Month: March 2019

By Gerald Dlubala

Quality wines start with quality grapes. Quality grapes start with quality care, meaning everything from the soil to the prevention of disease and insect damage. Proper mowers, mulchers and spray systems can help with this process.

Slimline Manufacturing: Go With The Flow

Wayne Riddle sells Turbo-Mist Agricultural Sprayers for Slimline Manufacturing, based in British Columbia, Canada. Slimline sprayers take advantage of the wind’s trajectory, transforming a potential setback into the sprayer’s key feature.

“Any successful chemical application is based on good circulation,” says Riddle. “So, we control the movement of the wind to direct chemically loaded droplets to their target. The terminology that we use is the gear-up, throttle-down method, which is to say that we can speed up or slow down our machinery at the proper times to effectively change the speed and strength of wind flow, which then controls the direction and reach of the applied product. There can be different coverage needs for different areas of the vineyard based on factors like soil type, terrain makeup, disease or insect problems. This is where we need to adjust for different wind speeds to apply the right amounts of chemicals for a particular situation.”

Controlling coverage in this way means less waste, easier maintenance, and more environmentally responsible chemical application.

“This [feature] eliminates chemical waste and saves money on both fuel and equipment wear and tear. The tractor and sprayer don’t have to work as hard, so fuel consumption is more economical,” Riddle says. “We stay socially responsible by using the least amount of product possible and applying it most efficiently and effectively. By approaching spraying this way, we leave less of a carbon footprint.”

Slimline’s Turbo-Mist sprayer systems are made for farms of all sizes, from small hobby farmers to massive vineyards requiring four hundred-gallon sprayers. Riddle told The Grapevine Magazine that no matter the size, Slimline tends to attract forward-thinking, progressive farmers.

When it comes to future trends, Riddle is most interested in the management of the sprayers through the use of a data loaded spray controller and GPS technology.

“It would be extremely useful to load a spray controller with information including GPS data to manage and disperse the gallons per acre needed depending on the agricultural needs, regardless of tractor speed or nozzle wear.

BDi Machinery Sales

Bill Reiss, owner of BDi Machinery Sales of Macungie, Pennsylvania, stresses the importance of quality, easy-to-use spray systems that assist wine growers while letting them do things their way.

“Whether growers prefer a high wire, vertical shoot or another canopy system, it’s all about the delivery of the chemistry [sic] to the intended target while using the smallest possible chemically loaded droplet,” says Reiss. “The canopy style the farmer chooses to use determines the correct spray head for the application. Our CIMA sprayer systems can be fitted with a multitude of available spray heads appropriate for a variety of crops. We pride ourselves in finding solutions to the needs of farmers in America.”

Reiss told The Grapevine Magazine that disease and insects are the most significant problems facing wine grape growers simply because wine grapes aren’t native to the U.S. “Wine grapes need to be treated and monitored, and it’s always better to spray early in the season rather than waiting and trying to eradicate a problem once it shows up. Effective coverage is critical, and it takes better delivery using minimal chemistry [sic], smaller droplets with less overspray to reach the target,” he said.

BDi Machinery sells the Italian-made CIMA sprayer line. These sprayers use an atomizer and air shear nozzle to push the dead air out of the canopy, ruffling leaves as it goes. This movement guarantees the chemicals will hit all surfaces outside and inside the canopy.

“We minimize overspray by opening and closing the atomizer which controls the width and reach of every dispersed droplet,” says Reiss. “Calibration is as simple as tightening or loosening a couple of wing screws on a regulator to get the needed orifice opening for the desired coverage. You can easily change the calibration from field to field, block to block, or season to season with little effort.”

Maintaining CIMA sprayers takes minimal effort, something Reiss feels is pivotal for busy farmers. “Sprayer maintenance needs to be easy, or it simply won’t get done,” he says. “Look for things like rinse tanks and minimal grease fittings. Our CIMA sprayers have only three grease fittings and include both hand rinsing tanks and internal chemical basket mixing systems for chemical safety.”

