Spur Pruning May Be a Viable Option for Oregon Pinot noir Producers Despite Industry Fears of Lower Productivity

REPORT Spur Pruning May Be a Viable Option for Oregon Pinot noir Producers Despite Industry Fears of Lower Productivity Patricia A. Skinkis 1 * and Kelli M. Gregory 2 Cite this article: Skinkis PA and Gregory KM. 2017. Spur pruning may be a viable option for Oregon Pinot noir producers despite industry fears of lower productivity. Catalyst 2:62-72. 1 Viticulture Extension Specialist and Associate Professor, Department of Horticulture, Oregon State University; and 2 Former graduate student, current Vineyard Manager and Grower Relations, Adelsheim Vineyard, Newberg, OR. *Corresponding author (Patricia. Skinkis@oregonstate.edu; tel: 541-737-1411) Acknowledgments: The authors thank Oregon winegrape industry members for their responsiveness to surveys, cooperation during interviews, and the use of vineyard sites for field data collection. The authors also thank Amelia Doyle for her assistance in review of this manuscript. Manuscript submitted Jan 2017, revised June 2017, accepted June 2017 Copyright 2017 by the American Society for Enology and Viticulture. All rights reserved. doi: 10.5344/catalyst.2017.17001 Summary Goals: Winegrape production is more costly in Oregon than in other US growing regions, and industry faces rising production costs and labor concerns. Growers are considering ways to reduce labor and introduce mechanization. Spur pruning requires less labor and is more readily mechanized than cane pruning; however, the majority of Oregon growers use cane pruning. We conducted industry surveys and interviews to understand why cane pruning is preferred and determine potential barriers to adopting spur pruning. We conducted a vineyard case study to quantify fruitfulness and yield of cane- and spur-pruned vines to determine the potential for spur pruning in Pinot noir. Key Findings: The majority of survey respondents (76%) primarily used cane pruning on cool climate cultivars because they believe that spur pruning reduces yields and fruit quality and increases fungal and mite pests. A total of 35% believed that spur pruning reduces yield due to vines having unfruitful basal buds. Interviews of Pinot noir growers who use both spur and cane pruning revealed that spur pruning could achieve desired yields, while reducing production costs and labor dependency. Their observations did not support survey respondent concerns about severely reduced yields, fruit quality, and increased mites or diseases. The Pinot noir vineyard case study revealed that cane and spur pruning led to similar yields, cluster size, and fruit ripeness. Data from spur-pruned Pinot noir vines showed that shoots arising from basal, first, and second buds were fruitful. Impact and Significance: Industry perception and lack of experience with spur pruning is preventing adoption. Expectation of low yields is based on industry hearsay, not direct experience. Concerns that spur pruning lowers quality may be derived from mechanization research from regions that focus on quantity, not quality. However, grower interviews and field data show that Pinot noir is fruitful at basal nodes and can be spur pruned without limiting yield or quality based on Oregon standards. Converting to spur pruning reduced pruning cost, and research/demonstration projects are needed to help small, quality-focused industries make necessary adaptations to their production systems. Key words: bud fruitfulness, mechanical winter pruning, Pinot noir, pruning, vineyard efficiency, yield Overview Oregon is an acclaimed premium Pinot noir production region and ranks fourth nationally based on vineyard acreage, 1 with 11,345 ha (28,034 ac) and page 62

Spur Versus Cane Pruning In Oregon Pinot noir 63 1052 vineyards. 2 The Willamette Valley, where 82% of the state s Pinot noir acreage is planted, 2 requires intensive canopy management due to invigorating growing conditions (i.e., high soil moisture and fertility and optimal climatic conditions for vegetative growth). High-density plantings also contribute to unbalanced vine growth, as vineyards with >4942 vines per ha (>2000 vines per ac) became popular during the late 1990s and early 2000s. Additionally, many Pinot noir producers in the region prefer cane pruning, which limits bud number per vine and exacerbates vigor issues, especially in high-density plantings. To achieve appropriate canopy density for disease control and fruit quality, these vineyards require significant manual labor inputs for dormant pruning, shoot thinning, shoot positioning, sucker removal, hedging, cluster zone leaf pulling, and cluster thinning. Most growers rely entirely on manual labor and have limited mechanization due to small vineyard sizes and lack of capital to invest. Canopy management costs total in excess of $5560/ha ($2250/ac) annually 3 and have increased by ~25% since 2008 due to increased agricultural labor costs in Oregon and the Pacific Northwest. 4 Although Pinot noir brings the highest price of all grapes produced in the state at an average of $2139/ t m ($2353/t), 2 due to low target yields, these prices are not substantial enough to offset production costs. 5 With further increases projected, labor costs will remain a primary concern for producers. Furthermore, with the availability of productive farm labor becoming a greater challenge, 6 growers need more efficient vineyard management methods and are seeking ways to adapt different forms of mechanization to their current systems. 7 Dormant spur pruning has been found to be a costeffective way to balance vegetative growth and yield, obtain consistent budbreak, and achieve desired yields when applied appropriately by variety. 8 Traditionally cane-pruned varieties have been managed successfully with spur-pruned cordon systems in winegrape regions across the world, including Burgundy, Italy, Australia, and California. 9 Spur pruning is more efficient than cane pruning, as it requires fewer steps, and mechanization can be more readily applied. Partial or complete mechanically spur-pruned systems for vineyards have been developed, 10 and spur pruning with mechanical pre-pruners and manual follow-up pruning can reduce labor requirements by 50 to 90%. 