Recent Blog Posts
Grower Survey to Assess Herbicide Drift Damage in the North Central U.S.
A special project group of the North Central Integrated Pest Management (IPM) Center wants to learn about your concerns and experiences with herbicide drift. The group is surveying growers of fruits, vegetables, and other specialty crops in the upper Midwest.
To truly understand the frequency, severity, and economic impact of herbicide drift on specialty crops, we need to hear from growers: growers who have experienced drift damage, growers who can share their concerns around this issue, and even growers who have not dealt with drift but who grow sensitive crops in drift-prone regions. Survey responses are needed to establish herbicide drift as a serious economic and regulatory concern in Ohio and across our region.
Please complete the survey at go.osu.edu/drift1.
Who should take this survey?
The study is for commercial growers of fruits, vegetables, and other specialty crops in IA, IL, IN, KS, MI, MN, MO, ND, NE, OH, SD, or WI. Even if you have never experienced herbicide damage, we would still like to hear from you if you grow specialty crops in one of these states.
Why is this survey necessary?
Dicamba and 2,4-D drift damage has made headlines in recent years, but no study to-date has attempted to quantify the overall impact drift has on the specialty crop industry. While all states have a way for growers to file a drift complaint, the process and requirements are inconsistent and may involve time and information that a grower does not have. In most states, for instance, the source of the drift must be identified. Research has found that dicamba and 2,4-D both have the potential to travel for miles in specific weather conditions, making source identification difficult.
What good will this survey do?
This study is designed to assess the potential and actual frequency of drift damage, along with the severity and economic impact of such damage. The survey includes questions on grower awareness, experience, actions, and decisions related to herbicide drift and drift-risk management. The responses will help establish needs for research on drift mechanisms, prevention, and remediation; and/or the need to review current policy and reporting requirements.
How long will it take?
The survey takes 5-20 minutes to complete, depending on your experience with drift damage.
How will this data be shared?
Summarized survey data will be shared broadly with regulatory agencies, university educators and researchers, agricultural policy makers, grower support organizations, and the general public using news articles, report summaries, and peer-reviewed journal articles. While this study is administered by The Ohio State University, it was planned in partnership with industry experts across the region who will assist with sharing results. Participants may also request a copy of the study summary.
How will my data be used and protected?
Your privacy is important. No individual survey data will be released or shared beyond the limited group of project staff. The survey questions and procedures have been reviewed by the institutional review board at The Ohio State University and are designed to protect your data and identity. Additional details on privacy and confidentiality are provided at the beginning of the survey.
How can I learn more?
The North Central IPM Center’s special project group created a series of fact sheets on herbicide drift especially for specialty crop growers. The series includes: Overview of Dicamba and 2,4-D Drift Issues, Frequently Asked Questions, Preparing for Drift Damage, and Responding to Drift Damage. Fact sheets and more information about our special project group and study are available at go.osu.edu/ipm-drift.
This study is facilitated by The Ohio State University and is funded by the USDA National Institute of Food and Agriculture through agreement 2018-70006-28884.This study is being conducted in cooperation with regional universities and non-profit grower organizations, including Ohio State Extension.
By: Melanie Lewis Ivey, Assistant Professor, Extension Fruit Pathologist, Department of Plant Pathology
You probably noticed that in 2020 we did not publish an updated Midwest Fruit Pest Management Guide (although updates were added to the on-line version). This was because the Midwest Fruit IPM Working Group spent 2020 working on a new format for the guide. The new format is driven by a database and will allow the group to develop a mobile-friendly version of the guide. The printed copy of the guide will continue to be revised every other year, with critical updates/corrections made in real-time to the on-line version of the guide.
For the 2021-2022 publication changes were made to the apple and grape sections only. The new format provides users with same information as previous guides but is more concise and in our opinion easier to understand. Over the next two years we will transition the other crops in the guide to this format.
The grape and apple sections now include charts displaying pest emergence by stage and tables that incorporate product efficacy, REI, and PHI into the spray charts. The new charts (Figure 1) allow users to make side by side comparisons of products for efficacy and target pests throughout the crop season! Instructions on how to make the most of the new charts are also included.
