PROJECT PROPOSAL July 1, 2013 – June 30, 2014

TITLE: and Enology programs for the Colorado Industry

PRINCIPAL INVESTIGATOR Horst Caspari Department of Horticulture and Landscape Architecture Colorado State University Western Colorado Research Center

COLLABORATING INSTITUTIONS  Colorado Department of Agriculture  The Industry Development Board  Colorado State University

JUSTIFICATION Colorado’s area expansion seems to have come to a (temporary?) standstill. While some of the vineyard area removed in early 2010 has been replanted some growers choose to exit the -growing business. According to the “2012 Colorado Wine Grower Survey” conducted by Colorado State University (Caspari, 2013) more than half the vineyard area planted in 2012 is replacement for vines removed since the extreme cold event of December 2009. The vineyard area in Delta County in particular is shrinking: over the past five years for any 1 acre planted 3.7 acres were removed. Frequent cold injuries (winter and spring) to cold-sensitive varieties have resulted in very low yields and inadequate financial returns. Some growers are opting to get out of the grape-growing business altogether rather than replanting with more cold- hardy varieties. It is envisaged that this trend will continue. While there is a potential for a further significant increase in the total Colorado grape production, the average yield per acre remains at a fairly low level: the 10-year average (2003-2012) is a meager 2.14 tons per acre. The average yield in 2011 was 1.14 tons per acre and increased to 2.43 tons in 2012. Several factors contribute to this low production. First, Colorado has a relatively high percentage of young grape plantings that are just starting to produce a crop. Second, many growers are new to the grape industry and are struggling with some of the basic growing practices. And third, cold temperature injuries (in late fall, winter, and spring) continue to reduce yields on some to often very low levels. In fact, the 2010 crop in Mesa County was reduced by about 55 % due to very cold temperatures in the second week of December 2009. As approximately 85-95 % of Colorado’s grape crop is produced in Mesa County this translated to a state-wide crop reduction of 53 %. And the relatively low yields of 2011 were the result of a combination of factors: a late spring freeze in parts of the Grand Valley, significant mid-winter damage in Delta and Montrose County, and poor management of vineyards following the 2009 cold event. Even in 2012, a year with above-average yield per acre, almost half the growers are operating at a loss.

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 1 Although current production is less than the industry goal the Colorado grape and wine industry is fortunate in that the main growing regions are relatively free of many of the pests and diseases that bedevil other grape growing regions of the world. This lack of many pests and diseases provides Colorado with a competitive advantage over other areas in the world in the development of “integrated”, “sustainable” or “organic” production systems. The research and extension program outlined below continues our long-term goal to develop an “Integrated Production System” for wine in Colorado. Most of the early development and research will be conducted in the research vineyard of the Western Colorado Research Center at Orchard Mesa. When we are confident that these new techniques are beneficial and/or not detrimental, we plan to set up larger-scale trials on grower properties. The development of an Integrated Production System requires many different skills so there is a continued emphasis on a multi-disciplinary or team approach to research. While the State Viticulturist retains overall responsibility for the research program and delivery of the outcomes, other team members will be the lead investigators in their field of expertise. As an example, Dr Stephen Menke, the State Enologist, will be in charge of using grapes from various experiments, and the subsequent evaluation of those . Another example of collaborative efforts across state boundaries is the NE-1020 project "Multi-state evaluation of winegrape clones and cultivars" involving viticulture researchers from more than 20 states. The current proposal is a continuation of the previous proposals since 2001. However, we are increasing our efforts in the area of “Cropping Reliability”. As outlined above, many growers struggle to achieve economic viability in their vineyard ventures. We need to develop alternatives to current practices that will make grape growing an economically viable enterprise, and those alternatives also need to be adopted by the grape industry.

RESEARCH PROGRAM

DISCLAIMER Very cold temperatures in late December 2012 and throughout the first half of January 2013 have caused significant bud damage in many vineyards in the Grand Valley, including our research vineyards. In addition, late spring frosts right before / at bud break caused further damage to buds / trunks. At the time of writing (mid May 2013) bud break in many vineyards is incomplete and very erratic (both between and within vines). We anticipate a very prolonged bud break period (> one month) and that some / many vines may not break bud at all, and thus will need retraining from suckers arising from near or below the soil level. Much of the research proposed below for the 2013 season will be impacted by the cold damage.

I. Cropping reliability The emphasis in this project is to develop techniques that reduce the risk of crop losses due to cold temperature injuries. Cold temperature injuries include damages caused by winter injury as well as late spring or early autumn frosts and are the MAIN cause for Colorado’s low yields.