11 However, despite available technology to mechanically pre-prune, which is likely a more amenable option for smaller vineyards in premium production regions, we observed that Oregon growers remain resistant to changing pruning methods. Although the effects of spur pruning and mechanization have been investigated with different varieties and regions, little work has been conducted to understand the barriers to adopting alternative methods that may help reduce production costs. We developed a multiapproach study involving industry surveys, interviews, and a field case-study to understand why the majority of growers in western Oregon continue to cane prune, when spur pruning is widely accepted in other grapegrowing regions and offers potential benefits such as labor efficiency and mechanical advances without compromising fruit or wine quality. The goals of our study were to better understand dormant pruning decision making in Oregon, to quantify differences in fruitfulness/yield, cluster size, fruit composition, and production costs associated with spur- and cane-pruned vineyards, and to explore the potential for adoption of alternative dormant pruning methods. Major Observations and Interpretations Industry survey. We sent an online survey to 247 individuals who own, operate, or manage winegrape vineyards within the state of Oregon. We received 68 responses for a response rate of 28% of total individuals recruited, representing 31% of the state s grape acreage. The majority (65%) of respondents were from the Willamette Valley, which is the largest production region in the state, with 74% of the state s vineyard acreage. Cane pruning was reported as the most common pruning method used, most often being applied in the Willamette Valley and the Umpqua River Valley, both cool-climate regions of the state (Figure 1). The main cultivars being cane-pruned were cool-climate cultivars: Pinot noir, Pinot gris, and Chardonnay. Spur pruning was the main dormant pruning method used in warm and transition regions in Oregon, where it is used on various cool- and warm-climate cultivars, including Pinot noir, Cabernet Sauvignon, and Syrah (Figure 1). The survey revealed industry observations and perceptions of different pruning methods. Seventysix percent of respondents (n = 52) used only cane pruning. The most common reasons for choosing cane pruning were concern about basal buds not being fruitful and simply because it was the most common method used in industry (Table 1). Growers were also concerned that spur pruning would result in reduced fruit quality, overly dense canopies, and increased disease or pests such as Grape Powdery Mildew (Erisyphe

64 Skinkis and Gregory necator), Botrytis (Botrytis cinerea), and grape rust mites (Calepitrimerus vitis Nalepa) (Table 2). These concerns were expressed primarily by survey respondents who do not spur prune. Respondents who primarily spur prune (24%, n = 16) reported better vine vigor, balance, and ability to meet yield and fruit quality targets. They also reported increased efficiency and reduced production costs (Table 1). Spur pruning is generally thought to be easier for manual laborers and thus less expensive than cane pruning. Twenty-seven respondents provided information on hours of manual labor per acre and total pruning costs (from pruning to brush removal) of spur and cane pruning. On average, cane pruning required 41 hrs per ac at a cost of $542 per ac, while spur pruning required 26 hrs per ac at a cost of $333 per ac, a reduction of 37% and 39% for labor hours and total pruning costs, respectively. Of those who spur prune, almost one-third (31%, n = 5) indicated their decision to spur prune was primarily influenced by the potential to mechanize for increased labor efficiency and reduced costs, but not all indicated that they were using mechanization. Ten percent of the survey respondents (n = 7) reported that they already use pre-pruning in spur or cane systems, and half of those respondents (57%, n = 4) were considering increasing the amount of mechanically pre-pruned acreage. Nearly one-third of survey respondents (32%, n = 22) reported trying different pruning practices within the two years prior to the survey. However, the majority of those respondents primarily cane prune (95%, n = 21), and the changes included improvement of cane pruning practices or the addition of mechanization to the system. Only a small Figure 1 The percentage of respondents with preferred pruning type reported by grapegrowing regions in Oregon (total n = 66, Cane = 53, and Spur = 13). Regions are categorized by their heat units (longterm average, 1 April to 1 Nov) 27 and the cultivars grown. Regions are defined as follows: Cool (Willamette Valley and Umpqua River Valley) with heat units GDD 10 = 1270, GDD 50 = 2287, and primarily cool-climate cultivars grown; Warm (Rogue Valley and Walla Walla Valley) with seasonal heat units GDD 10 = 1609, GDD 50 = 2896, and primarily warm-climate cultivars grown; and Transition (Columbia Gorge and Illinois Valley) with heat units GDD 10 = 1425, GDD 50 = 2565, and both cool- and warm-climate cultivars grown. Table 1 Reasons cited by industry survey respondents for using their preferred pruning method. Preferred pruning method/reason Respondents (%) Cane (n = 52) a Higher yields (avoids infertile buds) 35 Industry perception/standard 31 Fewer disease issues 19 Better fruit quality 10 Better vine balance 6 Spur (n = 16) More efficient and less expensive 31 Better suited for site conditions 31 Better fruit quality 31 Able to obtain target yields 31 Better vine balance 19 a n = the total number of respondents for each pruning type. Table 2 Summary of production concerns related to spur pruning compared to cane pruning in Oregon vineyards. Area of concern Industry survey Grower interviews Vineyard case study a Yield Lower Met target Met target Vine balance Overly vigorous canopy More balanced growth More balanced growth Disease status b Increased Decreased Decreased/unchanged Insect/mite status Increased Increase None found Fruit quality Decreased Increased/unchanged Increased Perception c Lack of acceptance Varied Well-accepted Production costs Unsure Reduced Reduced a Vineyard case study included field data and interviews with the vineyard manager from a premium tier estate Pinot noir vineyard and winery. b Fungal diseases of clusters, specifically Botrytis bunch rot (Botrytis cinerea). c Overall perception of others in the Oregon industry, including wineries and fruit buyers.

