                                  EPA Inquiry
                       Grape Turning/Girdling Practices
                                 June 1, 2020
                                       
Original Request from EPA

USDA was sent the following statement and questions from EPA's Office of Pesticide Programs:
"Thank you for facilitating BEADs previous communication with Mr. Ross Jones of the California Table Grape Commission. This information was very useful; however, we need additional information to characterize current practices involved with girdling and turning of table grapes from multiple regions. Furthermore, a detailed description, pictures, videos, etc of current worker activities performed in the orchards would allow us to compared current practices with the descriptions of the activities performed in the 1988 exposure study on which the Agency's current transfer coefficients (TCs) are based. This information could assist in determining whether girdling and turning of table grapes occurs as well as determining whether the Agency's current surrogate exposure study is still an accurate representation of potential post-application exposure resulting current practices and activities. Additional information could also assist in the potential selection of different surrogate exposure studies with lower TCs which could better represent the dislodgeable foliar residues resulting from a specific table grape activity. Below is a list of questions the agency would like for you to distribute to grape growers and interest groups to assist us in refining a description of current practices involved in girdling and turning table grapes." 
Questions from EPA to USDA:
 What percent of table grapes are grown using an open gable Y trellis system in California, Washington and New York?
 What percent of table grape vines are turned? If turning occurs has the practice/method changed since 1980 to present? If so how?
 Is cane turning used on other varieties of grapes (juice, wine, raisins)? If turning occurs has the practice/method changed since 1980 to present? If so how? Is the same Y-trellis system used?
 What percent of table grape vines are girdled?
 What percent of table grapes acres are of the new varieties that do not require or eliminate the need for girdling/turning?
 Do growers use plant growth regulators (PGRs) for increasing berry size and sweetness in place of girdling? If so what percent of table grapes incorporate use of PGRs?
 If girdling and turning of table grape vines occurs, how many hours a day is typically spent by worker(s) to perform each of these activities in a typical orchard. 

Email Chain Participants
USDA directly sent EPA's list of questions to the following individuals:
 Akif Eskalen, University of California, Agriculture and Natural Resources (UCANR)*
 Stephen Vasquez, Sun-Maid Growers of California
 Katie Gold, Cornell College of Agriculture and Life Sciences
 Michelle Moyer, Washington State University
 Caroline Stringer, California Fresh Fruit Association (forwarded responses from F. Gabler, M. Fidelibus, and M. Moyer)
 Anton Baudoin, Virginia Tech*
 Mizuho Nita, Virginia Tech*
 Gabriel Torres, UCANR (via Matt Baur, responded to PID questions)
 David Haughey, BASF
      * Did not respond
Several of the individuals that USDA contacted voluntarily the list of questions to other potential respondents in order to gather more information to answer EPA's questions. The following individuals subsequently provided information directly to USDA:
 Matthew Fidelibus, UCANR
 Franka Gabler, California Table Grape Commission
 Matt Baur, UCANR (forwarded response from G. Torres)
Unedited answers from the respondents bolded above are provided in the Appendix.
USDA Summary of Respondent Answers
      
 What percent of table grapes are grown using an open gable Y trellis system in California, Washington and New York?
   
   The California Table Grape Commission (CTGC) reported that 99% of the U.S. commercial table grapes are produced in California (Gabler, 2020). An extension viticulturist from Washington State University reported that the state does not have an economically significant table grape industry (Moyer, 2020). An extension representative from Cornell University (Cornell) reported that table grape production in New York is very limited, and mostly small-scale production (e.g., `you-pick' and farm market) (Gold, 2020)

   Respondents reported that open gable trellis systems are widely used for table grapes in the United States, and that the transition from cross arm T trellis systems to open gable Y trellis systems has been taking place over the past couple decades (Fidelibus, 2020; Gabler, 2020; Haughey, 2020). One respondent characterized open gable trellis systems as "the most common trellis system" (Fidelibus, 2020), and another estimated that "approximately 85% of table grapes are grown on an open gable trellis system" (Vasquez, 2020). The registrant, BASF, noted that any single line trellis systems currently in use would be with small growers, and not commercial operations (Haughey, 2020). 