Electrostatic Sprayers Use Laws Of Attraction For Efficient Coverage

“Honestly, the most important thing about vineyard sprayers is that they need to be reliable and work when we need them to work,” says Mark Ryckman, Sales Manager and co-owner of Progressive Ag Inc., in Modesto, California. “They need to be durable and heavy duty but offered in a simple package so they last while proving easy to operate. Ours are heavily constructed and powder coated to increase their longevity.”

Progressive Ag manufactures indirect charging, electrostatic sprayers in several models. “We put a static charge in each droplet coming out of our machines. Plants and vegetation are neutral, so the droplets are naturally attracted to the plant. With each droplet having the same amount of charge on it, the drops repel and push against each other like some of those magnets we’ve all played with as kids. By pushing against each other, they naturally space themselves apart, making sure the vine coverage is consistent and even,” says Ryckman.“The chemical loaded droplets can be dispersed in larger volumes through larger than the normal pinhole size nozzles. By using larger sized nozzles, we don’t have the plugging issue that standard pinhole nozzles can have. The chemical is then dispersed through air induction instead of pressure sprayed so it can naturally land where the attractive properties of the charged particles take them.”

Maintaining Progressive Ag’s LectroBlast sprayers doesn’t take long, but should be completed daily. Ryckman told The Grapevine Magazine it requires only a five-minute daily greasing along with cleaning the electrodes and regular flushing to “have the sprayer work when you need it.”

Ryckman is excited about future technological trends such as variable rate controls for the spray rates. “Through the use of drones, we’ll be able to locate insect problems or disease and fungus issues in specific locations of the vineyard. We’ll map it out, load it in the controller, and then be able to automatically apply variable rates of material depending on the specific needs of each location, more on the high-risk areas, and less on the areas that are doing well.”

Like Ryckman, Willie Hartman, President and owner of On Target Spray Systems in Mount Angel, Oregon, sees the importance of incorporating computerized rate control programming built through GPS or wheel sensors. “It’s one of the things that customers are continually asking for. They are looking for data and the valuable coinciding reports.”

Hartman also sells electrostatic sprayers for the vineyard and says that, now, more than ever, “It’s vitally important to get a sprayer that provides super coverage. Keep mildew at bay early with complete coverage, over leaves, under the leaves, and wrapping around the plant vines themselves.”

On Target sprayers charge the droplets through induction, meaning the particles run through an atomizer for absolute universal size. They don’t pick up their charge until run through the dispersing nozzle, where they get hit with one thousand volts on the way toward their target.

“We use the least amount of water per acre of all the other types of sprayers right now. With labor costs rising, we can save money on water use immediately. Less overall material to spread means less time on the tractor, translating into fuel savings. By using less water, we can concentrate our spray. When you use concentrated spray, there is less runoff, minimal drift, and improved chemical coverage leading to increased performance. In today’s world, that is extremely important because, with the organic farming push, we’ve moved away from systemic treatments and are now relying on contact treatments,” Hartman says. “Improved concentrations and better overall contact are critical and successful. We know it works because of situations like last year when the East Coast had terrible disease and fungus issues except for the handful of farms that were using our sprayer systems.”

Hartman told The Grapevine Magazine the maintenance step not to overlook is rinsing the sprayer after use. On Target sprayers reflect this belief through onboard rinsing tanks accessible with a flip of the switch. Additionally, all components, including liquid, air and the twelve-volt electric needed for droplet charging are separately enclosed.

Mowers And Mulchers For Ground Level Care

Replacement part availability is magnified when considering agricultural mowers and mulchers simply because of the complexity of these machines.

“It’s a real issue at times,” says Kevin Pereira, sales professional with Woodland, California-based Clemens Vineyard Equipment Inc. “We get calls all the time about replacement parts for mowers and mulchers because growers can’t get the right parts in a timely fashion. Sometimes we can help, but other times we can’t because they bought a machine that may not have a physical presence or supply outlet here in the states.”

Pereira says growers can avoid these issues by buying from an equipment company like Clemens Vineyard Equipment. “We have a tremendous history of over twenty years, with excellent support and a United States warehouse for priority parts availability when needed.”

