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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 ASEV CATALYST 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 2,3 1 Viticulture Extension Specialist and Associate Professor and 2 former graduate student, Department of Horticulture, 4017 ALS Building, Oregon State University, Corvallis, OR 95331; and 3 Vineyard Manager and Grower Relations, Adelsheim Vineyard, 16800 NE Calkins Lane, Newberg, OR 97132. *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. They also thank Amelia Doyle for her assistance in reviewing this manuscript. Manuscript submitted Jan 2017, revised Jun 2017, accepted Jun 2017 Copyright 2017 by the American Society for Enology and Viticulture. All rights reserved. Summary Goals: Winegrape production is more costly in Oregon than 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 readily mechanized compared to cane pruning; however, the majority of Oregon growers use cane pruning. We conducted industry surveys and interviews to understand why they prefer cane pruning and 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. 28 1 Copyright 2017 by.

29 Key Findings 30 31 32 33 34 35 36 37 38 39 40 The majority of survey respondents (76%) used primarily cane pruning on cool climate cultivars, as they believe that spur pruning would reduce yields and fruit quality and increase fungal and mite pests. A total of 35% believed that spur pruning would reduce 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, reduce production costs and labor dependency over cane pruning. 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. 41 42 43 44 45 46 47 48 49 Impact and Significance Industry perception and lack of experience with spur pruning is preventing adoption. Perception of low yields is based on industry hearsay, not direct experience. Concerns that spur pruning results in lower 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. Reduced pruning costs is possible by converting to spur, and research/demonstration projects are needed to help small quality-focused industries make necessary adaptations to their production systems. 2

50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 Key words: bud fruitfulness, mechanical winter pruning, pruning, Pinot noir, 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 a total of 1,052 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 are an additional factor contributing to unbalanced vine growth, as vineyards with >4,942 vines per hectare (>2,000 vines per acre) became popular during the late 1990 s and early 2000 s. 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. In order 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 the small vineyard size and lack of capital to invest. Canopy management costs total in excess of $5,560/ha ($2,250/ac) annually 3 and have increased by an estimated 25% since 2008 based on increased agricultural labor costs in Oregon and the Pacific Northwest 4. Although Pinot noir brings in the highest price of all grapes produced in the state at an average of $2,139/t m ($2,353/t) 2, these prices are not substantial enough to offset production costs due to low target 3

71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 yields 5. With further increases projected, labor costs will remain a primary concern for producers. Furthermore, with 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 cost-effective way to balance vegetative growth and yield, obtain consistent bud break and achieve desired yields when applied appropriately by variety 8. Traditionally cane-pruned varieties have been successfully managed with spur-pruned cordon systems in winegrape regions across the world, including Burgundy, Italy, Australia, and California 9. Furthermore, spur pruning is more efficient than cane pruning, as it does not require as many 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 the available technology to mechanically preprune, 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 grape growing regions and offers potential benefits such as labor efficiency and 4

92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 mechanical advances without compromising fruit or wine quality. The goals of our study were to better understand dormant pruning decision-making in Oregon, 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 out an online survey to a total of 247 individuals who own, operate or manage winegrape vineyards within the state of Oregon. We received a total of 68 responses for a response rate of 28% of total individuals recruited, which represented 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 included 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. A total of 76% of respondents (n=52) use 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). They were also concerned that spur 5

113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 pruning would result in reduced fruit quality, overly dense canopies, and increased disease or pests such as Grape Powdery Mildew (Erisiphe 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 that they were able to achieve better vine vigor, balance, and both yields 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 hours per acre at a cost of $542 per acre while spur pruning required 26 hours per acre at a cost of $333 per acre, 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 prepruning 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 change included improvement of their cane pruning practices or the addition of mechanization to the system. Only a small percentage of respondents who reported changing 6

134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 pruning practices (9%, n=2) experimented with spur pruning within primarily cane pruned vineyards. This indicates the 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 in order to better manage vine vigor, increase labor efficiency, and reduce production costs (Table 2). Half of the interviewees used mechanical pre-pruners in addition to spur pruning to lower their 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 lack of quantifiable information about how spur pruning affects yield, quality, and pests/disease outside of their own vineyards. All of the interviewees acknowledged that spur pruning was going against 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 compared to cane pruning. One interviewee reported difficulties selling fruit from spur pruned 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 2-bud 7

