Last week Denise wrote a blog post about her time at Penn State as our state’s extension enologist. This week, a few of us who worked closely with Denise wanted to share our thoughts and wish her well in her new endeavor.
Denise established this blog and she has worked incredibly hard to provide the industry with information that was both timely and critical to the success of any winery. Denise was an excellent team player and she understood that the industry would also benefit from posts that also focused on viticulture, entomology, marketing, and business management issues. Hense, several of us have contributed to the blog by writing posts, and we will continue to do so to maintain our an online presence. We will post at least once a month (on the last Friday of each month) and we hope to return to a weekly posting schedule at some point.
Until then, we hope that you will join us in wishing Denise, “Good luck and best wishes!”
From Bryan Hed, Jody Timer, and Any Muza
On behalf of the folks at the Lake Erie Regional Grape Research and Extension Center, we wish Denise success in her future venture ‘Denise Gardner Winemaking’. Her passion for improving the wine grape industry in Pennsylvania has made her an essential part of our grape team for 6 years and she will be sorely missed. However, we’re glad she’ll still be around actively working with Pennsylvania winemakers and we hope to be able to continue to interact with her in some capacity during the years to come. She has been, and will always be, an excellent source of knowledge, professionalism, enthusiasm, team work…and good humor. Cheers, Denise!
From Michela Centinari
Since I started my tenure at Penn State, about three and a half years ago, Denise has always been there to help, no matter how numerous and annoying were my questions and requests. I learned a lot from her, not only about the Pennsylvania wine industry but also how to navigate what was for me a completely new world – “Extension.” I have fun memories of every extension visit/trip we had together over the last three years and she will always be, in my opinion, the best-dressed person doing vineyard visits (a joke between viticulture and enology people).
Denise has been the pillar of our extension grape team, always keeping us organized and on track to meet our blog post deadlines, and that was not an easy job!
Likely, many of you know Denise for her extension activities and efforts, but you may not know that throughout her tenure at Penn State she dedicated a lot of her time teaching winemaking to graduate and undergraduate students, spending long days in the ‘cellar’ with them. Because of her dedication, several Penn State undergraduate students were able to find jobs in the Pennsylvania wine industry as well as in other states. Without her hard work and assistance, we would not have been able to include winemaking in several of our viticulture-based research studies.
She has been a great colleague but most important she is a great friend. I will tell her the rest in person while drinking a glass of wine together.
Cheers Denise to your new endeavor!
From Jen Zelinskie
Best of luck to you, Denise! As a young student, you inspired me to explore the wine industry through our time working on the winemaking projects in the Food Science lab way back during my freshman and sophomore year. As I continued to grow in my education, you impacted me on my decision to further my studies in pursuing a Master’s degree with a focus on wine marketing. Thank you for being an encouragement and inspiration throughout my undergraduate and graduate career. I am beyond excited for your next step in starting your own consulting business and wish you the best of luck! I believe you will achieve great things and make many more differences in the wine industry in the future!
From Laura Homich
I can say with certainty that I would not be where I am today if I had not met you. There are not enough words or thank yous to express my gratitude for all that you have done for me.
When I stopped by your office junior year eager to begin enology research, I could not have dreamed of the number of opportunities and rich experiences that were in store. You spent countless hours teaching me the ins and outs of winemaking and analysis, working alongside me through many long days of grape processing and fermentation and explaining the methodology of each laboratory test and its importance to the winemaking process. You also coached me through the processes of conducting scientific research, showing me how to plan and perform a research study, interpret and represent the data, and construct and present a scientific paper. These experiences not only equipped me with the knowledge, skills, and confidence to take ownership of my graduate work, but they are also proving to be invaluable as I continue my career in the wine industry. For that – I am forever grateful.
You are surely someone whom I admire – ambitious, innovative, and bold! You have been an amazing mentor to me both professionally and personally, and your passion for enology and viticulture is undeniable. I always enjoyed observing you in your element, sharing your immense knowledge and experience with industry members and students whether through workshops, seminars, conferences, or social media posts. It is exciting to see you continuing to grow in your career, and I cannot wait to see all that you accomplish in the years to come.
Penn State Extension and the PA wine industry have been so lucky to have you serving in the role of Enologist for the past six and a half years. I am incredibly excited for you as you launch your new consulting business and wish you all the best as you begin this next chapter in your career.
From Abby Miller
I remember meeting Denise for the first time; I was a Sophomore working with a Dr. Alter in the College of Ag & the generously set up a meeting because I had expressed interest in the wine industry. She was extremely knowledgeable, energetic & allowed me to pick her brain on all things wine. At first, I recall I was intimidated by her accomplishments & thought I was out of my league, but Denise always opened her door to any & all questions I had with welcoming arms.
Fast forward two years to when I began Graduate School; she, fortunately, agreed to be on my graduate committee. Throughout my two years in Grad School, Denise was not only a tremendous teacher & mentor but also a great friend & confidant. She was a brilliant instructor of all things relating to wine, of course, but was also there for any other setback I came across, including the traumatizing public speaking engagements I had to endure. I was always inspired by her poise, expansive knowledge & humor and am thankful to have had her as a part of my time at Penn State & beyond.
I wish you all the best, Denise, as you embark on your next adventure with Denise Gardner Winemaking & cannot wait to watch you flourish in your next endeavor. Saluté!
From Mark Chien
Gosh, I hardly know where to begin with Denise, we have a long and fun history together, but here goes…
We first met when she was a sophomore at Conrad Weiser HS in Berks County. I’m not sure who introduced us, but there was this really bright and nerdy (in the best way) kid who had an unusual interest in grapevines and wines. She told me that she was visiting Adams County Winery with her parents and looked at a book about wine and she was hooked. The next thing I know, we are stomping Chambourcin grapes together with her classmates in the science lab and making wine (much to the chagrin of school administrators). We planted a small teaching vineyard at the school and then she started to use tissue culture to propagate grapevines and consulting with university professors, which is very advanced for a high school student. She not only took the initiative and educated herself, but she got other students interested in grapes and wine as well. She came to Penn State extension meetings and worked with Joanne Levengood at Manatawny Creek Vineyards. That is how the Denise and her wine story got started.
What followed was pretty typical for a college student, but atypical for a student in the east, the pursuit of enology as a discipline and career. It’s hard to know exactly what to think about a young person who follows her dream and instincts into such a rare career. Agriculture was strange enough, but wine and enology were truly off the beaten path. Fortunately, she had a very supportive family and some great mentors along the way.