“Mowers are mowers, and when you get down to it, they all do the same job,” says Pereira, “but parts and available service are just as important as features and pricing. Cheapest isn’t always the best, and in the case of mowers and mulchers, you generally get what you pay for. Clemens mowers and mulchers are built for heavy-duty use featuring long-lasting plates and components, and a premium flex adjustability feature for variances in row lengths.”

Proper mowing and mulching protects roots, increases soil structure, reduces soil erosion and temperature, and increases the vigor and yield of crops. Approach mulching much like spraying chemicals, by formulating a mulch mixture to best suit the needs of the area. Sections of a vineyard that have less than desired growth may need mulches with higher nutrient components, while organic based mulches can assist with water dispersal in lower elevations.

Row mulchers and spreaders save time and labor by efficiently spreading mulch, organics, compost and other soil mixes within vineyards. Since they’re considered specialty equipment, it’s critical that they provide a return on investment. For multiple rows, side mulchers are equipped with either dual or single side dispersing, but if needed, mulchers are available with remote and distance spreading capabilities to get the mulch to the targeted location.

“The type of mower or mulcher you should get is tied to your needs. Do you need to mow weeds and mulch, or mow, mulch and prune? The type and amount of versatility you’re after will make a difference in the machine you need. They’re not all created equal, with some being better at certain functions than others,” Pereira says. “Find the happy medium that fits your budget and priorities, but whatever type you choose, regular maintenance is very important. Daily greasing and a quick visual inspection to spot any excessive wear on parts or components is recommended. Depending on the size of the acreage and amount of use, mower blades should be changed either annually or bi-annually. Bearing checks are always a good idea, and as should be done with all machinery, occasional professional inspections are a good idea.”

By Jessica Spengler

As mechanization of vineyards becomes the norm throughout the world, equipment manufacturers have seen an opportunity to specialize. Tractors, in particular, are being designed to fit down the narrow rows of vineyards and orchards, as well as with higher horsepower, better versatility and ease-of-use. Now is the time for vineyards to re-invest in a new machine, since industry leaders, including John Deere, Kubota, and New Holland, all sell models specialized for vineyards and orchards. With a little research and guidance, vineyard owners and managers can easily find the best tractor for their specific needs.

Many wine growers may question why they need specialized equipment when they can just purchase a utility tractor for their farming needs. However, the needs of vineyard and orchards extend beyond those provided by standard utility tractors.

“Many producers have specific crops and specific planting which require special tractor dimensions to operate in those fields, orchards, or vineyards. Although a utility tractor might fit some of these requirements, there will usually be modifications required to make the tractor completely fit the application. Our specialty tractors are designed to fit into those specific applications. Our narrow tractors offer spacious narrow cabs to fit perfectly in vineyard applications along with higher hydraulic flow than a standard utility tractor to meet those specialty implement requirements.” said Tyler Pittson, Kubota M-Series tractors product manager.

Nick Weinrich, Product Marketing Manager for John Deere, said the grapes, in particular, are a significant concern. “Producers, no matter their operation, need a tractor to meet their specific farming practice from horsepower, capability, and fit. In the case of vineyards fit, from a dimension standpoint, is the main need. When talking about vineyards and any other high-value crops, the fruit is the most critical subject, since it can easily be damaged, bruised, or even knocked off the plant if the machines operating in the field come in contact with it. This turns into loss revenue to the producer,” he said.

Essential Feedback

Kubota and John Deere have both sought out feedback from vineyard and orchard managers to improve and design the best machines for their needs.

Kubota found horsepower, comfort and versatility to be a high priority. “Through dealer and customer feedback we have learned vineyard and orchard managers are looking for higher horsepower, more versatile tractors,” said Pittson. “We designed Kubota’s M4N/M5N models to meet their specific needs and harvest demands. Take a seat in any one of these new tractors check out the comfort and space of our cab, and you’ll understand why they stand out against the competition.”  Pittson.

The result was their M series line of tractors.

“The M Series models feature updated engines, intelligently revamped operator stations and improved hydraulics. The M Series specialty models also feature highly versatile transmissions designed to provide superior power and efficiency, for the most rigorous specialty environments. The M4N/M5N tractors are equipped with wet hydraulic clutches standard which improves durability, life, and reduces maintenance. The M4N/M5N narrow tractors deliver Kubota’s renowned M Series power and reliability in tractors engineered specifically for work in vineyards, orchards and other narrow environments,” Pittson told The Grapevine Magazine.

