Month: August 2023

By: Kirk Williams, Lecturer-Texas Tech University

Drip irrigation systems are a critical part of vineyard infrastructure.  Drip irrigation systems need maintenance to deliver water efficiently and uniformly over a long period of time.   Where drip irrigation systems are used to deliver fertilizers and pesticides distribution uniformity becomes even more critical.  A distribution uniformity target of at least 85% is critical to producing high quality grapes and achieving good water use efficiencies.  Fall and the dormant season is a good time to examine your drip irrigation, measure distribution uniformity and see what maintenance or improvements need to be done. 

  Routine maintenance activities should include flushing drip lines and laterals to clear the system of contaminants.  Flushing of the lateral lines and drip lines is especially critical if you have had to fix large leaks that occur once the water has gone through the filtration system.   Severe leaks need to be fixed immediately but post-harvest time is a great time to fix all of the small leaks that may be occurring in your drip irrigation system. While flushing, pay attention to what kind of debris comes out of the hose ends.  Is it silt, clay, organic or chemical precipitates?    If you are having emitter clogging this debris could be a good tool for understanding what is causing the clogging. 

  Clogged or partially clogged emitters are the most serious problem in drip systems.  Drip emitter output can be measured by placing containers under emitters and measuring the amount of water collected over a known time period.  

  Grape growers spend lots of time calibrating sprayers, fertility sampling, measuring grape ripeness but many spend little time measuring the performance of their drip irrigation system.  One irrigation performance characteristic that can be measured and tracked over the life of an irrigation system is Distribution Uniformity(DU).     Distribution Uniformity is a measure of the uniformity of irrigation water over an area.   Lower Distribution Uniformity in a drip irrigation system can be caused by pressure losses, pressure variations or by partial plugging of emitters by physical, biological or chemical buildup.  Pressure testing of the drip line via a Schrader valve or pitot tube is a good practice to incorporate prior to or during a DU test to understand your irrigation system operating pressures.

  A DU Low Quarter value is calculated by dividing the average output of the lowest one quarter of the emitters sampled by the average output measured of all the emitters sampled.  A DU Low Quarter test can be done by selecting forty drippers across an irrigation block.  Select emitters that best represent an irrigation block and choose emitter locations where you would expect to find high or low pressures.  Collect emitter output for 30 seconds.   While various containers can be used to collect emitter output a 100 ml graduated cylinder will be needed to measure the relatively small amount of output.  63 milliliters per 60 seconds = 1 gallon per hour.  The formula is found below. 

 Convert the value found to a percentage by multiplying by 100. 

  An acceptable DU value is between 85% and 95%.  A DU value between 75% and 85% should be improved and a DU value lower than 75% needs to be improved.   A system with a lower DU value is applying extra water through the emitters that are in the top 75% of output in order to supply the vineyard with water for adequate vine growth for emitters that are in the lowest 25%.   The investment in time of measuring DU over a period of years can alert you to problems of partial clogging of emitters or pressure issues with your irrigation system.  This gives you time to implement management activities before the problem gets worse.  Some management strategies are discussed below. 

  Many areas of the country have issues with poor water quality.  Some ions dissolved in water can lead to chemical clogging of emitters.  Calcium carbonate (Lime or Scale) is one of the most common of these compounds.  Calcium carbonate formation is favored with water pH of greater than 7.5 along with bicarbonate levels of 100 ppm or higher.   Chemical and microbial oxidation or iron and manganese can cause clogging.  Other causes of emitter clogging can be bacterial or algal growth as well as suspended solids.   Testing irrigation water quality every five years is a good practice in understanding what is contained in your irrigation water.

  Acidification may be necessary for irrigation water that tends to form chemical precipitates such as calcium carbonates.  Depending on water quality, acidification can be constant, or it can be done occasionally to prevent chemical clogging of the drip emitters.   Acids that can be used include sulfuric, hydrochloric, phosphoric or urea sulfuric acid.  An alternative to acids are synthetic scale inhibitors which reduce scale formation by preventing precipitation reactions from occurring.  The amount of acid needed to reduce the pH of the water can be calculated by titration using a pH meter.   Analytical labs can also recommend how much acid to use per volume of water.   Target pH levels for different situations are found below. 

Target Irrigation Water pH levels

Continual……………………………………………….5.5-6.5

Moderate Cleaning……………………………………….4.5

Shock Treatments…………………………………………2.5

  If you are doing acid shock treatments check with emitter manufacturers to make sure that emitter parts are able to tolerate these low water pH levels. 

  Always add acid to water; do not add water to acid. Adding water to acid can cause a violent reaction, and may cause the acid to splash on the person pouring the water. Individuals working with acids should wear protective clothing and eyewear. 

