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Recent Blog Posts

By: Doug Jackson-Smith, SENR OSU

The Ohio Grape Industries Committee (OGIC) recently asked researchers at the Ohio State University (OSU) to carry out a full census survey of growers who grew grapes in Ohio in 2021.  This report was designed to capture the acres and estimated production of various grape varieties in Ohio, and updates a report last issued by the USDA in 2017. The survey was completed by 148 farms (an 83% response rate), and documents 112 varieties raised on 1,222 acres across 55 counties (including 95 acres of newly planted vines). The results are interesting and can help grape growers and processors plan for the future. To see a copy of the full report in PDF – click here. A copy of this report and the technical appendix will be hosted under the Grape Growers tab of the Buckeye Appellation website. Questions regarding the survey and results can be directed towards Doug Jackson-Smith at


Posted In: Viticulture
Tags: Grape Census, Viticulture, Surveys, 2021 Season
Comments: 0

By: Tom deHaas, AGNR Extension Educator Erie County, intro by Maria Smith, HCS-OSU

The following are republished updates from Tom deHaas on scouting and treatment efforts for the invasive Spotted Lanternfly (SLF) in northeast Ohio from June through August 2022. Currently, SLF infestations have been identified in 3 Ohio counties: Lorain, Cuyahoga, and Jefferson (Fig 1). However, individual SLFs have been found in other Ohio counties, and SLF infestations have been identified in Indiana and Michigan. Our collective goal continues to be limiting spread and minimizing population sizes by immediately reporting any suspected finds to the Ohio Department of Agriculture.

Fig 1. Distribution of SLF updated August 24, 2022. Image from New York State IPM

You'll see a recurring theme in this post, and it's SCOUT! SLF's appearance is most easily identifiable now that we are entering the time of year when SLF adults are emerging. In general, SLF are being found first on its main host, Ailanthus altissima (tree-of-heaven), but in some areas, as reported by Tom below, are also being found in grapes. Because of SLF's high affinity for grapes, it's important to add SLF into your routine vineyard scouting, since many Ohio vineyards are near rail corridors that may carry SLF and receive visitors from areas with known infestations. To aid scouting efforts ODA has provided a downloadable PDF checklist  of common items to inspect, especially if those items are coming from or going to counties with infestations. If you have further questions on the information provided below, please feel free to reach out to Tom deHaas at


Scouting and Spraying for Spotted Lanternfly in late June 2022 (Jul 6, 2022)

Multiple partners from Ohio Department of Agriculture, United States Department of Agriculture-Division of Forestry, The Ohio State University, Cleveland Metroparks, and USDA – APHIS (Animal and Plant Health Inspection Service) assemble to scout for Spotted Lanternfly in potentially infested areas in and around Cleveland – Cuyahoga County including Mill Creek Metropark, Paramelt, and St Joseph Cemetery. Additionally, and area in Amherst located in Lorain County was inspected and sprayed.

The group assembled on Tuesday, June 28th and 29th. Agency participation included from ODA, Dave Adkins and Scott Chelsa, USDA Division of Forestry Zoe Crist, Joe Ball, Ivich Fraser, and Taylor Dawes, USDA-Aphis Avi Eitam and Mark Hitchcox, Cleveland Metroparks Connie Hausman and Sarah Eysenbach, The Ohio State University Jim Jasinski, Ashley Leach, and Thomas deHaas. Scouting occurred on Tuesday and Wednesday.

The group surveyed Mill Creek Park on Tuesday morning. Visual inspections and trapping were used. A small number of 2nd instar nymphs were found at the site.

Next some of the group inspected Paramelt, a processing plant near West 117 in Cleveland. A number of nymphs were discovered including several 4th instar nymphs. Most numphs were found feeding on Tree of Heaven, but some were found on grapevines. Honeydew was present on several grape leaves

Next Saint Joseph Cemetery on the near east side of Cleveland was searched. A large population of nymphs was detected. The majority were found feeding on Tree of Heaven. They seemed to congregate in groups on the central leader as well as on the midvein of the leaves.

Finally, Amherst was scouted, and several nymphs were detected,

The sites at Paramelt, St Joseph and Amherst  were all sprayed to help control the spread.

Please continue to look for Spotted Lanternfly and contact Ohio Department of Agriculture if you detect it. Remember to take a picture and mark the location.

The following is a short video showing scouting and spraying:

We need your help. Keep Scouting!!!


City of Cleveland trains staff to scout for Spotted Lanternfly (Aug 11, 2022)

Cleveland Urban Forestry, Cleveland Division of Park Maintenance, Cleveland Metroparks, and The Ohio State University Extension Team Up to Teach employees to ‘SPOT’ Spotted Lanternfly.

Field Operation Forman, Arborists, Park Maintenance Staff, Unit Leaders and Managers from Cleveland spent Thursday afternoon, learning how to scout for Spotted Lanternfly at an active infestation at Mohican Park in Cleveland.

