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Twelve peach (Prunus persica) cultivars, six apricot (Prunus armeniaca) cultivars, two japanese plum (Prunus salicina) cultivars, three european plum (Prunus domestica) cultivars, four sweet cherry (Prunus avium) cultivars, and three tart cherry (Prunus cerasus) cultivars were monitored for winter damage at New Mexico State University's Sustainable Agriculture Science Center in Alcalde, NM (main site), and the Agricultural Science Center in Los Lunas, NM (minor site), in 2011. Uncharacteristically low temperatures on 1 Jan. and 3 Feb. were recorded as −7.2 and −11.3 °F, respectively, at Alcalde, and 4.8 and −13.9 °F, respectively, at Los Lunas. On 10 Jan. at Alcalde, live peach flower bud percentage varied by cultivar, ranging from 11% for Blazingstar to 25% for PF-1, and 85% to 87% for Encore and China Pearl. Apricot flower buds were hardier, with 70% survival for ‘Perfection’, 97% for ‘Sunglo’, and 99% for ‘Harglow’ on 10 Jan. By 10 Feb., almost all peach flower primordia were discolored, with no cultivar showing more than 1% survival. Based on this information, the 10% kill of flower buds for most peach cultivars occurred at temperatures equal to or slightly higher than −7.2 °F, and 90% kill occurred between −7.2 and −11.3 °F. On 10 Feb., 0% to 15% of apricot flower buds on spurs or shoots of the middle and lower canopy had survived. For vigorous shoots in the upper canopy, apricot flower buds on 1-year-old shoots had a higher blooming rate than those on spurs of 2-year-old or older wood. Flower buds of japanese plum were also severely damaged with less than 0.2% survival for ‘Santa Rosa’ and 4.8% for ‘Methley’, but european plum were relatively unaffected with over 98% flower bud survival for ‘Castleton’ and ‘NY6’, and 87% for ‘Stanley’ after −11.3 °F at Alcalde. Cherry—especially tart cherry—survived better than peach, apricot, and japanese plum after all winter freezes in 2011.

Jujube or chinese date (Ziziphus jujuba) has fruit that is developed mainly from ovary plus some nectary disk tissue, and the fruit can appear smooth or bumpy on the surface. The objective of this study was to investigate the unique fruit development of ornamental ‘Teapot’ jujube. Unlike ‘Li’ and ‘Lang’, ‘Teapot’ jujube fruit had one to five protuberances on the shoulder of the fruit and few entirely lack protuberances. The stamens of ‘Teapot’ jujube flowers were fewer in number, misplaced in location, and deformed in shape—some stamens were anthers only while others were filament only. Deformed stamens of ‘Teapot’ jujube were always anchored in the nectary disk instead of at their normal location—near the edge of the nectary disk. After bloom, the residue of stamens, nectary disk, and ovary were all constituents of the developing fruit. The deformed stamens developed into the fleshy protuberances and equaled them in number. Fruit with only two protuberances predominated, which is how the ‘Teapot’ jujube acquired its name, but the ratio among protuberance categories varied between trees. With its unique and decorative fruit shape, and acceptable fruit quality, ‘Teapot’ jujube could be used as a backyard tree, both as an ornamental and for its fruit.

The increased popularity of jujube (Ziziphus jujuba) combined with the difficulty of grafting have limited supplies of grafted trees in the United States. From 2011 to 2020, grafting was practiced for cultivar amplification after importation and cultivar trials in frost-prone northern New Mexico. Grafting success was related to not only grafting techniques but also climate factors. Bark grafting, whip/tongue grafting, and cleft grafting were commonly used in nurseries. Low temperatures had a critical role in jujube grafting success in marginal regions and were more important than the grafting technique. If frost occurs before or near the leafing time, then grafting should be delayed until the rootstocks are determined to be healthy and alive. If frost occurs after grafting, then grafting failure and/or thin and small plant percentages increased. If only branchlets appear after grafting, then pinching branchlets could stimulate new shoot growth.

