendrils start to attach, slide your arm into the canopy to separate shoots from the top and bottom canes.  Place the extra moveable foliage wire on top of the shoots from the bottom cane, and they will lean out into the row, assisted by any wind. Shoots from the top cane will form the top canopy, and they are trained vertically upwards between foliage wires, as is normal for VSP.

Then, at around early fruit set, move the bottom moveable foliage wire downwards and attach it to the post, say 2 ½ ft below the fruiting wire. This will form the second, downward pointing canopy.  Remember that you will need to apply any herbicide before flowering.

Normally shoot positioning the Vertical Shoot Positioned canopy (VSP) takes 3-4 labor passes through the vineyard with well managed teams, and requires 12 to 16 hrs per acre. This figure might be increased by say 25%  maximum when using Scott Henry.

Responses to Scott Henry

Training with Vinifera

The conversion cost is not high, to add only one wire per row to train shoots downwards, and a very modest increase in labor input, for shoot positioning. The benefits are however substantial, with yield increase to 30% or more, no change in other costs (apart from harvest), and typically less disease. It is well known that powdery mildew and Botrytis are higher in shaded canopies, and less for Scott Henry than VSP. Because of improved bunch exposure, there is better color, flavour and phenolics in vines trained to Scott Henry.

Most experience around the world is with vinifera grapes; in fact Oyster Bay wines of New Zealand has 5,240 acres of Scott Henry planted in both NZ and Australia, no doubt the largest in the world. Results from their vineyards reinforce the message above, and on a grand scale!

Responses to Scott Henry Training

With Hybrid Grapes in Wisconsin

Cold climate hybrid grapes cultivars have propelled the expansion of the grape and wine industries in the Northeast and upper Midwest of the United States, mostly due to their superior midwinter hardiness compared to vinifera and other hybrid cultivars. However, cold climate hybrids possess high vegetative vigor which can be intensified when vines are grown in very fertile soils, and summer rainfall such as in the Midwest. The high vegetative vigor of these hybrids can be challenging for growers to manage, and often results in dense canopies with shaded fruit that is high in acidity and has poor color development, as well as an overall delay in ripening. To control vigor, growers will usually hedge and skirt shoots multiple times during the season, and will implement shoot and leaf removal to increase light exposure of clusters, all of which requires labor and increases production costs. Particulary time consuming is the task of tucking shoots into the trellis wire in the VSP system, which can be a constant battle with cultivars that have a procumbent (droopy) growth habit such as ‘Brianna’ and ‘La Crescent’.

Alternatively, divided canopy training systems, such as Scott-Henry (SH), can be used to control vine vigor, as these systems increase the number of shoots and clusters per unit of row length, compared to those grown on single canopy systems like VSP or high wire. Studies across in the Midwest of the United State (Atucha and Wimmer, 2016; Cochran and Nonnecke, 2016) have shown that cold climate hybrids trained on divided canopy systems can achieve higher yields, reduce canopy shading, and improve fruit composition, compared to single canopy systems.

In a 5-year training system evaluation study in southern Wisconsin, yield of vines trained to the SH system produced more than double the yield than those trained to the vertical shoot positioning (VSP) system, and 25-35% more than vines trained to the high cordon (HC) system. For example, in ‘Frontenac’ the 5-year average yield on SH was 30 lb/vine (  8.7 t/ac), compared to 16 lb/vine (4.7 t/ac) in VSP, while in ‘Marquette’, HS and VSP produced 17 and 10 lb/vine (5 and 2.9 t/ac), respectively. In addition to higher yields, vines trained in the SH system had more consistent yields year to year, compared to the high variability in yields observed in VSP.

The higher yields in SH resulted in a considerable reduction in vegetative vigor, which required no to minimal hedging to control shoot growth in vigorous cultivars such as ‘Marquette’ and ‘La Crescent’, and an overall more open canopy with a higher percentage of clusters exposed to sunlight (Wimmer et al., 2018) .  There were no differences in sugar and acid composition at harvest between the higher yielding SH vines and those in VSP or HC, despite the significantly higher crop load of vines trained to SH. Separate studies in Wisconsin have shown that sunlight exposure improves berry colour and phenolics. A recent article in this magazine (Smart 2018) emphasised the need to do shoot positioning on the high wire trellis to avoid shading, which causes loss of yield and quality.