Jennifer Kipp-Cleveland Urban Forestry, Perrin Verzi-Cleveland Division of Park Maintenance, Connie Hausman and Megan Powell-Cleveland Metroparks, and Thomas deHaas-The Ohio State University Extension, led a tour of the infestation. Over 20 staff attended which is a credit to the leadership of the group.

Staff saw up close Adults and 4th instar nymphs on Tree of Heaven and on Grapevines and were able to see where they were feeding.

The goal was to teach how to scout and identify Spotted Lanternfly and favored host plants.

The insect will not bite but has been known to negatively impact vineyards in Pennsylvania.

Staff was provided ID cards with a QR code to send reports to the Ohio Department of Agriculture.

Many scouts will help identify locations of infestations.



Treating Spotted Lanternfly in Cleveland (Aug 25, 2022)

Ohio Department of Agriculture sprayed an infestation of Spotted Lanternfly on the West Side of Cleveland at Mohican Park.

An infestation was detected several weeks ago and the City of Cleveland – Division of Forestry, granted permission to spray the invasive pest.

Several hot spots were detected and treated to help control the spread of Spotted Lanternfly.

Scouting for the pest continues with help from the Ohio Department of Agriculture, Cleveland Metroparks, City of Cleveland, and The Ohio State University Extension.

Adults were found on Tree of Heaven and on Wild Grape vines. The pest continues to spread and threatens grape growers and orchards.

The insect will not hurt people but sucks the life out of fruit trees and vines.

Continue to look for the insect and report findings to ODA at 614-728-6400.


Posted In: Insect management, Viticulture
Tags: SLF, Viticulture, Entomology
Comments: 0

By: Imed Dami, HCS-OSU

In early June, members of the OSU Grape Team, Andy Kirk, AARS manager and Andrew Holden, Extension educator, visited vineyards in Lake and Ashtabula counties (NE-OH) and reported extensive cold injury ranging from bud to trunk injury (Figure 1). The cold events (temperature in low to high-20s) at the end of April were initially to blame. Even though these temperatures are lethal to young emerging shoots as it was observed in central and southern Ohio, this was not the case in northern Ohio since most buds were still closed. Therefore, we suspect that previous and successive cold events since January through March were the culprit for the extensive damage. The warm spells in late February and early March accelerated the timing and magnitude of deacclimation (loss of cold hardiness). Figure 2 shows the minimum temperatures in January that ranged between 0 and -11F. I doubt those temperatures had caused extensive damage in most varieties (except the most tender vinifera). So the extensive damage is unlikely from the January events. Figure 4 shows the lowest temperatures in late April that occurred mostly in NE-OH. Those temperatures may be lethal to early bud-breaking varieties, but most varieties did not break buds yet in late April. Figure 3 shows the lowest temperatures in March that ranged between 13.6 and 20.6F. Those temperatures likely caused the extensive damage. Figure 5 shows daily minimum and maximum temperatures of 2021 and 2022 at the AARS in Kingsville. Note warmer February in 2022 than 2021, and peaks of maximum temperatures (70s) in mid-March followed by sudden drop to 15.2F then 18.3F at the end of the month. Even though we don’t know the level of deacclimation in each variety, the low temperatures in the mid-teens were likely lethal. Furthermore, there was a large swing of temperature from 85.3F on April 24th to 28.2F on April 29th, which could have been damaging to buds in the early stages of development. Maria Smith and Andy Kirk also observed more damage in low lying vineyards and those with southern aspects (exposure), which tend to intensify deacclimation (due to excess heat accumulation) and hence exacerbate cold damage.

Regardless of the origin of the damaging cold events, vines sustained shoot damage, bud damage, or damage to the vascular tissues (cane, cordon, trunk). The following section describes the steps to take to address each type of cold damage.

Managing cold damage of frosted shoots: recommendations for managing the vineyard in the event of frost damage can be found in the APRIL 2020 OGEN.

Managing trunk damage: It is an ideal time now to assess trunk damage. The abundance of sucker growth is an indication of trunk damage. In 2014-2015, we experienced one of the worst cold damages to vineyards across Ohio. We conducted several trials to determine the best management practices after cold injury. The following are highlight of our findings and recommendations:

  • Train all suckers (Figure 6) produced by each vine. Do not keep 2 suckers per vine as this would promote bull growth in mature vines which is undesirable. 
  • Fan training (Figure 7): suckers can be trained vertically and onto a fan shape. Shoots can be kept straight by tucking them between the catch wires. This training promotes good exposure of shoots to sunlight and good penetration of fungicides. Labor is also minimized with this training as vines do the training by themselves.
  • Dead trunks and cordons can be removed with loppers during this season. Cut back trunks to 6-8” stumps to avoid fungal disease infection caused by Eutypa and other pathogens. Stumps can be removed later in the summer.
  • No need to train shoots to horizontal position to establish cordons for next season. It is best to save this job for next season when pruning.
  • Next year when pruning, you could select the best two canes as your new trunks. These canes will have medium size diameter, fully hardened-off, and disease-free.  Remove bull canes. The optimum-sized canes can be laid down on the fruiting wires to establish the new cordons. Once laid down, cut back each cane to about 24” (or 10-12 buds, whichever is the shortest) in each side. This practice would avoid apical dominance growth.