All jujube (Ziziphus jujuba) cultivars can be used as fruit trees and in landscaping, but there are four striking ornamental cultivars in our collection: Dragon, Mushroom, So, and Teapot. These cultivars are decorative and can be used for fruit, tree shape, or both as edible landscape plants. We evaluated these four ornamental jujube cultivars in central and northern New Mexico. All four cultivars grew and produced well but performed differently. ‘So’, imported from China in 1914, was a productive and contoured cultivar with medium-sized, sweet/tart fruit and bushy trees, with a decorative tree shape in winter. ‘Dragon’, a recent import from China, was the most dwarf cultivar tested, with small fruit and gnarled trees, and suitable for four-season ornamental use in landscapes. ‘Mushroom’, another recent import from China, had the most decorative fruit shape among the four cultivars tested, with vigorous and productive plants. ‘Teapot’, also a recent import from China, had irregular fruit shapes and vigorous and productive plants. All four cultivars were good edible landscape plants depending on customers’ preferences and space availability/limitation.

Five primocane raspberry (Rubus idaeus) cultivars were evaluated in a high tunnel and in the field at Grand Rapids, MN, which is located in U.S. Department of Agriculture (USDA) plant hardiness zone 3b. Bare root plants of five cultivars (Autumn Bliss, Autumn Britten, Caroline, Joan J, and Polana) were planted in the high tunnel and in the field, each with a randomized complete block design at 2 × 5.2-ft spacing on 8 May and 14 May 2008, respectively. A propane heater was used periodically for frost protection in the high tunnel. All five cultivars overwintered well and primocanes emerged with minor or no winter damage in the high tunnel in 2009. The high tunnel extended the growing season for ≈4 weeks in both years. Raspberry plants in the high tunnel produced higher yield than those in the field, total 154 lb (6655 lb/acre) from the high tunnel vs. 0.5 lb (43 lb/acre) from the field in 2008 and 379 lb (16,378 lb/acre) vs. 80 lb (3457 lb/acre) in 2009. ‘Caroline’ and ‘Polana’ had higher yields than ‘Autumn Bliss’; ‘Joan J’ and ‘Autumn Britten’ yields were intermediate and not different from ‘Caroline’, ‘Polana’, or ‘Autumn Bliss’ yields. In terms of harvest date, ‘Polana’ was the earliest among the five cultivars tested, followed by ‘Autumn Britten’, ‘Autumn Bliss’, and ‘Joan J’. ‘Caroline’ was the latest. Essential nutrients in leaves for all cultivars both in the field and in the high tunnel were within sufficient ranges. Spider mites (Tetranychidae) and raspberry sawflies (Monophanoides geniculatus) were the major insect problems. In conclusion, primocane-fruiting raspberries can be successfully grown in high tunnels and produce substantially higher yields than in field plantations in northern Minnesota or areas with similar climatic conditions.

Late frost is the number one issue challenging fruit production in northern New Mexico. We had apricot (Prunus armeniaca) trees in an open field planting at Alcalde, NM, and not a single fruit was harvested from 2001 through 2014. Apricot trees in surrounding communities produce sporadic crops. In 2012, we planted apricots in two 16 × 40-ft high tunnels (9.5-ft high point). Trees were trained to a spindle system in one high tunnel and an upright fruiting offshoot (UFO) system in the other, and there were identical plantings in the open field for each high tunnel. Supplemental heating was provided starting at blooming time. There were five cultivars planted in each high tunnel at 4 × 8-ft spacing in a randomized complete block design with two replications (rows) and two trees per cultivar in each plot. In 2015, relatively high yields were obtained from all cultivars. The average yields for the spindle system were (lb/tree): ‘Puget Gold’ (29.0), ‘Harcot’ (24.1), ‘Golden Amber’ (19.6), ‘Chinese Apricot’ (18.6), and ‘Katy’ (16.7). Yields for the UFO system were (lb/tree): ‘Golden Amber’ (18.6), ‘Katy’ (14.9), ‘Puget Gold’ (11.3), ‘Chinese Apricot’ (10.2), and ‘Harcot’ (8.6). On average across all cultivars, the UFO system produced 60% of the yield of the spindle system in 2015. A heating device is necessary for high tunnel apricot fruit production in northern New Mexico because trees normally bloom in early to late March, depending on the year, while frosts can continue until mid-May. In years like 2017 and 2018 with temperatures below 10 °F in late February/early March, some of the expanded flower buds were killed before bloom. On those cold nights, one 100-lb tank of propane may or may not be enough for 1 night’s frost protection. Economically, it would not be feasible in those years. Only in years with a cool spring, late-blooming trees, and mild temperatures in April and May can high tunnel apricot production generate positive revenue with high, direct-market prices. High tunnel apricot production with heating devices is still risky and cannot guarantee a reliable crop in northern New Mexico or similar areas.