She began with food science at Penn State and then enology at Virginia Tech. She nailed both and then moved to Napa Valley to work with Vinquiry, but the move itself was a challenge and maybe living in Napa was not the best place for someone from Berks County, so when Stephen Menke left for Colorado and the enology extension position opened up, she was the obvious and perfect choice!
It was a bit of an odd and delightful coincidence that Denise ended up at Penn State so we could work together for a few years before I departed for Oregon. Our relationship kind of went in a full circle. It was neat to see her grow into extension, especially her devotion to students and helping to prepare them for a career in wine, not something your average FST undergrad does at Penn State. Her interest in enology pegged her as a bit of an outlaw, and she always has had a feisty and independent attitude, going her own way and reaching her goals through sheer determination and preparation. She undertook the rigorous WSET course because she wanted to understand the people on the other side of the wine fence in the retail world.
Now she is off on yet another adventure, starting her own consulting business. I am certain that she will be very successful and hopefully happy working on her own and using her knowledge and skills to assist wine makers across the region. She’s lucky to have Josh as her partner and booster, to help bump up her confidence and nudge her forward. This is a great partnership that should flourish as they build their lives together.
I learned a lot from Denise over the years. Mainly that you can be very determined and reach your goals, but also have fun and enjoy the people who you meet along the way. Denise loves good food, wine, and people, so I hope everyone in the wine world will take advantage of her love of wine and life.
I have absolutely no doubt that Denise will continue to serve the wine industry in the Mid-Atlantic and help to improve the quality and reputation of the wines in the region. Denise has a really good attitude and spirit that has and will continue to serve her very well. We are delighted with the union between Denise and Josh and looking forward to the next chapter of their lives as it unfolds.
From Kathy Kelley
It is often said that having friends at work makes the job/tasks more enjoyable. I find that this is true and that working with Denise has made my job more enjoyable. Denise has an incredible work ethic and tons of energy and drive. In the six years that she has been with Penn State Extension, she has helped numerous businesses, established this blog, and worked with several undergraduate and graduate students who consider her a mentor/friend (as demonstrated in the messages above). Though she will no longer have a psu.edu email address – I look forward to opportunities when Denise and I can work on industry issues.
Good luck, Denise, there is no doubt that you will continue to be successful and that the industry will benefit from your knowledge, expertise, and that you truly care about their well-being.
By: Denise M. Gardner
While I know this has reached many of you, I would like to announce that my last day with Penn State Extension will be on September 1, 2017. After 6 and half years with Penn State Extension, I have decided to start a new venture and open ‘Denise Gardner Winemaking,’ a wine consulting business for wine producers and consumers.
While I had the opportunity to speak briefly about this decision at the 2017 PWA Annual Conference, I wanted to take some time to reflect upon my time at Penn State and my perspective on what I’ve seen change since I joined the Extension team in 2011.
Most of my interest in wine grapes and enology is affiliated with the mentorship provided by Mark Chien, Penn State’s previous Extension Viticulturist, and Joanne Levengood from Manatawny Creek Winery. The two of them worked a lot with me as a young high school student interested in the wine industry. Eventually, they helped me execute a research project pertaining to red wine color stability, and my success affiliated with that project provided me with an opportunity to work for Lallemand as a student intern in Toulouse, France the summer before I started college. Mark wrote about this story in one of his many newsletters in 2003. However, I will never forget the shock and disbelief I felt when I opened up a letter from Mark with an attached check containing a list of the Pennsylvania wineries that had financially contributed to support my travel costs associated with the internship. This act of kindness and support from so many local wineries that did not know me made an everlasting impression on me, and it had been my goal from that day forward to return to the Pennsylvania wine industry.
I share this story now to remind everyone how impressionable young adults are and the impact we can make on shaping their careers and futures. As I leave Penn State, I recognize that one of the greatest awards affiliated with this position was the opportunity to work alongside so many talented young adults while they were students at the University. Their involvement with Extension not only helped me manage the five year NE-1020 variety trial research project, but it also gave me an opportunity to expose many students to this industry. While many of them may not know their final career destination, I truly believe they have all been worth the grant funds, the introductions, the internships and co-ops, and the time that many of us have allocated towards developing their professional careers. Mentorship will definitely help shape our industry if we take the time to make it a priority, and I am excited to see where these young minds eventually lead us if they continue to integrate back into the wine industry. I hope many of them stay in the field, as I truly believe that in order for the industry to grow, stay competitive and progress, we will need their education, experience and application.
I am also proud of the educational workshops that have been developed since 2011 to address wine production and quality issues. While wine quality starts in the vineyard, its quality ends in the winery, and I am overjoyed to have been a part of the educational process that has assisted several winery operations within the state. The Wine Quality Improvement (WQI) Short Course, originally started by Dr. Stephen Menke and managed in interim by Mario Mazza, has reached almost half of the wineries in Pennsylvania through its attendance. It has always been a pleasure to hear about how this program has influenced those that have participated, and I would like to publically thank all of the previous students, both undergraduate and graduate, that have contributed to the success of the short course, as well as my industry volunteers: Mario Mazza, Jamie Williams, and Virginia Mitchell. Without their contributing time and patience, the success of the WQI would not be where it is today.
Finally, there is undeniably a wonderful team of individuals here at Penn State that works very hard to address industry questions and needs. Dr. Michela Centinari, Dr. Ryan Elias, Bryan Hed, Dr. Helene Hopfer, Dr. Kathy Kelley, Andy Muza, and Jody Timer, as well as Dr. Rob Crassweller, Mike Masiuk, and Dr. Michael Saunders are all committed to the success of making the wine industry and Penn State a lifelong collaboration. It was not an easy decision to leave this stellar group of people. I hope that you, as industry members, will continue to support them as the program should only evolve and grow from here. As the enologist in the group, I was fortunate enough to have a supportive and thought-provoking advisory committee. I hope that many of you will consider supporting the next enologist by serving on their own advisory committee in an effort to keep this growing program a part of Pennsylvania’s industry and academic communities.
Between the growth of our academic team and the involvement of students in industry-related research, Pennsylvania has shown well within the research spectrum. I have been very proud of all of the Penn State students that have taken their research and presented at state-wide, regional, and national conferences. Additionally, the research executed by our faculty is top notch. While the benefits of research may not always be immediately apparent, the caliber of research and outreach associated with students and faculty has helped make Pennsylvania’s industry recognizable at a national scale. Sometimes that recognition is small and other times it is monumental. With the financial support of the PA Wine Marketing and Research Board, I hope that we will continue to see the collaboration between industry and academia continue, as well as witness the growth and seriousness of the state’s industry and academic programs. After all, no great wine region has ever succeeded without the arms of science, education, and research coming together.