Spur Versus Cane Pruning In Oregon Pinot noir 65 percentage of respondents who reported changing pruning practices (9%, n = 2) experimented with spur pruning within primarily cane-pruned vineyards. This indicates a lack of adaptation or experimentation with different pruning types amongst the surveyed industry, suggesting that growers may need further information and justification to consider the transition. Grower interviews. The six growers we interviewed who use spur pruning in Pinot noir vineyards in western Oregon made the transition to better manage vine vigor, increase labor efficiency, and reduce production costs (Table 2). Half of the interviewees used mechanical pre-pruning in addition to spur pruning to lower pruning costs. Interviewees had concerns that mirrored concerns by survey respondents, including potential increases in rust mite pests, stunted shoots in spring, and difficulty establishing cordons in the early stages of the transition period (Table 2). They expressed concern about the lack of quantifiable information regarding how spur pruning affects yield, quality, and pests/disease outside of their own vineyards. All interviewees acknowledged that spur pruning was going against the status quo, as the majority of the industry has strong opinions against spur pruning, with winemakers and buyers often associating it with lower-quality fruit production than cane pruning. One interviewee reported difficulty selling fruit from spurpruned vineyards due to winemaker preference for cane-pruned vines, preventing him from making a full transition of acreage to spur pruning. However, those who did not face resistance from winemakers (n = 3) employed spur pruning in estate vineyards and were not selling fruit to outside buyers. Despite industry concerns about unfruitful basal buds, all interviewees who spur prune Pinot noir reported that basal buds were fruitful, and the majority (n = 4) were pruning to two-bud spurs. However, several (n = 3) thought cluster size and berry size were smaller, but overall yield was higher. The interviewees differed from the survey respondents in their assessment of fruit Botrytis infection (Table 2), as three interviewees reported less incidence of the disease with spur pruning. This was an important finding, as the survey and interviews were conducted after two cool, wet seasons that had high incidence of Botrytis across the state and region. We also interviewed the grower involved in the vineyard case study after the second year of the trial. He reported reduced shoot vigor that resulted in a better-balanced canopy with spur pruning, as the vineyard was too vigorous when cane pruned. This could be accounted for by spur-pruned vines having more buds per vine early in the season prior to shoot thinning than cane-pruned vines. In addition, he reported better shoot and cluster positioning in spur-pruned vines, leading to a less-dense cluster zone, better cluster exposure, and improved fruit quality. Two other interviewees reported similar observations. Despite industry concerns about reduced yields, the growercollaborator reached desired yields in the spur-pruned blocks. He noted that his pruning costs were reduced by 50% compared to cane pruning, when both pruning and brush pulling steps were included. The grower cited two disadvantages with spur pruning: establishing proper spur placement and the need to renew cordons over time. However, after 11 years of spur pruning on-site, he believed that the advantages outweighed the disadvantages and planned to convert more premium Pinot noir acreage to spur pruning. Because the case study was conducted in a vineyard from which all fruit goes into estate wines, his pruning decisions were not subject to the pervasive perception that spur pruning reduces quality that other growers may face when selling fruit on contract to wineries. Vineyard case study. We quantified differences in cane and spur pruning over two seasons using a pruning trial previously established by a grower in a premium-tier commercial Pinot noir vineyard in Dayton, OR. The grower had been conducting his own experiment for nine years prior to our collaboration. During the two years of our data collection, the grower did not observe a reduction in fruit set or yield as estimated prethinning, and there was sufficient fruit set during 2010 and 2011 that cluster thinning was required to meet the winery s target yields in both spur- and cane-pruned blocks. However, the grower reported reduced labor for cluster thinning in spur-pruned blocks, as those blocks had slightly lower lag phase yield estimates than the cane-pruned blocks during those years. When we collected our own prethinning cluster counts and weights from the vineyard case study, separate from those of the vineyard manager, we found that cluster count, vine yield, and cluster weights were similar in cane- and spur-pruned vines (data not shown). Yields were similar by harvest. The spur-pruned blocks had harvest yields and cluster weights that were 0.06 to 0.17 kg/vine and 5 to 9 g greater than the cane-pruned block, respectively. The vineyard manager reported harvest yields for spur-pruned vines between 5.6 and 6.7 t m /ha (2.5 and 3.0 t/ac) for the two growing seasons (Table 3). These yields fall within the desired range of

