from 143 to 245 d (same weather Evaluation of Rootstocks on Harvest Metrics of stations as aforementioned), making ‘Pinot Noir clone 02A’ Wine Grapes in Maritime frost risk for most of the AVA a non- major threat. Western Washington The average heat accumulation in the area ranged from less than 1100 1,4 2 3 to just greater than 2000 growing Michelle M. Moyer , Jaqueline King , and Gary Moulton degree days (GDD), base 50 °F (‘‘Sequim’’ and ‘‘Seattle’’ stations, re- ADDITIONAL INDEX WORDS. maritime wine grapes, wine grape rootstocks, Vitis spectively); however, 2000 GDD is vinifera generally considered the minimum heat units necessary to ripen tradi- SUMMARY. The Puget Sound American Viticulture Area (AVA), located west of the tional wine grape varieties (Amerine Cascade Mountain Range in Washington State, is a large and uniquely situated area with and Winkler, 1944; Moyer et al., diverse topography and mesoclimates. Given the young age of the AVA, little formal information exists on the appropriate rootstock–scion combination in wine grapes (Vitis 2014). Thus, heat accumulation in vinifera) for the region. This project reports on a series of rootstock trials from 2003 to the growing region is a potential pro- 2007, which evaluated the influence of ‘420A Millardet et de Grasset’, ‘3309 Couderc’, duction limitation in this AVA. To ‘101-14 Millardet et de Grasset’ (all Vitis hybrids), and a self-rooted control on basic help mitigate the challenges posed by harvest metrics of the wine grape scion ‘Pinot noir clone 02A’. At the warmer site in a cooler growing season, research on Everson, WA, rootstocks had no effect on final juice harvest metrics measured by soluble short-season/cool-tolerant varieties solids, titratable acidity (TA), and pH. At the cooler site in Mount Vernon, WA, the began in the 1970s at Washington use of rootstocks did not always influence soluble solids or pH but did reduce final State University’s Northwest Research harvest TA, a desired effect for the region that is typified by low sugar–high TA wines. and Extension Center in Mount Even with a reduction in TA in some rootstock–scion combinations, overall, TA Vernon, WA. These wine grape trials remained at the upper end or above the range typically desired for many wine styles. provided essential information to commercial wine grape producers acific northwestern North major metropolitan areas of Portland, on the best varieties for production America is the largest wine OR; Seattle, WA; and Vancouver, in this climate. As a result of this Pgrape production region out- BC, Canada. research, white-fruited varieties such side of California, with over 86,000 The Puget Sound AVA is char- as Siegerrebe, Madeleine Angevine, acres spread across Washington, Ore- acterized by its diversity in climates and Muller-Thurgau (all V. vinifera) gon, and British Columbia [Bremmer and is the only Washington AVA have already proven successful in and Bremmer, 2014; U.S. Depart- located west of the Cascade Moun- commercial production. ment of Agriculture (USDA), 2012, tains. To highlight this diversity, A renewed interest in variety tri- 2017]. There are 55,445 acres of weather (Washington State Univer- als occurred in the early 2000s, with wine grapes in Washington, of which sity, 2018) from extreme areas in this the focus on addressing the potential 99.8% lay east of the Cascade Moun- AVA in 2012 are described below. threat of phylloxera (Daktulosphaira tains (USDA, 2017). However, there The year 2012 was chosen, as the vitifoliae), the shift in wine consumer is a growing industry in the Puget grape and wine industry across the preference to red wine (Olsen et al., Sound AVA, which is climatologically state of Washington tends to charac- 2006), and the related increase in similar to most of the Oregon wine terize that year as ‘‘average’’ in terms price premiums associated with red grape production areas. This AVA is of temperature and precipitation. varietals. Specifically, there was an one of the largest in total available Rainfall in the region ranged from interest in the Puget Sound AVA to area, encompassing over 4.75 million 14.4 to 60.13 inches (‘‘Sequim’’ and produce ‘Pinot Noir’ after seeing the acres, but contains only 102 acres of ‘‘Tumwater SW’’ stations, respec- success of the variety in Willamette wine grapes (USDA, 2017). From tively). The rainfall pattern is domi- Valley, OR. However, the cool grow- a wine marketing standpoint, it is nated by winter precipitation; low ing season of the Puget Sound AVA one of the best-situated AVAs, given summer precipitation in some years posed challenges in adequately and that it includes or neighbors the typically results in the need for sup- consistently ripening ‘Pinot Noir’ and plemental irrigation. Modified by the controlling vine canopy development Support for this project was provided by the Wash- Pacific Ocean, the frost-free period in which resulted in very large vines with ington State Grape and Wine Research Program and the AVA averages at 188 d but ranges overshaded fruit. The lack of control the Northwest Center for Small Fruit Research. 