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 2 1. Grape varieties and rootstocks for Colorado We are part of a US-wide variety evaluation program (called NE-1020) that received approval in late 2004. The first planning meeting took place in late May 2005 at UC Davis, and the first annual meeting was held in November 2005. In November 2006, Dr Caspari was elected Secretary for the NE-1020 group and also took over the leadership for the Western Region (CA, CO, ID, TX). From November 2007 to November 2008 Dr Caspari was the Chair of the national group and he continues to lead the Western Region (which now also includes NM). The 2008 national meeting was held November 6-7, 2008 in Palisade, CO; the 2009 national meeting in Wooster, OH; the 2010 national meeting in Traverse City, MI; the 2011 national meeting in Boise, ID; and the 2012 national meeting in Mystic, CT.

 New variety and clonal trial at Rogers Mesa (Caspari/Menke) A new vineyard was planted at the Western Colorado Research Center at Rogers Mesa in the spring of 2004, with additional vines added in the spring of 2005 and 2006. With the exception of a few missing vines, this planting is complete. Genetic backgrounds of the varieties include both hybrids, mainly from the grapevine breeding program from Geneva, NY, and vinifera. Some of the varieties had a small crop in 2006, but most V. vinifera varieties had major cold damage during dormancy and did not carry a crop in 2007, and only a small crop in 2008. In contrast, hybrid varieties had no or minor winter damage and produced a full crop in all three years. Unfortunately, bird damage was excessive in 2007, and wine was made using micro-vinification techniques from only. Bird damage was negligible in 2008 and wines were made from 6 hybrid and 3 V. vinifera varieties. In 2009, the vineyard yielded the biggest crop to date (equivalent of 2.5 ton/acre), and wines were made from 6 hybrid and 6 V. vinifera varieties (including separate winemaking lots for 5 clones). In 2010, yields increased further for most hybrids as well as several V. vinifera varieties (, Regent, ) but were again disappointing for Pinot noir and P. Meunier (<0.7 ton/acre). Separate wines were made from all varieties but fruit from all Pinot noir clones and were pooled. In 2011, Pinot noir and P. Meunier had so little crop that it did not justify netting. Yields for the other varieties averaged 3 ton/acre, ranging from a low of 1.5 ton/acre for Riesling to a high of 5 ton/acre for Rkatsiteli. Again wines were made separately by variety. In 2012, Pinot noir and Pinot Meunier again had insufficient yield to justify netting. Trunks of all Riesling vines split, presumably the result of a late spring frost on 7 April when sap was rising in Riesling vines, and needed to be retrained from the ground. Yields for the other varieties averaged 2.4 ton/acre, ranging from a low of 1 ton/acre for GR 7 to 3.3 ton/acre for Corot noir. With the exception of GR 7, wines were made separately by variety. Results from this study have been presented at the 2010 Annual Meeting of the Western Colorado Horticultural Society (WCHS) in January 2010, as well as the joint WCHS and CAVE meetings in January 2011, 2012, and 2013. An overview of the trial and results to date are posted on the Viticulture web page.

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 3  Multi-state evaluation of wine grape cultivars and clones (Caspari/Menke) This is a long-term (2003-2017), multi-state research project that will test the performance of clones of the major global cultivars and of new or previously neglected wine grape cultivars in the different wine grape growing regions within the U.S. The project is a collaboration of more than 20 states. All participating states will follow the same experimental protocol. The viticultural protocol was finalized during the annual meeting in November 2007, but further work is required on the enological protocol. Researchers from 20 states provided lists of varieties to be included in the first planting, and the final vine order was assembled by Drs Tony Wolf (Eastern region) and Horst Caspari (Western region). Budwood was collected during February/March 2007 primarily by FPS staff from FPS sources. NovaVine Grapevine Nursery and Double-A Vineyards propagated the material in spring of 2007, and the first plantings took place in spring of 2008. Varieties that were planted in Colorado include: Hot climate (at WCRC-OM, all on 110R rootstock) – , Aleatico, , cl. 8 (standard), noir, Cinsaut, , Garnacha Tinta, , , cl. 3 (standard), Mourvedre, Rousanne, Souzao, Tocay Friulano, , , and . Two more varieties (Alvarinho and Verdelho) were added in summer 2009. Cold climate (at WCRC-RM, all but NY 81.0315.17 own-rooted) - Auxerrois, Bianchetta trevigiana, Blauer Portugieser, Grüner Veltliner, NY 76.0844.24, and NY 81.0315.17 on 101-14. Four more varieties [Chambourcin (standard), Marquette, MN 1200, and Vidal (standard)] were added in spring 2009. In February 2013, Cornell University released NY 76.0844.24 under the name of “Aromella”. For further detail on the NE-1020 project see http://nimss.umd.edu/homepages/home.cfm?trackID=4034 Another set of varieties on 101-14 rootstock are used as guard rows for the NE- 1020 block at WCRC-OM. Varieties planted in spring 2008 were Carmenere (own-rooted), Graciano, , , Tinta Carvalha, Touriga Nacional, and Verdelho. Vine losses were very high at WCRC-OM following the record cold event in December 2009. Replacement vines for 10 entries were planted in spring 2011. Also, due to the poor performance of Aglianico and Carignan noir, those varieties were replaced in spring 2011 with Chambourcin and Marquette. Further replacement vines were planted in spring 2012, and due to high vine mortalities Aleatico, Furmint, and Trousseau were replaced with , , and Cabernet Dorsa. The first crop of Grüner Veltliner, NY 76.0844.24, and NY 81.0315.17 was harvested at WCRC-RM in fall 2010, and wines were made from all three varieties. Yields of the two NY hybrids (3.5 and 3.9 ton/acre, respectively) were especially encouraging given the low Delta county average of 0.6 ton/acre. In 2011, all but Auxerrois and Blauer Portugieser produced at crop. Yields ranged from a low of 2.2 ton/acre for Bianchetta trevigiana and MN 1200 to a high of 7.2 ton/acre for Vidal (Delta county average was 0.96 ton/acre). Wines were made from all varieties that yielded a crop. In 2012, all varieties yielded a crop, ranging