  Once the amount of acid needed is determined are determined, you will need to know the volume of water that is being applied per treated irrigation block.  This information can come from a flowmeter or by calculating drip emitters per block.  Actual drip emitter output, which you get when you do a DU test, will be more accurate than what is provided by the drip emitter manufacturer when installed.  

  As a If you are doing infrequent or shock acid applications, inject the amount of acid in a known amount of irrigation water that will fill the drip lines at full operating pressure.  After the acid has been injected and distributed to its furthest point in the irrigation block turn the system off and let the low pH water set for several hours(overnight) to dissolve chemical precipitates.  Turn system back on and flush five to fifteen drip lines at a time. 

  For emitter clogging caused by biological problems such as algae, moss or bacterial slimes chlorination is the preferred treatment.   Depending on how severe the problem is, chlorine can be injected continuously or occasionally. 

  Filter maintenance is critical to prevent physical clogging of drip emitters.  If you do not have automatic back flushing filter systems you will need to monitor for pressure loss across the filter using pressure gauges.  A pressure loss across the filters will alert you to debris clogging the filters. 

  Your irrigation system is a critical piece of vineyard infrastructure that needs to be maintained like all other parts of the vineyard.   Take the time to measure your drip systems performance so it can deliver water efficiently and effectively.  This is especially true if you use your system to deliver fertilizers and pesticides to your vineyard. 

Here are some great videos to assist you:

Acidification to Clean Out a Drip Irrigation System: https://youtu.be/Kty6ykScfwQ

Calculating Acid Amount for Drip Irrigation System: https://youtu.be/eOJCDqC3n0E

Adding Acid to Irrigation System: https://youtu.be/5duPeWDAIns

 Sources

  Schwankl, Larry, Blaine Hanson, and Terry Pritchard.  2008.  Maintaining Microirrigation Systems.  University of California, Agriculture and Natural Resources:  Oakland, California.  Publication 21637.

  Zellman, Paul.  2016.  Drip Irrigation System Evaluations: How to Measure & Use Distribution Uniformity Tests.  California Sustainable Winegrowing Alliance. https://www.sustainablewinegrowing.org/docs/DUArticle.pdf

  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

As the fall season approaches, symptoms of virus infection become more pronounced in the vineyards.  Leafroll and red blotch are the most important viral diseases that manifest in late summer and the fall season.  Often, it is difficult to distinguish leafroll from red blotch disease symptoms in the vineyard.  This is especially true on red-fruited grapevine varieties.  In this article I will summarize and update information on the biology, symptoms, transmission, and management of the viruses responsible for these important diseases.  

The Viruses responsible for Leafroll and Red blotch Diseases

  There are four different viral species associated with grapevine leafroll disease.   The viruses belong to the Closteroviridae family and are named Grapevine leafroll associated virus followed by a number (GLRaV-1 to -4).  Except for Grapevine fanleaf and red blotch, Koch’s postulates have not been completed with most of the disease-causing grapevine viruses.   The postulates state that a pathogen must be isolated in pure form from a diseased plant, later the pathogen (virus in this case) is introduced to a healthy plant, and the newly infected plant must show the same symptoms as the original infected one.  Clearly Koch’s postulates are important because they prove the cause and effect of a pathogen causing disease.  Because it has not been possible to complete Koch’s postulates with GLRaVs, the word “associated” is added to the virus name.  As I will describe below, researchers can tweak the definition of Koch’s postulates to prove that a virus causes a specific disease and drop the word “associated” from a particular virus name.   Within the Closteroviridae family, species of GLRaV are classified in three genera, Ampelovirus, Closterovirus, and Velarivirus. Grapevine leafroll associated virus -1, GLRaV-3, and GLRaV-4 belong to the Ampelovirus genus.  Grapevine leafroll associated virus -2 is a Closterovirus and GLRaV-7 is a member of the Velarivirus genus.  Some researchers claim that GLRaV-7 should not be considered a leafroll virus.   Recent research has shown that GLRaV-7 was isolated from a mixed leafroll infected vine and symptoms may have been due to the other leafroll virus present in the vine.  When found in single infections, GLRaV-7 does not appear to show typical leafroll symptoms.

  Grapevine red blotch virus (GRBV) is the second DNA virus species discovered in grapevines (its genetic material is DNA rather than RNA).  Both its molecular and structural characterization has placed GRBV in a new genus (Grablovirus) within the Geminiviridae family.   As stated above, it has been difficult to demonstrate Koch’s postulates, with grapevine-infecting viruses. There are many reasons for this.  Mainly, there are not many alternative hosts that are susceptible to most grapevine infecting viruses.  But most importantly, grapevine viruses cannot be mechanically transmitted onto grapevines.  These viruses need to be introduced to a vine by an insect vector or via grafting (graft-transmission).   Dr. Marc Fuchs team at Cornell University was able to demonstrate that GRBV genetic material is responsible for red blotch foliar symptoms in red fruited grapevine varieties.  The work was done using sophisticated recombinant DNA technology to introduce the virus genetic material into tissue cultured grapevine plants.   Time will tell, after the plants grow, if the infected vines also display the detrimental effect of the virus in organoleptic qualities of the fruit (i.e., reduction of sugar).