I have learned that research helps us grow and get better as an industry. It can be slow, yes, but it shows us that we do not know it all after all, and it allows us to adapt to changing conditions like new pest integration in the vineyard or high pH winemaking practices. I hope I see many of you at the American Society of Enology and Viticulture – Eastern Section (ASEV-ES) Conference in Pennsylvania next year. This conference is a forum for regional research, but it also creates networking opportunities, highlights the wine quality affiliated with the hosting state, and includes a focused workshop on an industry relevant topic. For the 2018 conference, we believe the focused workshop will be related to high pH in the vineyard and cellar and how to address those problems. For the number of Pennsylvania wineries that contribute financially to support ASEV-ES scholarships, I thank you for supporting so many of our students, especially those at Penn State that I have seen benefit from these awards. No contribution – large or small – goes unnoticed.
For those that are concerned about the nature of the position, Penn State Extension is committed to the position, and the current job opening it is already posted on the Penn State jobs website. Please support the next hire! I know the team will find an amazing individual to fulfill this role, and I’m looking forward to all that they accomplish with the position.
My last day with Penn State Extension will be on September 1, 2017, but I hope I will not lose touch with many of you through the transition. I will continue to run this message through the next few V&E News email distributions, but you can also find the generation of Denise Gardner Winemaking on Facebook (www.facebook.com/GardnerDeniseM/) until the website’s (www.denisegardnerwinemaking.com) launch in September and reach my by email: email@example.com. This new venture will definitely be unique, and I hope many of you will consider exploring it in the coming months ahead as I am staying focused on Eastern, Southern and Midwestern production practices. Despite this transition, I will continue to work out of Pennsylvania and am hopeful that this new venture will be applicable for many of the local and regional wineries.
Again, it has been a pleasure working alongside many of you and I thank you for making me a valuable part of this industry. I wish you all a fruitful growing season and a successful 2017 harvest. I can’t wait to taste the vintage!
By: Jody Timer, Entomology & Lake Erie Regional Grape Research and Extension Center
Over the last ten years there have been an inpouring of newcomers to the insect community of Pennsylvania’s grape vineyards. These pest, combined with the numerous indigenous pest, have created an ever evolving challenge for the area’s grape growers. In this blog, I will briefly review the grape pest which I feel are becoming ever increasingly problematic for grape growers to control.
The Spotted wing drosophila has become a progressively severe problem in blueberries raspberries, and grapes. Recent research has shown that they are attracted to all cultivars of grapes that we tested. Spotted wing Drosophila, Drosophila suzukii, Matsumura (Diptera: Drosophilae) (SWD) is an invasive vinegar fly of East Asian origin, that was recently introduced into the United States. It was first found in California in 2008 and is now found in all major fruit-growing regions of the country including Pennsylvania. It was first discovered in Pennsylvania’s Lake Erie grape growing region in the late fall of 2011. The potential infestation rate of spotted wing Drosophila differs from other vinegar flies because the female possess a serrated ovipositor that cuts into healthy fruit to lay eggs. Consequently, spotted wing Drosophila (SWD) larvae can be found in fruit that is just ripening: https://youtu.be/dPr61VC2gyo
During egg-laying, it is believed that sour rot and fungal disease can also be introduced, further affecting the fruit quality. During peak temperatures, a female can lay more than 100 eggs a day. Such a high reproduction rate indicates the SWDs’ high potential for fruit infestation and their potential for spreading rapidly through a field or a vineyard. Because of this prolificity it has become increasing important to protect wine grapes starting at veraison. A good YouTube video on how to identify SWD damage is: https://youtu.be/DLNDnMMfWfs
In our research we have seen SWD showing up earlier in the spring each season and their numbers increasing yearly. SWD do attack injured grapes before non-injured, they tend to wait till veraison before attacking grapes, and they will reproduce in fallen berries. For this reason it is important to keep your vineyards as clean as possible and to maintain coverage of these wine grapes through harvest. Trapping and forecasting can lead to improvements in grower’s capability to optimally time pest management decisions which should reduce both the direct cost of pesticide treatments and the indirect cost to wineries. Information can also be found at:
The brown marmorated stink bug (BMSB) is currently a very serious pest in tree fruits and vegetables, and can be a nuisance when they overwinter in houses. Although BMSB prefer other fruits and vegetables to grapes, they do feed on grapes. Their damage can cause ugly scars on table grapes and grapes grown for sale at fruit stands. This type of damage is not important to wine grape and juice grape growers, however, the holes open pathways for fungal and bacteria late season infections. This season, in the Lake Erie region, we have begun to see a small number of BMSB damaged grapes. BMSB may also be easily harvest with the grapes. The insects tend to move to the interior of the cluster when disturbed and are hard to see. When they are killed they give off a foul odor – which is how they got their name. Our research has shown that this odor and resulting taste do survive the pasteurization of juice grapes, but disappears after being stored for longer periods of time. There is conflicting research on whether this taint transfers to wine, more research is ongoing. There are traps commercially available to trap these insect, but their efficacy is very low. BMSB have been found in both grape foliage and grape clusters; they seek the moisture, sugar, and warmth on the inside the clusters (especially overnight) and they often migrate to the cluster’s interior close to harvest. This makes the possibility of BMSB inside the cluster very likely when these grapes are mechanically harvested and transported to the processor.
With the yearly increase of numbers of BMSB in the Pennsylvania vineyards, it is very important for growers to scout for the adults and the presence of the eggs on the underside of grape leaves. There are one to two generations in Pennsylvania. A compilation of research can be accessed at www.STOPBMSB.org
The newest invasive poised to become a major problem to grape growers, the spotted lanternfly (SLF), Lycorma delicatula, (Hemiptera: Fulgoridae) is native to China, India, Japan, and Vietnam and has been detected for the first time in the United States in northeastern Berks County, Pennsylvania. This approximately one inch long insect with piercing-sucking mouthparts has the potential to impact the green industry, grape growers, tree fruit growers, and the forests and wood products industries in Pennsylvania as well as the United States. The host plants of the SLF in its native habitat include grapes, pines, stone fruits, and up to 50 other hosts. Early detection of the SLF is critical for effective control and protection of Pennsylvania’s agriculture and its related businesses. SLF group feeds on grapevines in numbers great enough to cause destruction of the entire grapevine. Grapes are listed as a primary host in its native regions. To date this insect has been confined to areas of Berks and Bucks counties in Pennsylvania. The PDA has issued a general order of quarantine for these areas over the past few years, however this insect is slowly increasing its range.
The following is a link to the PDA’s information on the SLF: www.pda.state.pa.us/spottedlanternfly. You may find a link to a pdf copy of the SLF Order of Quarantine, a PowerPoint on Lycorma Inspection Tips, and the SLF Pest Alert at this website.