The Kubota M-Series Specialty Tractors Lineup includes the M4N-071, M5N-091, M5N-091 Power Krawler and M5N-111 narrow tractors; and the M5L-111 low profile tractor, the M6L-111 low profile tractor, and the M6H-101 high clearance tractor. The M4 and M5 models are equipped with Kubota’s V-3800 Tier IV engine and redesigned operator stations that enhance ergonomics and efficiency. The M5L-111 low profile tractor has standard shielding and a sloping hood to reduce crop damage.

“Another excellent model that we have is our M5N-091 Power Krawler which has wheels in front and tracks in the rear. This model offers superior traction and better stability than the standard wheeled version for those more performance demanding applications. The Power Krawler can be an essential tool for producers located in rocky and hilly areas,” Pittson said. For pricing and finance, visit your local dealer Kubota dealer.

Ease-of-use was at the top of many of John Deere’s customer’s lists of needs. “The largest hurdles producers are facing today is labor and uptime. They need tractors that work when they need them to, and John Deere has the best dealer network and parts availability to keep machines operating in critical times. To help with labor issues, John Deere manufactures tractors that are intuitive to a range of operator skill sets, as well as comfortable to operate to keep the labor coming back,” said Weinrich.

Years of experience and the time spent gaining insight into the needs of vineyards and orchards resulted in John Deere’s 5 Series.

“John Deere offers a variety of tractors that meet the need of narrow row/vineyards, from our six 5G models ranging from 75-100 horsepower, and then our narrow cab offering on our 5M and 5R models ranging from 75-125 horsepower. The 5G’s can get as narrow as 38.7” which is the narrowest offering in the NA market,” said Weinrich. “Vineyards stand to benefit from these by having a variety of offerings to meet their needs, most of which have the best maneuverability, turning radius, power, and hydraulic capacities in the industry, giving them the performance and productivity they need in the critical times, such as harvest.” Starting price for a base 5G 75 horsepower tractor is around $38,500 up to $58,000 for the 100 horsepower.

Getting Attached

The narrowness and ease-of-use of a tractor mean nothing if it cannot accommodate the implements needed to maintain a vineyard. Both John Deere’s 5 Series and Kubota’s M Series offer attachment capabilities for new and existing implements.

“The compatibility of implements with these tractors is high. Vineyards require a number of unique implements and attachments to maintain, manage, and harvest. Most of their current implements and attachments are compatible with our offerings. The 5Gs can have up to seven mid-SCV’s to attach implements and the highest hydraulic flow in the industry for these implements,” said Weinrich.

“The M Series specialty tractors have more hydraulic valve options, ready to accept implements requiring multiple valves with different flow requirements. The new models offer two self-canceling detent deluxe built-in flow control valves, with an option to add up to five total valves on the M4N/M5N. Each tractor features a Category II three-point hitch with easy adjust stabilizers to handle the wide range of specialty implements,” said Pittson.

Keeping Up With Technology

The newest technologies – from touch screens to remote access to guiding systems – have proven beneficial to growers of all shapes and sizes. John Deere, in particular, has embraced these systems, which feature prominently in their 5R series.

“At this time the 5R narrow cab is the most advanced utility tractor offering with integrated AutoTrac guidance and JDLink. Optional JDLink provides remote access for monitoring critical tractor systems and functions. Machine information and programmed custom alerts can prevent downtime by helping customers avoid equipment failures.   When JDLink is combined with Remote Display Access, producers can give their dealer remote access to the machine to troubleshoot potential problems, provide faster repairs or schedule routine maintenance. The 5M’s also offer a field installed JDLink option,” said Weinrich.

Kubota’s M-series includes a touch screen control panel, optional guidance system, and are designed to maximize the operator’s comfort.