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 4 from a low of 0.4 ton/acre for Auxerrois to a high of 5.1 for NY 76.0844.24 (Delta county average was 1.7 ton/acre). Wines were made from all varieties. Results to date were presented at the joint WCHS and CAVE meetings in January 2011, 2012, and 2013, and have also been posted to the WCRC Viticulture web page.

 Early hardiness of wine grape cultivars and clones (Caspari) This is a continuing project to evaluate hardiness of grape cultivars at the early dormancy stage. Severe cold events in November 2003, 2004, and 2006 have caused significant bud injury in many vineyards. In fact, these late-fall freeze events appear to have caused more damage than mid-winter and spring freezes. Certain varieties seem to be more susceptible than others, with Merlot and most sensitive. While much information is available about cultivar differences in maximum cold hardiness, little is known about differences at the early stage of dormancy. Under Colorado conditions, early cold hardiness might be as important, if not more important, than mid-winter hardiness. Controlled-freezing tests were conducted in fall 2005, 2006, and 2007 to determine the temperature thresholds at which Colorado’s most important grape varieties sustain damage. Results so far indicate that both Merlot and Syrah were acclimating slower than most of the other varieties grown in CSU's variety trial, but gained mid-winter hardiness levels similar to most V. vinifera varieties. Those results suggest that the higher damage observed on Merlot and Syrah compared to other varieties following the November cold events in 2003 and 2004 are indeed due to differences in fall acclimation. Data collected annually since fall 2007 indicate that hybrid varieties such as Chambourcin and Corot noir are more hardy than Rkatsiteli, one of the most cold-hardy V. vinifera varieties, in late fall and throughout winter. Information on bud cold hardiness is provided on about a weekly basis during dormancy on our web page. This web site has been well visited, receiving more than 2,000 “hits” since the 2010-11 dormant season. In fact, many growers used this information during the cold events of December 2012 and January 2013 to decide when to start their wind machines. We will continue with the controlled-freezing tests and posting of results during dormancy 2013-14.

 New rootstock trial with (Caspari) A rootstock evaluation project has been initiated with a commercial grower in the Grand Valley AVA. This study will compare the performance of Sauvignon blanc grafted to five different rootstocks (four of which have not yet been evaluated under Colorado conditions) to own-rooted vines. The first vines were planted in spring 2006, with some vines added in spring 2008. Vine dieback has been a problem, and evaluation will start when all graft combinations are established and vines are at least three years old.

 New rootstock trial with (Caspari) The guard rows and end vines for the new variety trial at Orchard Mesa (see "Multi-state evaluation of wine grape cultivars and clones" above) are being used for a rootstock evaluation project with Viognier. Rootstocks to be tested include CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 5 5BB, 5C, 110R, 1103P, and 140R. Grafted vines will be compared to own-rooted vines. Own-rooted Viognier vines and Viognier grafted to 5BB and 140R were planted in spring 2009, additional vines added/replanted in spring of 2010, 2011, and 2012. Again, vine dieback has been a problem. Own-rooted vines and vines grafted to 5C have established well but vines on the other rootstocks have struggled. In 2012 there was not enough fruit to make wine lots and early indications are that this also will be the case in 2013 (due to cold injury).

 Temperature profiles in vineyards (Caspari) From fall 2006 to spring 2012 we have collected data on the temperature fluctuations and profile during the dormant seasons in our Syrah block. Data indicate that during calm nights a strong vertical temperature inversion develops. Temperatures might be as much as high 12 F higher at 72” height compared to 6” above the ground. Differences appear to be more pronounced during calm nights when snow is present. We suspect that the much colder temperatures near the soil surface may be causing damage to the trunks, and that such cold damage happens during the first severe fall freezes when vines are not yet fully acclimated. Since May 2010 we are continuously monitoring the temperature at 10” height in our Syrah block using a data logger that is connected to the CAVE weather station network. Temperatures from fall 2012 to early May 2013 have also been recorded at the cordon height in two commercial vineyards having pronounced elevation changes throughout the vineyards. During calm nights, temperature differences as high as 8 F have been observed with virtually no differences during windy nights. Differences in cold temperature injuries observed in May 2013 are consistent with the temperature profiles. The temperature information has been used to make adjustments to the pruning strategy in the different parts of the vineyards.