What to do if you:
- See eggs: Scrape them off the tree or smooth surface and place the eggs in a tightly sealed container with 70% alcohol or hand sanitizer to kill them.
- Collect a specimen: Send the adult/nymph specimen or egg mass to the PDA Entomology Lab for verification. The mailing address for the lab is: PDA, Entomology Room-111, 2301 N. Cameron St., Harrisburg, PA 17110. First, place the sample collected in 70% rubbing alcohol or hand sanitizer in a leak proof container. Complete the PDA Entomology Program Sample Submission Form. This sample form can be found in the PDA SLF website www.pda.state.pa.us/spottedlanternfly.
- Report a site: Call the Bad Bug hotline at 1-866-253-7189 with details of the sighting and your contact information.
The most destructive insect pest in the Lake Erie region remains the native Grape Berry Moth (GBM), Paralobesia viteana. This insect is becoming increasingly harder to control as result of shorter residual time of insecticides, resistance to insecticides, and abandoned vineyards. GBM larval burrow into the grape berry soon after hatching, making precise timing of spray applications a critical component of control. This insect has four generations per year. Each generation increases in number exponentially if control measures are not applied to the early generations. Spray timings can be calculated by following the NEWA model recommendations (see earlier posts). Growing seasons with large populations of GBM, will require a second spray in July and/or August to control the populations, and to prevent them from moving farther into the vineyards. Scouting for GBM damage often during the season is a critical component of control, as the pheromone traps capture only the males and are not a good indicator of infestation after the first generation. More information can be found on extension pages and on the LERGP Podcasts on Youtube.
Grapevine leafroll associated virus; A brief introduction to an old disease. Should Pennsylvania grape growers be concerned?
By: Bryan Hed, Michela Centinari, and Cristina Rosa
As if wine grape growers don’t have enough challenges in this day and age, the effects of grapevine viruses have been taking on greater importance in eastern vineyards over the past several years. Studies examining grapevine leafroll-associated viruses are developing a growing body of information that will be essential for vineyard managers to continue moving the eastern wine grape industry forward. Grape growers in the eastern United States need not feel they are the only ones with this disease management challenge (as is the case with many fungal diseases of grapes); grapevine leafroll-associated viruses (GLRaVs) are found in vineyards all over the world (Compendium of Grape Diseases). This group of viruses causes a disease known as grapevine leafroll disease, and the association of symptoms with grapevine leafroll viruses was recognized over 80 years ago. As is the case with so many plant pathogens, the worldwide distribution of these viruses occurred as a result of increased movement of plant material/goods across the globe; the ever widening dissemination of infected planting stock (Compendium of grape diseases). The effects of these leafroll viruses is most severe on – you guessed it – cultivars of V. vinifera, where the disease is known to greatly reduce yield, vine vegetative growth or vigor, and cold hardiness; a factor of critical importance for these cultivars grown in the northeastern United States. Grapevine leafroll disease can also delay fruit maturity, reduce color development in red grapes, and fruit quality (decreased soluble solids, increased titratable acidity) of V. vinifera grapes (Fuchs et al. 2009), which can negatively impact perceived wine quality. The severity of the effects of leafroll viruses is dependent on a great number of factors such as grapevine cultivar, virus strain, climate, soil, cultural practices, stress factors, etc. So naturally, the severity of symptoms can vary from one season to the next (Compendium of Grape Diseases). With respect to cultivar, the effects of these viruses on Vitis interspecific hybrids and Vitis labrusca are generally considered to be less serious, but are also less well defined and studied.
Infection by leafroll viruses results in the degeneration of primary phloem tissues in grapevine shoots, leaves and clusters (Compendium of Grape Diseases). As one can imagine, this can have profound effects on all parts of the vine. Symptoms of the disease, which are generally most observable on V. vinifera, consist of cupping and discoloration of older leaves in late summer and fall. On red fruited varieties, leaves of infected vines can display a distinct red coloration of the interveinal tissue, while veins remain green (Figure 1). On white fruited varieties of V. vinifera, symptoms are less striking and leaves tend to look yellowish (chlorotic) and cupped (Figure 2). Leaf discoloration generally affects older leaves first, but these symptoms are not diagnostic of the disease, as they may be due to other causes such as nutrient deficiencies, water stress, and even crown gall. Analysis of grapevine tissues in the laboratory is the only way to confirm the presence (or absence) of these viruses.
Currently, there are about seven GLRaVs found in cultivated grapes, the most common being GLRaV-3. These viruses are easily spread over long distances through the movement of infected nursery stock, but can be spread (vectored) within the vineyard by mealybugs (Compendium of Grape Diseases). Unfortunately, there are no known sources of resistance to GLRaVs among Vitis species and they have been found in many cultivated grape varieties, including V. labrusca, Vitis interspecific hybrids, and V. vinifera. Interest in grapevine leafroll disease and the extent of its effects has been growing in the eastern United States over the past ten years or so. Surveys conducted in New York, Ohio, and Virginia (Fuchs et al. 2009, Jones et al. 2015, Han et al. 2014), have provided confirmation of the presence of GLRaVs in commercial vineyards and have yielded important information necessary to the management of grapevine leafroll disease. For example, infection by GLRaVs is permanent and infected vines must be destroyed to reduce the incidence of grapevine leafroll disease. Therefore, management of the disease would naturally include planting only stock that is free of GLRaVs. Insecticides that target mealybugs and soft scales can prevent vine to vine spread (within the vineyard) of GLRaVs that are known to be vectored by these insects (Compendium of Grape Diseases). Indeed, studies have shown that applications of insecticides like dinotefuran (Scorpion) and spirotetramat (Movento) can significantly reduce mealybug counts and result in a slowing of the progress of the disease in vineyards. One study from New York (Fuchs et al. 2015) showed that insecticide applications should target overwintered and second instar mealybug crawlers from bud swell to bloom and summer generation crawlers later in mid-summer. A study with grape phylloxera as a potential vector of these viruses showed that phylloxera can acquire the virus through phloem feeding on infected vines, but there was no evidence that phylloxera can transmit it (Wistrom et al. 2017).
As was mentioned earlier, cultivars of Vitis labrusca (Concord, Niagara) can also become infected with GLRaVs, but the infections appear to remain latent or dormant (Bahder et al. 2012) and have not been shown to result in visual symptoms of the disease (Wilcox et al. 1998). On the other hand, cultivars of V. vinifera are severely affected by GLRaVs and make up a very important and growing sector of the PA wine grape industry. Surveys conducted in New York, Ohio, and Virginia (Fuchs et al. 2009, Jones et al. 2015, Han et al. 2014) have revealed the presence of GLRaVs in commercial vineyards to the north, west, and south of Pennsylvania and have led to the development of some important guidelines for management of grapevine leafroll disease.
