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Baby-leaf salad green crops such as lettuce (Lactuca sativa), kale (Brassica oleracea), arugula (Eruca sativa), andmustard greens (Brassica juncea) thrive in the cool, humid climate of themaritime Pacific Northwest, particularly in the extended spring and fall seasons. To identify cultivars best suited for extended-season production in northwest Washington, nine leafy green cultivars were grown at two locations in the spring and fall seasons for 2 years. A high level of variability in crop performance was observed between seasons, locations, years, planting dates, and cultivars, indicating low-yield stability in baby-leaf salad crops across diverse environments and conditions. Overall, cultivars had a higher marketable weight in the spring than in the fall. Marketable weight was higher in Spring 2013 than in Spring 2014, and was higher in Fall 2013 than in Fall 2012. Days to harvest (DTH) were shorter in the spring than in the fall both years, and in both seasons DTH varied by’1 week between the two trial locations. Fresh weed biomass was almost 5.5 times higher in spring than in fall both years. Overall, pak choi ‘Joi Choi’ and mustard ‘Komatsuna’ had the highest marketable weight, lowest DTH, and lowest weed biomass across the widest range of environments and conditions, while beet ‘Bull’s Blood’ had the lowest marketable weight, relatively long DTH and highest weed biomass. These results suggest that baby-leaf salad crop cultivar selection differs for spring and fall seasons, and production can be highly variable between years and locations. Further, results suggest that growers should plant a diversity of crop cultivars each season to protect from crop loss and to achieve overall yield stability. Ready-to-eat salad mix has experienced more than a 5-fold increase in supermarket sales over the last 20 years in the United States, increasing from $197 million in 1993 to $2.7 billion in 2008, while the sales of iceberg and romaine head lettuce have decreased (Cook, 2008). Bagged ready-to-eat salad mixes were first widely distributed in supermarkets in 1989, and were composed of mature heads of lettuce (Lactuca sativa; primarily iceberg type) cut into bite-sized pieces using specialized head lettuceprocessing equipment (Thompson andWilson, 1999). Today, a diverse array of leafy green salad crops are grown for baby-leaf salad mix in the United States, including lettuce, spinach (Spinacea oleracea L.), mustard greens (Brassica juncea L. and Brassica oleracea L.), pak choi (Brassica rapa L.), kale (Brassica oleracea L.), arugula (Eruca sativa L. and Diplotaxis tenuifolia L.), and beet greens (Beta vulgaris L.) (Hardesty and Leff, 2009). Although the widespread consumption and distribution of baby-leaf salad mix is a relatively recent development in the United States, the practice of harvesting leafy greens at an immature stage of development originated with the concept of mesclun, or ‘‘spring mix’’ in Provence, France, in the 1700s andwas introduced to American cuisine in metropolitan restaurants in the late 1960s (Hardesty, 2010). Growers in California and Arizona are able to produce leafy green salad crops yearround because of the region’s mild winter climate (Koike et al., 2011; Reader, 2003; Smith et al., 2011). These two states accounted for 96% of all lettuce grown in the United States in 2012, and the Salinas Valley alone accounted for 70% of leafy green salad crops (City of Salinas EconomicDevelopment, 2013; USDA, 2010), which included 57,200 t of spring mix, 15,100 t of baby-leaf spinach, 11,800 t of radicchio (Cichorium intybus L.), 21,900 t of kale, and 945,000 t of leaf lettuce (Monterey County Crop Report, 2012). In most other states, leafy green salad crops are grown seasonally on smallandmoderate-sized farms, with over 70% of lettuce and over 60% of spinach producers growing less than one-half hectare (USDA, 2010, 2012b, 2014). In Washington State, lettuce was produced on 222 farms totaling 83 ha in 2012 with leaf lettuce as the dominant lettuce type, followed by crisphead and romaine types (USDA, 2012b). Spinachwas produced on 44 farms totaling 64 ha in 2012. There is strong demand in northwest Washington for locally grown baby-leaf salad greens. While the market is well supplied throughout the summer in this region because of the mild climate that is conducive to baby-leaf salad green production, growers require production information to enable them to extend the season as much as possible in the spring and fall. Research on salad crop production has historically focused on crop performance at the mature growth stage (Clarkson et al., 2003; Farnham and Garrett, 1996; Hoque et al., 2010; Sanchez and El-Hout, 1995; Zhao and Carey, 2009). Babyleaf salad greens are harvested between 30 and 45 d after planting, and in recent studies it has been shown that cultivar performance at the baby-leaf stage differs from performance at the mature stage because of physiological and morphological differences between the developmental