Finally, make sure you contact your local FSA representative and report damage. You need to document the damage. In 2014, we developed a factsheet that shows different types of vine damage. Please visit this link Assessing cold damage in early summer to read or download. It is also used by FSA reps to assess freeze damage.

As always, please do not hesitate to contact our Grape Team (Gary Gao, Andy Kirk, Maria Smith and Imed Dami) if you have any questions regarding managing vines after cold damage.

Figure 1. Cold damage of Cabernet franc grapevine grown in NE-OH. Note growth of suckers at the vine base. Photo by: Maria Smith.

January 2022 Minimums

Figure 2. Minimum temperatures in January 2022 and corresponding dates of occurrence in parentheses. Note that minimum temperatures ranged between 0 and -11F with lowest in northern Ohio (west to east). Source: Dr. Aaron Wilson, OSU state climatologist.   

Figure 3. Minimum temperatures in late March 2022 and corresponding dates of occurrence in parentheses. Note that minimum temperatures ranged between 13.6 and 20.6F with lowest in NE-OH. Source: Dr. Aaron Wilson, OSU state climatologist.  

Figure 4. Minimum temperatures in late April 2022 and corresponding dates of occurrence in parentheses. Note that minimum temperatures ranged between 24.7 and 34F with lowest in NE-OH. Source: Dr. Aaron Wilson, OSU state climatologist.

Figure 5. Daily minimum and maximum temperatures in 2021 and 2022 at the AARS in Kingsville.

Figure 6. Sucker growth is an indication of trunk injury. Keep all suckers when retraining new trunks for following season. 

Figure 7. Suckers of Cabernet franc trained on fan shape system during summer after trunk cold injury.


Posted In: Viticulture
Tags: Cold injury, 2022 Season
Comments: 0

By: Maria Smith, HCS-OSU

This past week, I have received several questions on when, where, and what to shoot thin (ST), so now is the perfect time to highlight the importance of this practice. In 2017, I co-authored an in-depth article on shoot thinning with Dr. Michela Centinari at Penn State that can be used as a cited companion resource to this blog post.  

Shoot thinning is the first important canopy management practice following dormant pruning, especially throughout Ohio and the Eastern US where high humidity, temperatures, and precipitation pose significant challenges to vigor control and disease management. This practice reduces the density of the canopy through the selective removal of excess shoots, in turn opening the canopy to increased sunlight exposure and airflow. The main benefits of ST include:

  • Reduce excess yield and decrease fruit shading, thus improving fruit composition at harvest  
  • Improved winter bud cold hardiness through increased sunlight exposure during bud development
  • Lower disease pressure due to a less humid, faster drying canopy environment and, again, more sunlight penetration through the canopy

Timing ST:

ST is best performed when shoots are between approximately 6-12” in length  and, if possible, following the last date of frost. However, as Hickey, 2021 noted, constraints for timing ST may be dependent on labor availability. Also, hybrid varieties can be thinned before Vinifera due to the highly fruitful nature of secondary and latent/basal buds in the event of a spring frost. Very early ST (< 4”) can reduce the practice benefits by inducing emergence of secondary and latent buds, while late ST (> 12”) can be difficult due to the lignification of the shoot base. Late thinning should be performed using pruning shears to reduce injury to the vine.

As of this week (5/16/22), we are approaching the start of the window for shoot thinning at Unit 2 in Wooster (Fig 1).

Fig 1. Shoot growth at E-L stage 12 on 5/14/22 on Marquette. At this stage, shoots are about 5 leaves unfolded and 4” in growth.

Density of shoots:

For the sake of speed, keep in mind that these are estimates and visual inspections are sufficient as you are thinning. Only in academia will we stand around precisely counting shoots!

  • Vinifera: 3 to 5 shoots per foot of cordon (= 18 to 30 shoots per vine at 6’ spacing)
  • Hybrids: 4 to 6 shoots per foot of cordon (= 24 to 36 shoots per vine at 6’ spacing)
  • Native or Labrusca varieties: up to 15 shoots per foot of cordon (= up to 90 shoots per vine at 6’ spacing)

As Dr. Patty Skinkis mentioned at the OGWC in February, spur vs. cane pruning tends to shift labor demands in the vineyard: spur pruning, while quicker to perform during dormancy, often requires more labor for ST than cane pruning. This is because spurs from older cordons tend to produce latent shoots that require removal, while cane pruning will typically produce one, or occasionally two shoots depending on secondary bud break, at each node position along the cane (Fig 2, Fig 3).