   Sun-Maid Growers of California (Sun-Maid) noted that "the reason that table grape growers like the open gable trellis is that allows for a larger, natural canopy. However, with larger canopies, hand labor is needed to direct shoot growth to either side to allow light into the middle of the trellis. The hand labor that is needed is focused on leaf removal, shoot thinning [i.e. the removal of sterile or poorly positioned shoots, not `cane turning'] and cluster thinning and positioning (i.e. adjusting or untangling clusters so they are easy to harvest). The trellis type that is used other than an open gable is the T-trellis, which currently used in older vineyards or in new vineyards that are planted to low vigor, low yielding varieties" (Vasquez, 2020).

 What percent of table grape vines are turned? If turning occurs has the practice/method changed since 1980 to present? If so how?

   Several respondents indicated that `turning' refers to a practice that is no longer common in table grapes, particularly with the adoption of open gable Y trellis systems. Previously, shoots or canes that were dangling at the top of the trellis would be turned (i.e., moved) by hand to open up airflow, expose clusters for applications, or shade clusters from sun on single line trellis systems (Haughey, 2020). An extension specialist in viticulture from the University of California, Agriculture and Natural Resources (UCANR) indicated that turning may still be done on T trellises, but also noted that not many table grape growers currently use this type of trellis system (Fidelibus, 2020). Some respondents indicated they were unfamiliar with the term `turning,' and that the term does not appear in general viticulture reference books (Gold, 2020; Gabler, 2020; Vasquez, 2020).  
   Sun-Maid reported that, "because `turning' canes was a costly [i.e., labor-intensive] practice, it's been replaced by a tractor outfitted with cane cutters on the front of the tractor. Growers use the mechanical cane cutters to remove canes near the top of the trellis system throughout the season, which allows for more light and air movement. The increased air flow improves the management of powdery mildew and bunch rots." Sun-Maid further suggested that the term "turning" should be omitted from future surveys, since the practice was been eliminated approximately 30 years ago (Vasquez, 2020).
   USDA Comment: Given the lack of clarity from extension experts and industry stakeholders, USDA is concerned about the potential for unintended confusion on pesticide labels. We fully recognize the need to assess all sorts of post-application exposures and to clearly provide label directions that protect workers. We are concerned that if `cane turning' is not a widely recognized practice even among experts, the potential restrictions or label verbiage could lead users to conflate turning with other similar activities as described earlier. In a number of pesticide cases, the `cane-turning' task is a primary driver of REI restrictions that are highly impactful to producers. We are happy to discuss this further and do additional outreach to help EPA and table grape stakeholders to reach some common understanding, if not full agreement on how best to resolve the problem.
 Is cane turning used on other varieties of grapes (juice, wine, raisins)? If turning occurs has the practice/method changed since 1980 to present? If so how? Is the same Y-trellis system used?

   Some respondents reported hand-labor activities for wine and raisin grapes, but did not associate these with `cane turning.' Cornell described the practice of `shoot positioning' or `vertical shoot positioning' for wine grapes, which involves manually "manipulating shoots by repositioning moveable `catch wires' to constrain the shoots" (Gold, 2020). UCANR described "shoot tucking" in overhead raisin vineyards as "taking pendant shoots hanging below the trellis wire and pushing them back into the canopy above the trellis wires" (Fidelibus, 2020). Sun-Maid noted that "some hanging shoots get hand tucked back into the canopy, but the majority that are near the top of the trellis get cut mechanically. Other workers that are shoot tucking will use a stick or hook to push the shoot into the canopy because the trellis wires are above their head" (Vasquez, 2020). BASF described certain activities, such as hand harvesting and training of canes for wine and raisin grapes (Haughey, 2020) (see additional details in Appendix).
   USDA Comment: The other types of hand-activities described here and in prior response summaries do not appear to be consistent with cane turning, as described in the 1988 study on which EPA's transfer coefficient is based. That study describes cane turning as "involving very close exposure to foliage," and "a dusty operation." While USDA does not believe these activities are related to cane turning, we are providing for EPA's reference a link to several videos on cultural practices in wine grapes, including videos related to the shoot positioning activities referenced by respondents. USDA further suggests that for practical risk assessment and management purposes, the aforementioned tasks related to shoot tucking and redirection seem far more similar to `hand tying' activities than what might have been assumed for `cane turning' under older production systems. We are happy to discuss this further with EPA as mentioned above.
 Videos from the Minnesota Grape Growers Association: https://www.youtube.com/channel/UCIwFK5jsk4eEYfI8DBPyYpw/videos
 What percent of table grape vines are girdled?