As part of our hardy strawberry (Fragaria ×ananassa) breeding program, winter hardiness of 15 strawberry cultivars was evaluated in the field after Winter 2005–2006 and a test Winter 2006–2007 with no snow cover at Grand Rapids, MN. After the snow-covered Winter 2005–2006, plant stand (percent leaf coverage for the designated area for each plot) increased for all cultivars in the mulched treatment and some cultivars in the unmulched treatment with slight decreases only for several cultivars in the unmulched treatment. However, after Winter 2006–2007, the plant stands of all cultivars drastically decreased in both mulched and unmulched treatments. ‘Clancy’, ‘Evangeline’, and ‘L'Amour’ were the three most sensitive cultivars among the 15 cultivars tested. ‘Kent’, ‘Mesabi™’, ‘Cavendish’, and ‘Brunswick’ were the highest yielding cultivars for both 2006 and 2007 in the mulched treatment. In the unmulched treatment, ‘Brunswick’, ‘Mesabi™ ’, ‘Cavendish’, ‘Sable’, and ‘Kent’ were the top yielding cultivars after Winter 2006–2007. During Winter 2005–2006, with 20 to 30 cm snow cover throughout the season, the 5- and 10-cm soil temperatures remained constant at ≈30 to 31.5 °F in both mulched and unmulched treatments. In contrast, during Winter 2006–2007, there were 16 and 24 days (consecutive) in February below 18 °F at 5-cm soil depths for mulched and unmulched treatments, respectively, which probably led to the severe winter damage. Although straw mulch afforded the plants some protection, snow cover is critical to the survival of strawberries in northern Minnesota and other areas with similar weather conditions.

A decrease in available farmland worldwide has prompted interest in polyculture systems such as intercropping where two or more crops are grown simultaneously on the same land to increase the yield per farm area. In Alcalde, NM, a year-round intercropping system was designed to evaluate organically produced blackberry cultivars (Rubus, subgenus Rubus) and winter greens in a high tunnel over a 2-year period. Two floricane fruiting blackberry cultivars, Chester Thornless and Triple Crown, were grown intercropped with ‘Red Russian’ kale (Brassica napus) and ‘Bloomsdale’ spinach (Spinacia oleracea) in a high tunnel. In an adjacent field, the planting of blackberry was repeated with no winter intercrop and no high tunnel. Both cultivars of blackberry were harvested July to September, and fresh weights were measured to determine suitability to the intercropping system in the high tunnel. Both species of winter greens were harvested January to April, and fresh yield weights were measured to discern fitness as possible intercrops in this system. Row covers were used for kale and spinach, and air temperatures were monitored November to April inside the high tunnel. High tunnel temperatures were within acceptable ranges for the production of greens with the use of rowcovers. Yield data from this study indicates that ‘Triple Crown’ blackberry outperformed ‘Chester Thornless’ blackberry in both the high tunnel and field trials with significant difference in the second season. Additionally, blackberry yields from both cultivars were observed to be higher in the field than in the high tunnel for both years. High temperature damage to high tunnel berry canes was noticed for both cultivars, with observed yield decreases in the second year in the high tunnel. Overall, this study indicates that the phenology and climate needs of the two winter greens and blackberry cultivars were not compatible for sustaining year-round organic high tunnel production.