66 Skinkis and Gregory Table 3 Whole-block yields at harvest for spur- and cane-pruned Pinot noir over two seasons in a commercial vineyard in Dayton, OR. Yield Year/pruning method a t m /ha t/a 2010 1 bud spur 5.8 2.6 1, 2 bud spur 5.4 2.4 2 bud spur 5.8 2.6 Cane 6.1 2.7 2011 1 bud spur 6.5 2.9 1, 2 bud spur 6.7 3.0 2 bud spur 7.2 3.2 Cane 8.1 3.6 a Pruning method includes the following four pruning methods: three spur pruning lengths, including unilateral cordon-trained, spur-pruned vines with spurs pruned to one bud per spur, alternating one- and two-buds per spur along the cordon (1, 2 bud spur), two buds per spur, and cane-pruned vines. 4.5 to 6.7 t m /ha (2 to 3 t/ac) reported by the majority of survey respondents (83%, n = 56). During both years, cane-and spur-pruned blocks had similar yields at harvest, both as reported by the grower (Table 3) and in data collected during our vineyard case study (Table 4). Cane-pruned vines had yields 0.66 kg/vine less than spur-pruned vines in 2011, but there were no differences in mean cluster weight, berries per cluster, or berry weight in 2011 based on standard deviations (Table 4). There was no difference in cluster weight and little to no difference in berry number or berry weight from cane- and spur-pruned vines within the case study vineyard in either year. The clusters measured in the case study vineyard were within the same range of mean cluster weights, berry weight, and berry number per cluster found in other cane-pruned vineyards that we sampled for comparison across the Willamette Valley each year (Table 4). The comparison between vineyard case study results and other sites is of value to growers as they seek to understand the relative range of cluster sizes achieved in a given year, making note that differences are anticipated due to variation in clone, rootstock, or site characteristics. Within the spur-pruned block, the grower implemented a replicated trial with variable bud number per spur at pruning, including one-, two-, and alternating one- and two-bud spurs along the cordon, which we used to investigate the fruitfulness of basal buds. The grower managed all spur-length blocks to the same number of shoots and cluster thinning regimes each year. As a result, spurs and shoots per vine were consistent across the experimental blocks (Table 5). Also, there was little variability in yield and cluster weight from any of the three spur lengths and no difference in berry weight (Table 5). Since the grower thinned all vines to two shoots per spur in early spring, preserving the lower two shoots that grew, the one-bud spur treatments had shoots arising from non-count and first-count node positions (if both buds grew), and the other two treatments (oneand two-bud spurs and two-bud spurs) had shoots arising from non-count, first-, or second-bud positions. To understand how bud position impacts cluster size, we sampled clusters at harvest from shoots arising from non-count, first-, and second-node positions both years. We found that shoots from basal buds (non-count positions) consistently bore fruit, but cluster weights were 23 and 40 g less than clusters from first- and secondbud shoots in 2010 and 2011, respectively (Table 6). Table 4 Harvest yield components from spur- and cane-pruned Pinot noir vineyards in Oregon s Willamette Valley. a Year/pruning method Shoots/ vine Clusters/ vine Yield/vine (kg) Cluster wt Berries/ cluster Berry wt 2010 Spur, Dayton b 10 (1) 11 (2) 0.93 (0.22) 76 (26) 71 (24) 1.1 (0.2) Cane, Dayton c 10 (1) 11 (1) 0.91 (0.22) 78 (27) 66 (21) 1.1 (0.1) Cane, WV d nd nd nd 97 (40) 100 (43) 0.9 (0.3) 2011 Spur, Dayton b 11 (1) 6 (1) 1.72 (0.17) 143 (36) 116 (29) 1.2 (0.1) Cane, Dayton c 11 (1) 7 (1) 1.06 (0.28) 145 (43) 114 (29) 1.2 (0.1) Cane, WV d nd nd nd 160 (54) 138 (48) 1.1 (0.1) a Means and (standard deviations) presented, nd = not determined. b Data obtained from six field plots used in the spur-length trial within the vineyard case study in Dayton, OR. c Data collected from a cane-pruned block adjacent to the spur-pruned blocks used in the vineyard case study in Dayton, OR. d Data collected at harvest from multiple commercial cane-pruned Pinot noir vineyards from across the northern and mid-willamette Valley in 2010 (n = 4) and 2011 (n = 6).