Conclusion

We think that Scott Henry and Smart Dyson might have application in the Midwest USA, as has been found elsewhere. Certainly the initial research results are encouraging. The SH training system is a great option to control vegetative vigor and increase yields in cold climate hybrid grape cultivars without reducing fruit ripeness, and quality for winemaking will likely be improved.

References Cited

Atucha, A. and M. Wimmer. 2016. Brianna, Frontenac, La Crescent, and Marquette Training Trial. West Madison Agricultural Research Station (WMARS), Verona, WI. Northern Grapes Project publication. http://northerngrapesproject.org/wp-content/uploads/2016/02/WI-training-study-Year-4.pdf

Cochran, D.R. and G.R. Nonnecke. 2016. Iowa Training Systems Trial. Snus Hill Winery, Madrid, IA. Northern Grapes Project publication. http://northerngrapesproject.org/wp content/uploads/2016/02/IA-training-study-Year-4.pdf.

Smart, R. E. (2018) Managing high wire trellis for improved yield and quality. The Grapevine. Nov-Dec, pp 54-58.Wimmer, M., Workmaster, B. and Atucha, A. 2018. Training Systems for Cold Climate Interspecific Hybrid Grape Cultivars in Northern Climate Regions. HortTechnology 28(2): 202-211.

About The Authors

  Dr. Richard Smart: is an Australian viticulturist and leading global consultant on viticulture methods and is often referred to as “the flying vine-doctor”. He is considered responsible for revolutionizing grape growing due to his work on canopy management techniques.

  Dr. Smart is a graduate from Sydney University with Honors in Agricultural Science in 1966. Additionally he holds the degrees M.Sc (Hons) from Macquarie University following a study of sunlight use by vineyards, a Ph.D from Cornell University in New York State studying under the Professor Nelson Shaulis, and in 1995 awarded a D.Sc. in Agriculture by the Stellenbosch University, South Africa, in recognition of research into canopy management effects on vineyard yield and quality.

  Dr. Smart is the author of the book Sunlight into Wine as well as a contributor to several trade publications, and the viticulture editor of The Oxford Companion to Wine. Consulting has been a full time occupation since 1991, and he has consulted to over 300 clients worldwide. While many clients want to use Richard’s expertise in canopy management to improve wine quality and vineyard yield, complete viticultural advice has been given on a range of issues like choice of site, variety, rootstock, irrigation and nutrition management.  Dr.Richard E. Smart: International Viticultural Consultant, Smart Viticulture, Truro, UK, richard@smartvit.com.au

Amaya Atucha: is an assistant professor and Gottschalk Chair for cranberry research in the department of Horticulture at the University of Wisconsin-Madison and State Fruit Crop Specialist with UW Extension. She earned a B.S. in horticulture from the Pontificia Universidad Católica de Valparaíso (Chile) and a Ph.D. in horticulture from Cornell University. Her research program focuses on fruit crop physiology and production of deciduous fruit crops, predominantly cranberries and cold climate grapes, and her extension program delivers up to date, research-based information to fruit growers in Wisconsin. She edits the Wisconsin Fruit Newsletter, a biweekly newsletter distributed statewide in Wisconsin, and is a contributor to the Cranberry Crop Management Journal, a publication highlighting research and extension in cranberry production at UW-Madison.

By: Judit Monis, Ph.D.

This year I was invited to speak at different events organized by the Chilean Nursery Association (AGV) and Wines of Chile. While in Chile, I attended the 19th Congress of the International Council for the study of virus and virus-like diseases of the grapevine (ICVG). The ICVG meeting was held and hosted in Viña Santa Carolina Winery facilities near Santiago.  While I was traveling in South America, I had an opportunity to visit vineyards in Argentina and Chile.  Today I will share information I learned about winegrowing in Argentina and Chile.  As you know my interests are in grapevine diseases, how to prevent disease development and spread in the vineyard.   So, it will not be surprising that this article will focus on vine diseases.

Grapevine Diseases Originate Where Vitis Species Originate

It is easy to guess that grapevine pathogens (disease causing agents) originated at the same place where Vitis (the grapevine genus) species originated.  These disease agents (bacteria, fungi, and viruses) were introduced to other places in the world with the propagation and planting material.  Specifically, the varieties and clones that are grown in vineyards belong to the Vitis vinifera species (of Eastern European and Asian origin) while the rootstocks grown commercially belong to American Vitis species.  When grape cultivation started countries were not set up with quarantine programs, neither modern diagnostic tools we use today (PCR, ELISA, etc.) to detect pathogens were available.  Consequently, since the early days of grapevine cultivation European and American grapevine pathogens have been moving from one site to another for many generations.