  Leafroll and Red Blotch Symptoms are Similar

  Vines infected with leafroll viruses produce smaller grape clusters that ripen unevenly with lower sugar content. Foliar symptoms include downward rolling, reddening, or yellowing of leaves depending on the grapevine variety. Other foliar colors associated with leafroll virus infection include pink, purple, and orange speckles. The leaf veins may remain green or take many other colors (yellow, purple, or red).  

  Grapevine red blotch virus infection displays different leaf discoloration which usually appear spotty or blotchy.  However, these symptoms are indistinguishable from leafroll, especially when rolling of leaves are absent in GLRaV- infected vines.  In red fruited varieties, GRBV infected vines can display red veins, but red veins have also been observed in non-infected vines, and many red-blotch infected vines do not display red veins.   In my opinion, red vein symptoms cannot be used as a diagnostic tool.   In white-fruited varieties red blotch disease displays yellow blotchy discoloration in leaves. While the symptoms of leafroll and red blotch can be confused, these diseases are caused by different viruses. As described above.  Further, visual diagnostics is complicated by the fact that grapevines often carry mixed infections of viruses and other pathogens.  Although, the change in colors of the leaves in the fall is a tale-tell of virus infection, the most important negative effect of both GLRaV and GRBV infection is the reduction of sugar in fruit resulting in lower Brix values and delayed fruit maturity.

  Some GLRaVs and their strains are more aggressive than others.  Researchers have described the Alfie (Australia and New Zealand), BD (Italy), and Red Globe (U.S.A) strains of GLRaV-2. These strains are molecularly similar and have been associated with graft incompatibility, vine decline and death.  Some researchers report that GLRaV-1 and -3 induce more severe symptoms than GLRaV-4.  However, symptoms vary depending on the grape variety, rootstock, and climatic conditions.  Now, two different genetic groups (clades) of GRBV have been reported but no differences in their biology or effect on symptoms in the vineyards have been described.  Just as seen with leafroll, the symptom expression of GRBV infected vines is affected by climatic conditions and the author has noted differences in the effect on sugar reduction in sunnier and warmer areas (i.e., California coastal areas with more fog and lower sunshine yield fruit with lower sugar concentration than the same grape clones grown inland with more sun/heat exposure).

Transmission and Spread of the Viruses

  Ampeloviruses (GLRaV-1, -3 and -4) are transmitted by mealybugs and soft scale insects in a non-specific manner.  This means, different mealybug and soft scale insect species can transmit any leafroll virus in the Ampelovirus genus.  Research has shown that the citrus (Planococcus citri), grape (Pseudococcus maritimus), long-tailed (Pseudococcus longispinus), obscure (Pseudococcus viburni) and vine (Planococcus ficus) mealybugs as well as the soft scale insects Pulvinaria vitis and Ceroplastes rusci are able to transmit GLRaVs. Mealybugs and soft scale insects feed on the vine’s sap by inserting their sucking mouthparts into the plant’s vascular system (phloem). The honeydew excreted during the feeding process attracts ants that nurse and aid mealybugs to be transported to different positions of the vine or a different vine in the row.  Mealybugs may be difficult to observe as they may hide beneath the bark.  However, the presence of sooty mold (a fungus) and ant activity can be a good indication that mealybug are present in the vineyard.  No insects able to transmit GLRaV-2 or GLRaV -7 have been reported to date and the propagation of these viruses is performed by humans who produce, graft, and distribute cuttings from infected vines.  

  Work by researchers at Cornell University and the University of California reported that the three-cornered alfalfa hopper (Spissistilus festinus) can transmit the GRBV in greenhouse and laboratory conditions.  Although, the three-cornered alfalfa hopper has been found in vineyard blocks where red blotch disease has spread, transmission experiments in the field have not been completed to date.   It is interesting that grapevine is not the preferred host for Spissistilus festinus that prefers to feed on legumes, grasses, and shrubs.  Furthermore, the insect is not able to complete its reproductive cycle in grapevines.  While research continues to determine if other vectors are capable of transmitting GRBV it is clear that the rapid expansion of this virus in vineyards was due to propagation and grafting of cuttings from infected vines.  This also explains the arrival of GRBV to many countries in Asia, Europe, and South America where GRBV had not been previously reported.   In summary, both, GLRaVs and GRBV are graft transmissible and predominantly propagated by producing cuttings of infected rootstock and scion material. 