Figure 1. Example of the new chart format in the Midwest Fruit Pest management Guide that allow users to make side by side comparisons of products for efficacy and target pests. Table layout and database development was supported by the USDA National Institute of Food and Agriculture, Crop Protection and Pest Management Program through the North Central IPM Center (2018-70006-28883).
We welcome your comments, criticisms and suggestions on the newly formatted apple and grape sections. A short on-line survey has been set up to collect your feedback. Even if you don't grow apples or grapes, we appreciate your feedback to improve the new layout design and its usefulness and effectiveness. The new layout for apple and grape will be applied to the remaining crops in the 2022 guide.
You can access the survey by scanning the QR Code below or you can click here. If you don’t have access to the internet and want to give us your feedback you can call an OSU Extension Specialist or your county Extension office. We will record and submit your feedback.
As with all pesticide spray guides, the recommendations for product usage (i.e., rate, PHI, REI, number of applications) are based on information provided in the product label. Remember, the label is the law!
How to get a copy of the 2021-2022 Midwest Fruit Pest Management Guide?
Download for free. To download a free digital copy of the 2021-2022 guide, click here (go.osu.edu/2021fruitpestguide)
Purchase from the Purdue Website. A print copy can be purchased directly from Purdue University at a cost of $15 (plus shipping) per copy.
Purchase from OSU. Print copies can be purchased directly from OSU at a cost of $15 per copy. There is no charge for shipping. Due to the state mandated COVID-19 restrictions in-person pick-ups are not permitted at this time.
You can request a print copy of the guide by contacting your county OSU Extension office or Dr. Melanie Lewis Ivey (firstname.lastname@example.org; 330-263-3849). Cheques should be made out to "The Ohio State University" and mailed to Melanie Ivey, Department of Plant Pathology, 1680 Madison Avenue, Wooster, OH 44691. Please do not send cash through the mail.
By: Imed Dami and Diane Kinney, Horticulture & Crop Science, The Ohio State University
This article summarizes the 2020 dormant and growing seasons and the impact of weather on grape varieties grown on the research vineyard at the OSU-OARDC in Wooster, Ohio.
2020 was a very different year from its very beginning. The first quarter of the year was unusually warm with mean January temperatures in the 30s. At our research vineyard, the lowest recorded winter temperature was 3.7 °F, which occurred on February 15th. However, the temperature trend was reversed during the second quarter, with both April and most of May having cooler temperatures than normal. A statewide frost event occurred the week of April 12th; temperatures dropped to 24.6 °F in Wooster on April 16th. We were fortunate to receive little injury as we had no budbreak at this time, but another drop in temperature to 29 °F on May 9th caused small amounts of injury to some primary shoots. June temperatures leveled out, but July temperatures were above normal and over 90 °F daytime maximum temperatures for 8 days. During the ripening period of August through October, temperatures were very moderate and on track with the long-term average. The killing frost occurred on November 13th. Both months of November and December followed the 2019 trend of being warmer than normal by 3-4 6 °F.
The 2020 precipitation changed drastically from the previous two seasons. The 2020 cumulative precipitation was only 34.24” (2.66” over the long term) vs. the very wet 2018 (44.5”) and 2019 (44.1”). Although we started off gaining over 8.9” by the end of March, July was very dry (more than 2” below the long-term average). Precipitation during ripening was a bit over normal but not excessive. Discounting rainfall from late winter/early spring, the season ended with below-normal precipitation.
2020 Spring freeze injury: We were fortunate to escape the winter months without winter injury. Thanks to a cool April, which slowed down budbreak, the April 16th freeze did not affect us in Wooster since grapevines had not broken bud at that time. After the May 9th temperature drop, we did observe a small amount of freeze damage to the earliest budbreak varieties, but not much due to the late bud break. The cool weather actually may have helped us during the COVID-19 restrictions and later than normal pruning practices.
Diseases and insects: For the most part, fruit remained clean throughout the growing and ripening season. There was some concern for berry shrivel during the drought months of July and early August but that was quickly remedied with ample rain following hurricane Laura. Timing harvest with small amounts of rain occurring resulted in sour rot in some susceptible varieties. We also observed significant bee and bird pressure in early September that likely contributed to sour rot development. As always, the Japanese beetles made their presence known but only small amounts of defoliation occurred when coupled with timely insecticide sprays in the vineyard.