“A redesigned cab on the M4N/M5N models features an updated dashboard with a multi-function, multi-view Intellipanel and LED cluster lighting,” said Pittson. “The M4N/M5N steering wheel has 40 degrees of tilt, making it easier to get in and out of the suspension seat. All of our specialty tractors are ergonomically designed, with all main controls located on the right side.  The narrow cabs feature’s a spacious cab, hydraulic shuttle, and an optional air ride seat. These tractors can also easily be fitted with Auto-Guidance systems and controls.”

Choosing Well

As mechanization grows in popularity, vineyard operators see greater efficiency, less fruit variability, happier, healthier workers, and a bigger bottom line. These benefits only occur, however, when the vineyard owner or manager chooses the right model for the size and needs of the vineyard. Knowing the land, doing the research, and talking to a reputable dealer will make that decision much easier.

By Judit Monis, Ph.D.

Last January I attended the virus management session organized by the Unified Symposium in Sacramento, CA. Maher Al Rwahnih, James Stamp, Rick Hamman, and Eric Pooler were invited speakers.  While it is common sense that it is important to plant healthy vines to avoid the perpetration of viral diseases, we are learning that it is not that simple.  A couple of years ago we heard that even the most tested and best maintained foundation block in California is susceptible to becoming infected by viruses.  I will present my take on the different presentations and add my ideas on solving such important issues.

The Russell Ranch Foundation Block Virus Status

Maher Al Rwahnih from The University of California Foundation Plant Services (FPS) opened the session describing the discovery in 2017 of five vines infected with Grapevine red blotch virus (GRBV) in the Russell Ranch mother block.  The block was planted in 2010 and is the regulated by for the California Food and Agriculture (CDFA) Registration and Certification (R&C).  After completing a two-mile radius survey, researchers at FPS were able to trace the origin of the positive findings in the mother block to vines planted in a home backyard, a school yard, and a home garden center.  The vines from the outside source as well as the mother block selections were removed and destroyed as soon as the infections were confirmed.  Due to the seriousness of finding virus in their mother block, FPS decided to test annually all the plants in the CDFA R&C mother blocks for Grapevine leafroll virus associated -3 (GLRaV-3) and GRBV.  After completing the tests in 2018, FPS found 24 vines infected with GRBV and none infected with GLRaV-3.

To reduce the inoculum levels in the foundation block, all infected vines have been removed.  To control the spread of virus the FPS has devised a strategy that consists in monitored the blocks routinely for vectors (GRBV is transmitted by the Three-cornered alfalfa tree hopper and GLRaV-3 is transmitted by mealybugs and soft scale insects).  Additionally, preventative treatments are carried out with feeding deterrents and systemic and contact insecticides.  A survey of the block’s surrounding areas has been increased to a five-mile radius to find the original source of infection.  Moving forward all ordered selections will be tested individually for GRBV (Test to Order program) prior to distribution to assure that material has no detectable levels of virus.

Preventing the Introduction of Disease in the Vineyard

James Stamp, from James Stamp and Associates, voiced his concern on the difficulty of securing clean planting material and presented standards he applies prior to ordering vines for planting.  The mother plants must be tested and show no evidence of infection of GLRaV-3 and GRBV.  In addition, grafted vines need to display good physical characteristics.  In his opinion, a vine with a solid graft union is likely to have a lower incidence of fungal pathogens.

Similar to my advice, he recommends to work cooperatively with nursery personnel to obtain testing results and always perform independent sampling and testing.  The vines that are sampled from a nursery increase block should be marked so that if the results show no detectable levels of virus, cuttings can be collected for grafting.  He prefers “protocol 2010” vines (these are the vines that are planted in the Russell Ranch mother block described above).  However, he has had success with nurseries that propagate older vines from the “classic” U.C. Davis mother blocks.

It is best to choose a nursery that has adopted cleanliness standards (i.e., no dust, paved roads, etc.). It is recommended to visit the nursery increase blocks in the fall to observe typical symptoms (red leaves in red grape varieties) and be present when cuttings are being collected (those that were submitted to testing) to assure that these are used to fill the order.  It is advisable to keep in touch with the nursery personnel to make sure that the delivery of the order will be on time.  Generally, the nursery will graft more material than needed to make sure that the correct number of grafted vines are delivered – but it is best to be in touch to make sure this happens.  If vines are to be finished in the field, it is recommended to take samples and test them for GLRaV-3 and GRBV as these viruses can be transmitted in the field.