Spur Versus Cane Pruning In Oregon Pinot noir 67 The lower weight of basal clusters was a result of fewer berries per cluster and smaller rachis size (weight and length) in both years. Berry size of basal clusters differed only slightly between node positions and was variable by year (Table 6). This slight difference in cluster size may explain why only minor differences were found between the three spur-length treatments for whole-block and vine yields at harvest (Tables 3 and 5). The vineyard case study found no differences in berry composition at harvest, regardless of pruning method (cane or spur) or spur length (one-bud, one- or two-bud, or two-bud spurs). In 2010, fruit composition at harvest ranged from 20.2 to 21.1 Brix, ph from 3.15 to 3.21, and titratable acidity from 9.2 to 9.6 g/l. Fruit composition at harvest in 2011 ranged from 20.4 to 20.7 Brix, ph from 3.17 to 3.22, and titratable acidity from 9.2 to 9.7 g/l. Furthermore, there were no differences in Botrytis bunch rot or Grape Powdery Mildew between the spur- and cane-pruned blocks at harvest. While a portion of survey respondents and interviewees indicated that their preferred pruning method was a way to reach balance and manage vigor (Tables 1 and 2), this was difficult to investigate, as most growers use qualitative assessments rather than quantifiable measures such as pruning weights to make these judgments. The grower performing the vineyard case study quantified dormant pruning weights by block and found no difference between the spur-length trial and the cane-pruned vineyards. The lack of difference is likely due to the blocks being managed similarly to a defined number of shoots and clusters per vine. This also suggests that cane- and spur-pruning can result Table 5 Two seasons of harvest yield component and cluster size data from Pinot noir vines pruned to different spur lengths at dormancy in a commercial vineyard near Dayton, OR. a Year/spur length b Spurs/ vine Shoots/ vine Clusters/ vine Yield/vine (kg) Cluster wt Berries/ cluster Berry wt 2010 1 bud 5 (0) 10 (0.7) 10 (1.6) 0.84 (0.14) 73.8 (5.6) 67 (3) 1.1 (0.1) 1, 2 buds 5 (0.2) 10 (0.5) 10 (0.2) 0.9 (0.03) 77.1 (2.9) 70 (1) 1.1 (0) 2 buds 5 (0.2) 10 (0.5) 11 (0.6) 1.00 (0.13) 78.5 (8.0) 75 (2) 1.0 (0.1) 2011 1 5 (0.1) 11 (0) 7 (0.2) 1.69 (0.05) 133.9 (8.4) 105 (1) 1.2 (0.1) 1, 2 buds 5 (0.1) 10 (0.3) 6 (0.1) 1.72 (0.06) 152.5 (4.6) 123 (2) 1.2 (0) 2 buds 5 (0.2) 11 (0.9) 7 (0.9) 1.75 (0.20) 142.9 (9.9) 119 (5) 1.2 (0) a Means and (standard deviations) were obtained from two field replicates of each spur length treatment. b Spurs were cut at dormant pruning to one bud, alternating one and two-bud spurs on successive spur positions along the cordon (1, 2 buds) or two buds per spur. Table 6 Harvest yield components of Pinot noir clusters (n = 30) selected from specific node locations on the spur in a commercial vineyard in Dayton, OR. Year/shoot position on spur a Cluster wt Berries/ cluster Berry wt Rachis wt Rachis length (cm) 2010 Basal 86 b b 82 c 1.04 4.6 10.1 b 1st 107 a 97 b 1.14 5.7 11.1 a 2nd 111 a 119 a 0.90 5.6 11.3 a p 0.0001 c <0.0001 c 0.0364 d 0.0016 d 0.0001 2011 Basal 134 b 106 b 1.20 a 6.2 b 9.1 b 1st 169 a 142 a 1.14 ab 8.0 a 10.3 a 2nd 179 a 155 a 1.10 b 8.2 a 10.5 a p <0.0001 <0.0001 0.0039 <0.0001 0.0005 a Shoot position refers to the node along the spur that the shoot arose from, including the basal (non-count) position with a shoot located at the juncture of the spur and the two-year old shoot, 1st refers to the shoot arising from the first count node, and 2nd refers to the shoot arising from the second count node. b Different letters indicate difference of means by Tukey s honest significant difference mean separation test. c log-transformed data analyzed by ANOVA and back-transformed means shown. d Non-normal data analyzed with Kruskal-Wallis. All others analyzed by ANOVA.

68 Skinkis and Gregory in similar quality if canopy management practices are similarly applied. Broader Impact The industry survey was designed to gain understanding of the industry s perceptions of spur and cane pruning in Oregon, and it focused largely on how the industry conducts dormant pruning of Pinot noir, the most economically important variety in the state. Survey respondents indicated concerns about spur pruning: specifically, reduced yields and quality. These were determined to be perceptions rather than reality, as the majority of respondents were not conducting spur pruning. The vineyard case study and industry interviews provided insight from growers who use both cane and spur pruning and could relate actual observations of the two systems. Observations from growers who incorporated spur pruning into their previously cane-pruned vineyards did not support the concerns that prevented survey respondents from pursuing spur pruning. While there is a significant body of literature describing differences resulting from dormant pruning methods, few have focused specifically on premium wine production regions, particularly with respect to technological advances. The majority of pruning studies over the last 30 years focused on mechanized pruning in large-scale vineyards where volume production is the focus; however, more recent efforts have focused on advanced fruit and wine quality. 12 Research from those larger production regions may have indirectly influenced industry perception of spur pruning, when new management practices were covered in trade journals and at regional symposia. Survey responses showed growers who cane prune associated spur pruning with low-input systems where high canopy density and disease issues may become rampant. Many of these survey respondents seemed to ignore the fact that they would still employ in-season canopy management practices similar to their cane-pruned systems if they were to change their dormant pruning method. Winemaker perception also likely influenced negative responses for spur pruning in the survey, but this was not revealed until interviewees indicated that winemakers preferred cane pruning. Similarly, in a South Australian study, winemakers detected sensory perception differences between dormant pruning methods of Cabernet Sauvignon but did not indicate what those differences were. 13 However, no differences in wine quality of caneand spur-pruned Cabernet Sauvignon were found in that study or in others. 14 Over-simplification of research results or lack of knowledge regarding bud fruitfulness and yield may also have led to industry belief that yield decreases with spur pruning. The majority of our survey respondents thought that they would have lower yields due to unfruitful buds. Some interviewed growers had the same concern, yet they had not quantified the observation, as they cluster-thinned, and target yields were always reached at harvest with spur pruning. Target yields are relatively low for Oregon and cluster thinning is employed by the majority of producers, 3 suggesting that lack of fruitfulness may be of minor concern for Oregon producers who focus on quality rather than quantity. Despite literature that suggests coolclimate varieties are unfruitful at basal buds, 15 results from our vineyard case study show that spur-pruned Pinot noir is fruitful at lower nodes, including shoots that arise from non-count buds. The belief that certain Vitis vinifera varieties have low basal bud fertility which reduces yield in spur-pruned systems could be associated with summaries of studies conducted on a vast array of cultivars worldwide. 16 It may also have been misinterpreted based on the basal (non-count) buds rather than all proximal (basal) nodes on certain varieties or based on data arising from Sultana, which lacks fruitfulness of basal buds and is one of the most-studied varieties in bud fruitfulness literature. 17 Similar to our study, other researchers have shown sufficient basal bud fruitfulness for production with little to no impact between spur- and cane-pruned systems for overall fruitfulness or yield of winegrape varieties. 18 Spur pruning has also been recommended in Burgundy, France, for productive clones of Pinot noir. 19 The complex link between fruitfulness, productivity, and vine vigor may have complicated interpretation of the relationship between pruning type and yield. Studies found low bud fruitfulness or primary bud necrosis in vigorous vines with heavy canopy shading, but this was likely related to a lack of light exposure and canopy management within those systems. 20 These systems differ vastly from those in Oregon, where vigorous vines are trained to vertically shoot-positioned canopies with multiple hedging passes and leaf removal to ensure airflow and sunlight exposure. Conversely, other studies showed greater bud fruitfulness with increased vine vigor. 21 However, in our vineyard case study, spur pruning resulted in no difference in yield, cluster architecture, or fruit composition when shoot density and farming practices were kept the same and only the pruning method changed.