2. Delay of bud burst  Delay of bud burst using spray-on materials (Caspari) Late spring freezes can cause significant crop losses – as was the case last year due to a series of late freezes (27 & 30 April, 1 & 2 May 2011). Varieties that break bud early, e.g. and Gewürztraminer, are most at-risk. If cultural practices can be developed that delay bud break they will reduce the risk of crop losses, and thereby increase the profitability of growing grapes in Colorado's high elevation. Studies have so far focused on materials that might be sprayed onto grapevines during dormancy to delay bud break. We have initiated a trial on Chardonnay in the fall of 2009 with support from Valent BioSciences. However, the cold damage from the December 2009 event precluded any data collection, and the experiment was repeated in the fall of 2010. Results from this experiment are very encouraging – due to several late spring frost events in 2011. Bud development was delayed by two of the spray-on treatments, and bud injury from the frost events was minimal compared to the non-treated control. As a result, yields were 75 % and 120 % higher than the control. We plan to continue to evaluate spray materials as they become available.

 Effect of pruning time/method on bud burst (Caspari) CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 6 Another option to delay bud break is through timing and/or method of pruning. Early pruning is thought to accelerate bud break, and may reduce winter hardiness. We have evaluated the effect of pruning time on bud break of Chardonnay over the last eight years. Although some aspects of the studies differed between years, early pruning (as early as November 1) was compared to late pruning (late March to mid April) in each year. Generally, time of pruning did not alter the timing of bud break. In the winter 2005/06 and 2006/07 we also evaluated the effect of pruning method on bud break. Standard spur pruning was compared to the so-called double- pruning method. Shoots were pruned to either short (the standard 2-3 buds) or long spurs (~8 buds). Each pruning method was applied in late December as well as early April. In spring, as buds started to push on the top of long spurs, these spurs were pruned again (back to 2-3 buds). Data from spring 2006 suggest a delay of bud break with the double-pruning technique, but data from 2007 are inconclusive due to the high level of cold damage during the dormant season. The methods were slightly altered during the 2007/08 dormant season. Vines were pruned early (November 1, 2007) or late (in early April) either short (the standard 2-3 buds) or long. The long pruning treatment was changed from previous years as follows: pruning was restricted to removing unwanted shoots only, i.e. the shoots left for spur positions were not pruned back. Preliminary analysis of the 2008 data suggest a delay of bud break of Chardonnay by more than 14 days with the later technique compared to short pruning (early or late). During the 2008/09 dormant season we again used Chardonnay. In this experiment early and late long pruning were compared to standard (i.e. late, short) pruning only. Results indicate that long pruning delayed bud break by as much as 2 weeks, but also reduced the percentage of buds that broke (88 % for standard versus 69 % for long pruning). Analysis of a similar trial during the 2011/12 dormant season confirmed both a potential delay in bud break but also a lower percentage bud break with long pruning. Due to cold injury all vines at the research stations were long pruned in March/April 2013 and we are currently adjusting shoot numbers on a vine-by-vine basis, as required.

3. Maintaining yield potential Low yields and large year-to-year fluctuations in yield are characteristic of grape growing in Colorado, even in the Grand Valley AVA. Most times the reasons for low yields are related to cold temperature injury (fall and/or mid-winter and/or spring). While growers are advised to make an assessment of bud damage prior to winter pruning and adjust their pruning level accordingly, few growers seem to follow this advice. Vines pruned to a “standard” bud number (e.g. 30 buds on vines planted at 1.52 m in-row spacing) and having a low percentage bud break by default will have reduced yields. To safeguard against a low percentage bud break, some growers use different strategies to leave far more buds than the shoot number needed for a full crop. So if bud damage is high (= low percentage bud break) there should still be enough shoots for a modest crop. In contrast, if bud damage is minimal (= high percentage bud break) vines need to be shoot-thinned shortly after bud break. On bilateral, cordon-trained, spur-pruned vines trained to a VSP (the standard in Colorado) there are several ways to leave a high bud number: a) leave more spurs; and/or b) leave spurs longer (four to six buds versus the

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 7 standard two); and/or c) leave an extra cane or two that could be tied down in case of low bud break on the cordon. In the case of cane pruning (such as in spring 2011, following the vine dieback from the December 2009 cold event) growers may opt to tie down three or more canes (rather than the standard two). Irrespective of the method used, when bud break percentage is high there are too many shoots on a vine necessitating shoot removal.