Fruit quality: Our harvest season came fast and furious between the dates of September 1st and October 7th. Overall, yields were low for two reasons: newly established vines were still recovering from the winter injury in 2019; and the negative impact of the spring frost in May 2020. As shown in the table and figures below, sugars were lower and acids were higher than in previous years. This is likely related to the lower mean temperatures and GDDs than those in 2018 and 2019 during ripening. Nevertheless, based on tasting of berry juice at harvest, fruit flavors developed nicely and were characteristic of most red and white varieties.
2020 Harvest fruit composition of selected grape varieties at the Wooster research vineyard:
By: Maria Smith, HCS-OSU
In our last post, we announced the return of GeoVine, a GIS-based vineyard site assessment tool that is currently maintined by the Virginia Tech Center for Geospaitial Information Technology. This tool is supported for users in Virginia, Maryland, and now Ohio. The webinar on December 15 was recorded and can be viewed here. If, after watching the video and exploring the tool, you still have questions or suggestions for additional parameter estimates, please send your comments to email@example.com. The following write-up will provide my re-cap and experiences using the tool, benefits, and caveats to use.
Temporary site access for Ohio stakeholders: https://cgit04.cc.vt.edu:2002/vineyards/
So, let's get started...
What is GeoVine?:
GeoVine is a tool that aggregates publicly available data provided from regional weather stations, USDA soil surveys, and other databases to provide a broad overview of site suitablity for vineyard plantings. In essence, GeoVine simplifies the task of investigating your site's characteristics. It can provide valuable insights into climatic suitability for grape varieties and highlight factors that may impede the success of a new vineyard.
While GeoVine gives a good generalization of site suitability, it does not provide all site-specific information or recommendations that would be needed for properly preparing a site, such as soil analyses for fertilization/pH amendments and tile drainage recommendations. It is also limited in its ability to determine variety compatibility for your site. You are encouraged to consult with us, your County Extension, and County NRCS services for further details into your site and variety selection.
How to use Geovine?:
Loading the site brings you to this main page. The tool can be used without registering, however, registering an account enables editing of site boundaries and saving of all site vineyard reports.
Fig 1. GeoVine home page. Registration, login, and management of site reports can be found at the top in the red menu bar.
Developing a new vineyard report:
To obtain a new vineyard report, select “Vineyard Manager” in the top menu and click “New Vineyard” from the drop-down list. This page then shows you all current regions where GeoVine is available.
Fig 2. “Create a New Vineyard” page under “Vineyard Management”
Entering your site name or clicking on the state of interest allows you to locate your vineyard either through scrolling or (more easily), entering your address information in the top right corner of the page. Note: the view of the map itself can be changed to show satellite view, streets/roads, and current AVAs by changing the “Basemaps” and “Layers” that are shown.
Fig. 3 Locating your site on the map.
Drawing the boundary
Once you have found your site of interest on the map, you can select out the parcel for which you wish to develop a report by using the “draw new boundary” tool on the left side-menu. This boundary tool allows you to select any area that is a closed polygon, with a single mouse click indicating a new directional change, and a double-click (or click back on the first blue dot) to close the boundary. This boundary can then be edited or deleted if you wish to select a different area or modify the existing area. Note: You can only generate one report per boundary area. Other areas of interest within your sites will require you to create another “new vineyard”.
Fig 4. An example of a closed boundary created using the “draw boundary” tool.
Once you have clicked “done”, you can then generate a report for that area. According to Peter Sforza at CGIT-VT, this can take several minutes depending on the queue for their server use. In my experience, this is usually under 5 minutes, so please be patient with the spinning red ring!
GeoVine features the ability to provide daily forecasts for your site based on the closest regional weather station. This feature is automatically enabled but can be easily be turned off depending on your needs.
Understanding the report
Vineyard site reports contain approximately 18 pages worth of data, data sources, and convenient definitions so that you can interpret your own results. Again, the key to using this resource is to keep in mind that GeoVine output is only as good as the data sources that feed it. While GeoVine provides a very reasonable guide to base decisions, you are the ultimate final say in your site selection, variety selection, and planting preparation. Make sure you are using all of the available resources and references to you before finalizing your decisions.