155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 spurs. However, several (n=3) thought cluster size and berry size was smaller yet overall yields were higher. The interviewees differed from the survey respondents for 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 a reduction in shoot vigor that resulted in a better balanced canopy with spur pruning, as it 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 compared to cane pruned vines. In addition, he reported better shoot and cluster positioning in spur-pruned vines which led 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 grower-collaborator was able to reach desired yields in the spur pruned blocks. He noted that his pruning costs were reduced by 50% compared to cane pruning when considering pruning and brush pulling steps. The grower cited two disadvantages with spur pruning, including establishing proper spur placement and the need to renew cordons over time. However, after eleven years of spur pruning on-site, he believed that the advantages outweighed the disadvantages, and he planned to convert more premium Pinot noir acreage to spur pruning. Because the case study was conducted in a vineyard where all the fruit goes into estate wines, his pruning decisions were not subject to the 8

175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 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 the course of 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 estimated pre-thinning, and there was enough 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, he 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 pre-thinning cluster counts and weights from the vineyard case study separate from the vineyard manager, we found that cluster count, vine yield and cluster weights were similar between 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/a) for the two growing seasons (Table 3). These yields fall within the desired range of 4.5 to 6.7 t m /ha (2 to 3 t/a) reported by the majority of survey respondents (83%, n=56). During both years, cane and spur pruned blocks had similar yields at harvest when reported by the grower (Table 3) and in data collected in our vineyard case study (Table 4). Cane pruned vines had yields 0.66 kg/vine lower compared to spur pruned vines in 2011, but there 9

196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 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 from cane and spur pruned vines within the case study vineyard during the two years of sampling. Furthermore, there was little to no difference in berry number or berry weight between the two pruning methods 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 as 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 size 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 1, 2, and alternating 1 and 2 bud spurs along the cordon, which we used to investigate 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 2 shoots per spur in early spring, preserving the lower two shoots that grew, the 1-bud spur treatments had shoots arising from non-count and first count node positions (if both buds grew), and the other two treatments (1,2 bud spurs and 2- bud spurs) had shoots arising from non-count, first or second bud positions. To understand how 10

217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 bud position impacts cluster size, we sampled clusters at harvest from shoots arising from noncount, first and second node positions both years. We found that shoots from basal buds (noncount positions) consistently bore fruit, but cluster weights were 23 and 40 g lower compared to clusters from first and second bud shoots in 2010 and 2011, respectively (Table 6). The lower weight of basal clusters was a result of fewer berries per cluster and smaller rachis size (weight and length) 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 results did not show differences in berry composition at harvest, regardless of pruning method (cane or spur) or spur length (l-bud, l,2-bud, or 2-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 observed between the spur and cane pruned blocks during harvest. While a portion of survey respondents and interviewees indicated that their preferred pruning method was a way to reach balance and manage vigor (Table 1 and 2), it was difficult to investigate, as most growers use qualitative assessments rather than quantifiable measures such as pruning weights to make these judgments. The vineyard case study grower quantified dormant pruning weights by block and found no difference between the spur length trial and the cane 11

238 239 240 pruned vineyards. The lack of difference is likely due to the block being managed similarly to a defined number of shoots and clusters per vine. This also suggests that cane or spur pruning can result in similar quality if canopy management practices are similarly applied. 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 Broader Impact The industry survey was designed to gain understanding of the industry s perceptions of spur and cane pruning in Oregon, and it was largely focused on how the industry conducts dormant pruning of Pinot noir, the most economically important variety for the state. Survey respondents indicated concerns about spur pruning, namely 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 between 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 advances in technology. The majority of studies on pruning over the last thirty years have focused on mechanized pruning in large scale vineyards where volume production is the focus, but 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 they learn of new management practices covered in trade 12

259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 journals and at regional symposia. Survey responses from those who cane prune showed an association between spur pruning and 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, a study in South Australia indicated that 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 cane and spur pruned Cabernet Sauvignon were found in that study or in that of 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 would decrease with spur pruning. The majority of our survey respondents thought that they would have lower yields due to unfruitful buds. Even a few growers interviewed 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 suggest cool climate 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 13

