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By: Maria Smith, HCS-OSU

It sure does feel like March Madness, especially with the recent arrival of Ohio’s infamous “second winter”. Thankfully, the cooldown from February’s warm, spring-inspired weather will help us keep the vines asleep a little bit longer. This cooldown should help us complete this most important dormant-season activity: pruning. As a follow up to last week's pruning workshop, let’s go down the reminders of when, what, and whys of pruning.

Why prune?

In young vines (< 3yo), pruning is intended to build the vine to conform to the intended training system. This means, selecting healthy wood for trunk and/or cordon establishment.

For mature vines (>3 yo), the main goal of pruning is to adjust the vine size and yield potential to produce a healthy crop in the upcoming season (i.e., create a balanced vine). For new grape growers, this seems dramatic, but in “normal” years, this means removing more than 90% of the 1 yo wood that is on the vine (Fig 1).

Figure 1. Vine before pruning (left) and after pruning (right). High wire, bilateral cordon-trained Vitis hybrid.

What to prune? Or how many buds to retain?

Normally, we suggest a method called “balanced pruning”, or retaining bud numbers according to vine size based on the pruning weight of 1-year-old canes.

Table 1. Balanced pruning formulas for different grape types. Adapted from Midwest Grape Production Guide. The formula follows the number of buds to leave for the 1 lb of pruning weight + the number for each additional lb of pruning weight.



Pruning Formula

Cluster Thinning


30 + 10


French Hybrids

20 + 10


New Hybrids

20 + 20


Seedless Table

30 + 10



20 + 20

Yes / No


A general rule of thumb: this should equate to approximately 4-6 buds per foot of vine spacing (e.g., if the vine spacing is 5-8’, retain 20-50 buds per vine). *Note, buds on hybrid and Vinifera wine grape varieties are typically more fruitful on the basal nodes. Therefore, when retaining buds, it is often best to leave more 2-3 bud spurs instead of fewer, longer spurs. This is not the case with Concord, Niagara, and other American varieties where the most fruitful buds are nodes 3-6.

But winter 2022-2023 wasn’t “normal”. The Christmas Eve polar vortex may have caused significant bud injury to your vines, especially in the most cold-sensitive varieties or in the colder locations in the state (see: Pre-Christmas Freeze and Impact on Grapevines). In Ohio where we have a propensity for winter injury, it’s important to check your bud injury and adjust pruning accordingly to maintain cropping levels (Fig. 2, Table 2). At Wooster, we assess bud injury as a % of 100 buds (10-bud canes). This is performed by variety.


Figure 2. Assessing bud mortality by cross-sectioning buds using a sharp razor blade. Notice the alive (left) vs. dead (right) status of the primary buds in the figure above.  

Table 2: Adjusted pruning based on % bud mortality.

% Primary bud injury


0 to 14%

No adjustment needed

15 to 34%

Retain an extra 35% buds

35 to 50%

Retain an extra 50% buds


Minimal prune to 5-bud spurs

80 to 100%

Likely trunk damage, renew trunk by retraining suckers


Why minimal prune? Yes, it’s a pain to shoot thin, but what we have noticed is that hedge pruning can aid in maintaining yield levels despite extensive (70-80%) primary bud injury. We have observed in the past that the rates of bud injury tend to be higher on node positions in the middle and end of canes vs. towards the base of canes. This means that buds retained from minimal hedge-styled pruning tend to be more alive than leaving more buds through cane pruning modifications (e.g., double-wrapping canes, quad-cane pruning).

Wood quality. Healthy, sun-exposed, reddish-brown wood that is approximately ¼ to ½” in diameter is optimal (think: Sharpie™, Pencil, Pen; Figure 3). This wood will contain buds with better cold hardiness, higher fruitfulness, and have the carbohydrate availability to support the development of 2-3 shoots. AVOID: bull wood (large, vegetive wood > ½” in diameter) and weak (< ¼” diameter).