Stamp’s presentation concludes suggesting that consumers need to be educated and engaged to accept genetic engineered resistance.  He urges for the availability of more funding for research to apply CRISPR (a gene editing technology) for disease resistance development.  In his opinion, this will be the only way to fight diseases as he has given up that the certification programs will be able to keep viruses out of planting material.

The Economics of leafroll Disease and the Need to Prevent Virus Spread

Rick Hamman, a vineyard manager in Washington State focused on the economic impact viruses have on grape production (particularly leafroll viruses).  He stated that he has learned the lesson the hard way and refers to the loses due to virus infection as a “virus tax.”

In 2001 leafroll symptoms were noticed in a three-acre block and after testing it was found to be 100% infected with GLRaV-3. The vineyard was removed and replaced with “clean” planting stock.  However, in a short period of time the block became 85%. Infected.  This was due to the presence of mealybugs in the residual roots that were not carefully removed.  The speaker was able to calculate losses due to GLRaV 3 infection and these are significant. In 2010, the crop did not meet the required winery Brix value and represented a $500/ton loss.  This vineyard manager has experimented with rogueing material as symptoms appear in the vineyard block.  In Washington state, growers are able to burn the removed material but he admits that this may not be possible in other wine growing areas.  In one case, the virus presence and vine removal in the block was monitored by Naidu Rayapati’s research at Washington State University.  The study showed that by replacing infected vines with healthy stock the inoculum levels decreased each year and allowed to keep the block productive.  However, in other cases the removal of symptomatic vines was not as successful as the infection rate in the block continued to increase (perhaps due to spread of virus from infected vines not showing symptoms).

Eric Pooler from the Silverado Investment Management Co. is very familiar with viral infected block as the company manages vineyard blocks throughout California.  The company has worked very hard to monitor and control the life cycle of mealybug vectors that transmit leafroll viruses.  The speaker noted that it is Important to continue with insecticidal treatments after harvest and during dormancy as vector population will increase if they are not treated.  Just as important is to make sure to get full coverage of plants during insecticidal treatment.  The company has designed a modified sprayer that has many spray nozzles to assure the complete coverage of the vines with the insecticides. The speaker suggested that their personnel manages disease by increasing irrigation and /or the application of cytokines (plant growth hormones).  Their observation has been that a healthy canopy has correlated with better fruit set regardless of infection.  When it comes to planting a new vineyard, the company has developed a checklist of requirements prior to ordering vines from a nursery.

Conclusions

As a plant pathologist I recommend always planting healthy (pathogen tested) vines.  Since viruses, their vectors, and other grapevine pathogens can be present in the vineyard, growers need to be vigilant of pathogen spread and potential new infections.  For viruses, unfortunately the industry is focusing only in GLRaV-3 and GRBV exclusion.

However, I recommend to test for other leafroll viruses (GLRaV-1 through -4), Vitiviruses (Grapevine virus A = GVA, GVB, GVD, etc.), and Grapevine fanleaf virus (GFLV).  Presently, the crown gall causal agent (certain pathogenic strains of Agrobacterium vitis) and fungal pathogens are not regulated or excluded from certification programs.  However, these pathogens should also be kept in check as they cause important diseases.  The good news is that disease diagnostic assays have evolved to be able to be more sensitive and specific.  The application of next generation sequencing also known as high throughput sequencing will help reduce inoculum levels and consequently reduce infections in the vineyard.  Vineyard managers and growers must continue to be attentive of the infection status in their vineyards and their neighbor’s vineyards.  Coordinating insecticidal treatments and communicating openly on the presence of disease and vectors in vineyards is imperative.  We all must be reminded that it is possible to fight viral spread in the vineyards cooperatively.  Work performed in South Africa has shown a drastic area-wide reduction of leafroll virus with a simple but dedicated management strategy.  The heavy use of insecticidal treatment of mealybugs combined with complete removal of infected vines and replacement with virus tested vines was a success in reducing disease incidence In South African vineyards.