   Most respondents were unable to provide a percentage of table grapes vines that are girdled, but indicated that it is still done with some varieties -- particularly older varieties like Thompson Seedless, which need to be girdled because of the small natural berry size (Fidelibus, 2020; Vasquez, 2020). BASF estimated that less than 50% of table grapes are girdled. BASF also noted that, with Y trellis systems, workers have little interaction with foliage when girdling canes (Haughey, 2020). Sun-Maid reported that there are 4-5 breeding programs, including USDA-ARS in Parlier, CA, that are working diligently to eliminate the need for girdling, and estimated that 35-40% of table grapes are girdled (Vasquez, 2020).
   Respondents also indicated that many newer varieties do not need to be girdled due to the large natural berry size (Gabler, 2020; Vasquez, 2020). CTGC noted that a key objective of table grape breeding programs is to develop varieties that require fewer inputs and cultural practices like girdling (Gabler, 2020). Sun-Maid reported that girdling is "a costly practice that can have varying results based on variety, location, season, etc. Growers would prefer not to girdle since it is costly and can be debilitating to the vine and on occasion, deadly, if not done correctly" (Vasquez, 2020).
   USDA Comment: We note that cane turning, as described in the 1988 study on which EPA bases its transfer coefficients, is the surrogate scenario for assessing post-application exposure from girdling. Below are links to two videos on girdling that we believe are representative of the practice, and which may be useful to EPA in refining the transfer coefficient for girdling and/or qualitatively characterizing exposure. In general, these indicate very limited contact with foliage (or dust), especially compared to the cane turning scenario. Based on the estimates we received, we would also suggest that about 35-50% of table grapes are girdled.
 Video on girdling from Columbine Vineyards, located in the San Joaquin Valley in California: https://www.youtube.com/watch?v=qgzS5IfQDAo
 Video on girdling from Superior Equipment, a WA-based supplier of professional tools to the tree fruit industry: https://www.youtube.com/watch?v=PFhLAn680Fs

 What percent of table grapes acres are of the new varieties that do not require or eliminate the need for girdling/turning?

   Sun-Maid reported that there are 4-5 breeding programs, including USDA-ARS in Parlier, CA, that are working diligently to eliminate the need for girdling, and estimated that 35-40% of table grapes are girdled. Because breeding programs have been successful at eliminating the need for girdling, finding a labor crew to girdle can be difficult (Vasquez, 2020). 
   BASF indicated that varieties requiring girdling are still an important part of the industry, but are decreasing in acreage for various different reasons. They estimated that "less than 50% are varieties that require girdling and that value [is] continuing to decrease." BASF also indicated that "most table grape fields that have been recently removed have been those varieties that require girdling, with most new plantings representing the newer types that do not require these operations" (Haughey, 2020). 
   Other respondents were unable to provide a percentage of acres for varieties of table grapes that do not require girdling/turning. As noted in the responses to Questions 1-3, turning has become much less common with the changes in trellis systems over the past several decades.
 Do growers use plant growth regulators (PGRs) for increasing berry size and sweetness in place of girdling? If so what percent of table grapes incorporate use of PGRs?

   Respondents were unable to provide a percentage of table grapes incorporating use of PGRs, but indicated that use of PGRs is still common, particularly for older varieties (Fidelibus, 2020; Haughey, 2020; Vasquez, 2020). As noted in the previous question, many newer varieties have reduced the need for cultural practices like girdling (Gabler, 2020). When PGRs alone are not sufficient to optimize berry size, some varieties may be treated with PGRs and girdled (Fidelibus, 2020).
   Sun-Maid noted that the use of PGRs is dependent on the grape variety, location, and market preferences. "The same variety could be grown/harvested at two different sizes and shipped to two different countries and be considered premium. Shipping a variety with a 20mm berry to a location that has a preference for that variety with a 25mm berry could `kill' the market for the variety (Vasquez, 2020)." 
   BASF reported that "PGRs, especially gibberellic acid, are widely used in table grape production. The three potential uses are set, stretch and size. These are three distinct times in the production season that PGRs may be used, with some operations using all timings and others using just one or two. The use of PGRs does not take the place of girdling but may supplement it in some cases."  BASF did not have an estimate for the percentage of operations that use PGRs, but believed the use to be relatively high in the industry. They further noted that "some varieties and production systems may use PGRs annually at each of the timings, but others will make the decision on a case by case basis depending on how the season is going" (Haughey, 2020).
   USDA Comment: While available usage data should help EPA identify what PGRs are most commonly used for table grape size and firmness enhancement, some varieties still require girdling regardless of PGR usage. We suggest given the inconvenience and costs of girdling, very few growers would go to the effort and expense if there was a viable PGR option that delivered comparable results. We think there are few if any scenarios where PGRs could serve as an adequate replacement for girdling, that would not already be reflected in the estimate of 35-50% of table grape acreage that is still girdled.