Fig 5. Example cover page for Vineyard Report output
OK, so let’s review some of the major items to consider when interpreting the output from Geovine, starting from page 1.
- The site selection area is “planar”. Therefore, it does not represent topographical contributions to area. Use an accurate on-site survey for the proposed planting area. You will NOT be estimating correctly using the planar area on the page
- CEC, Bulk Density, organic matter, and pH are estimates from past soil surveys. Depending on previous land use and management, these values may differ. It is always recommended to obtain new soil analyses prior to planting and once every 3 years after planting to maintain your soil conditions for vine health.
- The climate data reflect averages dating back to 1980. Therefore, it will not account for weather extremes that have happened prior to 1980. It is also not site-specific microclimate conditions, which would require an onsite weather station. That means the climate data would not capture the propensity for some issues such as winter cold injury and spring frost, which are very dependent on the topography of your site (this info is included in the report, though!).
- The variety suitability list provided is not exhaustive and does not consider sensitivity to winter extremes (extremes and frequency of them are not provided in the report). The probability for events down to 14 °F are reported but remember that midwinter bud injury does not generally occur until temps < 0 °F in Ohio for the most sensitive Vinifera. Also, the variety list does not take into account your risk tolerance for seasonal variability. That means, in general, some varieties in the report may appear to not attain optimal maturity based on season length in an “average” year for your site, but if you are willing to accept that risk for the vintages that do and have a plan in the winery to deal with suboptimal fruit maturity, then that is your prerogative.
- Slope and land suitability: “Unsuitable” does not necessarily mean unsuitable – less desirable was considered the better term. However, > 15% grade should generally be avoided for planting just from a practicality standpoint.
That said, GeoVine is a very useful tool in determining GENERAL site and variety suitability. I have had a lot of fun playing around with it over the past week or so and have found it informative when considering issues that a grower may encounter with a potential site. Whether you are planting new acreage or are curious about your current site, we encourage you to take the time to thoroughly explore the tool. If you have any questions regarding your output, please do not hesitate to contact us
Thanks to the support of the Ohio Grape Industries Committee (OGIC), we are excited to announce the return of Geovine, an online tool from Virginia Tech that assists growers in evaluating vineyard site suitability. A webinar training on how to use the tool will be provided by the Center for Geospatial Information Technology at VT on December 15 from 10am to 11:30am EST. The registration details and link can be found below in addition to the "events" tab of the Buckeye Appellation website.
Topic: Ohio Geovine Training
Time: Dec 15, 2020 10:00am - 11:30am (Eastern Time)
Register in advance for this meeting, and provide any prior questions regarding GeoVine in the registration form:
After registering, you will receive a confirmation email containing information about joining the meeting.
Beginning in mid-December 2020, through funding provided by the Ohio Grape Industries Committee, the GeoVine application (https://www.geovine.org/) will be available for the State of Ohio to support vineyard site evaluation for soil, climate and topographic factors from various data sources. The Center for Geospatial Information Technology at Virginia Tech (https://www.cgit.vt.edu) will provide a live training and Q&A for Ohio stakeholders on Dec 15, 2020 10:00 AM - 11:30 AM (Eastern). Tutorial videos and example reports are currently available on the website for exploration prior to the training session. A recording of the training will be made available following the meeting.
By: Maria Smith, HCS-OSU
Yesterday, the Ohio Department of Agriculture released a press statement regarding the first population of the invasive Spotted Lanternfly (SLF; Lycorma delicatula) found in Mingo Junction along the Ohio River. Please view the statement below along with the following information for continued public monitoring for this insect over the winter months.
If you suspect a sighting of SLF in Ohio, file a report immediately with ODA at https://agri.ohio.gov/wps/portal/gov/oda/divisions/plant-health/invasive-pests/slf or by calling the ODA Plant Pest Control line at 614-728-6400. The link to high-resolution photos for media use can be found here.