stages (Borrelli et al., 2013; Coolong et al., 2013; Egea-Gilabert et al., 2013;Wallace et al., 2012). The objective of this experiment was to evaluate nine salad crop cultivars for suitability as baby-leaf salad greens in the spring (April–June) and six cultivars for the fall (September–November) growing seasons in northwest Washington. Overall productivity, earliness, and ability to compete with weeds were measured. Materials and Methods This study was conducted at two locations 65 km apart in northwest Washington: Cloud Mountain Farm Center (CMFC) in Everson, and Washington State University’s Northwestern Washington Research and Extension Center (WSU NWREC) in Mount Vernon. Soil at CMFC was Squalicum gravelly loam and at WSU NWREC was Skagit Received for publication 24 June 2015. Accepted for publication 5 Aug. 2015. We thank Wild Garden Seed, Philomath, OR; Johnny’s Selected Seeds, Winslow, ME; and Osborne Seed Company, Mount Vernon, WA; for donating the seed used in this experiment. Funding support from the Washington State Department of Agriculture Specialty Crop Block Grant Program and the Washington State University Emerging Research Issues Extension grant are gratefully acknowledged. Corresponding author. E-mail: milesc@wsu.edu. HORTSCIENCE VOL. 50(10) OCTOBER 2015 1467 silt loam (Table 1). Weather data including air temperature, relative humidity, soil temperature, and light transmission (photosynthetically active radiation) were monitored at both field sites with aHOBOweather station (Onset Corporation, Bourne, MA). The CMFC location was managed organically as per U.S. Department of Agriculture (USDA) guidelines, and the WSU NWREC location was in transition to certified organic. At CMFC, a mixed small grain and pea cover crop was grown before the field study, and a pea cover crop was grown previously at WSU NWREC. At both locations the research design was a randomized complete split block with three replications. The main plot was planting date and the split plot treatment was cultivar. The study included two planting dates, 2 weeks apart, in the spring and fall seasons, and was repeated for 2 years. There were nine cultivars in the spring season, and six in the fall season; crop cultivars are provided in Table 2. Plots were one bed wide and 10 m long at both locations. At CMFC, beds were 0.75 m wide and 8 cm high, and at WSU NWREC, beds were 0.75 m wide and 18 cm high; at both locations bed spacing was 1.75 m center-to-center. At both locations, preplant organic fertilizer Wil-Gro Proganic 8-2-4 (Wilbur-Ellis Company, Yakima, WA) was broadcast applied at 56 kg·ha to bed centers before bed shaping. On each bed, cultivars were planted in six rows spaced 10 cm apart. Seed spacing within each rowwas 1 cm and planting rate was 80 seeds per meter-row to achieve a seeding density of 2.7 million seeds/ha. Irrigation was applied at a rate of 36 mm·d three times per week and was adjusted for precipitation. At CMFC, irrigation was applied using microsprinklers (Nelson Irrigation Corporation, Walla Walla, WA), and at NWREC, drip irrigation was applied using two tapes (8-inch emitter spacing, 2.5 L/min/30.5 m; T-Systems International, San Diego, CA) per bed spaced 20 cm apart equidistant from the center of the bed. Weeds were not managed within beds so that weed growth could be measured for each cultivar. Row cover (85% transmittance Agribon AG-19; Polymer Group Inc., Charlotte, NC) was applied to all Brassica crops (mustards ‘Yukina Savoy’, ‘Komatsuna’, and ‘Bekana’, kale ‘Winter Red’, arugula ‘Adagio’, and pak choi ‘Joi Choi’) for spring plantings at WSU NWREC in 2013 and 2014 after flea beetles were observed in those plots. Flea beetle damage at CMFC was negligible, thus rowcover was not used at this site. Rowcover was not applied during the fall at either location as no flea beetle damage was observed during that period. Data collection. Seedling emergence was measured twice weekly in each plot until no newly emerged plants were observed within that plot for a period of 1 week. The center 1 m of each plot was harvested when the majority of plants had leaves 10 cm long (the marketable size for baby-leaf salad). Leaves were cut by hand 3 cm above the soil surface. Although it is possible to harvest baby-leaf salad crops up to three times if the crop is left in the field to regrow, data were only collected for the initial harvest of each plot. Harvest date, weight (g) of marketable leaves, and the fresh weight (g) of weeds in the harvested area were recorded for each plot; however, weeds were not measured at CMFC in Fall 2012 due to an oversight. In this study, damage that rendered leaves unmarketable was primarily because of flea beetle feeding; an insect feeding hole larger than 0.5 cm in diameter classified the leaf as unmarketable per local market acceptability standards. Leaves that exhibited discoloration, decay, or disease symptoms as well as plants that had bolted were also co

Production of Baby-leaf Salad Greens in the Spring and Fall Seasons of Northwest Washington