Diagnosis and Disease Management

  The distribution and concentration (titer) of leafroll and red blotch viruses is different in infected plant material.  While leafroll detection appears to be seasonal (best detected late in the growing season), detection of red blotch virus can be performed any time of the year.   Further, work performed in my lab showed that red blotch virus can be detected in high titers in any part of the vine.  The work showed that red blotch virus can be detected in any tissue tested, new or mature leaves, petioles, green or lignified canes, as well as cordons and trunks.  In contrast, leafroll viruses are generally found in low concentrations and are best detected in mature leaves, canes, cordon, and trunk.  If a vine has been infected through cuttings, the older the plant material is, the easier it is to detect GLRaVs. 

  Keeping both leafroll and red blotch viruses out of the productive vineyards relies on clean planting stock programs.  Because both viruses are graft transmitted (and some also have biological vectors) it is important to implement a monitoring and sampling program at the nursery and production vineyards.  Vines that are symptomatic or that test positive must be removed from the vineyard to avoid spread (especially if one of the Ampiloviruses or GRBV are detected and the vector is present in the vineyard.  Depending on the disease incidence (I have developed a statistical sampling formula to calculate and help make decisions), the removal of a few vines or the whole vineyard is recommended. Different chemical and biological control strategies are available for the control of mealybugs that transmit leafroll viruses.  The use of chemical control, although might be used to control GRBV vector is not presently recommended.

Conclusions

  This author has been involved in applied research with the goal to determine the ideal process to protect clean planting grapevine stock and newly planted vineyards from infection of viruses and fungal pathogens.  Presently, information on what is the distance needed at the foundation and nursery blocks to avoid infection from diseased blocks is lacking. The results of the research will develop the best strategy to isolate and monitor clean planting stock.  Until we have this information my recommendation is that nurseries and growers determine the health status of grapevine stock prior to planting to avoid the propagation and/or introduction diseased vines to the vineyard.  Yet, it is imperative to isolate and monitor newly planted vineyards to avoid the introduction of disease via insect vectors.  It is important to remember that lack of symptoms does not always correlate with a healthy diagnostic result (rootstock varieties as well as non-grafted vines are usually asymptomatic), so it is best to test a statistical sample of the nursery propagated material to be sure of its health status.

  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.

By: Becky Garrison

The Southern Oregon AVA, established in 2005, consists of five distinct regions: Rogue Valley AVA, Applegate Valley AVA, Umpqua Valley AVA, Red Hill Douglas County AVA and Elkton Oregon AVA. Multiple rivers – Umpqua, Applegate, Illinois and Rogue – traverse throughout this region, thus creating a number of small valleys and hillsides and a range of mesoclimates. This region’s latitude, climate and rich terroir with elevations from 350 to 2,000 feet, average precipitation of 19 inches annually and approximately 175 frost-free days afford winemakers with a European-like growing season.

  Even though Hillcrest Vineyard in the Umpqua Valley was the first vineyard to plant pinot noir grapes in Oregon in 1961 commercially, Willamette Valley’s pinot noirs tend to dominate the Oregon wine scene, thus overlooking the 70 different wine varietals produced in Southern Oregon. This includes grapes unique to the Pacific Northwest.

  For example, in 1997, Earl and Hilda Jones of Abacela Winery in Roseburg were the first in the Northwest to grow and vinify the tempranillo grapes commercially. This was followed by Stephen and Gloria Reustle of Reustle Prayer Rock Vineyard in the Umpqua Valley, who planted the first grüner veltliner wine made in North America in 2003 to 2005. Also in the Umpqua Valley, Girardet Vineyards & Winery in Roseburg was the first to plant baco noir grapes in Oregon and produce a baco noir wine in 1971. Other varieties grown in Southern Oregon that are not widely grown elsewhere in the Northwest include albariño, dolcetto, grenache, malbec, and petit verdot.

  According to Nichole Schulte, head winemaker and an owner of Barrel 42, a full-service custom crush winery in Jacksonville, very favorable Oregon laws allow for winemakers to be creative and have a little bit more control over the grapes that come into the winery. These laws allow for more flexibility in blending non-pinot noir wines such as the GSM (grenache syrah mouvedre) blends that originated in the Rhone region of France, as well as other blends that are not as well known.

  “These wines require a bit more storytelling behind them,” Schulte said. “This is where our friendly tasting rooms and winemakers come in because they can explain what they’re doing and the intention behind that particular wine.”