Monitoring SLF into the fall and winter
Our goal is to delay SLF establishment within Ohio and minimize population growth. We can do this with public help in monitoring and reporting any suspected sightings of this insect currently in its adult form and throughout the winter months by being on the lookout for egg masses. It is important to be also be vigilant for any hitchhikers if you are planning to visit or have visitors/materials that have traveled from known regions with established SLF populations. A current map of SLF distribution may be found at https://nysipm.cornell.edu/environment/invasive-species-exotic-pests/spotted-lanternfly/.
To identify SLF, it's crucial to understand how it appears at various stages of its lifecycle. SLF exhibits only one life cycle per year, with adults that lay eggs beginning in the late summer through fall seasons. Adult SLF are approximately 1 to 1.5" in length with wings closed and 1.5 to 2" in length with wings open. They are known for their distinct coloring and patters (Image 1). During this time, live adults may be found feeding on a range of host plants, although their most preferred host is tree-of-heaven (Ailanthus altissima; Image 2). At the end of the female lifecycle, SLF lay gray, putty-like egg masses on trees or other hard surfaces such as grills, lawn furniture, trailers, etc. (Image 3). These egg masses may contain between 30 to 50 eggs which will hatch during the spring months. For additional details on identifying all life stages, please visit the OSU Extension SLF Factsheet at https://ohioline.osu.edu/factsheet/anr-83.
Image 1. Adult SLF wing open (top) and wings closed (bottom). Photos are sourced from the Pennsylvania Department of Agriculture (www.bugwood.org) and published in ANR-83 at https://ohioline.osu.edu/factsheet/anr-83.
Image 2. Leaves and seeds of tree-of-heaven, and invasive and weedy tree species from SE Asia. Image source and descriptions can be found at https://bygl.osu.edu/node/1346
Image 3: SLF egg mass example. Photo source: https://news.psu.edu/story/613936/2020/04/02/impact/extension-educators-offer-tips-managing-spring-spotted-lanternfly-egg
Each year grape growers report indicidence of herbicide drift injury in Ohio vineyards. Working together with you and DriftSense, we hope to eliminate one of the root causes of drift injury - bad herbicide application timing. The following is a message from Dr. Doug Doohan, Weed Specialist with OSU Horticulture and Crop Science, describing the goals of DriftSense. If you are interested in collaborating with us on this promising technology, please reach out to Dr. Doohan at firstname.lastname@example.org.
Over the past month I (we) have met on 4 occasions with colleagues from Israel who own and manage a company called DriftSense (https://www.drift-sense.com). DriftSense is a startup firm that is dedicated to helping growers and pesticide applicators reduce the risk of herbicide drift from row-crop fields to vineyards and orchards. They are developing a real-time tool that will forecast time periods when it is safe or unsafe apply herbicides, from the drift-management point of view. We think this technology will be of interest to commercial pesticide applicators and to owners/ managers of high value crops like grape. For you as a vineyard owner and operator the tool, when fully developed, will help you to communicate in real-time with adjacent property owners and applicators, providing them with a science-based risk assessment ie when it is safe or unsafe to spray herbicides. It should also be useful in conducting investigations of drift of uncertain origin and timing.
After listening carefully to their background information, the science and the technology behind DriftSense, I have agreed to reach out to several of my vineyard associates about participating in a validation exercise of their technology. Specifically I am reaching out to you because I know that you have been impacted from herbicide drift from a neighbor’s field. If you agreed to work with DriftSense, at no cost to you and no financial benefit to me or Ohio State University, their team would contact you and garner a few key pieces of information from you; your geographic location, the date and time (if known) of the drift event, and the herbicide involved. With these few pieces of information they will model the 48-72 hour time-periods before and after the drift event(s) you experienced. The outcome of the procedure will be a clear representation of how chemical, application technology, weather conditions, and local geography played into the drift you experienced and it will help DriftSense fine-tune their models and prepare to seek additional startup funding.
By: Maria Smith, HCS-OSU
Precipitation: Much of August has followed July, with warm, dry conditions. It has only been in the past couple of weeks that we have begun seeing a reprieve from this pattern (Fig. 1). Notably, southern Ohio has had several large storms come through, alleviating previous drought conditions (Fig. 2). In contrast, northwestern and portions of central Ohio have continued remaining dry.