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Fig 2. Shoot density of 2-bud spur (left) vs. canes (right). Note: increased density often arises from latent buds of older cordon wood or on vines with excessive bud retention in spur-pruned vines. Photos from Unit 2, Wooster. 5/14/22

Fig 3. Ideal shoot density, representing approximately 4 shoots per 1’ of space in V. vinifera Chardonnay. Photo from Unit 2, Wooster. 5/14/22

What shoots to keep/remove?

In a spur-pruned vine, the fruitful primary shoots from count nodes 1-2 on each spur should be prioritized (Fig 4). If a spur is becoming stacked, one well-positioned healthy shoot closer to the cordon may be prioritized for spur renewal. Fruitless basal and latent, diseased, weak-growing, and poorly positioned shoots should be the first to go, especially in highly dense portions of the canopy (Fig 5).

Lastly, unless retaining a shoot for potential cordon or trunk renewal, vine trunks should be suckered to prevent dense growth from shading the fruitful shoots (Fig 6). This can be accomplished easily at the 6-12” shoot growth stage by simply running a hand down the trunk of the vine to remove excess shoots.

Fig 4. Shoot emergence on a 3-bud spur on V. vinifera Cabernet Franc. 5/14/22, Unit 2, Wooster. Note: shoots that emerge on “non-count” buds are often fruitless in Vinifera and can be thinned. Fruitful shoots from nodes 1 and 2 should be prioritized for retention due to proximity to the cordon.

Fig 5. Example of a weak, fruitless latent shoot that should be removed during thinning

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Fig 6. Example of a vine with dense growth on the trunk that requires suckering to remove the excess shoots and prevent canopy shading. 5/14/22, Unit 2, Wooster

Posted In: Viticulture
Tags: Viticulture, Best Practices, Shoot thinning
Comments: 0

By: Maria Smith, HCS-OSU

Finally! In the past week, the sun’s come out and so have the growing degree days (GDD). In fact, we have added 80 GDD (base 50 F) in Wooster since Monday alone. We pay so much attention to GDD because it is the primary driver of phenological development for plants. But did you know that it also determines insect lifecycles as well?

…It does, and we can use it to take advantage of when to monitor and manage insect pests in the vineyard. And even if not in the vineyard yet, like Spotted Lanternfly (SLF), we should still be taking advantage of GDD to know when we need to look for various life stages on major host plants.

SLF Egg Hatch prediction map

As of today, SLF range anywhere between about 1% hatch through 100% hatch, depending on location in the state (Fig 1).

Fig 1. SLF Percent of predicted hatch, from

What should you be on the lookout for?

Currently, Ohio has 3 known counties with SLF populations: Cuyahoga, Lorain, and Jefferson counties (Fig 2). We expect egg hatch to be further along in Jefferson County than in the more northern Lorain and Cuyahoga counties. It is not unreasonable to suspect that there are other populations out there yet to be identified, therefore it would be prudent to regularly scout for tree-of-heaven (Fig 3) and SLF (Fig 4, 5). At this early point in the season, if you find SLF, you're most likely to encounter older or hatched egg masses (Fig 4) or early instar nymphs (Fig 5). In contrast to egg masses (immobile) and adults (large, showy), newly hatched nymphs are small and mobile, and more difficult to find (Fig 5). At this stage, the first instar nymphs are approximately ¼” in length with black and white spots. They are easily confused with other small insects, but to me look most like ticks. If you have a regular tree-of-heaven that you scout and would like to capture nymphs, using circle traps is one of the preferred methods for catching early SLF nymphs. Circle traps can be purchased through Great Lakes IPM or can be made DIY.


Fig 2. Current SLF distribution map, March 28, 2022. From

Fig 3. Tree-of-Heaven stand (left) and trunk (right), found near downtown Wooster, OH, October 2021. Tree-of-heaven has shallow-fissured, greenish-brown bark, large compound leaves with two terminal leaflets, and persistent, prolific number of seeds on female trees that develop mid-summer.

Fig 4. SLF egg masses at various ages and coverings. Photo from:

Fig 5. Early instar nymph, SLF, Photo: L. Barringer, PA Dept. of Agriculture,

Increasing the search beyond tree-of-heaven (republished from ODA):

Spotted Lanternfly (Lycorma delicatula) has been identified on 172 hosts, some of which were determined to not be hosts on which feeding occurred.  Through survey and research observations, there are several hosts on which SLF life stages are seen in higher frequency.  Listed below are the hosts which can be surveyed to increase the potential for detection of SLF.  SLF population levels and life stage will affect visual survey efforts with lower populations and early instars being more challenging to detect even with the higher frequency hosts at the time of survey.