Spur Versus Cane Pruning In Oregon Pinot noir 69 Similar to our findings, no differences in yield, fruit composition or sensory analysis were found when comparing cane- and spur-pruned training systems in Italy. 22 While our vineyard case study found no differences in yield at harvest between the two dormant pruning methods, there were differences in cluster architecture, with basal bud (non-count) shoots having smaller cluster weight, fewer berries per cluster, and smaller rachis size (length and weight) than clusters from the first- and second-count buds. Other studies showed similar yields between cane- and spur-pruned vines, with differences in cluster size, but these were not always statistically different. 23 In our study, basal shoots were smaller and often contained one cluster, suggesting that pruning to fewer buds would allow growers to achieve desired yields with reduced cluster-thinning costs. If growers desire higher yields for greater assurance of crop level, greater bud numbers may be retained per spur at pruning. Spur pruning may be a viable option for Pinot noir. Increased efficiency, reduced labor demands, and decreased production costs are important benefits if quality is maintained. The primary reason for not changing pruning practices has been fear derived from misinformation and inexperience, which led to buyers (wineries and winemakers) driving vineyard management decisions and not accepting new management methods. Others recognize that adoption of different pruning practices has been hard to achieve. 24 Although the majority of the wine industry in western Oregon seems resistant to changing pruning practices, there is substantial interest in and need to investigate alternatives to reduce production costs and dependence on manual labor, where possible. This will require individual assessment of each production step and its impact on different quality levels that address buyer decision-making, including vineyard aesthetics, wine quality, and brand image. This is especially important in small-scale operations such as those in Oregon and other regions of the US where any form of mechanization is seemingly impossible due to artisan brand identity, initial investment costs, human resource management concerns, site characteristics, or lack of economy of scale. Continued multidisciplinary and applied on-farm/ in-winery research and demonstration that allows grapegrowers and winemakers to observe direct impacts within their vineyard or region will lead to greater adoption of new pruning methods that recent studies have not been successful in attaining. 25 Such work is not easily conducted and requires significant logistics management in which many academic researchers and their programs are not interested or lack preparation. However, it offers extension specialists and applied viticulture researchers the opportunity to work in this holistic area of vineyard management adaptation to further scientific and economic research efforts and help advance the industry. Other extension specialists have employed participatory research and demonstration projects on-farm to encourage farmer innovation and adaptation, which agricultural producers have deemed successful, 26 a tactic required in small, premium-focused winegrape industries where labor resources or economy of scale are not sufficient for on-site experimentation. Furthermore, it is imperative that individual vineyard practices be evaluated to encourage adoption of more advanced technology, including that which goes beyond what is currently available in pruning mechanization to the future of robotic pruning, which is currently under development. Experimental Design Industry surveys and interviews. We surveyed Oregon vineyard owners, operators, managers, and winemakers in 2011 to determine their most common dormant pruning practices. The survey consisted of 28 multiple choice and short-answer questions aimed at understanding how industry currently manages pruning in their vineyards, why they chose those practices, and their interest in changing pruning or other management practices. The survey was approved by the Institutional Review Board (IRB) at Oregon State University. A recruitment email was sent to the industry, and those choosing to participate were directed to an online survey. The survey was open for 90 days and participants were only able to respond once. All responses were downloaded per IRB regulations and analyzed. We selected six industry members for interviews based on their experiences with spur pruning as reported in the surveys. We held interviews in-person or over the phone in winter 2012, asking a series of questions about their decision-making processes for dormant pruning practices to gain insight into their experiences with different pruning methods and to understand the impact that their current pruning has on their vineyard production costs. Vineyard case study. We gathered field data from a commercial vineyard in 2010 and 2011 to test findings obtained from interviews and surveys and to understand the practical implications of transitioning a vineyard from cane to spur pruning. Three main