 If girdling and turning of table grape vines occurs, how many hours a day is typically spent by worker(s) to perform each of these activities in a typical orchard.

   While most respondents were unable to provide daily estimates for the number of hours spent by workers on performing girdling or turning, several noted the high costs associated with these activities, as well as the seasonality of their relevance (Fidelibus, 2020; Haughey, 2020; Vasquez, 2020). UCANR provided a link to several table grape cost studies, which detail labor costs and associated hours for various activities: https://coststudies.ucdavis.edu/en/current/commodity/grapestable/ (Fidelibus, 2020). [From these studies, USDA gleaned that girdling is a seasonal activity, taking place primarily in the month of June. Depending on variety/conditions, labor costs per acre ranged from 10 hours/acre (e.g., early maturing flame seedless and Sheegene-21 (Ivory(TM)) varieties) to 12 hours/acre (e.g., late maturing Autumn King variety). No girdling costs were reported for mid-season maturing Scarlet Royal variety.]

   BASF reported that girdling is a specialized skill, usually carried out by a specialized team of workers, because if the girdle is too shallow, it minimizes the intended effect, but if it is too deep it can harm or even kill the vine. BASF further characterized girdling as "a relatively difficult task with lots of bending over and moving quickly through fields by a specialized team. It would be unrealistic to assume that a team works a full work day without breaks or travel between fields when assessing exposure. Girdling is also not an operation that occurs year round, so it may be busy for a few weeks but that specialized crew would be doing other operations for the majority of the season. It would be realistic to assume additional breaks and travel time as well as a limited amount of time per year when determining exposure during girdling operations" (Haughey, 2020).
   Sun-Maid indicated that girdling and `turning' cultural practices are costly. Although growers are inclined to select varieties that can be grown with minimal hand labor over those that require large crews of people to produce and harvest the product, market conditions still dictate what is grown (Vasquez, 2020).
   USDA Comment: Based on the preponderance of stakeholder feedback, it is USDA's view that girdling should be considered a somewhat specialized skilled labor task. Given the logistical and ergonomic considerations around the task, we suggest that assessing 8 hours of day for this task is probably an over-estimate and that the average worker would conduct this activity fewer than 30 days per year. More importantly, we suggest that despite the assumptions agreed upon by the prior Agricultural Reentry Task Force, this task entails very little direct foliar contact and certainly far less than hand-turning of vines. From a practical risk management standpoint, USDA believes the available information (including demonstrative videos) shows that the task is more comparable to tasks such as pruning, tying, or hand-harvesting at worst.
Additional Responses to Questions Posed in the Boscalid and Pyraclostrobin PIDs
Response from Gabriel Torres, Viticulture Farm Advisor, University of California, Agriculture and Natural Resources. Forwarded by Matthew Baur, Acting Director, Western Integrated Pest Management Center. Received via email to USDA on June 10, 2020.

 What techniques and equipment are used for girdling and turning? Are there new technologies or equipment that could reduce worker exposure during turning and girdling relative to older technologies and equipment? 
   I am not aware of new technologies for girdling. I know about the interest of growers to develop a mechanical system for it, but I haven't seen it in the market.

 How prevalent is the adoption and use of Y-trellises or other aspect of table grape production that reduce dependence on girdling and turning?
   Gridling is cultivar dependent and grower dependent. Table grape scenario is changing fast and one of the decision of plant one cultivar or another is how much labor is involved. Y trellis system is prevalent on table grape production in the San Joaquin Valley." 