Egg mass hosts are not listed in terms of high frequency of occurrence as egg masses can be found on many different tree and plant species as well as inanimate objects.



Penn State Extension Spotted Lanternfly website, Spotted Lanternfly Management for Residents, Landscape Professionals, Vineyards

Houping Liu, Seasonal Development, Cumulative Growing Degree-Days, and Population Density of Spotted Lanternfly (Hemiptera: Fulgoridae) on Selected Hosts and Substrates, Environmental Entomology, Volume 49, Issue 5, October 2020, Pages 1171–118

Houping Liu, Richard Hartlieb, Spatial Distribution of Lycorma delicatula (Hemiptera: Fulgoridae) Egg Masses on Tree-of-Heaven, Black Walnut, and Siberian Elm in North America, Journal of Economic Entomology, Volume 113, Issue 2, December 2019, pages 1028-1032.

Joseph Keller, J. Rost, K. Hoover, J. Urban, H. Leach, M. Porras, B. Walsh, M. Bosold, and D. Calvin, Dispersion Patterns and Sample Size Estimates for Egg Masses of Spotted Lanternfly (Hemiptera: Fulgoridae), Environmental Entomology, Volume 49, Issue 6, October 2020, pages 1462-1472.

Lawrence Barringer, Claire M Ciafré, Worldwide Feeding Host Plants of Spotted Lanternfly, With Significant Additions From North America, Environmental Entomology, Volume 49, Issue 5, October 2020, Pages 999–1011.


If you suspect presence of SLF, report your findings to the Ohio Department of Agriculture by calling 614-728-6400, emailing plantpest@agri.ohio.gove, or filling out the online report. Sightings of all invasive species in Ohio can be reported using the Great Lakes Early Detection Network App, which can also be used to report repeated negative or positive findings of tree-of-heaven and SLF. Please take photos and exact locations (GPS, identifiable landmarks, etc.) to file with your report.

Posted In: Insect management, Viticulture
Tags: SLF, Entomology
Comments: 0

By: Maria Smith, HCS-OSU

Following last weekend’s warm weather, bud break has arrived in many early varieties (e.g., Marquette, La Crescent, Itasca, Marechal Foch). These varieties are now more vulnerable to freeze and frost events since more developed shoots are progressively less tolerant of temperatures below 32 F (Figure 1, Table 1).

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 Figure 1. Bud break, E-L stage 4, Monday, April 25, 2022. Photo credit: Diane Kinney

Table 1. Estimated critical temperatures (°F) of Pinot noir at different stages of bud/shoot development



Bud break

First leaf

Second leaf

Third leaf

Pinot noir







Once again, Ohio is forecast for widespread frost and freeze through Saturday (Figure 2).



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Figure 2. Freeze warnings and forecast temperatures for Apr 27, 2022. Figures from

Thanks in part to the persistent cold temperatures throughout March and April, overall bud break is behind where we were at this time in both 2020 and 2021, which means total expected damage should likely be lower relative to the past 2 years. However, if your vineyard might be affected by the upcoming frost/freeze advisory, reviewing options for protection may be helpful in mitigating damage this week and in future spring cold injury events.

Be prepared - Resources on spring frost protection and recovery:

Spring frost is a topic we have covered extensively in 2021 and 2022. We have republished guidance here, and more detailed information can be found in the newly published Bulletin 920: “Spring Frost Injury of Grapevines and Protection Methods”

Methods prior to frost event

  • Delayed pruning: similar to 2020, vines have more advanced phenology than normal and buds are pushing earlier as a result of above average temepratures. Delayed pruning helps with delaying budbreak.
  • Double-pruning: the rationale is similar to delayed pruning. With 1st pruning, you leave extra buds per vine. Due to apical dominance, apical buds push earlier than basal buds. If frost occurs, basal buds (which are delayed in growing) will be less likely to be injured. With the 2nd pruning, apical shoots (injured or not) will be pruned by retaining a final bud count per vine. Note: the 2nd pruning should occur when apical shoots are less than 2" in total growth to avoid potential issues with fruitless shoots developing from the basal buds regardless if you are past the last date of freeze.
  • Row middle and cover crop: bare ground in row middles provide more heat to keep vines warm during a frost event. Mowed grass cover crop will also do the same. So, it is crucial that you mowed your grass as short as possible for added frost protection.
  • Products that delay budbreak: Some products can be effective, but it is too late to apply now if you have not already done so. Please view the recorded webinar presentation with Dr. Imed Dami (link) for an overview of the available budbreak delay products.  
  • KDL (0-0-24) fertilizer: Even though growers would like to use this product, research has shown that KDL does not protect shoots against frost injury once vines resume growth. Therefore, it is not recommended. Dr. Smith researched this product and can be contacted directly for more information.
  • Copper: has been shown to protect young shoots against frost injury by killing ice forming bacteria present on vine foliage. You may start spraying as soon as budbreak and repeat every 5-7 days (washes off easily and must be reapplied after an inch or more of rain) until you’re out of the frost threat period (2 – 3 weeks) in your vineyard. Read the label for the application rate. In CA, 0.75 actual copper per acre was used. Read the label to avoid plant injury. To avoid injury, apply when not cold or wet (slow drying) and use formulation with lime.