Argentine and Chilean Grape growing Regions are Strikingly Different

  Being from Argentina, I frequently visit vineyards and wineries in South America.  Argentina ‘s viticulture is very different from what I am used to in California growing regions.  Most of the vineyards in Argentina have planted vines on their own roots (i.e., not grafted onto a rootstock) as the philoxera pest is not commonly found in Argentine grape growing areas.     Besides providing protection from philoxera, rootstocks confer resistance to nematodes, salinity, and can control the vigor of the vines in the vineyard.   Consequently, more vineyards in Argentina are being planted with grafted vines, especially in Mendoza’s newer and more sophisticated growing regions (Valle de Uco).   In contrast, the vineyards in Chile are very similar to the ones I visit in California and strikingly different from those in Argentina.   The majority of the vines in vineyards are grafted and trained in a similar fashion to Californian vineyards. The Andes Mountains that divides Argentina from Chile influences the climatic conditions of each of the countries.  Therefore, the rainy seasons, availability of water and stresses present in each winegrowing area are very different.

Grapevine Diseases are Found Wherever Grapevines are Grown

When it comes to diseases Argentine and Chilean viticulture is not different from other growing areas.   As I mentioned earlier, common diseases caused by Leafroll viruses, Vitiviruses, Fanleaf, Agrobacterium, and fungal trunk diseases must have arrived on site when plant material was imported.  These are important diseases that affect both grape quality, yield, and longevity of the vineyards.  In Chile and Argentina, I have witnessed the presence of Syrah Decline, a disorder that affects both grafted and not grafted plants.  At the ICVG meeting, Joshua Pucket from UC Davis Foundation Plant Services reported that Syrah Decline symptoms are linked to genetic markers present in certain Syrah and Shiraz clones.   Interestingly, when symptomatic Syrah selections were subjected to the meristem tissue culture technique used to eliminate known viruses and viroids, the symptoms persisted, suggesting that Syrah Decline is not caused by any of these infecting agents.  Research in France support these findings as symptoms are restricted to certain grapevine genotypes.  The news that Syrah Decline is a genetic rather than pathologic disorder will help growers prevent planting certain genotypes to avoid loss of production.   It is expected that we will learn more about this disorder as more research is published on this topic.  To date, surveys in both Argentine and Chilean vineyards were not able to detect Grapevine red blotch virus (GRBV).  The most likely reason for the lack of GRBV in Argentina and Chile is that these countries have historically imported grapevines from Europe and the virus so far has not been reported in EU vineyards.

None of these South American Countries have a Grapevine Clean Planting Certification Program

Grape growers and winemakers are aware of the detrimental effect of grapevine pathogens and would prefer to purchase and plant certified grapevines. Unfortunately, neither Argentina or Chile have a current certification program.  In other words, certified pathogen free vines (scion or rootstock varieties) are not available.  This is not completely true, as I learned that Argentina has one certified Malbec clone available. However, there is no use of having a certified scion if it is to be grafted onto a non-certified rootstock.  Consequently, most nurseries and growers are grafting non-certified scion and rootstock varieties.  In Argentine the grapevine certification program is going through administrative revision.  The current law requires that all mother plants are tested every year using the woody indexing method.  However, this is not practical as the results of this test are obtained two years after starting the index. The proposed changes include the application of molecular (PCR, ELISA) instead of biological testing (index) to detect viruses in the foundation and nursery increase blocks.  In Chile, supported by public funding a virus tested germplasm collection is being preserved.  It is expected that the material will become available to interested nurseries that could multiply and distribute the material for planting new healthy vineyards.

In both countries, the available planting material produced at the nurseries is not sufficient to fulfill the demand of the industry.  Therefore, grafted vines can also be imported from “approved” nurseries primarily from Europe (France and Italy) and must pass the government quarantine and sanitation requirements.  Generally, quarantine is done at facilities owned by the importing party as neither SENASA or SAG, the National sanitary authorities in each of the countries have the space to complete the quarantine in their facilities.

It is my hope that, with time, future changes will include the availability of certified pathogen free tested and true-to-type scion and rootstock planting material.  Only with clean planting grapevine material these important wine grape growing areas will see an improvement of the health and longevity of their vineyards.

  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 their vineyard blocks.   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.