Given the fact that grapevine leafroll disease is common worldwide and that grapevine leafroll disease can profoundly impact wine quality and grapevine health, researchers at Penn State University are initiating a project to look for GLRaVs in Pennsylvania vineyards. As in other states, the study is targeted to help growers recognize the impact that the disease may be having on the Pennsylvania wine industry and help them to address the effects of these viruses on productivity and fruit quality, reduce their spread and impact, and thereby grow and improve the wine grape industry in Pennsylvania.
The short term, initial objectives of this project will focus on the development of an online survey to collect information from growers with regard to the presence of symptoms of grapevine leafroll disease in Pennsylvania vineyards and their interest in participating in the project. The project will then follow up with tissue sampling from participating, symptomatic and non-symptomatic vineyards throughout the state and serological analysis to determine the presence of Grapevine leafroll virus-1 and Grapevine leafroll virus-3 – the most common of the leafroll viruses – in commercial vineyards in Pennsylvania. The collection of vineyard samples across the state will map the incidence and geographical distribution of these viruses on cultivars of Vitis vinifera and Vitis interspecific hybrid grapevines. The project will also determine and compare the impact of grapevine cultivar and age on infection by Grapevine leafroll virus-1 and -3 in Pennsylvania. Once infected vines have been identified in Pennsylvania vineyards, future objectives will focus on studying the impacts of grapevine leafroll disease on grape quality and productivity in Pennsylvania, and management techniques to mitigate the economic impact of the disease on the Pennsylvania wine industry.
Vineyards will be selected from all parts of Pennsylvania, but the number of locations will favor northwestern and southeastern PA, where the majority of vineyards are located. The study will be expanded as new findings are made and the results will be made available to growers at various meetings throughout the next several years.
Bahder, B., Alabi, O., Poojari, S., Walsh, D., and Naidu, R. 2013. A Survey for Grapevine Viruses in Washington State ‘Concord’ (Vitis x labruscana L.) Vineyards. Plant Health Progress, August 5, 2013. American Phytopathological Society (online).
Compendium of Grape Diseases, Disorders, and Pests. 2nd edition, 2015. Editors Wayne F. Wilcox, Walter D. Gubler, and Jerry K. Uyemoto. The American Phytopathological Society. Pp. 118-119.
Fuchs, M.; Marsella-Herrick, P.; Hesler, S.; Martinson, T.; Loeb, G. M. 2015. Seasonal pattern of virus acquisition by the grape mealybug, Pseudococcus maritimus, in a leafroll-diseased vineyard. Journal of Plant Pathology Vol.97 No.3 pp.503-510
Jones, T. J., Rayapati, N. A., Nita, M. 2015. Occurrence of Grapevine leafroll associated virus-2, -3 and Grapevine fleck virus in Virginia, U.S.A., and factors affecting virus infected vines. European Journal of Plant Pathology 142:209-222.
Wistrom, C. M., G. K. Blaisdell, L. R. Wunderlich, M. Botton, Rodrigo P. P. Almeida & K. M. Daane. 2017. No evidence of transmission of grapevine leafroll-associated viruses by phylloxera (Daktulosphaira vitifoliae). European Journal of Plant Pathology. Volume 147, issue 4. pp 937–941.
By: Denise M. Gardner
The eastern U.S. growing seasons can be somewhat unpredictable. Late season rains or untimely hurricane events can be a recipe for disaster for local grape growers (http://www.pawinegrape.com/uploads/PDF%20files/Documents/Viticulture/Harvest/Rain%20at%20Harvest.pdf), and a few have been unprepared for such events in the past. These weather events can lead to higher incidences of the grey-rot form of Botrytis in addition to other rots, which may also be related to pest damage. Furthermore, these weather incidences and pest damage can ultimately impact picking decisions for growers and wineries (Osborne, 2017).
It is almost inevitable that wineries need to be prepared for end-of-season weather flops, and plan for the best possible ways to manage or maintain wine quality in light of above-average disease pressure.
One disease that winemakers can prepare for prior to harvest is Botrytis. For the purpose of this article, we’ll be using the term Botrytis to indicate the grey-mold or grey-rot form of the disease. Grey-mold, the form of Botrytis more commonly noticed in humid regions or during heavy-precipitation seasons, can ultimately affect wine quality. Peynaud (1984) has defined 4 ways in which the grey-mold can negatively affect wine quality:
- Deplete wine color (especially important in red varieties),
- Increase the risk of premature browning (through oxidative enzymes),
- Deplete varietal character (through degradation of grape skins), and
- Contribution to off-flavors developed by the mold’s presence on the fruit.
Based on a 1977 study by Loinger et al., guidelines pertaining to wine quality were developed with regards to a visual assessment of Botrytis incidence on incoming fruit:
- 5-10% Botrytis rot on clusters: noticeable reduction in wine quality; wine quality is still “good” (as opposed to very good with 0% rot on clusters)
- 20-40% Botrytis rot on clusters: marked reduction in wine quality; wine quality is “low”
- >80% Botrytis rot on clusters: wine is commercially unacceptable
With a noticeable sensory and chemical difference in Botrytis-infected clusters, it is best for wineries to develop a standard operating procedure (SOP) for assessing rot-infected fruit, as well as how the grapes should be handled and processed during production. While there is no one correct way to work with the wine, below are some suggestions or options that wineries can integrate when dealing with Botrytis-infected grapes. For a full list of possibilities, please visit: http://extension.psu.edu/food/enology/wine-production/producing-wine-with-sub-optimal-fruit/fermenting-with-botrytis-101
Some wineries will sort through all incoming grape clusters prior to the crushing/destemming process to assess for any cluster damage or presence of unwanted material. If your operation is not set up with this equipment, sorting can also take place in the vineyard. Depending on the concentration of disease and on the projected wine style or quality parameter the fruit will go towards, disease portions of clusters can be cut out in the vineyard. Or diseased fruit can be left in the vineyard to deal with after the harvest is complete. Sorting out diseased fruit from that of decent quality will reduce the impact of the mold on the wine’s aroma, flavor, and quality.
Limit Contact Time with Skins
Depending on the resource, there are various recommendations for how to handle diseased fruit. In whites, some recommend whole cluster pressing and tossing the first 10+ gallons, which are rich in Botrytis metabolites (Fugelsang and Edwards, 2007). Many recommend separating juice press fractions for white and rosé wines, as this will give the vintner more control over the chemical constituents (e.g., phenolics, enzymes, and disease-related off-flavors) in the final wine.