Methods during a frost event

  • Wind machines: wind machines, although expensive, are effective against radiative spring frost events (clear, cold nights with temperature inversions).
  • Overhead irrigation (sprinklers): None of our growers in OH has this system. Having said that, DO NOT SPRAY YOUR VINES WITH WATER USING A SPRAYER. You will cause more damage than doing nothing.
  • Heaters: same as above; not a common method in Ohio. When temperature inversion exists, heaters are effective alone and best with wind machines. However, cost of fuel and pollution are main limitations.

Since threats of below freezing temperatures can persist into May, it is a good idea to also review the recommendations for managing the vineyard in the event that freeze causes shoot injury. Those recommendations can be found in the APRIL 2020 OGEN.

Posted In: Viticulture
Tags: 2022 Season, Spring Frost
Comments: 0

By: Imed Dami, Diane Kinney, and Megan Soehnlen, HCS-OSU

Last week, we experienced one of the coldest temperatures since 2019 and minimum temperatures ranged between 1F and -12F across the state.  On January 22nd, temperatures dropped to -4.4 F (for few minutes only) and -9.2F at the OARDC in Wooster and the AARS in Kingsville, respectively. The good news is that these temperatures occurred during the maximum cold hardiness of grapevines. To address growers’ concern about the impact of this cold snap on grapevines, our group conducted freezing tests in the lab to assess cold hardiness status of several grape varieties. We found that grapevines, in general, had achieved “good” cold hardiness despite a mild December. In fact, cold hardiness expressed as LT50, or temperature that kills 50% of primary buds, ranged between -4F (most cold tender vinifera) and -16F (most cold hardy hybrids).  Based on this information, grapevines most likely sustained minimum to no bud injury following the freezing event on January 22. To verify that claim, and on January 24, our group collected canes and visually assessed bud injury of the most cold tender varieties grown at the OSU research vineyard in Wooster. Vitis vinifera varieties Arneis and Verdejo sustained 8% and 10% primary bud injury, respectively, with no injury of secondary buds.  

We may have dodged the bullet from the January 22 event. However, we are not out of the woods yet as we still have four more weeks of potential damaging cold events. The status of bud injury reported here is only valid up to January 24th. In other words, % bud injury could remain the same as of January 24th or increases if damaging temperatures occur again. In both situations, it is important this year to assess bud damage prior to pruning. 

Information on assessing winter damage and pruning adjustment are from previously published articles in OGEN and excerpts are listed below. Most information is from the book titled “Winter Injury to grapevines and Protection Methods” which I strongly recommend (online order: ). 

  • Prune cold hardy varieties that break buds late then those that break buds early and finally most tender varieties last. 
  • Collect enough canes to yield 100 “representative” nodes per variety.  By representative I mean evaluate nodes that you would otherwise retain as spurs or canes when pruning. 
  • Place canes indoor to thaw for 48-72 hours.
  • Using a sharp razor blade, cut across the bud tip at a third or half of its height.
  • Visually assess if the primary bud (largest size) is alive (green color) or dead (brown). You may also evaluate the status of secondary buds if many primary buds are dead.
  • We have added photos and links to You-Tube videos to assist with assessing bud winter damage (see below). 
  • A data sheet could be used to record and compute bud mortality as a percent.
  • Conduct bud damage assessment for each variety separately and sometimes for each block of same variety separately (for example one block of chardonnay on top of the hill will likely have different bud damage than a block of same variety at the bottom of the hill).
  • If primary bud damage = 0 to 14%, then no adjustment of pruning is needed.
  • If primary bud damage = 15 to 34%, then leave about 35% extra buds.  For example, if you prune to leave 30 buds/vine, and bud damage = 20% then leave an extra 35% or 40 buds/vine.
  • If primary bud damage = 35 to 50%, then double the number of buds retained.
  • If primary bud damage >50%, then it is best to minimally prune vines by hedging. 
  • Generally, basal buds (buds on the basal positions of the cane) are more cold hardy than distal buds.  Thus, it is best to increase the number of spurs per vine than buds per spur when adjusting bud number per vine.
  • Note that hybrids with fruitful secondary and base buds will produce a normal crop even with relatively high % primary bud injury.  Examples include, DeChaunac, Seyval, and Vidal.