One question brought up by the audience was if it was necessary to have a fallow period after removing an entire vineyard.  In my opinion, the fallow period is needed to control leafroll viruses transmitted by mealybugs.  However, we are just learning about red blotch disease epidemiology and expect that in the coming years better disease management recommendations will be available to help keep foundation blocks and vineyards free of disease.  In the future I plan to contribute another article to expand with my recommendations for virus control in the vineyard to help growers manage disease.

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.

I am writing again about Grapevine Trunk Diseases (GTD) in the Midwest, following the article with Mike White (ISU extension viticulturist) published in this magazine in September-October 2018. In that article we raised the question as to whether the commonly seen “winter kill” symptoms of dead cordons and spurs, and poor budbreak, may be mis-diagnosed in the region, as they also correspond to common GTD fungi symptoms. I raised this with some “old hands” in the industry, and they laughed at the suggestion. I hope this article might cause them to reconsider (but probably not).

We have two developments to report. Firstly, there has been quite some activity in testing of samples, much of it by Mike. Initially this was by local diagnostic laboratories, but there was concern with apparently inconsistent and negative results which caused us to send samples further afield. We have been concerned about test results for some samples which may lead growers to believe that there is no problem. However, as we have discovered some testing procedures are more reliable than others. This problem is not unique to samples from the Midwest, as Richard has also had problems with some samples from California tested in different laboratories.

GTD Fungi Isolated in Iowa

The following is a list of fungi and one bacterium which have been diagnosed in samples from Iowa, provided by Mike:

1. Botryosphaeria dothidea (“Bot”)
2. Crown Gall (Agrobacterium vitis, a bacterium)
3. Cytospora viticola (associated with trunk disease)
4. Diatrylpella species. (associated with Eutypa, a major trunk disease)
5. Eutypa species including Eutypa lata
6. Phaeoacremonium species. (associated with Young Esca (Petri Disease)

Phaeoacremonium minimum

1. Phomopsis species (associated with foliar, cane, fruit and trunk disease)
2. Seimatosporium species. (associated with Dead Arm Disease)
3. Pestalatiopsis (foliage, fruit and trunk disease)
4. Phaeomoniella species. (associated with Young Esca – Petri Disease)

Phaeomoniella chlamydospora

1. Diaporthe species (Phomopsis)
2. Stereum species (typically saprophytic feeding on dead wood)

In fact, as more samples are properly tested, it is likely there will be found other fungi. It would appear from this limited experience that Polymerase Chain Reaction (PCR) testing as is carried out by some Californian laboratories is the more reliable method. Many samples will have multiple infections.

The attached figures show the vine appearance of three samples analysed in California. Concord samples which showed internal streaking and necrosis (dead tissue), centered on the pith, and necrosis associated with cankers. The sample contained four fungi, Eutypa spp., Phomopsis spp., Phaeoachremonium minimum and Phaeomoniella chlamydospore, see Figure 1.

Figure 1

Similarly Marechal Foch yielded Eutypa spp.,Diatrypella spp. and Phaeomoniella minimum, see Figure 2.

The last sample to be discussed was especially interesting, being Vitis riparia from the wild, harvested at Indianola, Iowa, from a creek bottom. Mike and I on our travels together had found suspicious staining in several wild vines, here was some confirmation. The sample showed necrosis and streaking, and some dark tar-like deposits, and white rot in the center. The diagnosis was for Phaeomoniella minima, Phaeoachremonium chlamydospora and Botryosphaeria dothidea, see Figure 3. There may be some implications for new varieties bred from Riparia parents re GTD susceptibility.

The Riparia was to be the first confirmation of Botryosphaeria in Iowa. In my tour with Mike last summer, I often spoke of “Bot” in a general sense as being the likely cause of some symptoms we saw. I should have been more careful. Botryosphaeria symptoms are like those of other GTD, but in particular those of Phomopsis. This finding in Riparia was interesting from other points of view. Was Botryosphaeria present in wild vines before present grapevine plantings were introduced? Whatever the answer to that question, wild vines may constitute a reservoir of spores for infection of adjacent vineyards. Of course, other native plant species may be infected is as well.