Depending on the desired outcome for a red wine, treating or limiting skin contact with diseased fruit may be ideal post -primary fermentation. This would include avoiding extended maceration processes. Due to the fact that the presence of Botrytis on red varieties reduces anthocyanin and phenolic extraction (Razungles, 2010) in addition to the varietal aromatics, excessive skin contact may not be ideal during primary fermentation. Whole berry fermentations, as opposed to a more aggressive crush and destem process, may help minimize extraction of Botrytis metabolites, which can also contribute to mouthfeel variations or off-flavors.
Tannin additions pre-fermentation may also be good considerations to compensate for phenolic losses associated with Botrytis infection. Pre-fermentation and post-fermentation additions may help rebuild the wine’s structure or provide constituents for color stabilization.
Flash pasteurization (i.e., flash détente) has been previously recommended for Botrysized fruit to inactive the laccase enzyme associated with Botrytis, enhance color stability in reds, as well as improve the aromatics and flavors associated with the final wine. Wines that undergo a thermovinification step tend to extract more anthocyanins and phenolics compared to traditionally fermented wines (Razungles, 2010). Additionally, this heat step helps to inactivate laccase, which can contribute to early browning or oxidation of young wines. However, commercial producers may not find this technological application easily accessible.
Therefore, in addition to minimizing skin contact time, winemakers will want to reduce contact time with the gross lees, and may also remove the wine from fine lees associated with the mold-infected fruit quickly. The integration and use of clean, fresh lees, however, is still encouraged. Removing the lees associated with mold-infected fruit can help reduce additional contact time with rot metabolites that have settled out with the lees. This inhibits further integration of those metabolites into the wine.
Inoculate with a Commercial Yeast Strain
The presence of rot is one incidence in which processing techniques (e.g., cold soak) that encourage native microflora to dominate the fermentation are probably not desired. Things like cold soak and native ferments allow ample opportunity for the mold to progress and contribute to the wine’s flavor.
Fruit that has rot or microflora issues is best inoculated with commercial yeast and malolactic bacteria strains to outcompete the native microflora (including those microorganisms that contribute to the rot), and to give the fermentation its best chance at completing the fermentation cleanly. Remember that proper yeast nutrition is important to support the yeasts’ growth and to reduce the risk of hydrogen sulfide development. For more information on determining the starting nitrogen concentrations (YAN) and how to properly treat your fermentation with added nutrients, please refer to:
Penn State Extension’s Wine Made Easy Fact Sheet: Nutrient Management During Fermentation
With high Botrytis concentrations, a more robust yeast strain may be preferred in order to quickly get through primary fermentation. A quicker fermentation may simplify the aromatics associated with the wine, but it will also ensure little opportunity for additional spoilage. Saccharomyces bayanus strains are often selected as more robust yeast strains.
Use of Sulfur Dioxide
Sulfur dioxide additions at crush will be determined based on the style of wine in which you are producing (e.g., white, rosé, red, etc.), but in general, the use of sulfur dioxide can help inhibit further spoilage of your product and retain antioxidant capacity. Sulfur dioxide additions in the juice stage will help minimize early browning, but primarily inactivate PPO.
In general, botrysized wines tend to require more sulfur dioxide as Botrytis metabolites bind with free sulfur dioxide (Goode, 2014). This is true even when processing wines with the noble rot version of Botrytis.
When primary fermentation, and malolactic fermentation (dependent on style), is complete it is a good idea to ensure that the wine has an adequate free sulfur dioxide content in order to retain its antimicrobial protection.
Some fining agents may also be applicable in the juice stage. For example, some producers find it helpful to fine juice with bentonite in order to reduce protein content, as well as help minimize rot-associated off-flavors or partially reduce laccase concentrations.
PVPP can be added to the juice to reduce potential browning pigments or their precursor forms (Van de Water, 1985).
In both of these scenarios, neither bentonite or PVPP is specific for rot-related constituents, but each could be helpful to avoid potential challenges later on in the production process.
The presence of Botrytis can also contribute glucans to the must/wine, which can cause filterability problems for heavily-infected wines. In this situation, many suppliers have beta-glucanase enzymes that can be applied either to the juice, wine, or both, to help breakdown the glucans and enhance ease of filterability.
A Word about Laccase
Both polyphenol oxidase (PPO) and laccase can cause early browning in grapes and wine. However, PPO is inhibited by the alcohol content that is developed during primary fermentation. Laccase, however, is not inhibited by the presence of alcohol, and can only be inactivated by a pasteurization step, heated to at least 60°C (140°F) (Wilker, 2010).
Grapes tend to be higher in laccase concentration when infected with Botrytis, and, thus, wines produced from grapes that had a high incidence rate of Botrytis can develop a brown hue post-primary fermentation. This oxidative activity can occur even in young wines.
If you are concerned about the prevalence of laccase in diseased-fruit, wineries can submit wine samples to a wine lab for a laccase test. Or, if you own a copy of “Monitoring the Winemaking Process from Grapes to Wine: Techniques and Concepts” by Patrick Iland et al., pg. 90 and 94 have 2 laccase test protocols that outline how wineries can assess oxidation by laccase. The results of these test will indicate if extreme treatments are required during production to avoid the rapid and early oxidation caused by laccase.
- Fermenting with Botrytis 101
- Management of Botrytis Infected Fruit
- Managing Botrytis Infected Fruit Fact Sheet
Goode, J. 2014. The Science of Wine: From Vine to Glass. (2nd Ed.) University of California Press: Berkley, California. 216 pg.
Fugelsang, K.C. and C.G. Edwards. 2007. Wine Microbiology: Practical Applications and Proceedings. (2nd Ed.) Springer: New York, NY. 393 pg.
Loinger, C., S. Cohen, N. Dror, and M.J. Berlinger. 1977. Effect of grape cluster rot on wine quality. AJEV. 28(4): 196-199.
Peynaud, E. 1984. Knowing and Making Wine. Wiley-Interscience: New York, NY. 391 pg.
Razungles, A. 2010. Extraction technologies and wine quality. In Managing Wine Quality, Vol. 2 Oenology and Wine Quality. Andrew G. Reynolds, Ed. Woodhead Publishing: Philadelphia, PA. 651 pg.
Van de Water, L. 1985. Fining Agents for Use in Wine. The Wine Lab.
Wilker, K.L. 2010. How should I treat a must from white grapes containing laccase? In Winemaking Problems Solved. CRC Press: Boca Raton, Florida. 398 pg.