 What is the relative acreage of table grape varieties that depend on turning and girdling and varieties that do not?
   [No response]

 When are workers performing girdling and turning relative to when fungicides (in this case, boscalid) are applied?  
   What I have observed in my clientele is that they follow strictly the label, and don't perform any activity that requires contact with the canopy during the REI. 

 What other important activities in vineyards would be impacted by a 22-day REI, or REIs of duration between five days and 22 days?
   Leafing, pest, and diseases scouting, research, harvest estimates, water potential analysis. Leaves sampling for nutrient analysis.  

 Are there activities other than turning and girdling that have similar potential for worker contact with treated foliage? 
   [No response]

 How much time is spent performing girdling and turning during the course of the year (i.e., days per year) and are these activities that a worker would be likely to engage in for a full work day?
   A fieldworker can do between .8 and 1 acre a day, table grape blocks normally are 40 acres. 

 Multiple fungicides may be applied to grapes to treat various diseases during the course of the year. To forestall fungicide resistance, growers are encouraged to use different chemistries in rotation. Is there a way to sequence the applications of the different fungicides so that the fungicide applied directly before girdling and turning take place is one for which the calculated REI would generally be shorter?  For example, the fungicides X, Y, and Z are used in rotation. The REIs are 22 days, 10 days, and 5 days, respectively. Is it feasible that the application sequence can be adjusted so that fungicide Z is the last fungicide that is applied prior to the time when girdling and turning are needed?
   22 REI is going to put too much pressure on the growers. Table grape productions requires field workers in the field frequently. The use of boscalid is preferred because its double action against botrytis and powdery mildew. A big win from the fungicide rotation part is to have an extra tool for controlling PM resistance. However, from the botrytis side, resistance has been widely documented. Growers need to take this in account depending of which pathogen are they targeting. Put a 22 REI will force growers to put the product at the very back list of resources available. FRAC 7 fungicide are critical for powdery mildew management in grapes.  

   USDA comment: Many fungicide products (e.g., boscalid) are co-formulated with other fungicide active ingredients (e.g., pyraclostrobin) with curative activity. Therefore, application sequencing in the manner proposed by EPA is not likely to be feasible. USDA therefore suggests that that removal of the availability/viability of one active ingredient via restrictive mitigation could amount to a de facto cancellation of other co-formulated active ingredients, compounding the potential impacts to growers.
References

Fidelibus, M., 2020. Specialist in Cooperative Extension in Viticulture, University of California, Agriculture and Natural Resources. Personal communication received via email to USDA on June 10, 2020.

Gabler, F., 2020. Viticulture Research Director, California Table Grape Commission. Personal communication, received via email to USDA on June 11, 2020.

Gold, K., 2020. Professor of Grape Disease Ecology and Epidemiology, Cornell AgriTech Extension. Personal communication received via email to USDA on June 9, 2020.

Haughey, D., 2020. Product Registration Manager, BASF. Personal communication received via email to USDA on July 2, 2020. 

Moyer, M., 2020. Extension Viticulturist, Washington State University. Personal communication received via email to USDA on June 10, 2020.

Torres, G., 2020. Viticulture Farm Advisor, University of California, Agriculture and Natural Resources. Personal communication received via email to USDA on June 10, 2020, forwarded by M. Baur, Acting Director, Western Integrated Pest Management Center. 

Vasquez, S., 2020. Technical Viticulturist and Grower Relations, Sun-Maid Growers of California. Personal communication received via email to USDA on July 6, 2020.

Appendix: Unedited Answers from Respondents

Response from Katie Gold, Professor of Grape Disease Ecology and Epidemiology, Cornell AgriTech Extension. 