Here in Wooster, we had a combined total of 4.25” of rain throughout August across 8 days of measurable precipitation. Approximately 30% of that accumulated total came from a single 1.31” event on August 28 from the remnants of hurricane Laura (www.newa.cornell.edu). Despite that event, Wooster and much of northern Ohio were still at or below the 30-year average precipitation for the month (Fig. 1).
Figure 1. Accumulated precipitation during the past 30 days (left) and accumulated precipitation departure from the 30-year average (right). Figures retrieved from https://climate.osu.edu/climate-tools/climate-maps-ohio.
Figure 2. Ohio drought monitor for 1 Sep 2020. Figure retrieved from https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?OH.
Temperature: A clear delineation between eastern and western Ohio could be made for temperature trends (Fig. 3). All but the northeast corner of northern Ohio continued July’s trend of above long-term average temperatures by 1-3 °F, while southern and western Ohio tended to be closer to average temperatures.
Figure 3. Maximum, minimum, and average temperatures during the past 30 days (top), and their respective departures from the 30-year average (bottom). Figures retrieved from https://climate.osu.edu/climate-tools/climate-maps-ohio.
In the vineyard:
Harvest has begun for several of the early-season varieties over the past couple of weeks. While we were grateful to get the rain to help stave off any potential berry shrivel from the summer drought, awaiting anymore right now seems to walk a fine line between “okay, this is fine” and “harvest that fruit now”.
The ability to wait out rain events should largely be determined around your fruit’s proximity to maturity, overall fruit quality (i.e., are the berries healthy and intact or are you noticing wounding, splitting, rot, or other issues that significant rain would worsen?), and the size of the anticipated rain event. Thankfully, the season has been generous so far in limiting disease pressure and allowing us to get to this point with overall healthy fruit. If you are new to tracking your fruit maturity and deciding your harvest date, please see our resources from Dr. Imed Dami and Diane Kinney: Fruit maturity factsheet and 2020 Fruit maturity updates - OARDC Wooster.
One concern for this fall that has recently caught my attention is bird pressure. Afterall, what would 2020 be without a real-life version of Alfred Hitchcock’s The Birds, right? Several growers have reported much higher than normal bird pressure and damage over the past couple of weeks. Indeed, I observed this myself during our first harvest with ‘Marquette’ last week where robins were seen trapping themselves up and under the fastened bird netting. The concern, of course, is both in yield loss and in creating wound sites for sour rot and Botrytis development. If you are in search of options for bird control, check out this comprehensive factsheet from UNH: https://extension.unh.edu/resources/files/Resource001797_Rep2514.pdf. In general, we advocate netting as the most traditional, reliable control method. However, we recognize that different operations have different limitations, and there are various methods on the market that are worth exploring.
Lastly, if you are planning for new vineyard plantings, now through October is an ideal time to get underway with vineyard site preparation. This includes tile installation, soil decompaction, plowing, weed control, pH and some nutrient amendments, and sowing ground cover. The soil is still very warm from the summer heat, but the cooling days should bring about higher soil moisture, which makes for easier cultivation and sod establishment.
With the aim to increase grape acreage across the state, the Vineyard Expansion Assistance Program (VEAP) is back and available to new and existing growers in Ohio!
Thanks to the support of the Ohio Grape Industries Committee, new and existing growers are eligible for up to $3000 per acre with a maximum of three acres or $9000. All applicantions must be postmarked by September 23, 2020 in order to be eligible for consideration.
Please click the following link ("2020 VEAP Application") below to find a copy of the full application. If you are unable to view this link and would like a copy, please email Maria Smith at email@example.com.
For any questions for related to the application itself or the VEAP process, please contact Christy Eckstein, Executive Director of the Ohio Grape Industries Committee at firstname.lastname@example.org.
By Maria Smith, HCS-OSU
Veraison, or the onset of ripening, marks the home stretch of the growing season (Fig. 1). At this stage, berries change colors, soften, and swell with water and sugars. During ripening, vines are heavily taxed by the fruit’s carbohydrate, water, and nutrient demands. In the case that one or more of these 3 vine resources are limited, both fruit maturity and vine vegetation can visibly suffer.