Figure 3. Healthy, optimal wood selection for spurs and trunk and cordon training

When to prune? We acknowledge that larger vineyards are time-constrained and likely begin pruning earlier in the winter. However, if possible, small vineyards should wait as long as possible into spring. This is to allow compensation in case of winter injury, but can also help stave off early bud break by suppressing the development of the most basal buds on the cane (explained in our 2019 OGEN article: Grapevine Dormant Pruning). If waiting is not possible, begin with the most cold hardy varieties first, then proceed to the most cold sensitive varieties last (note* If you’re growing cold hardy MN hybrids, prioritize the later breaking varieties like Frontenac to prune first and prune the most early bud break varieties prone to spring freeze like Marquette and La Crescent last).

Pruning should be completed by the beginning of bud swell. Although bud break timing depends on numerous factors, we typically see signs of bud swell in mid to late-April in Wooster (may be 2-3 weeks different in southern and northern parts of Ohio). If you are double or delayed pruning as a spring frost avoidance strategy, final pruning needs to be completed no later than 1” in apical shoot growth. This is to avoid potential yield losses associated with basal bud break delays.  

Posted In: Viticulture
Tags: pruning, 2023 season
Comments: 0

The Wine Production Guide from Todd Steiner in collaboration between OSU and OGIC is now available for purchase through OSU Extension.

Useful to both beginning and experienced winemakers, the Wine Production Guide provides commonsense direction for establishing a winery, an overview of wine production practices, and in-depth information about ensuring fruit quality, harvest decisions, must handling, fermentation management, cellar operations, bottling, and storage of table wines. Intended as a complete guide to consistent production of sound, quality wines and written by respected experts in the field, the guide covers winery best practices on all aspects of winemaking.

Order Today: At $51.50 for a printed publication and $33.50 for a PDF version, this publication is a great investment to learn about wine production and includes a digital cash flow spreadsheet that can be customized with the specifics of anyone looking to start and operate a successful winery. Visit to view sample pages. If you work at a state Extension office ask about our partner pricing.

***All current Ohio A2 permit holders can receive a complementary print copy through The Ohio Grape Industries Committee (OGIC). Also, all commercial Ohio A2 permit holders receive access to a free digital (PDF) version through their OGIC industry login***

Learn More: Looking for more resources on grape production, visit The Ohio State University Department of Horticulture and Crop Science at; Buckeye Appellation at; or search for “grapes” at OSU Extension’s Ohioline at


Posted In: Enology
Tags: Wine Guide
Comments: 0

By: Imed Dami, HCS-OSU

On December 23-24, Ohio experienced the coldest temperatures of the year 2022. Temperature lows ranged between 3F and -13F (see map). Statewide, the lowest temperatures occurred in West central Ohio and ranged between -9 F and -13F. In central Ohio, minimum temperatures ranged between -5F and -10F. In southwest, temperature dropped to -7F to -12F. In southeast, 3F to -6F were recorded. In Northwest, temperatures ranged between -3F and -11F. Northeast (majority of vinifera grape acreage) experienced the mildest temperatures ranging between -2F and -6F. At our research vineyard in Wooster, we recorded -7F on December 23, 2022.

To have a preliminary assessment of cold injury, we collected canes from our most cold sensitive vinifera varieties. We also collected a cold hardy hybrid, Frontenac blanc for comparison. Our findings were disappointing with higher-than-expected cold damage across the board. Table 1 summarizes cold injury of primary and secondary buds from 8 varieties. In vinifera primary bud injury ranged between 87% and 100%. Frontenac blanc sustained only 5% primary bud injury. Our results suggest that cold damage of vinifera varieties could be more severe than expected across the state. Hybrids (with LT50 of -13F or lower) should have minimum to no injury from this cold event. 

The extensive cold damage of vinifera varieties is puzzling. In late November, buds showed a good level of cold hardiness. For example, Chardonnay had LT50 = -7.7F. In December, low temperature of -7F was recorded in that vineyard in Wooster. So, at that temperature, we should have 50% or more bud survival. But, that was not the case and we had 10% primary bud survival (see Table 1). One way to explain this discrepancy is that vines lost cold hardiness in December. This is possible since we had a mild December with mean temperature 3F above the 30-year average (Figure 2).  