 Comparison of bilateral and quadrilateral training system (Caspari) A new experiment was initiated on a grower’s vineyard in March 2011 to compare a quadrilateral training system to a bilateral system - the “standard” in Colorado. Own-rooted vines were planted in 2009 at a vine x row spacing of 1.52 m x 2 m and trained to a VSP trellis. The two treatments are replicated 4 times using entire rows for each replicate. For the bilateral system, two 15-node canes were tied to the cordon wire for a total of 30 nodes per vine. An additional one or two canes were left long but not tied to the cordon wire (such “spare” canes may be tied down later to increase shoot number when percentage bud break on the tied canes is less than desired). For the quadrilateral system, a second cordon wire was installed 8” above and on the opposite side of the post from the original cordon wire. Four 15-node canes were tied to the cordon wires for a total of 60 nodes per vine. The idea was that once the final percentage bud break was known both systems would be “optimized” to achieve the target of 30 fruitful shoots per vine (20 shoots per m of canopy) – this might require tying down one or two of the “spare” canes to increase the shoot number on the bilateral system or thin shoots on the quadrilateral system. However, percentage bud break in 2011 was very low (~35 %) and final shoot numbers were well below the target of 20 shoots per m of canopy for both training systems even when “spare” canes were added. Shoot density was 6.5 shoots per m of canopy for the bilateral system and 10.5 shoots per m for the quadrilateral system. Consistent with higher shoot number the quadrilateral system increased the yield by 41 % over the bilateral system. A second trial evaluating the potential of the quadrilateral training system was set up in the Syrah block at the Western Colorado Research Center that is used for a training system evaluation (see below). Two rows previously trained to bilateral cordon/cane were converted to a quadrilateral system following the same procedures as described for the Tempranillo above. Bud number retained, shoot number, bunch number, and yield were determined separately for the lower and upper wire. Similar to the results with Tempranillo, percentage bud break was very low (~42 %) resulting in sub-optimal shoot densities (13.7 per m) even when the bud number retained was doubled. The addition of the two canes led to a yield increase of ~90 %, making the quadrilateral the most productive of the six training/trellis systems that are being evaluated in this block (see below). In the 2012 season, we continued with both the Tempranillo and Syrah trials while adding a third trial site with Gewürztraminer. The latter trial was initiated on a grower’s vineyard in March 2012. Own-rooted Gewürztraminer vines were planted in 2007 at a vine x row spacing of 1.52 m x 2.44 m and trained to a VSP trellis. The two treatments were replicated 8 times using 6-vine panels for each replicate. Four panels in four adjacent rows in the center of a block were selected

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 8 and vines pruned in early March 2012. In each row panels were alternately pruned to bi- or quadrilateral cane. At all sites shoots were thinned (if required) during May/June 2012. Shoot number post-thinning, bunch number, and yield were determined. Berry samples were taken during the ripening period and at to determine basic juice parameters (pH, soluble solids, titratable acidity). Similar to the results from the 2011 season, the quadrilateral system led to a significant yield increase over the “standard” bilateral system (1.0 ton/acre with Gewürztraminer; 1.4 ton/acre with Tempranillo; 1.6 ton/acre with Syrah) with no differences in basic juice parameters. Only in the Tempranillo did we observe a reduction in mean cluster and berry weight with the quadrilateral system. The Tempranillo and Gewürztraminer blocks have been severely damaged by the cold events in December 2012 and January 2013, and vines have been cut down to soil level. Therefore we set up a new trial with in March/April 2013. The Cabernet Franc block is in the same vineyard as the Tempranillo, and all other details are as outlined above for Tempranillo. There is some cold injury in both the Cabernet Franc and the Syrah but we plan to use those blocks for our 2013 comparison of the bilateral versus quadrilateral system. Results from the 2011 and 2012 season were presented at the joint WCHS and CAVE meetings in January 2012 and 2013, and have also been posted to the WCRC Viticulture web page. SEVERAL GROWERS IN THE GRAND VALLEY HAVE NOW STARTED TO USE THE QUADRILATERAL SYSTEM FOR THE 2013 SEASON IN PARTS OR ALL OF THEIR VINEYARDS.

 Adjustment of training system to increase grape yield (Caspari, Menke) A trial comparing various trellis systems and cane versus spur pruning method was initiated in 2006 using a 1.3-acre block of own-rooted Syrah vines growing at CSU's research vineyard at Orchard Mesa (see below for details). The Lyre has been the highest-yielding trellis/training system to date. Like the quadrilateral VSP system described above, the Lyre is a four-arm system that is horizontally divided. Shoots are trained upright with Lyre. Another commonly used horizontally-divided trellis system is the Geneva Double Curtain where shoots are allowed to droop. Given the advantages of the four-arm systems (Lyre and quadrilateral VSP) we decided to evaluate the potential of the GDC in the Syrah block. In March 2012 we began the conversion of one row of high single wire to a Geneva Double Curtain. Given encouraging results from the 2012 season we began converting the remaining two rows with single wire trellis to GDC in March 2013. We expect this conversion to be completed within two years. As with the other trellis systems (see below) we will determine the effects on yield and fruit quality.