  While most wine regions focus on either warm or cool climate grapes, Southern Oregon can grow both warm (tempranillo, cabernet sauvignon, malbec, syrah) and cool (pinot noir, pinot gris, riesling) climate grape varieties grow very well due to the many and diverse microclimates, vineyard elevations and terroir differences across the region.

  According to Rob Folin of Ryan Rose Wines in Medford, “These cooler nights and hotter days are awesome for the grapes, allowing the grapes to ripen over a longer growing season with greater concentration and balanced acid levels.” He added that they “seldom get spring frosts and only the occasional fall frost.” 

  A key difference between the two regions is that the Umpqua Valley relies on the ocean for its diurnal swings (warm days and cool evenings to help preserve acidity in the grapes), whereas the Rogue Valley relies on elevation for its diurnal swings. Ross Allen, president of the Rogue Valley Vintners and owner and vineyard manager at Padigan Wine in Medford, points to a few examples of how the climate and climate suitability in the Rogue Valley makes them unique as a key factor to the quality of fruit they produce.

  “The Rogue Valley’s precipitation is less than the Willamette Valley and more similar to Napa, making for lower disease pressure and cleaner fruit,” Allen said. “In addition, the Rogue Valley’s growing season temperatures and heat accumulation clearly distinguish us from the Willamette and California. Also, the Rogue Valley has one of the widest diurnal temperature swings of any wine region worldwide, enabling greater potential flavor and aroma development.”

  Family-owned, multigenerational vineyards dominate the landscape, with the winemakers often pouring the wine in their tasting rooms while sharing their vast knowledge of viticulture with visitors. Eric Weisinger, owner and winemaker at Weisinger Family Winery in Ashland, points to the camaraderie within fellow Southern Oregon winemakers that creates a healthy culture.

  “People want each other to succeed,” Weisinger said. “Our region may not be that old but we’ve done a lot in a short period of time.”

  The towns that dot Southern Oregon, such as Ashland, Grants Pass, Jacksonville, Medford and Roseburg, have emerged in recent years as wine destinations with food, art, music and a wide range of lodging options from budget motels to B&Bs nestled within a vineyard estate. Unlike more populated Western wine regions such as the Willamette Valley or Napa Valley, Southern Oregon is far away from major population centers, so one can avoid the touristy crowds that tend to congregate, especially during the weekends and holidays. While this intimacy creates a unique wine experience for the consumer, Ted Gerber of Foris Vineyards in Cave Junction notes how this region’s distance from major populations can make direct-to-consumer (DTC) sales difficult. However, some wineries, like the Weisinger Family Winery, sell almost all of their wine in the tasting room or online.

Rogue Valley AVA

  This AVA is dominated by the Rogue River that flows south into the AVA at the town of Shady Cove, turns west outside of Eagle Point and flows through Gold Hill and out of the AVA northeast of Grants Pass. This region is home to Oregon’s first official winery, founded by Peter Britt in 1873. Currently, the Rogue Valley’s approximately 180 vineyards run along three valleys of this river’s tributaries: the Illinois, Applegate and Bear Creek. While this valley’s heat results in prime growing territory that naturally benefits big Bordeaux and Rhône varieties, winemakers like Jean-Michel Jussiaume of Maison Jussiaume Wines find this climate well-suited for producing sparkling wine. He moved to the United States from France in 2005 with the intent of producing handcrafted sparkling wines. In his estimation, the growing conditions of the Rogue Valley are less challenging than the region of Muscadet, where he grew up.

  The Illinois Valley, the southernmost part of this AVA, receives some marine influence due to its proximity to the coast, thus resulting in a cooler, wetter climate than much of the rest of the appellation. This climate attracts vintners like Ted Gerber, who established the family-owned Foris Vineyards in 1974 with his late wife, Meri. He chose Cave Junction as the location for his winery, as it lies halfway between the pinot noir growing areas of Sonoma and the Willamette Valley. Also, this region has a very large diurnal swing with plenty of ripening for alsatian varieties. In 1977, he had the distinction of being one of six growers to receive a few dozen clones of pinot gris, pinot blanc and gewürztraminer that Oregon State University imported from France, and Floris continues to produce these varieties.

  Like many other winegrowers in the Rogue Valley, Chad Day, owner and manager of RoxyAnn Winery in Medford, came from an agricultural tradition where he describes his winemaking process as farm-to-fork. Currently, Day oversees farming the vineyard and managing the winery while a cousin manages the orchards and field crops, all farmed on the same 250 acres their extended family has owned since the 1890s. While they grow 17 different varietals, their focus is on the Bordeaux and Rhône varieties that grow well in this warm region with their craft claret blend consisting of cabernet sauvignon, cabernet franc merlot, malbec and petit verdot. At this juncture, climate change has proven beneficial for them as the green cabernet that came from the Rogue Valley 10 to 20 years ago is now more full-bodied.