We still have a few weeks to go with winter weather and potential damaging temperatures are still possible.  Growers should be mindful of that and bud assessment, before pruning, is recommended. Pruning adjustment is definitely needed this year.  

Figure 1. Minimum temperatures on December 23-24, 2022. Note that minimum temperatures ranged between 3F and -13F. Source: Dr. Aaron Wilson, OSU state climatologist.

Table 1. Bud injury of 8 grape varieties exposed to -7F on December 23, 2022. Wooster, OH.




Primary bud injury (%)

Secondary bud injury (%)

V. vinifera


FPS 01




Cabernet franc

FPS 11





FPS 37





FPS 02





FPS 03




Sauvignon blanc

FPS 27









Frontenac blanc









Figure 2. Monthly mean temperature deviation from the 30-year average in 2022 in Wooster.  Bars above 0F means temperature was above the 30-year average. Bars below 0F means temperature was below the 30-year average.



Posted In: Viticulture
Tags: Viticulture, 2022 Season, Winter Injury
Comments: 0

By: Imed Dami and Diane Kinney, HCS-OSU

This article summarizes the 2022 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

The Wooster weather through the month of November has been nearly identical as 2021 with the averages being within 2 degrees each month. Once again, our winter low was within the tolerance level for all of our grape varieties, which had achieved maximum cold hardiness despite the fact we had a mild December when our lowest recorded temperature of -4.4 o F occurred on January 22nd.  Although our average temperatures for March and April were on track, we had a wide swing hitting 70+  oF a couple of days in early March,  as well as lows of 11 oF later in the month.  These low temperatures held off bud break due to low GDD’s.  The last week of April the temperatures finally warmed and induced bud break. Although many areas of the state were hit hard by a spring frost, in Wooster, damaging temperatures were avoided due to limited or no bud break of most varieties. The early ripening period during August and September remained largely on pace with not only 2021 but our 30 year-long term average while temperature dropped in October averaging 51 oF in comparison to 60 oF in 2021.  Our first hard freeze occurred on November 17th resulting in a growing season length of 201 frost-free-days.

Weather:  GDD 

We were very slow to gain GDD’s this year only hitting 100 in the later part of April but May roared ahead gaining over 300 GDD’s during the month putting us ahead of both 2021 and the long-term average.  We then settled down into normal gains until October were things just abruptly stopped, including fruit ripening.  Cumulatively, that averages out overtime, but we were well below our 2021 number of 3283 vs 3104 (thru November) in 2022.

Weather:  Precipitation

2021 ended the year with a total cumulative rainfall of only 30.99”.  We exceeded that amount in August of 2022.  By the end of November, we have recorded 39.62” which is 10” over the long-term average.  This is a change over the past 4 years where rainfall declined each year over the long term. 2022 has been very wet keeping us above the long-term averages every month up until October.   

Vineyard Notes:

2022 Spring freeze injury:  In Wooster we were fortunate to avoid a spring freeze event which wreaked havoc on a majority of the state the end of April.   We would have likely faired a bit better as our buds were in early developmental stages at this point versus southern regions of the state.

Diseases and insects:  Regular cover sprays were a must as we had consistent rains which resulted in sour rot.  Other diseases such as botrytis, downy mildew were seen in smaller amounts which caused minimal damage in our vineyard.  Our typical bird and other wildlife pressure was low while yellow jackets caused a fair amount of damage thereby helping encourage the spread of sour rot.

Fruit quality:   Sour rot caused a real challenge in fruit quality.  Our first harvest occurred on August 17th for Brianna and our final harvest occurred on October 25th for Chambourcin. Overall, fruit maturity was not as ideal as in 2021. In 2022, we recorded lower pH and higher TA as compared to 2021.

Table: 2022 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




























Sauvignon blanc 27














Posted In: Viticulture
Tags: vineyard updates, Viticulture, 2022 Season
Comments: 0

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