 What percent of table grapes are grown using an open gable Y trellis system in California, Washington and New York?
   0%.
 What percent of table grape vines are turned? If turning occurs has the practice/method changed since 1980 to present? If so how?
   Table grape production in NY is very limited  -  small scale production, largely `you-pick' and farm market.  We are not sure what turning is. Do you mean shoot positioning? 
 Is cane turning used on other varieties of grapes (juice, wine, raisins)? If turning occurs has the practice/method changed since 1980 to present? If so how? Is the same Y-trellis system used?
   Some producers use vertical shoot positioning.  Which involves manipulating shoots by repositioning movable `catch wires' to constrain the shoots.  This is often a manual operation. 
 What percent of table grape vines are girdled?
   0%.
 What percent of table grapes acres are of the new varieties that do not require or eliminate the need for girdling/turning?
   0%.
 Do growers use plant growth regulators (PGRs) for increasing berry size and sweetness in place of girdling? If so what percent of table grapes incorporate use of PGRs?
   No.
 If girdling and turning of table grape vines occurs, how many hours a day is typically spent by worker(s) to perform each of these activities in a typical orchard.
   Not sure.  Shoot positioning would be a couple of weeks in late June-early July.  Probably (guesswork) 4-6 h/day.
 

Response from Michelle Moyer, Extension Viticulturist, Washington State University. Received via email to USDA on June 10, 2020.

   Washington State does not have an economically significant table grape industry, and these products are not used on our juice grape vineyards. 
 


Response from Matthew Fidelibus, Specialist in Cooperative Extension in Viticulture, University of California, Agriculture and Natural Resources. Received via email to USDA on June 10, 2020.

 What percent of table grapes are grown using an open gable Y trellis system in California, Washington and New York?
   The vast majority of table grapes in the United States are grown in California. Open gable trellis systems are currently the most common trellis system for table grapes in the US. I don't know of any statistics on what percentage of vineyards have an open gable versus some other trellis system.
 What percent of table grape vines are turned? If turning occurs has the practice/method changed since 1980 to present? If so how?
   By "turning" I think you are referring to lifting the pendant shoots on the north side of a trellis and laying them across the top and south side of the trellis. If not, please define what you mean by "turning". If that is what you meant, it is something that may still be done on the old style T-trellises, but not many table grape growers are still using trellises like that. There may be some people who do something similar on open gable trellises, especially on young vines, but I don't think it is a widespread practice at this point.
 Is cane turning used on other varieties of grapes (juice, wine, raisins)? If turning occurs has the practice/method changed since 1980 to present? If so how? Is the same Y-trellis system used?
   I am not aware of anyone doing this particular practice on raisin or wine grapes, though some growers with overhead raisin vineyards may do some shoot tucking, basically taking pendant shoots hanging below the trellis wire and pushing them back into the canopy above the trellis wires.
 What percent of table grape vines are girdled?
   I am not aware of any statistics on this practice. It is still done with some varieties, but I do not know what percentage.
 What percent of table grapes acres are of the new varieties that do not require or eliminate the need for girdling/turning?
   Same answer as above.
 Do growers use plant growth regulators (PGRs) for increasing berry size and sweetness in place of girdling? If so what percent of table grapes incorporate use of PGRs?
   Yes, PGRs are widely used to increase berry size. In some cases PGRs may be sufficient to optimize berry size without the need to girdle, but some varieties are still sprayed with PGRs and girdled.
 If girdling and turning of table grape vines occurs, how many hours a day is typically spent by worker(s) to perform each of these activities in a typical orchard.
   There is some information in the table grape cost studies: https://coststudies.ucdavis.edu/en/current/commodity/grapestable/


Response from Franka Gabler, Viticulture Research Director, California Table Grape Commission. Received via email to USDA on June 11, 2020.

 What percent of table grapes are grown using an open gable Y trellis system in California, Washington and New York?
   Approximately 99% of the U.S. commercial table grapes are produced in California. The table grape industry has transitioned from T/cross arm trellis systems to mostly open gable/Y trellis systems over the past couple decades.
 What percent of table grape vines are turned? If turning occurs has the practice/method changed since 1980 to present? If so how?
   We are not sure about what "vine turning" means. 
 Is cane turning used on other varieties of grapes (juice, wine, raisins)? If turning occurs has the practice/method changed since 1980 to present? If so how? Is the same Y-trellis system used?
   Again, we are not sure about what "vine turning" means. 
 What percent of table grape vines are girdled?
   A key objective of table grape breeding programs is to develop varieties that require fewer inputs/cultural practices such as girdling. Most of the new varieties have naturally large berry size eliminating the need to girdle for size.
 What percent of table grapes acres are of the new varieties that do not require or eliminate the need for girdling/turning?
   Most newer varieties do not require girdling.
 Do growers use plant growth regulators (PGRs) for increasing berry size and sweetness in place of girdling? If so what percent of table grapes incorporate use of PGRs?
   Older varieties still require the use of PGRs; as noted above, a benefit of newer varieties is they typically require very little to no inputs/cultural practices (e.g., PGRs).
 If girdling and turning of table grape vines occurs, how many hours a day is typically spent by worker(s) to perform each of these activities in a typical orchard.
   We don't have this information. Presumably, hours by worker varies by operation, variety, time of year, etc.