70 Skinkis and Gregory objectives of this vineyard case study were devised to address responses from surveys, where respondents had concerns about reduced fruitfulness, yield, and fruit quality in spur pruned systems. We used an experimental plot established by a commercial Pinot noir producer in Dayton, OR to evaluate spur and cane pruning. The vineyard, planted in 1989 to Pinot noir (Pommard clone grafted to 3309C rootstock) at a vine and row spacing of 1 m 1.3 m, was initially cane pruned. However, a portion was converted to unilateral cordons with spur pruning in 2001. An adjacent block of the same clone, rootstock, and vine spacing remained cane pruned for comparison. All blocks in the trial were trained to unilateral canes or cordons and vertically shoot-positioned. Spur-pruned vines had five spurs per vine with two shoots per spur. All vines, whether cane- or spur-pruned, were thinned to 10 shoots per vine early in spring and cluster thinned to one cluster per shoot during lag phase. Both caneand spur-pruned blocks were managed with the same in-season disease control and farming practices. The grower implemented a replicated trial within the spur-pruned block with variable bud number per spur at pruning, including one-, two-, and alternating one- and two-bud spurs along the cordon. Each treatment was replicated across two sub-blocks in a randomized complete block design, and each experimental unit consisted of six vine rows of more than 100 vines per row. While we as researchers prefer a minimum of three field replicates for research studies, this trial was established well before we began the case study. Therefore, the vineyard design allowed data collection from only two replicates per spur length treatment, and data are presented with descriptive statistics rather than inferential statistics. Vines were shoot-thinned in early spring by commercial vineyard labor crews, using their standard practice of thinning to two shoots per spur, regardless of the length of the spur at pruning. Therefore, depending on the number of buds that grew into shoots, there were shoots arising from either non-count or first-count node positions in the one-bud treatments, and two-bud spur treatments had shoots arising from either non-count, first- or second-count bud positions maintained after thinning. At harvest, we quantified spurs, shoots, and clusters per vine and measured whole-vine yields in all spur length treatment plots by measuring nine vines spatially distributed across each plot. This was done to quantify whether there were major differences in shoot density that may explain differences in yield, should there be any. We collected a sample of five clusters from each of the nine vines per plot. Samples were brought back to the lab where they were measured for cluster weight, rachis weight, rachis length, berries per cluster, and berry weight. This was done to determine whether there were differences in cluster size and architecture among pruning methods. On the same day, another sample of 30 clusters was selected from each plot based on the different shoot positions on the spur. This was done to determine the cluster size as it relates to shoots arising from the basal (noncount), first- and second-shoot position along the spur. Because of the standardized thinning of shoots to two shoots per spur in all blocks, we had to define the location of each position visually. The basal bud shoot was determined as a shoot that arose from base of the spur and were found on many spurs within the block pruned to one-bud spurs. First- and second-bud positions were determined based on an assessment of location relative to the basal node position. The 30-cluster sample was collected randomly from across the entire spur-pruned block. Samples were brought back to the lab where they were analyzed as individual clusters as mentioned above. Once subsampling was completed, the block was harvested for commercial production within one day, and the vineyard manager measured whole-plot yields. Immediately after measuring cluster and berry size, we analyzed fruit to determine if there were differences in cluster ripening based on spur length or position on the spur. The berries were pressed and the juice was extracted through three layers of cheese cloth and analyzed for soluble solids using a digital refractometer (Sper Scientific), ph using a digital ph meter (Pinnacle Scholar 425, Corning), and titratable acidity using 0.1 N NaOH to an end point of ph 8.2. The same berry composition data was collected from fruit samples obtained from the adjacent cane-pruned block in the same vineyard; however, those data were not compared statistically because the experimental plot was not spatially distributed among the spurpruned vines. To compare the results of the vineyard case study with other sites, data on yield, cluster size and weight, and berry composition were obtained from other commercial Pinot noir vineyards in the region, including four vineyards in 2010 and six vineyards in 2011 from northern and mid-willamette Valley. We analyzed survey and interview data using descriptive statistics. Appropriately replicated field data from the vineyard case study was analyzed through