Applegate Valley Sub-AVA

  Ensconced inside the Rogue Valley AVA is the Applegate Valley Sub-AVA, an area consisting of 19 wineries and a total acreage of 278,190. This valley was formed by the flow of the Little Applegate and Applegate Rivers that wind between the peaks of the Siskiyou Mountains, with Jacksonville in the southeast and Grants Pass in the Northwest. As this region receives rainfall from the surrounding Siskiyou Mountains and cooling marine temperatures from the west, this AVA receives more moderate heat than Illinois Valley, with granitic alluvial gravels as the predominant soil type.

  Despite its overall warmth, this AVA poses a challenge to winemakers, as it has the shortest frost-free period in southern Oregon: 137 days compared to 150 to 165 days in other parts of the Rogue Valley. This is attributed to the higher vineyard elevations and the surrounding mountains that restrict sunlight late in the day. Also, water availability can be challenging due to little rain and moderately high heat. But according to Schulte, they are well-positioned to deal with the ongoing climate challenges.

  “We have a lot of people who are creatively thinking ahead,” Schulte said. “Also we have so many microclimates here that we’re able to grow many different varietals well, so we’re not pigeonholed into any specific sort of style or varietals.”

In response to increasingly warm summers, they are among those wineries replating some of their vineyards with varieties more amenable to hotter and drier climates. As reported in the July/August 2023 issue of The Grapevine Magazine, Schulte is one of the leading experts in researching collaborative approaches to handling smoke in the vineyard and winery.

Umpqua Valley AVA

  The topography of the Umpqua Valley is over 75 percent hills and mountains, which creates an extremely diverse climate and terroir. This area is known as “the land of a hundred valleys,” with three mountain ranges: Klamath, Coast and Cascades converging in the Umpqua Valley. This resulted in numerous ancient faults, folds and outcroppings, as well as 140 soil types, including silt, clay, sediments and alluvial dirt. This makes the valley one of the most diverse growing regions in the world, according to Terry Brandonborg of Brandborg Vineyard and Winery in Elkton.

  Overall, the Umpqua Valley tends to be wetter than the rest of Southern Oregon, with the northern part of the appellation typically receiving the most rain. Within this AVA, one finds the Red Hill Douglas County AVA and Elkton Oregon AVA, both of which are further north with a cooler climate. The Elkton Oregon AVA lies within the northwest corner of the Umpqua Valley and is closer to the ocean. At the same time, the Red Hill Douglas County AVA is comprised of a single vineyard consisting of rich volcanic soil from the ancient, uplifted seafloor that produces pinot noir and pinot gris wines.

  The overall climate is such that they can ripen bigger reds in the warmer areas of the Umpqua Valley, like Bordeaux and Rhône varieties, but still dry farm. Per Scott Kelley from Paul O’Brien Winery, who used to be the director of winemaking for Mondavi in California, “There is not another region in the U.S. that can lay claim to that.”

   Also, a growing number of Umpqua Valley wineries are exploring the sparkling side of wine, including Pet-nats, such as Brandborg Vineyard and Winery in Elkton, which produces alsace-inspired white wines along with pinot noir. After getting his garage bonded as a home occupation in 1986, Brandbog moved to a rented warehouse space in Richmond, California in 1990. After he connected with wine pioneers like Scott Henry of Henry Estate Winery, he and his wife, Sue, began looking for a cooler coastal climate in 2000. After moving here, Brandborg joined the board of the Oregon Winegrowers Association, which later became the Oregon Wine Board, and then served as president of the Umpqua Valley Winegrowers Association.

Marketing Southern Oregon Wines

  In Gerber’s estimation, the cooperation within the Oregon wine industry was extremely helpful to their historically small appellation. He found the marketing door opened for them with an “Oregon” appellation when they began selling in Canada, Japan and over 40 states. Along those lines, Wine Enthusiast named the Rogue Valley as one of five regions selected internationally as the wine region of the year in 2022. In recent years, the Rogue Valley Vintners and the Umpqua Valley Winegrowers Association have served as marketing organizations to bring awareness to the wines produced in Southern Oregon.

By: Alyssa L. Ochs

Various weather hazards put delicate wine grapes at risk, including hail, high winds, wildfires and droughts. Frost is another major issue in vineyards across the country, especially spring frosts that attack emerging shoots and buds when they are just beginning to form. The riskiest time, which requires strategic planning and advance preparation, is when bud break has occurred, but the frost risk has not yet passed.

  To address these cold-weather concerns and help vineyards protect their grapes from frost damage, industry experts weigh in to share their knowledge and provide guidance for a successful yield.