Response from David Haughey, Product Registration Manager, BASF. Received via email to USDA on July 2, 2020.

 What percent of table grapes are grown using an open gable Y trellis system in California, Washington and New York?
   Nearly all table grapes are on the Y shaped trellis systems commercially. If there are any single line trellis systems left they would be with small growers that probably sell to farmers markets, not commercial operations.
 What percent of table grape vines are turned? If turning occurs has the practice/method changed since 1980 to present? If so how?
   The traditional definition of "turning" is no longer a practice in table grapes since the adoption of the Y shaped trellis systems. Canes would be turned to open up airflow, expose clusters for applications or shade clusters from sun on single line trellis systems. With the adoption of Y shaped trellis systems the traditional "turning" of canes is no longer a practice in table grapes. 
 Is cane turning used on other varieties of grapes (juice, wine, raisins)?  If turning occurs has the practice/method changed since 1980 to present? If so how? Is the same Y-trellis system used?
   Juice: Unknown as it is not a major product in CA.
   Wine:
 Bulk Wine: Some bulk wine operations have adopted the Y or T shaped trellis systems to allow exposure of clusters. Many newer operations have shifted towards trellis systems that allow for fully mechanical pruning along the row. There may be some worker operations in season but this is greatly limited. Various trellis systems, turning isn't an operation and limited use of workers. 
 High Value Wine: This is going to depend on region, variety, value of grapes and how each operation chooses to operate. The general trend is to reduce use of workers if possible but if the grapes are worth enough growers will use them as appropriate. Trellis systems will vary by region but turning in the traditional sense isn't a normal operation. 
   Raisin:
 Tray Dry: This is the traditional raisin production system where clusters are hand harvested and left to dry on paper on the ground. Early in the season there may be some level of worker interaction to train canes then at harvest clusters are hand harvested. Besides these operations there isn't commonly any workers present in the fields. Canes are left to grow down from the trellis system in most cases. Different trellis system, turning isn't an operations and limited use of workers. 
 Dry on Vine: Early in the season there may be some training of canes to ensure they are on the overhead trellis system but worker interaction is relatively limited. Late in the season workers will go through the snip canes in the harvest rows to the allow clusters to dry while hanging prior to mechanical harvest operations. Different trellis system, turning isn't an operation and limited use of workers. 
      
 What percent of table grape vines are girdled?
   Best estimate is that less than 50% of table grapes are girdled. This is related to specific varieties that require girdling and some that use girdling to increase sugar accumulation in the grapes. With the Y shaped trellis systems workers have little interaction with foliage when girdling canes. 
 What percent of table grapes acres are of the new varieties that do not require or eliminate the need for girdling/turning?
   Varieties that require girdling are still an important part of the industry but are falling out of favor for various different reasons. Less than 50% are varieties that require girdling and that value continuing to decrease. Turning operations are related to trellis type primarily and has essentially been eliminated. Most table grape fields that have been recently removed have been those varieties that require girdling, with most new plantings representing the newer types that do not require these operations. 
 Do growers use plant growth regulators (PGRs) for increasing berry size and sweetness in place of girdling? If so what percent of table grapes incorporate use of PGRs?
   PGRs, especially gibberellic acid, are widely used in table grape production. The three potential uses are set, stretch and size. These are three distinct times in the production season that PGRs may be used, with some operations using all timings and others using just one or two. The use of PGRs does not take the place of girdling but may supplement it in some cases. I am not confident in the percent of operations that use PGRs but it is relatively highly used in the industry. Some varieties and production systems may use PGRs annually at each of the timings but others will make the decision on a case by case basis depending on how the season is going.
 If girdling and turning of table grape vines occurs, how many hours a day is typically spent by worker(s) to perform each of these activities in a typical orchard.
   Turning is essentially no longer done in table grapes. As for girdling it is usually a specialized team that will girdle canes because if the girdle is to shallow you don't get the intended effect but if it is too deep you can harm or even kill the vine. Girdling is a relatively difficult task with lots of bending over and moving quickly through fields by a specialized team. It would be unrealistic to assume that a team works a full work day without breaks or travel between fields when assessing exposure. Girdling is also not an operation that occurs year round, so it may be busy for a few weeks but that specialized crew would be doing other operations for the majority of the season. It would be realistic to assume additional breaks and travel time as well as a limited amount of time per year when determining exposure during girdling operations.