Video links for assessing bud injury:

Posted In: Viticulture
Tags: Winter Injury, Viticulture
Comments: 0

A new factsheet series developed by Dr. Erdal Ozkan, our Extension State Specialist in the Department of Food, Agricultural and Biological Engineering (FABE) is now available on-line.  The series includes seven factsheets each covering a specific topic associated with effective and efficient spraying in orchards and vineyards. The topics include: best practices for effective spraying, selecting the right type and size of nozzles, strategies to minimize spray drift, strategies to maximize pesticide deposit and coverage on target, Calibration and adjustment of sprayers, new developments in spraying equipment, and overall best practices for effective and efficient spraying in orchards and vineyards. A list of all seven factsheets with links is provided below.​

This series of Fact Sheets is the most complete collection of all the essential aspects of spraying in vineyards and orchards. For example, Sprayers for Effective Pesticide Application in Orchards and Vineyards (FABE-533) provides details, with 41 photographs, about some of the different sprayers that are used to spray fruit crops. It is the first factsheet of its kind in the United States with information in one single publication on different kinds of sprayers: hydraulic, air-assisted, sprayers with adjustable spouts, multi-row adjustable sprayers, tower type airblast sprayers (Figure 1), air-assisted sprayers with multi-head fans, tunnel sprayers, and pneumatic air shear sprayers.  Another unique factsheet (FABE-538) gives information on advancements in orchards and vineyards. All the best practices one can follow to achieve best efficiency and effectiness in spraying vineyards and orchards. If you have not calibrated your sprayer because you think it is complicated, and if you want to use the air assist provided by airblast sprayers, you should take a look at FABE-537 which covers both topics: an easy way to determine the actual gallons per acre application rate, and adjustment of air flow to achieve maximum deposit of pesticides on the target while minimizing spray drift.

Although it is possible to get printouts of these publications once you reach them online using the links given below, Dr. Ozkan is currently working on designing user friendly print versions of the factsheets.  These factsheets will be available on-line sometime in February.  For more information of the factsheet series please contact Dr. Ozkan (


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Figure 1. One of the several tower-type airblast sprayers as shown in the factsheet Sprayers for Effective Pesticide Application in Orchards and Vineyards (FABE-533) by E. Ozkan and E. Gill


FABE-533: Sprayers for Effective Pesticide Application in Orchards and Vineyards

FABE-534: Selecting the Right Type and Size of Nozzles for Effective Spraying in Orchards and Vineyards

FABE-535: Strategies to Minimize Spray Drift for Effective Spraying in Orchards and Vineyards

FABE-536: Strategies to Maximize Pesticide Deposit and Coverage for Effective Spraying in Orchards and Vineyards

FABE-537: Calibration of Orchard and Vineyard Sprayers

FABE-538: Advancements in Technology for Effective Spraying in Orchards and Vineyards

FABE-539: Best Practices for Effective Spraying in Orchards and Vineyards


Posted In: Viticulture
Tags: Viticulture, Sprayers, Pest Management
Comments: 0

By: Imed Dami and Diane Kinney, HCS-OSU

This article summarizes the 2021 dormant and growing seasons and the impact of weather on grape varieties grown on the research vineyard at the OSU-OARDC in Wooster, Ohio. 

Weather: Temperature

Our weather trends for 2021 were nearly identical during January and March to 2020 with very warm temperatures.  We had a slight drop during February with a recorded low in Wooster of -2.4 oF on the 17th.  That was our lowest temperature for the winter months.  We were fortunate to avoid any spring frost events. Temperatures during the ripening period of August through October remained above the long-term average. October temperature was nearly 8F above average, which was ideal for fruit ripening. The fall killing frost occurred on November 3rd in Wooster. The year ended with nearly 10F above normal in December which is not ideal for vine cold acclimation.

Weather:  GDD

In comparison with 2020, although our average daily temperature was about 8 degrees warmer in January for 2021, we did not gain any GDDs until March.  But we doubled the average that single month.   In October, GDD (300) were more than double the 30-year average. Warm temperatures during the ripening season pushed us well above both 2020 (3000 GDD) and the 30-year average (3063 GDD) ending with 3295 GDD. 

Weather:  Precipitation

2021 ended with a total cumulative rainfall of only 30.99”.  Rainfall was below normal in 8 out of the 12 months, especially in the winter and spring months. The trend in the downward direction has continued over the past 4 years, which may be an indicator of drought cycle in Ohio that may linger for a period of time. July was the wettest month with 6.75”.  The ripening period was relatively dry which helped keep the fruit clean.

Vineyard Notes:

2021 Spring freeze injury:  Once again, we dodged the spring frost bullet in Wooster.   This was a very good thing as the warm temperatures in mid-March (low 60’s on March 24th) found bud swell occurring earlier than we would hope.  Thankfully, the temps dropped at the end of March and early April to slow growth down a bit.