 Vineyard floor management - soil and irrigation (Caspari, Kearney) A new experiment will be initiated in the fall of 2013 to evaluate the long-term effects of changes to both irrigation and soil management on vine performance and vine and soil fertility. Results from the 2004 variety trial at Rogers Mesa (see above, and Viticulture web page) show a very strong effect of soil / irrigation CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 9 system on both yield and fruit quality. With the exception of Valvin (no change), vines that are sprinkler irrigated with a grass cover crop growing in the inter-row area have produced on average 2.8 times more yield than drip irrigated vines with a bare soil inter-row area. Fruit maturity was almost always enhanced (higher soluble solids and pH, lower titratable acidity) under drip irrigation / bare soil. A preliminary analysis of data from the 2012 survey also suggests higher yields with furrow or sprinkler irrigation versus drip irrigation. We plan to convert the irrigation system in the Chardonnay block at WCRC-OM that was planted in 1992 from drip to sprinkler. At the same time we will change the soil management in the inter-row area from bare soil to cover crop. Prior to harvest soil samples will be taken from both the inter-row as well as under-vine area for future analysis of soil mineral content (and possibly other soil “health” measures). Shortly after harvest, the sprinkler system will be installed and two, possibly three different cover crops will be sown: one will be a grass-only cover crop; one a grass-legume mix; and a potential third one a pure legume such as alfalfa, or another grass-legume mix with a much higher legume content. Another treatment will be the status quo - drip irrigation and bare soil (the “Control”). The three or four treatments will be randomized with at least three replications per treatment. This project is long-term and most of the research is intended to be done by Masters candidates.

II. Development of Integrated Wine Grape Production 1. Disease Control The long-term objective of our research is to reduce the amount and toxicity levels of disease control substances. There are a number of avenues through which this can be achieved. First, sprays should be applied only if and when needed. Second, alternative control substances with lower toxicity may be used. And third, other cultural practices that may reduce disease development should be utilized (e.g. canopy management, use of natural control organisms, selection of resistant varieties). This latter point illustrates the link to and need for an inter-disciplinary approach to research. Powdery mildew (Uncinula necator) continues to be the most important disease of grapevines in Colorado. In recent years, we have provided evidence that a calendar- based spray program to control powdery mildew often results in spray applications in excess of what is needed. Since 2001 we have shown in several studies that the number of powdery mildew sprays can be reduced without increasing the incidence or severity of powdery mildew infections (Larsen and Caspari, 2001; Caspari and Larsen, 2003; Larsen and Caspari, 2004, 2005, 2006). Based largely on our research results, many growers have adopted a more restrictive spray program. We plan to continue our research on powdery mildew control with testing of new control materials (as they become available). Currently there are no specific projects planned for the 2013 season.

2. Sustainable resource use Within an Integrated Production System there is a holistic view of the vineyard environment that requires a sustainable use of vineyard resources, including soil, water, and air. Again, the individual projects listed below are the continuation of our long-term program on the sustainable use of resources. CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 10

 Water use of grapevines There is a definite lack of understanding of the water needs for grapevines in the Colorado climate. Irrigation inputs vary widely within the Colorado grape industry from too little to grossly excessive watering. An understanding of grapevine water use is a prerequisite for the development of sound irrigation practices. In addition, irrigation management can be a powerful tool to influence not only grapevine growth but also fruit quality. In the 2001 season, we have used the heat-pulse technique in an attempt to determine the water use of mature grapevines growing at the Western Colorado Research Center at Orchard Mesa. While some progress was made, further work on the heat-pulse technique with grapevines was required. In collaboration with Dr Steve Green of HortResearch in New Zealand, heat-pulse probes were installed in July 2004 in two mature Cabernet Sauvignon vines growing at the Western Colorado Research Center at Orchard Mesa and sap flow recorded for more than three months. In 2005, sap flow was recorded in four Merlot vines from late June until leaf fall, and in 2006 in two vines from early July to early November. Although sap flow per vine differed substantially between varieties/years the water use per unit canopy surface area was very similar. In very simple terms plant water use is a function of climate and canopy size. The most important climate variables are solar radiation, temperature, and vapor pressure deficit. The most important plant parameters are total leaf area, and its arrangement (i.e. canopy configuration). While climate parameters are relatively easily measured using automated weather stations, methods for leaf area measurements are very time consuming. Starting in the 2011 season, we used a non-destructive, yet indirect method to assess canopy size (and thus light interception). We used large panels with a 0.1 x 0.1 m grid (in conjunction with digital photography) placed under vines / in the inter-row area to determine the ground area that is being shaded by grape leaves. Initial work with those panels was promising, but compromised by the incomplete and highly variable canopy development that resulted from very low percentage bud break due to cold injury. Cold injury appears to be even more severe for the 2013 season and at this point it is not known if there will be sufficient canopy development for measurements.