Types of Frost and the Risks

  Different kinds of frost can harm delicate grapevines depending on where a vineyard is located. Advection frosts occur when temperatures are below 32 degrees Fahrenheit, and the wind is greater than 10 miles per hour. This type of frost happens with a weather front moves into an area, and cold, dry air replaces warmer air. Radiation frosts are associated with temperatures above 32 degrees Fahrenheit and calm winds. These frosts occur during clear skies and due to lost heat as radiant energy.

  Both weather patterns are problematic for vineyard operators and influence whether active frost protection methods are effective. Frost is a significant issue for vineyards because of the dangers of uneven ripening, decreased fruit quality and damage to an entire vintage in severe cases. Frosts can happen unexpectedly during the growing season and when grapes are dormant. Meanwhile, some types of grapes are more susceptible to frost damage than others.

Overview of Frost Protection Methods

  Frost protection methods are typically divided into two categories: active and passive. Active methods involve intentionally modifying the energy and climate of grapevines through wind machines, heaters, sprinklers and other measures. Overhead impact sprinklers, water micro-sprayers and cold air drains are other active methods to prevent frost damage.

  In contrast, passive frost protection methods do not require energy input or adjust the climate, instead focusing on strategies like cultivar and site selection, which must be considered before establishing a vineyard. Other passive approaches include looking at soil water content, cover crops and barrier management. A combined strategy with active and passive measures is often most effective in the vineyard, especially alongside good vineyard design, vineyard floor management, sprayable products and late pruning if necessary.

Professional Help with Frost Protection

  Fortunately, equipment manufacturers and specialty companies are available to help vineyards address their frost protection concerns. Since 1967, Orchard-Rite, a family-owned business, has engineered and built wind machines with precision technology. With its headquarters surrounded by vineyards, orchards and farms in Yakima, Washington, Orchard-Rite operates one main manufacturing and assembly plant and has supplied an estimated majority of wind machines and frost fans in operation worldwide.

  Shawn Miller, who leads sales and dealer support for Orchard-Rite, told The Grapevine how wind machines are an effective tool for protecting various crops from the damaging effects of frost and critical temperatures worldwide.

  “During radiation cooling nights, wind machines pull down warmer air and ventilate the growing area to prevent the pooling of cold air,” Miller said. “Most importantly, they provide air movement across the plant surfaces, which prevents them from supercooling. Even with a weak inversion layer or on clear, cold nights, Orchard-Rite machines substantially reduce the chance of supercooling.”

  Orchard-Rite serves customers with wind machines that protect against frost throughout North America, South America, Africa, Europe, Australia and New Zealand. Miller said these regions have special seasons that benefit from Orchard-Rite’s wind machines. For example, these machines help protect blooms from critical temperatures and frost in the spring, and they aid in drying the clusters and canopy of excess moisture in the summer. He said they also protect critical autumn temperatures when more time is needed before harvesting and during winter months when temperatures have fallen to the point of damaging or killing the vine.     

  “What makes us unique, is that we manufacture many of our wind machine parts, verses buying off-the-shelf-parts,” Miller said. “This gives growers the confidence in the quality of our equipment. As for the market share, warranty, product support, research and development and dealer support, we are by far the leader in the world market. With over 39,000 Orchard-Rite wind machines sold throughout the world, we have the longest proven track record, providing the best value, highest performing, quality wind machines with a worldwide dealer network to support parts, service and sales.” 

In addition to the products that Orchard-Rite provides, Miller told The Grapevine that other sources for frost protection can be used for supplementary heat, such as irrigation micro-sprinklers and fuel-burning devices.

  “Additionally, when supplementary heating is used with the wind machines, this can improve results of your protection,” he said.

  Another company that helps vineyards get a handle on their frost prevention tactics is Vigneron Toy Store, a Sutherland, Virginia-based business with products and services to assist vineyards with harvesting, spraying, canopy management, floor management, pre-pruning, leaf removal and frost mitigation. Kirk Thibault from Vigneron Toy Store told The Grapevine Magazine about how his company’s AgroFrost frost protection equipment is based on sublimation. He explained that this phase change of the water vapor releases energy into the bud and protects the crop from frost damage. He said these machines could protect with or without a thermal inversion down to 23 degrees Fahrenheit. 

  “AgroFrost machines are now in use throughout the world,” said Thibault. “They started in European orchards and have been protecting grapes, blueberries, apples and pears for many years. The tow-behind Frostbusters and stationary Frostguards are mobile and can adjust to changing conditions or changes to the vineyard. We have several differently sized units that can concentrate on individual blocks or entire fields depending on a growers needs.”

  Thibault told The Grapevine Magazine that something that makes this frost prevention solution unique is the fact that AgroFrost machines will recover your cost in one year’s potential fruit loss. 