Diseases and insects:  Our biggest enemy this year by far was a larger than normal population of bald faced hornets, yellow jackets and honey bees. We did observe some Downy Mildew in susceptible varieties.  The dry spring and early ripening period allowed for a clean fruit at harvest  Little damage occurred from wildlife this year which is dramatically different from past years.

Fruit quality: The dry/warm weather in August and September helped our fruit develop quickly with our first harvest being on August 23rd. After an initial burst, fruit ripening slowed to a more manageable  harvest schedule ending on October 19th. Crop yields were high in most varieties. In general, berry weights and sugars were higher and acid was lower than in 2020, an indication of more ripe fruit for 2021 vintage.

2021 Harvest fruit composition of selected grape varieties at the Wooster research vineyard:


Harvest Date

100 Berry wt (g)

SS (%)


T.A. (g/L)
















Cabernet franc





















Crimson Pearl





















Frontenac blanc





















La Crescent














Petite Pearl














Sauvignon blanc 27





















Posted In: Viticulture
Tags: 2021 Season
Comments: 0

By: Maria Smith, HCS OSU

It’s like a scene out of the 1992 classic horror movie Candyman in the vineyard this fall. Yellow jackets, hornets, bees, wasps (1; Fig. 1)… but I promise, it’s the sugar content in the grapes and not because we’re summoning a man with a hook for a hand.

Fig. 1. Bald faced hornet in Frontenac blanc, Sep 2021

So, a real question: why so many stinging friends joining us in the vineyards this fall? (By the way, it’s not just us in Ohio, this same issue has been reported this fall in Michigan, Wisconsin, and Minnesota).

One suggested answer is the transition to newer selective insecticides that, in addition to being safer for us, are safer for the wasps (2). Another is that populations of these insects are cyclical, and they may just simply be more abundant (3). Whatever the reason, they are a problem for both the human pickers and for the grapes.

As previously mentioned, stinging insects are attracted to the increasing berry sugars as the grapes ripen. They may either feed on existing damaged berries or cause damage by boring into intact berries (Fig 2). Fruit quality may then be further compromised by the vectoring of yeasts and bacteria that induce sour rot (4; Fig 3). Wasps themselves have been found to be vectors of sour rot microbes (5), while other may come in following berry damage, including fruit flies (Drosophila melanogaster), spotted wing drosophila (Drosophila suzukii), and sap beetles among others.

Fig. 2. Dessicated, damaged berries following wasp feeding, Frontenac blanc, Sep 2021

Fig. 3. Wasp damage and sour rot in Sauvignon blanc, Sep 2021

Managing Sour Rot in the Winery

With harvest wrapping up, the focus now should be on how best to manage fruit rot in the winery. A 2016 article from Penn State Extension details some key take home points on how to minimize the impacts of fruit rot in wine and are summarized here:

  • Minimize rot coming into the cellar by sorting fruit from harvest
  • Select an appropriate yeast strain that can survive harsher fermentation conditions
  • Create a nutrient management strategy to maintain a healthy fermentation
  • Monitor and manage SO2
  • Improve wine sensory attributes using additives, including tannins and inactivated yeast products
  • Blend with low volatile acidity (VA) wines
  • Sterile filter wines prior to bottling for microbial stability

Looking to next year: ways to control wasp populations in the vineyard

Harvesting at night or very early in the morning when conditions are cooler can certainly help the pickers when it comes to exposure to wasps, but it doesn’t eliminate the problem for ripening fruit.

Control for these insects is challenging but can be more effectively managed by deploying traps along the perimeter of the vineyard at the onset of ripening (Fig. 4), eliminating nests (bee careful!), and ensuring that fruit is harvested at maturity. Additional information on trapping and eliminating nests can be found at

As for insecticides, information from UW-Madison suggests that Entrust, Mustang Maxx, and Delegate have “good” efficacy when it comes to wasp control. Although these insecticides are not labeled for wasps, they are used to manage fruit flies and other pests near harvest. Keep in mind, several low-PHI insecticides are restricted use and require a pesticide applicators license to purchase and use.

Fig. 4. Purchased wasp trap deployed in Wooster, Unit 2 vineyard, Sep 2021


  1. Guedot, C et al. 2018. Species Composition, Abundance, and Seasonal Phenology of Social Wasps (Hymenoptera: Vespidae) in Wisconsin Vineyards. Insects.
  2. Warner, G. 2014. The Increasing Problem of Yellow Jackets and Hornets. Good Fruit Grower.   
  3. Milkovich, M. 2020. Wasps Becoming More Worrisome for Grape Growers. Good Fruit Grower.
  4. Ivey, M et al. 2021. Sour Rot Disorder of Grape. PLPATH-FRU-50.
  5. Madden, A et al. 2017. The Emerging contribution of social wasps to grape rot disease ecology. PeerJ.