III. Grape and wine quality The emphasis in this project is to continually improve the quality of the grapes, and the wines made from those grapes. Improving the quality of Colorado wines has been a high-priority area for the Colorado Wine Industry Development Board. While much of the work done so far has and continues to contribute towards the production of high quality grapes, we have not had a specific project on grape and wine quality. This lack of grape-to-wine quality projects was due in large parts to limited resources. Grapes are processed into wine, and the final assessment of grape quality is the assessment of the resulting wine. While CSU does have micro-vinification capabilities at the Western Colorado Research Center we did not have the staff resources nor the required expertise to make wine from various viticultural experiments. However, with the help of Bill Musgnung, the consulting winemaker contracted by CWIDB, wine was made in 2005, 2006, and 2007 from a crop load trial initiated in the 2005 season. The viticultural part of

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 11 this trial is now complete but wines made from the trials will continue to be evaluated over time and used for education. In fact, Dr Stephen Menke, the new State Enologist, has been using some of those wines for his enology class on campus as well as various industry workshops/seminars.

 Effect of crop load on grape and wine quality (Caspari, Menke) It is generally accepted that there is a negative relationship between grape yield and grape (and thus wine) quality. In simple terms, as yield per vine increases the quality of the grapes decreases. Initially, a small increase in yield may not alter grape quality at all or cause only a small decrease, but as the grape yield increases each subsequent yield increment leads to a stronger negative effect on quality. And while such yield:quality relationships have been shown in many studies in different parts of the world, there are no data from Colorado. A trial was established in 2005 to provide such data. A crop load trial was established on three different commercial vineyards (two Cabernet Sauvignon, one Cabernet Franc) in 2005. On each site, a low crop load was established on 15 vines by removing ~25-33 % of bunches just prior to . Another 15 vines that had no crop removed were selected as control (high crop load). Berry samples were collected for juice analysis about every ten days starting in early September. At harvest, bunch number and yield was determined for each vine, and a 100-berry sample taken for juice analysis. For each site, fruit from each crop load treatment were pooled, then crushed and fermented separately at CSU's Western Colorado Research Center. Each year vines were pruned in February/March and the pruning weight determined for each vine. On two sites many of the vines used in the previous two years had significant cold injury and needed to be re-trained from the ground. Hence, new vines were selected for the 2007 season. However, one site had almost 100 % damage so we shifted the experiment and used Syrah vines growing at CSU's research vineyard. All wines made from this trial have been bottled and are now being used for comparative tastings, evaluation, education, and demonstration.

 Effect of training system and pruning method on grape yield and wine quality (Caspari, Menke) A trial comparing various trellis systems and cane versus spur pruning method was initiated in 2006 using a 1.3-acre block of own-rooted Syrah vines growing at CSU's research vineyard at Orchard Mesa. The row x vine spacing is 1.52 m x 2.73 m. Trellis systems include Vertical Shoot Positioning (VSP; the industry "standard"), Halbbogen, low and high single wire, high Sylvoz, and Lyre. In March 2012 we began the conversion of one row of high single wire to a Geneva Double Curtain. Vines with Halbbogen are cane pruned with the remaining vines cordon-trained and spur pruned (long spur in the case of Sylvoz). Replacement vines were planted in spring 2007, and more were added in spring 2009 and 2011. For each training system we are collecting data on the time required for dormant pruning. As the block matures we will determine yield per vine, and basic juice parameters (soluble solids, titratable acidity, pH). If possible, the time requirements for other cultural practices (e.g. wire lifting, shoot thinning, crop CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 12 load adjustment, harvest) will also be recorded. Separate wines will be made from each trellis/pruning system. Fruit from this block was used in 2008 and 2009 for a separate enological study evaluating the effect of varying skin contact time (13 versus 38 days in 2008; 19 versus 42 days in 2009) on wine quality. Wines have been bottled and will be used for industry tastings and education. Further, fruit from this Syrah block has been and will be used to create different blends with other V. vinifera as well as hybrid varieties. Those blends have already been used and will continue to be used for industry tastings and educational events (such as the wine blending workshops in September 2010 and August 2011; with consumers at Colorado Mountain Winefest 2010 and 2011; Colorado Urban Winefest 2012; CSU Denver Alumni 10th Annual Fall Wine Tasting event, 2012).

TECHNICAL ASSISTANCE 1. Technical assistance to growers This consists of office consultations, inquiries via phone calls, fax, or e-mails, and field visits addressing a wide range of viticultural aspects. We will also continue to work on updating the “Colorado Grape Growers’ Guide” (Bulletin 550A, Colorado State University Cooperative Extension). This Bulletin 550A is currently out of print but the complete text can be downloaded from the web page of the Western Colorado Research Center (www.colostate.edu/programs/wcrc). Since November 2003, many articles have been added to our viticulture web site, and the whole WCRC web site got updated in fall of 2007. We will continue to use our web site as the primary means to provide information resources for Colorado growers. Also, as part of the “Application of Crop Modeling for Sustainable Grape Production” project, current weather information from seven vineyard sites is accessible to grape growers and the public via the internet. We will continue to service both the software and hardware for this weather station network. In addition, meteorological data from a GroWeather station located at the Western Colorado Research Center at Orchard Mesa are also accessible to growers via the web page of the Western Colorado Research Center.