1Department of Horticulture, Washington State University-Irrigated Agriculture Research and Exten- Units sion Center, Prosser, WA 99350 To convert U.S. to SI, To convert SI to U.S., 2Department of Horticulture, Washington State multiply by U.S. unit SI unit multiply by University-Northwest Research and Extension Cen- ter, Mount Vernon, WA 98273 1 % g/100 mL 1 0.4047 acre(s) ha 2.4711 3 Formerly Department of Horticulture, Washington 29.5735 fl oz mL 0.0338 State University-Northwest Research and Extension 0.3048 ft m 3.2808 Center, Mount Vernon, WA 98273 2.54 inch(es) cm 0.3937 4Corresponding author. E-mail: michelle.moyer@ 0.4536 lb kg 2.2046 wsu.edu. 1.6093 mile(s) km 0.6214 https://doi.org/10.21273/HORTTECH04170-18 (°F – 32) O 1.8 °F °C(°C · 1.8) + 32 830 • December 2018 28(6) over the timing of water application due to rainfall patterns in the area lim- ited the greatest tool in canopy man- agement: deficit irrigation (Wample and Smithyman, 2002). However, the use of rootstocks may help over- come these challenges associated with pest resistance, timing of ripening, and canopy management, thus expand- ing the range of areas where high quality red wine such as ‘Pinot Noir’ can be produced. The trial described herein aimed to look at the influence of rootstocks on the harvest parame- ters of ‘Pinot Noir 02A’. Rootstocks used in this study were selected for pest resistance, for their potential to advance fruit maturity or influence fruit composition, and/or control vine vigor (Bettiga et al., 2003; Catlin, 1991; Reynolds and Wardle, 2001; Ruhl et al., 1988; Shaffer et al., 2004), but only the effects on fruit maturity are discussed in this report. Materials and methods WEATHER DATA. Temperature data were collected using local tem- perature loggers (RH-52; Avatel Technologies, Brandon, FL) at each of the vineyard sites (site-specific in- formation reported below). Growing degree day unit accumulation was calculated from 1 Apr. to 31 Oct. for each year, using 50 °F as a base temperature. To calculate GDD units per day, the base temperature was subtracted from the average daily temperature. In the event that this calculation resulted in a negative num- Fig. 1. Monthly average minimum temperature, maximum temperate, and total ber, the calculated negative number precipitation from AgWeatherNet Stations (Washington State University, 2018) was reset to zero. Figure 1 also displays nearest the research sites of Mount Vernon, WA [WSU Mount Vernon (left column)], and Everson, WA [Nooksack (right column)] for the years of 2004–07; the monthly average minimum and ° L O ° maximum temperatures, and total ( F 32) 1.8 = C, 1 inch = 2.54 cm. precipitation that were recorded at AgWeatherNet stations nearest the research sites. These stations included its general early-ripening behavior [3309C (Vitis riparia · V. rupestris ‘‘WSU Mount Vernon,’’ which was and widespread planting in similar selected for phylloxera resistance, low less 0.6 miles from the Mount Vernon climate areas (i.e., western Oregon). to moderate vigor, adaption to deep research site, and ‘‘Nooksack,’’ which The primary goal was to deter- soils, and ease of propagation)], and was within 6 miles of the Everson site mine if rootstocks could advance vine 3) ‘101-14 Millardet et de Grasset’ and was the only AgWeatherNet sta- phenology (specifically, ripening) to [101-14 Mtg (V. riparia · V. rupest- tion that was installed in that area at combat limitations of a cooler grow- ris selected for phylloxera resistance, the time of the study. ing season. The following rootstocks moderate vigor, adaption to deep ROOTSTOCK EVALUATION TRIALS. were used for evaluation; secondary soils, and ease of propagation)]. Self- To consistently evaluate the influence considerations for rootstock selec- rooted vines were used as control. of rootstock on scion development, tions are also listed: 1) ‘420A Mill- Before the selection of these three the same variety clone of Pinot Noir ardet et de Grasset’ [420A (Vitis rootstocks, an additional minitrial of was used across both locations and berlandieri · Vitis rupestris selected rootstocks which also included ‘Riparia all rootstocks. ‘Pinot Noir 02A’ for phylloxera resistance, low vigor, Gloire’ (V. riparia), ‘44-53 Malegue’ (Wadenswil clone Bl 10/16), a adaption to fertile soils, and ease of [V. riparia · (Vitis cordifolia · V. Swiss-origin clone, was selected for propagation)], 2) ‘3309 Couderc’ rupestris)], ‘Teleki 5C’ (V. berlandieri · • December 2018 28(6) 831 PRELIMINARY AND REGIONAL REPORTS V. riparia), and ‘Kober 5BB’ (V. completed in late July and again in STATISTICAL ANALYSES. All data berlandieri · V. riparia) was con- late August to facilitate the installa- were analyzed using JMP statistical ducted.