280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 belief that certain Vitis vinifera varieties have low basal bud fertility and spur pruning will result in reduced yields may likely be associated with summarization of literature reviews of studies conducted on a vast array of cultivars worldwide 16. It may have also 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, others show 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 suggested as a suitable pruning method 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 have shown 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 have shown 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. Similar to our findings, no difference in yields, fruit composition or sensory analysis were found when comparing cane and spur pruned training systems in Italy 22. While our 14

301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 vineyard case study showed no differences in yields 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 have shown similar yields between cane and spur with differences observed 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 has 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 in order to reduce production costs and dependency on manual labor where possible. This will require assessment of each production step individually 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 15

322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 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 grape growers and winemakers the ability 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. This type of work is not easily conducted and requires significant logistics management that many academic researchers may not be interested in or prepared to explore within their research programs. However, it offers Extension specialists and applied viticulture researchers the opportunity to work in this holistic area of vineyard management adaptation to further our 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, and this is the route 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 in order to encourage the 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. 340 341 342 Experimental Design Industry Surveys and Interviews. We surveyed Oregon vineyard owners/operators/managers and winemakers during 2011 to determine the most common 16

343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 dormant pruning practices being used. 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, and interviewees were asked a series of questions about their decision-making processes for dormant pruning practices in order 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 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 x 1.3 m, was initially cane pruned. However, 17

364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 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 ten shoots per vine early in spring and cluster thinned to one cluster per shoot during lag phase. Both cane and 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, including1, 2, and alternating 1 and 2 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 through inferential statistics. Vines were shoot-thinned in early spring by labor crews of the commercial vineyard 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 1-bud treatments, and 2- bud spur treatments had shoots arising from either non-count, first or second count bud positions maintained after thinning. 18

385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 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 if there were differences in cluster size and architecture between different pruning methods. On the same day, another sample of 30 clusters were 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 (non-count), first and second shoot position along the spur. Because of the standardized thinning of shoots to 2 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 1-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 sub-sampling was completed, the block was harvested for commercial production within 1 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 19

406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 berries were pressed and the juice was extracted through three layers of cheese cloth and analyzed for soluble solids (SS) using a digital refractometer (Sper Scientific, Scottsdale AZ), ph using a digital ph meter (Pinnacle Scholar 425, Corning, Lowell, MA) and titratable acidity (TA) using 0.1 N NaOH to an end point 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 spur pruned vines. To compare the results of the vineyard case study with other sites, yield, cluster size and weight, and berry composition data were obtained from other commercial Pinot noir vineyards in the region, including 4 vineyards in 2010 and 6 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 inferential statistics using SAS 9.3 software (SAS Institute, Inc., Cary, NC). 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. 423 References and Footnotes 424 425 426 1. U.S. Department of Agriculture National Agricultural Statistics Service. 2016. Noncitrus Fruits and Nuts Report. 2015 Summary. July 2016. http://usda.mannlib.cornell.edu/usda/current/noncfruinu/noncfruinu-07-06-2016.pdf. 20

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560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 24. Dokoozlian N. 2013. The evolution of mechanized vineyard production systems in California. Acta Hort 978: 265 278. Kasimatis A, Bowers K and Vilas E. 1985. Conversion of cane-pruned Cabernet Sauvignon (Vitis vinifera L.) 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 Hort 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 Hort 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 Hort 204: 88 98. 26. Getz C and Warner KD. 2006. Integrated farming systems and pollution prevention initiatives stimulate co-learning Extension strategies. J Ext 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 Ext 39: 6RIB7 http://www.joe.org/joe/2001december/rb7.php 27. Oregon Climate Summaries, Western Regional Climate Center (http://www.wrcc.dri.edu/climatedata/climsum/) 25

Table 1 Reasons cited by industry survey respondents for using their preferred pruning method Preferred Pruning Method Reason Respondents (%) Higher yields (avoids infertile buds) 35 Industry perception/standard 31 Cane (n=52) Less disease issues 19 Better fruit quality 10 Better vine balance 6 More efficient and less expensive 31 Better suited for site conditions 31 Spur (n=16) Better fruit quality 31 Able to obtain target yields 31 Better vine balance 19 n = the total number of respondents for each pruning type 26

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 interview with 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. 27