Spur Versus Cane Pruning In Oregon Pinot noir 71 inferential statistics using SAS 9.3 software (SAS Institute, Inc.). The analyses included general linear models analysis of variance with mean separation by Tukey s honestly significant difference test at α = 0.05. We used non-parametric analyses when data could not be transformed for normal distribution. References/Footnotes 1. U.S. Department of Agriculture National Agricultural Statistics Service. 2016. Noncitrus Fruits and Nuts. 2015 Summary. July 2016. http://usda.mannlib.cornell. edu/usda/nass/noncfruinu//2010s/2016/noncfrui- Nu-07-06-2016.pdf. 2. Southern Oregon University Research Center-SOURCE. 2016. 2015 Oregon Vineyard and Winery Census Report. 10 Oct 2016. http://library.state.or.us/repository/2013/201311141259224/. 3. Julian JW, Seavert CF, Skinkis PA, VanBuskirk P and Castagnoli S. 2008. Vineyard economics: Establishing and producing Pinot noir wine grapes in western Oregon. EM 8969-E. 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72 Skinkis and Gregory 14. Holt HE, Francis IL, Field J, Herderich MJ and Iland PG. 2008. Relationships between berry size, berry phenolic composition and wine quality scores for Cabernet Sauvignon (Vitis vinifera L.) from different pruning treatments and different vintages. Aust J Grape Wine Res 14:191-202; Kasimatis AN, Bowers KW and Vilas EP. 1985. Conversion of cane-pruned Cabernet Sauvignon vines to bilateral cordon training and a comparison of cane and spur pruning. Am J Enol Vitic 36:240-244. 15. Jackson DI and Lombard PB. 1993. Environmental and management practices affecting grape composition and wine quality A review. Am J Enol Vitic 44:409-430. 16. Khanduja SD and Balasubrahmanyam VR. 1972. Fruitfulness of grape vine buds. Econ Bot 26:280-294. 17. May P. 2004. Flowering and fruitset in grapevines. 1st ed. Lythrum Press, Adelaide, South Australia; Winkler AJ, Cook JA, Kliewer WM and Lider LA. 1974. The Grape Flower and Berry Set. In General Viticulture, pp. 111-137. University of California Press, Berkeley, CA. 18. Eltom M, Winefield CS and Trought MCT. 2014. Effect of pruning system, cane size and season on inflorescence primordia initiation and inflorescence architecture of Vitis vinifera L. Sauvignon blanc. Aust J Grape Wine Res 20:459-464; Kasimatis AN, Bowers KW and Vilas EP. 1985. Conversion of cane-pruned Cabernet Sauvignon vines to bilateral cordon training and a comparison of cane and spur pruning. Am J Enol Vitic 36:240-244; Khanduja SD and Balasubrahmanyam VR. 1972. Fruitfulness of grape vine buds. Econ Bot 26:280-294; Rosner N and Cook JA. 1983. Effects of differential pruning on Cabernet Sauvignon grapevines. Am J Enol Vitic 34:243-248. 19. Bernard R and Leguay M. 1985. Clonal variability of Pinot noir in Burgundy and its potential adaptation under cool climates. In Proceedings of the International Symposium On Cool Climate Viticulture and Enology. OSU Agr Expt Sta Tech Publ 7628. Heatherbell DA et al. (eds.), pp.63-74. Oregon State University, Corvallis, OR. 20. Dry PR. 2000. Canopy management for fruitfulness. Aust J Grape Wine Res 6:109-115; Sanchez LA and Dokoozlian NK. 2005. Bud microclimate and fruitfulness in Vitis vinifera L. Am J Enol Vitic 56:319-329; Shaulis NJ and May P. 1971. Response of 'Sultana' vines to training on a divided canopy and to shoot crowding. Am J Enol Vitic 22:215-222; Smart RE, Shaulis NJ and Lemon ER. 1982. The effect of Concord vineyard microclimate on yield. II. The interrelations between microclimate and yield expression. Am J Enol Vitic 33:109-116. 21. Eltom M, Winefield CS and Trought MCT. 2014. Effect of pruning system, cane size and season on inflorescence primordia initiation and inflorescence architecture of Vitis vinifera L. Sauvignon Blanc. Aust J Grape Wine Res 20:459-464; Khanduja SD and Balasubrahmanyam VR. 1972. Fruitfulness of grape vine buds. Econ Bot 26: 280-294. 22. Peterlunger E, Celotti E, Da Dalt G, Stefanelli S, Gollino G and Zironi R. 2002. Effect of training system on Pinot noir grape and wine composition. Am J Enol Vitic 53:14-18. 23. Rosner N and Cook JA. 1983. Effects of differential pruning on Cabernet Sauvignon grapevines. Am J Enol Vitic 34:243-248; Eltom M, Winefield CS and Trought MCT. 2014. Effect of pruning system, cane size and season on inflorescence primordia initiation and inflorescence architecture of Vitis vinifera L. Sauvignon blanc. Aust J Grape Wine Res 20:459-464. 24. Dokoozlian N. 2013. The evolution of mechanized vineyard production systems in California. Acta Hortic 978:265-278; Kasimatis AN, Bowers KW and Vilas EP. 1985. Conversion of cane-pruned Cabernet Sauvignon vines to bilateral cordon training and a comparison of cane and spur pruning. Am J Enol Vitic 36:240-244; Poni S, Tombesi S, Palliotti A, Ughini V and Gatti M. 2016. Mechanical winter pruning of grapevine: Physiological bases and applications. Sci Hortic 204:88-98; Rosner N and Cook JA. 1983. Effects of differential pruning on Cabernet Sauvignon grapevines. Am J Enol Vitic 34:243-248. 25. Dokoozlian N. 2013. The evolution of mechanized vineyard production systems in California. Acta Hortic 978:265-278; Poni S, Tombesi S, Palliotti A, Ughini V and Gatti M. 2016. Mechanical winter pruning of grapevine: Physiological bases and applications. Sci Hortic 204:88-98. 26. Getz C and Warner KD. 2006. Integrated farming systems and pollution prevention initiatives stimulate co-learning extension strategies. J Extension 44:5FEA4. https://www. joe.org/joe/2006october/a4.php; Mitchell JP, Goodell PB, Krebill-Prather R, Hembree KJ, Munk DS, May DM, Coviello RL, Hartz TK and Pettygrove GS. 2001. Innovative agricultural extension partnerships in California s Central San Joaquin Valley. J Extension 39:6RIB7 ht tps:// www.joe.org/joe/2001december/rb7.php. 27. Oregon Climate Summaries, Western Regional Climate Center (https://www.wrcc.dri.edu/summary/climsmor. html).