Response from Stephen Vasquez, Technical Viticulturist and Grower Relations, Sun-Maid Growers of California. Received via email to USDA on July 6, 2020.

 What percent of table grapes are grown using an open gable Y trellis system in California, Washington and New York?
   I would say approximately 85% of table grapes are grown on an open gable trellis system. The reason that table grape growers like the open gable trellis is that allows for a larger, natural canopy. However, with larger canopies, hand labor is needed to direct shoot growth to either side to allow light into the middle of the trellis. The hand labor that is needed is focused on leaf removal, shoot thinning (i.e. the removal of sterile or poorly positioned shoots) and cluster thinning and positioning (i.e. adjusting or untangling clusters so they are easy to harvest).  The trellis type that is used other than an open gable is the T-trellis, which currently used in older vineyards or in new vineyards that are planted to low vigor, low yielding varieties.
 What percent of table grape vines are turned? If turning occurs has the practice/method changed since 1980 to present? If so how?
   "Turning" is an old term used for moving shoots or canes that are dangling to the top of the trellis. I saw the term referenced once but cannot not find that reference anywhere. I looked throughout A.J. Winkler's General Viticulture book but didn't find it there either. Because "turning" canes was a costly practice, it's been replaced by a tractor outfitted with cane cutters on the front of the tractor. Growers use the mechanical cane cutters to remove canes near the top of the trellis system throughout the season, which allows for more light and air movement. The increased air flow improves the management of powdery mildew and bunch rots. The term "turning" is an old term that should be omitted from future surveys, since the practice has been eliminated at least 30 years ago.
 Is cane turning used on other varieties of grapes (juice, wine, raisins)? If turning occurs has the practice/method changed since 1980 to present? If so how? Is the same Y-trellis system used?
   As Dr. Fidelibus mention, some hanging shoots get tucked back into the canopy, but the majority that are near the top of the trellis get cut mechanically. Often times workers that are shoot tucking will be use a stick or hook to push the shoot into the canopy because the trellis wires are above their head.
 What percent of table grape vines are girdled?
   Girdling is used to increase berry size or improve color depending on when it is done. Girdling is still used on some varieties, however, breeding programs have been developing new varieties that don't need to be girdled. An old variety like Thompson Seedless needed to be girdled because it has a small natural berry size (i.e. 10-12mm). Newer varieties do not need to be girdled because they have a large natural berry size (>14mm). Girdling is a costly practice that can have varying results based on variety, location, season, etc. Growers would prefer not to girdle since it is costly and can be debilitating to the vine and on occasion, deadly, if not done correctly.
 What percent of table grapes acres are of the new varieties that do not require or eliminate the need for girdling/turning?
   In California there are 4-5 breeding programs, including the USDA-ARS, Parlier CA, that are working diligently to eliminate the need for girdling. If I had to guess, I'd say 35-40% of table grapes are girdled. Because breeding programs have been successful at eliminating the need for girdling, finding a labor crew to girdle is difficult.
 Do growers use plant growth regulators (PGRs) for increasing berry size and sweetness in place of girdling? If so what percent of table grapes incorporate use of PGRs?
   The use of PGR's is dependent on the variety, location and market preference for a certain size berry. The same variety could be grown/harvested at two different sizes and shipped to two different countries and be considered premium. Shipping a variety with a 20mm berry to a location that has a preference for that variety with a 25mm berry could "kill" the market for the variety.
 If girdling and turning of table grape vines occurs, how many hours a day is typically spent by worker(s) to perform each of these activities in a typical orchard.
   Girdling or "turning" cultural practices are costly. A grower will select a variety that can be grown with minimal hand labor over one that will need a large crew of people to get the grape grown and harvested. However, the market will also dictate what gets grown.

 