  “No matter the weather conditions, our system works,” Thibault said. “Labor and start-up costs are far less than other systems, as one machine and operator can cover 15 to 20 acres and no further infrastructure is needed to operate the machine. At Vigneron Toy Store, we train you on every aspect of the machine and all operating procedures.”

Beyond the offerings at Vigneron Toy Store, Thibault said that promoting the vineyards’ natural environment to prevent frost is a helpful start.

  “Keeping grass short with bare ground under the vines helps return more ground heat to the vines,” he said. “It also allows better flow of warmer air across the vineyard. Wind machines and sprinkler systems also provide frost protection but require much higher infrastructure costs and can damage crops as well.”

  H.F. Hauff Company, Inc., based in Yakima, Washington manufactures the Chinook wind machine, which is popular among vineyards because one machine will cover up to 18 acres in a vineyard – 150 feet more than other competitive units. Dean Hauff from H.F. Hauff Company told The Grapevine Magazine that this product’s exclusive trailing edge wedge increases sector angle coverage to 80 degrees – a full 60 seconds of direction protection in the horizontal plane. He said warmer temperatures pull from higher up in the atmosphere in the vertical plane, raising temperatures more quickly on the vineyard floor. Another benefit he shared about the Chinook wind machine is its one-piece fan blade design, as air movement from the air foil starts 14 inches from the fan hub center with increased air movement directly under the fan. It’s also easy on fuel consumption (13.5 gallons of propane per hour or six gallons of diesel per hour), is competitively priced and comes standard with auto-start capabilities and a stainless-steel engine hood.

  “We are a conservative, family-owned business and have been in the agricultural manufacturing business for 58 years – 54 years directly involved in wind machines for frost protection,” Hauff said. “We were trained by the originators of the first wind machines and have grown up with the evolution of the wind machine from the ground up. Our quality manufacturing process is based on sound engineering principles and aerodynamics dedicated to our customer needs.”

  In addition to the Chinook wind machine, Hauff said that horticultural practices are an important tool in any overall frost protection strategy.

  “Besides wind machines, low emitter sprinklers work well,” Hauff said. “From grass to dry dirt, you can pick up one to two degrees, from dry dirt to wet dirt another one to two degrees. If possible, planting your vineyard rows with the natural drift will help by giving extended time before the cold air drain begins to back up. Also, planting on the higher ground will aid in delaying the frost. Frost is a lot like water because it flows to the low ground first and then begins to back up to the higher ground, freezing out the crop as it goes.”

Frost Strategy Management and Tips

  Many vineyard owners and managers are turning to high-tech solutions like weather stations, data monitoring and flow meters to manage frost protection in the vineyard. Yet some instances of frost damage are inevitable despite all the latest innovations. Therefore, it is vital to know the steps to manage the damage, including assessing injury to grapes after a frost and deciding whether to remove damaged parts of the plants or allow them to remain intact.

  Miller from Orchard-Rite offered some advice for vineyards looking to improve their frost prevention strategies this year.

  “It is very important not to wait until you are at a critical temperature to start your wind machine,” Miller said. “We recommend that if the forecast conditions are going to reach critical temperatures, farmers should start their wind machines three to four degrees Fahrenheit above the critical temperature for the crop being protected. Additionally, make sure that you have opened areas up that can trap or dam the cold air, such as fence lines full of debris.”

  Thibault from Vigneron Toy Store recommends determining the vineyard’s coldest area or most frost-sensitive variety and placing a Frost Alarm at the fruit level.

  “Our Frost Alarms provide cell phone warnings based on wet temperatures for the temperature you set,” Thibault said. “Frost doesn’t always happen at 32 degrees but can occur at 34 or 35 degrees sometimes. You should start to protect your vineyard slightly before the damage temperature. The most common mistake we see people make with any frost protection system is starting after damage has already happened.”

  Finally, Hauff from H.F. Hauff Company advised that those with no frost protection in place should seriously consider putting in a wind machine.

  “It is less labor-intensive than other options, operating costs are low and unit coverage can be great,” Hauff said. “In addition, a wind machine will keep on protecting your crop year after year.”

  For those with wind machines in place already, he said they should look at improving the efficiency of the systems currently in place. 

  “Upgrading your current wind machine is not out of the ordinary,” Hauff said. “Not all fan props are created equal. Many improvements have been made with regard to technological breakthroughs, aerodynamics, increased horsepower and increased performance. In the 1940’s, six to eight acres was the standard fan coverage. Today, the advanced aerodynamic features of the Chinook fan prop protect a full 15 to 18 acres. Matching your current fan and engine horsepower and replacing it with a properly sized Chinook fan will improve your fan coverage by roughly more two acres.”