Growth Regulator Herbicides Negatively Affect Grapevine Development: Identification of Herbicide Drift Damage, How to Prevent it, and What to do if it Occurs in your Vineyard
By: Michela Centinari
The Penn State Extension grape team has been receiving reports on herbicide drift damage in vineyards from a number of Pennsylvania wine grape growers this growing season, definitely many more than in previous years. All herbicides registered for grapes can potentially harm the vines if not applied in accordance to the pesticide label (e.g., glyphosate products) . However, in many of the reported cases through the 2017 growing season the damage was caused by herbicides not registered for grapes, which drifted into the vineyards from nearby fields.
Damage from herbicide drift is, unfortunately, something that grape growers across the country are too familiar with. It represents an economic threat for the grape and wine industry and should not be underestimated. Herbicide drift damage can, indeed, result in significant crop losses which may extend to multiple seasons, and in some cases it also results in vine death. Several extension web resources are available to assist grape growers in preventing and dealing with herbicide drift damage. Some of them are listed at the end of this article, including one from Andy Muza, extension educator at Penn State (Growth Regulator Herbicides and Grapes Don’t Mix).
Due to the increase in reports of herbicide drift damage in Pennsylvania vineyards it seems appropriate to discuss some key points surrounding this issue. This article will review how to identify herbicide drift symptoms, what measures grape growers and pesticide applicators can take to prevent herbicide drift, and what steps to take if the drift occurs.
Plant growth regulators (PGR) herbicides are those most likely to injure grapevines, mainly through drift.
I will only focus on the herbicides which belong to the plant growth regulators (PGR) mode of action group. Common active ingredients of PGR herbicides are 2,4-D (2,4-Dichlorophenoxyacetic acid; phenoxy family), dicamba (benzoic acid), tricolopyr or picloram (pyridine family). A partial list of common PGR herbicides as well as other herbicides that may injure grapevines can be found at Preventing Herbicide Drift and Injury to Grapes, Table 1.
PGR herbicides are widely used for controlling broadleaf weeds in many crops, such as wheat, corn, soybean, pasture, rangeland, etc. They are also frequently utilized to control unwanted broadleaf vegetation in turf, by railroads, road ditches, fence lines, and rights-of-way. These herbicides are not registered for use with grapes. However, when applied to a nearby field, they can drift into the vineyard and cause significant injury to grapevines.
Most of the herbicide drift damage reported this season by Pennsylvania grape growers were caused by drift of PGR herbicides (Figure 1). Physiological symptoms to PGR exposure is not too surprising because grapevines are extremely sensitive to PGR herbicides, including the phenoxy, benzoic, and pyridine classes of compounds . For example, herbicides containing 2,4-D can damage grapes at a concentration 100 times lower than the recommended label rate. Moreover, drift from PGR herbicides can injure grapevines located half a mile or more from the application site.
What is “drift”?
Drift is defined as “the movement of herbicides off the site where they were applied” . Non-target drift can occur either as spray drift or vapor drift. Spray drift occurs during herbicide application when small droplets move off the application site under unfavorable wind conditions. Vapor drift occurs after herbicide application as the spray material volatizes or evaporates and is carried away from the application site by wind or temperature inversions. Some PGR herbicides, such as ester formulations of 2,4-D, readily volatilize, especially when used under high temperatures and low humidity conditions (high vapor pressure) .
How PGR damage occurs in grapevines
PGR herbicides mimic auxins, plant hormones that regulate growth and development. Applications of PGR herbicides disrupt plant hormone balance causing growth abnormalities. PGR herbicides can be absorbed by both roots and leaves, however grapevines are usually injured through foliar absorption.
How to tell if the vines have been damaged by PGR herbicide drift
Damage from PGR herbicides typically appears within 2 days of the drift occurrence. Herbicide drift can damage leaves, shoots, flowers, and fruit. Leaf symptoms are often easy to recognize, but sometimes can be mistaken with those of fanleaf degeneration, a viral disease . Growers can send pictures of damaged vines to a local extension specialist for confirmation.
Typical symptoms include:
- Distorted leaf appearance: Symptoms are typically more severe on the youngest leaves and shoot tips. Affected leaves are “smaller, narrow, deformed, and they have closely packed, thick veins that lack of chlorophyll” . They may also have a distinct fan-shape appearance, and depending on the herbicide’s active ingredient, they can bend downward or cup upward (Figures 2, 3). Leaves may or may not outgrow the symptoms, it largely depends on the severity of the injury and other factors listed in the following section (“Factors affecting the severity of injury”). It is also common to see regrowth of deformed leaves after drift exposure .
- Shoot growth: Damaged shoot tips rarely resume growth, but lateral shoots can keep growing giving in some cases a “bushy” appearance to the vine resulting in a highly shaded canopy and poor fruit sun exposure.
- Flower clusters (inflorescences): symptoms can include aborted or failed flowers, and poor fruit set (Figure 4). If the injury is severe enough it can cause reduced yield at harvest and poor fruit quality, in addition to potentially illegal residues of herbicide on the exposed crop.
In some cases, depending on the timing and level of drift exposure, floral symptoms may be much more pronounced than those on the leaves making the diagnosis more difficult (i.e., growers may relate poor fruit set or dead flowers to other causes rather than herbicide drift) (Figure 5).
If the damage occurs early in the season, between bud burst and bloom, as it usually does, a significant reduction in healthy leaf area during the period of rapid shoot growth may affect vine photosynthetic capacity, lowering vine ability to fully ripen the crop and possibly its ability to survive cold winters.
Unfortunately there is no guarantee that the vines will fully and rapidly recover from herbicide drift damage. Carry-over effects into the following years, such as reduction in vine vigor, yield, fruit quality, and increased susceptibility to diseases, are common if the damage is extensive and/or the vines have been repeatedly exposed to PGR-herbicide drift. Finally, vines may die as a consequence of their weakened condition .
What factors affect the severity of PGR-herbicide drift damage?
Some of the most important factors affecting the severity of drift damage are:
- Vine growth stage at the time of exposure. Grapevines are always sensitive to PGR herbicides, but they are most susceptible during the early part of the growing season, from bud burst through bloom. While dependent on the growing season and site, in Pennsylvania this usually occurs around April through June. Early in the growing season shoots are rapidly growing and PGR herbicides are quickly translocated to the shoot tip, where the natural concentration of auxins is greatest inside the grapevine. If exposure occurs later in the season, vines typically outgrow the damage and still produce good yield .
- Vine age: Younger plants are more vulnerable and they have a lower ability to recover from the PGR herbicide damage than mature vines. Young vines may be killed even at low exposures .
- Level of exposure: Higher concentration and/or repeated exposures will result in higher disruption of the vine’s physiology and lower ability of the vines to rapidly and fully recover from the damage .