2. Field demonstrations/workshops/tours We will continue to provide grape growers with annual field demonstrations (e.g. pruning) and workshops. Tours of the research vineyard and/or the research facilities are provided upon request. In May 2012 we have started a series of monthly vineyard visits. Each month during the growing season a different owner/operator will host a late afternoon meeting in his/her vineyard. The idea is for visitors to see what fellow growers are doing, to demonstrate/discuss both current vineyard practices as well as what should be done during the next month, and to interact and share ideas with other growers. During the 2012 season we held four of those visits, and we plan to hold 3 to 4 during the 2013 season.

3. Off-station research and demonstration plots We know from past experience that the uptake of new research results and new production techniques is fastest when growers are directly involved in their development. CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 13 One way of involving growers in research is to establish research plots on grower properties. Where feasible, we plan to establish research trials in grower vineyards. We will continue to use the vineyard at the Western Colorado Research Center at Orchard Mesa in the first or early stages of testing of new methods and/or trials that carry a high risk of crop damage. However, it is envisaged that off-station research and demonstration plots will play an important part in transferring new technologies once they have been found to be successful. The project “Application of Crop Modeling for Sustainable Grape Production” involved five commercial vineyards, and we used two of those vineyards for the GPS study. In addition, one of our collaborators in this study provided a second Chardonnay block for evaluation. The crop load study started in 2005 was located on three commercial vineyards. Also, in spring 2006 a new rootstock trial with Sauvignon blanc has been initiated on a commercial vineyard. The comparison of bilateral and quadrilateral pruning systems initiated in spring 2011 is located on another commercial vineyard, with a second site added in 2012. Both those vineyards are now using the quadrilateral system on the whole vineyard (except the trial plots). The new vineyards at Rogers Mesa Research Center also fill a need for more demonstration resources in Delta county.

4. Colorado Wine Grower Survey Colorado State University has conducted this annual survey for a number of years. The survey will again be conducted in late autumn / early winter 2013. The data will be compiled, summarized and presented to the CWIDB as well as at the VinCO 2014 meeting. A summary will also be available via the viticulture web page.

DURATION The duration of this project will be from July 1, 2013 through June 30, 2014. However, the research activities that occur during this period will be a continuation and expansion of the entire mission, goals and objectives of the Colorado Wine Industry Development Board.

RESULTS Results of this project will be presented to the Wine Board directors in the form of progress reports and up-to-date articles posted on the viticulture web page. Research results will also be presented to the general public locally through newsletter, web pages, presentations at CAVE and grower meetings, and/or state- and nation-wide through scientific presentations and journals.

LITERATURE CITED Caspari, H.W. 2013. 2012 Grower Survey (accessible via www.colostate.edu/programs/wcrc/viticulture.htm) Caspari, H.W. and H.J. Larsen. 2003. Application of crop modeling for sustainable grape production. In: Western Colorado Research Center Research Report 2002, pp. 29- 32. Colorado State University Agricultural Experiment Station Technical Report TR03-7. Caspari, H.W. and H.J. Larsen. 2006. Application of crop modeling for sustainable grape production. In: Western Colorado Research Center Research Report 2005.

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 14 Colorado State University Agricultural Experiment Station Technical Report TR06-06. Larsen, H.J. and H. Caspari. 2001. Cropping reliability and powdery mildew control studies during 2001. In: Western Colorado Research Center Research Report 2001, pp. 25-31. Colorado State University Agricultural Experiment Station Technical Report TR01-13. Larsen, H.J. and H.W. Caspari. 2004. Application of crop modeling for sustainable grape production: Year two results. In: Western Colorado Research Center Research Report 2003, pp. 29-35. Colorado State University Agricultural Experiment Station Technical Report TR04-05. Larsen, H.J. and H.W. Caspari. 2005. Application of crop modeling for sustainable grape production. In: Western Colorado Research Center Research Report 2004, pp. 27- 33. Colorado State University Agricultural Experiment Station Technical Report TR05-08.

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 15 BUDGET OUTLINE July 1, 2013 –June 30, 2014

Salaries $126,500

Fringe Benefits1 (payroll costs) $29,854

Domestic Travel $2,750

Materials and Supplies2 $12,658

Equipment3 $5,500

Total Direct Costs $177,262

Indirect Costs @ 26 % (excluding equipment) $44,658

TOTAL BUDGET $221,920

This budget does NOT include funding by the CWIDB for the enology position

Note: Budget line items are agreed to be estimates. This budget contemplates the potential that the budget as a whole can be adjusted by line item to the needs of the project without prior approval (e.g. substitution of funds within line items, including equipment), but without exceeding the total budget of $221,920.

1 23.6% of salaries 2 for field and laboratory research; includes chemicals, glassware, parts, plant materials, vineyard materials, etc. 3 items in excess of $5,000 (e.g. self-powered mulcher/mower ~$6,500)

CSU Research Proposal to CWIDB for 1 July 12 through 30 June 13 Page 16