Outstanding Webinar on GTD by World Expert Dr. José Ramón Úrbez Torres of British Columbia 

This webinar was held Tuesday, December 11, and organized by Dr. Tim Martinson of Cornell University. Around 300 persons registered for the event, indicating a heightened awareness and interest, especially in cold winter climate regions. The webinar lasting a little over an hour is now posted on the Northern Grapes Project website for viewing. If you have unexplained dead or unhealthy vines in your vineyard, we suggest that you watch it here: https://northerngrapesproject.org/

The seminar was very comprehensive. It began by describing the many species of fungi now known to be involved in grapevine trunk disease, and described how they are spread, both between and in vineyards. The seminar concluded by presenting a range of methods of protecting vineyards from GTD.

GTDs are caused by a group of fungi of different genera and species, and they often occur as mixed infections. The fungi have in common a typically insidious nature when pathogenic on grapevines. For some diseases, there are no conspicuous foliar symptoms, and the first a grower may know of the problem is spur then cordon then vine death. Unfortunately, by the time the first vine dies, many others can be already infected and they will gradually die unless the problem is treated. But treatment must commence early if the vines are to be saved. So, it is very important to recognise early disease symptoms in just a few vines where they exist.

Grapevine trunk diseases can affect and kill vineyards of many ages. Some deaths may even be recorded in the year of planting, and, typically as the vineyard ages, more and more vines die. For growers concerned with vineyard profitability this is an issue; some vineyards in some parts of the world are being replanted at 20 years of age due to trunk disease. Unfortunately, vines delivered to growers from nurseries may be already infected with grapevine trunk diseases. This is a worldwide problem, and research shows that it can be involved with the bench grafting process, but even own rooted vines may be infected, as can occur in the Midwest.

Vigilant growers should inspect nursery stock for staining within the stem. It is normally particularly evident at the base of the rootstock cutting and in the graft union. The webinar was excellent for showing a full range of symptoms in both young and old vines, including many sections across the trunk. Sometimes fungi will be resident within young vines without causing problems; however, it is known that when the vines experience any stress that these fungi will become pathogenic and will affect the growth of the vine and eventually kill it. Severe winter temperatures are known as an important stress. In fact, as was emphasized in the article referred to above, the common death of cordon and spurs which is typically called “winter injury” may in fact sometimes be due to trunk disease.

There has been much more concern globally about GTD since 2000 even though there are reports that the diseases had been present for a long time, and some of the early research has been forgotten. For example, the roles of Phomopsis in trunk disease was shown by early research at Geneva New York in 1909 and again more recently with Eutypa in several Eastern states from the 1970s onwards. In France it has been declared that “wood diseases are a national crisis responsible for 12% of French vineyards being non-productive”. So, while some might think trunk diseases are new, they are not, but there is clear evidence that they are becoming more of a problem worldwide.

 What to do about trunk disease? They can be controlled using a range of management techniques. In regions of cold winters there is evidence that early pruning may be more effective, whereas the opposite is the case in California for example where late pruning in the dry part of the spring helps to prevent spread.

It is imperative to protect pruning wounds, and fortunately a range of fungicides are available in the USA although not in Canada. There is certainly a need for local research in places with very cold winters as to how these may be applied in freezing temperatures. For larger vineyards in other regions using a modified vineyard sprayer is becoming popular. Protection of pruning and other wounds is the first line of defence against GTD, and likely in the majority of Midwest and Eastern vineyards this is not now practiced, which may change if GTDs are found to be a widespread problem.

The second line of defence against trunk disease is trunk renewal. This is now practiced of course to overcome “winter injury”, and thankfully at the same time can be protective against trunk disease. Provided the trunk is renewed from below the level of staining in the trunk, then the vine may be rejuvenated and is free of disease.

Conclusion

Growers in the Midwest and Eastern states have not been concerned as they might about trunk diseases, probably because some symptoms have been thought due to winter injury. Yet as was declared in the webinar, GTD occur everywhere in the world where grapes are grown! At the earliest signs of disease/poor health we encourage growers to take sections of the trunk and look for staining. If any is found, a lab confirmation should be sought.

I urge all growers, advisers and nurserymen to watch this webinar. It is an hour very well spent and may give you a new perspective on your vineyard and its health and profitability.