- Grapevine variety. All grapevine varieties are sensitive to PGR herbicides, but some may show more visual and physiological symptoms than others (see for example Table 1, Questions and Answers about Vineyard Injury from Herbicide Drift)
- Other factors include herbicide concentration and formulation (for example ester formulations of 2,4-D are more volatile than amine formulations, thus ester formulations of 2,4-D are more prone to move off-target as vapor), weather conditions (temperature, humidity, and most importantly wind speed) at the time of herbicide application.
What is the best strategy to protect vines from herbicide drift injury?
Prevention is undoubtedly the best strategy for grapevine growers to avoid herbicide damage. To reduce the risk of herbicide drifting into their vineyard, vineyard managers and/or owners should be proactive. Some prevention steps both grape growers and nearby growers of other crops can take are listed below:
- Maintain good relations with neighbors. Vineyard owners and managers should make sure their neighbors within approximately a half-mile to 1 mile radius, are aware that vines are extremely sensitive to PGR herbicides . It is also recommended to encourage neighbors to “use drift-reduction spray nozzles (nozzles that produce large droplets) and to select herbicides that are less likely to injure grapes” . If growers of other crops are unaware of damage to grapevines, collecting information such as this blog post, may be an important educational tool to share. Mike White, viticulture extension specialist at Iowa State University, suggests to share an aerial map of the property showing the vineyard location with neighbors and commercial pesticide applicators to increase their awareness. It is also recommended to communicate the presence of the vineyard to state and county highway departments.
- Windbreak (shrubs, trees, physical barriers) and a buffer area between the vineyard and the edge of the field being sprayed are always a good idea. Penn State offers a free publication or pdf print-out regarding windbreaks: http://extension.psu.edu/publications/uh172/view
- For those states where the service is available, growers can register the location of their vineyard on https://driftwatch.org/. This online service is not available in Pennsylvania, but in many Midwestern states growers and pesticide applicators can use this web resource free of charge to report (growers) and locate (applicators) potential drift hazards.
Taking all these steps may not guarantee that herbicide drift will not occur in your vineyard, but increasing pesticide applicators awareness of grape sensitivity to PGR herbicides, the resulting economic loss, and potential litigation risks may very well serve the purpose.
Applicators should always follow all the measures available to minimize the risk of herbicide drift into a nearby vineyard or to other sensitive crops. Legal complaints may result in expensive settlements. In an extreme example, an owner of a 150-acre vineyard in Australia was awarded AUS$ 7M in damages over pesticide drift (Grape grower Awarded $7M in damages over spraying) that occurred from 2013 to 2015.
If PGR herbicides are applied after vine bud burst, applicators should consider eliminating volatile compounds and apply only non-volatile products.
Extension personnel could also facilitate communication between grape and crop field growers as it happens in Long Island, NY. Extension personnel from Cornell University-Long Island, including Alice Wise and Andy Senesac, organized a meeting with local grape and sod growers to tackle the herbicide drift issue which was affecting local grape growers without having to resort to regulatory restrictions. The result of that meeting was a ‘gentleman’s agreement’ not to spray herbicides containing 2,4-D after April 15, around bud burst for the earliest grapevine varieties in Long Island. To keep all parties informed, extension sends out a weekly reminder about this issue.
What to do if the drift occur
Here some key steps Mike White put together on what to do right after a drift incident :
- Identify area affected.
- Document the date, time and growth stage of the grapes.
- If possible, identify the source of the drift and make a determination if you want to settle the problem amongst your neighbors.
- Contact your state department of agriculture (Pennsylvania Department of Agriculture, PDA) as soon as possible if you cannot determine the source of the drift and/or you want to formalize the complaint (30 – 45 day deadline in many states).
- Flag both affected and unaffected plants, take high resolution pictures weekly until symptoms subside and measure final yields per plant.
- Severe injury settlements should be delayed until after next season’s harvest. Photo and yield documentation should be continued. Unless the settlement offered seems exceptionally lucrative, I would suggest delaying any settlements until after next season’s harvest to assess for potential carry-over vine damage.
For information on where to find a drift consultant please refer to Need Help? Pesticide Drift Consultants
How to estimate the loss in revenue
Tim Martinson, viticulture extension specialist at Cornell University, provided useful examples on how to estimate the economic loss associated with herbicide drift damage under different scenarios. Scenarios include vine recovery across multiple years, with and without the need of vines replacement. Please refer to: Diagnosis, Economics, Management of Grape Injury from 2,4D and other Growth Regulator Herbicides.
How to manage damaged vines
There is limited information available on best management practices for vines affected by herbicide drift damage. To favor a full and a rapid recovery it is recommended to still implement good management practices and avoid further stress to damaged vines, as for example over cropping (assuming damaged vines have fruit). Fungicide applications made to protect the fruit should not be necessary if the fruit has been removed . It is also recommended to adjust pruning strategies to smaller vines, with the intent of regaining full vine size .
- Growth regulator herbicides and grapes don’t mix. Penn State. https://psuwineandgrapes.wordpress.com/2015/10/16/growth-regulator-herbicides-and-grapes-dont-mix/
- Watch out for: Grapes. Purdue University. DW-10-W. https://www.extension.purdue.edu/extmedia/ho/dw-10-w.pdf
- Preventing herbicide drift and injury to grapes. Oregon State University. EM 8860. http://extension.oregonstate.edu/yamhill/sites/default/files/spray_drift/documents/3-preventing_herbicide_drift_to_grapes_osu_8660.pdf
- Avoid phenoxy herbicide damage to grapevines. Texas Cooperative Extension. http://winegrapes.tamu.edu/files/2015/11/phenoxy1.pdf
- Avoiding 2,4-D injury to grapevines. Colorado State University. http://webdoc.agsci.colostate.edu/cepep/FactSheets/Avoiding%202,4-D%20Injury%20to%20Grapevines.pdf
- Questions and answers about vineyard injury from herbicide drift. Kansas State University. MF-2588. https://www.bookstore.ksre.ksu.edu/pubs/MF2588.pdf
- Need Help? Pesticide drift consultant. Northern Grapes Project. http://northerngrapesproject.org/wp-content/uploads/2013/01/11-3-NE-Find-Drift-Consultant.pdf
- Top 10 questions about herbicide drift into vineyards. Iowa State University. https://www.extension.iastate.edu/wine/growersnews/243-may-29-2013#Top
- The view from New York: Diagnosis, economics, management of grape injury from2,4‐D and other growth regulator herbicides. Northern Grapes Project. http://northerngrapesproject.org/wp-content/uploads/2013/01/Martinson-2-4D-Presentation.pdf