Fig. 1 Early veraison indicated by color change from green to red in Marechal Foch. July 27, 2020.
While this growing season hasn’t been as stressful for disease management as 2018 and 2019, we have had notably dry weather over more than a 2 month stretch. This has brought about “abnormally dry” to “moderate drought” conditions that now cover nearly 85% of the state (Fig. 2). For young vines, this has driven a need for irrigation throughout this growing season to aid in establishing root systems and canopy growth, and for both young and mature vines, a need to keep a closer eye on changes to vine nutrient status (Fig. 3).
Fig. 2: Drought conditions for Ohio, as of 7/30/2020 (source: https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?OH)
Chlorosis in basic terms means a yellowing of leaves due to the loss of chlorophyll (the molecules responsible for light absorption during photosynthesis). Several reasons may explain chlorosis, including nutrient deficiency and drought stress. Visual symptoms aid in detecting acute issues with the vine, but ultimately for remediating nutrient deficiencies, vine nutrient status should be assessed to determine whether and which deficiencies are the exact cause.
Why vine nutrient status? Soil testing is great for identifying availability and, in the case of pH, accessibility of nutrients (it should still be performed regularly every 3-5 years), but it does not tell you what is in the actual vine. That’s where petiole tissue testing enters. Long-term nutrient management is best when the two are used together to develop an annual fertilization management plan.
As a reminder, veraison is the preferred time to sample and test for vine nutrient status (regardless of symptoms) due to the relative stability of nutrient concentrations. For details on how to sample, recommended values and testing facilities, please see the following resources:
- OSU factsheet on Grapevine Nutrient Management: https://ohioline.osu.edu/factsheet/hyg-1438
- Taking foliar samples in vineyards and orchards (UMN Extension): https://www.youtube.com/watch?v=eyPs1rTFoNc&t=2s
Fixing nutrient deficiencies now. Is it too late?
Veraison is about the last point of the growing season that fertilization should be done to avoid delaying or harming vine acclimation in the fall. For acute deficiencies, foliar fertilization with soluble formulations is ideal for quickest uptake. Additionally, late-season foliar applications of urea (46-0-0), especially under drought conditions, may increase yeast assimilable nitrogen (YAN) in fruit at harvest. Stuck/sluggish fermentations and hydrogen sulfide by-products that generate “rotten egg” aromas can often be attributed to low YAN. However, baseline YAN values for a given cultivar and site should be understood before using foliar urea as a means of adjusting YAN values in fruit.
Foliar applications are temporary band-aids and do not adequately address chronic deficiencies. It is best to avoid deficiencies altogether through routine monitoring of soil and vine nutrition and annual soil fertility maintenance.
The list below addresses commonly observed deficiencies and remediations via foliar fertilizing. These recommendations are only intended as a short-term solution to situations where deficiencies have been clearly identified through tissue testing and/or visual symptoms. In general, a healthy vineyard with routine soil fertility maintenance does not benefit from additional foliar fertilization, and its use may create unnecessary management costs. We additionally suggest avoiding the use of commercial mixed-nutrient products for foliar fertilizer, as they may either provide insufficient quantities of a target nutrient or unnecessary additions of others. When applying any fertilizer, applicators must be careful in calculating rates to avoid excess fertilization and, with foliar application, burning vines. Tank mixing foliar fertilizers and pesticides may cause phytotoxicity. Consult all labels and/or spot-test before applying to all vines.
- No. applications: 3x
- Rate: 5 lbs urea (2.3 lbs N) per 100 gallons water, applied at 200 gallons per acre
- No. applications: 1x
- Rate: 6-10 lbs potassium sulfate (0-0-53) or chloride (0-0-63) per 100 gallons water, apply at 200 gallons per acre
*Note: excess K additions can result in Mg deficiencies and lead to high pH in fruit.
Phosphorous (P): Foliar application is not recommended
- No. applications: 2x, 1 then again after 2 weeks (bloom time preferred for first application)
- Rate: 16 lbs Epsom salts per 100 gallons water, applied at 200 gallons per acre
- No. applications: 2x (pre-bloom to bloom time preferred for application)
- Rate: 1-2 lbs Solubor (20% B) per acre