In a two-part study, we examined the effect of sowing date and harvest schedule on the yield of spinach (Spinacia oleracea) grown during the winter in 16 × 32-ft-high tunnels in northern New Mexico. Each part of the study was conducted for two growing seasons and took place between 2012 and 2015. In Study A (2012–13 and 2013–14), spinach was sown four times at roughly 2-week intervals (mid-October, early November, mid-November, and early December) and plant density (plants per square foot), plant height (centimeters), and yield (grams per square foot) were measured for three harvests in mid-January, mid-February, and mid-March. The earliest sowing date had the least-dense stands, and plant density increased with each subsequent sowing. The two earliest sowing dates had significantly higher season-long yield than the later two sowings. In Study B (2013–14 and 2014–15), all plots were sown in mid-October, but harvest schedule treatments were staggered such that harvests began at 9, 11, 13, or 15 weeks after sowing and continued at irregular intervals. Treatment 2, with harvests beginning after 11 weeks, had the greatest season-long yield, slightly greater than when harvests began at 9 weeks, and significantly more than when harvest began 13 weeks or later. More importantly, a staggered harvest schedule can provide spinach weekly for direct marketing opportunities.
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Robert F. Heyduck, Steven J. Guldan and Ivette Guzmán
David H Suchoff, Frank J. Louws and Christopher C. Gunter
Interest and use of grafted tomato (Solanum lycopersicum) in the United States continues to grow. Pioneered in Asia, herbaceous grafting is a commonly used cultural practice to manage many soilborne pathogens. Bacterial wilt (BW), caused by the pathogen Ralstonia solanacearum, is an aggressive soilborne pathogen that affects tomato grown in the southeastern United States. Traditional fumigation methods have limited effectiveness in the management of this pathogen. The present study was conducted to compare the bacterial wilt resistance of three commercially available tomato rootstocks, which are purported to be resistant to bacterial wilt: ‘Cheong Gang’, ‘RST-04-106-T’, and ‘Shield’. The determinate hybrid tomato ‘Red Mountain’, which is susceptible to bacterial wilt, was used as the scion and nongrafted control. Three locations were used over 2 years in North Carolina: an on-farm site with a history of bacterial wilt and two North Carolina Department of Agriculture Research Stations with no recent history of bacterial wilt. No disease symptoms were observed in any of the three grafted treatments, whereas the nongrafted controls showed between 30% and 80% disease incidence at the on-farm location. The resultant rootstock-imparted resistance improved marketable yields by between 88% and 125% compared with the nongrafted plants. When grown in locations lacking BW there were no yield benefits to grafting with any of the three rootstocks.
Russell Galanti, Alyssa Cho, Amjad Ahmad and Javier Mollinedo
Nitrogen (N) management in macadamia (Macadamia integrifolia) orchards is an important concern for growers. Leaf tissue analysis is the accepted method for determining N status in macadamia; however, this process is expensive and time-consuming. The chlorophyll meter has been used in other crops to estimate N status in plants through estimation of the amount of chlorophyll in leaf tissue. The use of the chlorophyll meter in two macadamia cultivars (Kakea and Kau) at two locations in Hawai’i (Kapa’au and Pahala) and five time periods (12 Apr. 2017, 13 June 2017, 15 June 2017, 18 Dec. 2017, and 20 Feb. 2018) was assessed. Leaf samples were collected based on a tissue-sampling protocol, chlorophyll meter (SPAD) values were collected, and leaves were analyzed for total N concentration. Data were analyzed statistically using linear regression. Leaf tissue N concentration had a positive monotonic relationship to SPAD values for both macadamia cultivars, both locations, and all sampling periods. The sampling period of Apr. 2017 for ‘Kakea’ macadamia had the greatest R 2 value for the linear regression at 0.85. The Feb. 2018 sampling period had an R 2 value for the linear regression of 0.74. ‘Kau’ macadamia had the greatest R 2 value for the linear regression of 0.24 in the Dec. 2017 sampling period. The slopes of the two macadamia cultivars for June 2017 were different from each other, suggesting that N recommendations need to be customized for specific macadamia cultivars if sampled in summer. The chlorophyll meter can be used for general estimation of tissue N in macadamia. Additional methods need to be considered and researched to refine procedures for direct estimation of total N concentration when using the chlorophyll meter.
Abigail R. Debner, Harlene Hatterman-Valenti and Fumiomi Takeda
Outdoor production of floricane-fruiting (FF) blackberry (Rubus subgenus Rubus) is problematic in the Northern Great Plains region of the United States because cane injury and plant death will occur from exposure to temperatures −15 °C and colder. An annual FF blackberry production system using hardwood floricane cuttings would overcome some of the existing limitations of traditional production methods. Several experiments were performed to induce adventitious root formation from one-node hardwood floricane blackberry cuttings taken in winter for the purpose of subsequent growth of a floral shoot. One-node hardwood cuttings of multiple blackberry cultivars (Apache, Arapaho, Kiowa, Osage, Ouachita, Siskiyou, and Triple Crown) were evaluated for rooting potential with and without auxin treatments. Root formation was virtually nonexistent for ‘Apache’, ‘Kiowa’, and ‘Triple Crown’ regardless of the auxin treatment. In general, lower auxin concentrations and the powder formulation produced more roots and had higher root ratings. However, rooting success of cuttings and plant development was low regardless of the rooting method used. Adventitious root production of one-node dormant hardwood FF blackberry cuttings for use in an annual production system had low success regardless of the cultivar, auxin application, rate, and formulation. The variable propagation success rates using single-node hardwood cuttings from ‘Apache’, ‘Arapaho’, ‘Kiowa’, ‘Osage’, ‘Ouachita’, ‘Siskiyou’, and ‘Triple Crown’ plants grown in containers in North Dakota suggested insufficient rooting success for the recommendation of this practice. Additionally, the results suggested these cultivars are not suitable using this method for an annual production system or as a means for large-scale propagation. Although this approach to developing plants from cuttings is of great interest, without a more effective FF blackberry cutting rooting method that can progress through fruit production, an annual blackberry production system in the Northern Great Plains region of the United States is unlikely.
Youngsuk Lee, Hun Joong Kweon, Moo-Yong Park and Dongyong Lee
Nutrient content assessment of plant tissues is widely performed by farmers to determine the appropriate amount of fertilization to use for their crops. A nondestructive leaf chlorophyll meter is one of the most commonly used devices for performing field assessments of the nutrient status of leaves. However, it is challenging to use a chlorophyll meter to assess the nutritional status of perennial plants, such as the apple (Malus ×domestica) tree, because of the difficulty estimating nitrogen (N) during the entire growing period. We compared the chlorophyll meter readings with leaf nutrient profiles collected from young ‘Arisoo’/M.9 apple trees throughout the growing period. A significant positive correlation between the chlorophyll meter readings and leaf N content was found from May to August during the midseason. Regression analysis indicated that the best sampling time for predicting the foliar N content of apple tress is from late June to late July. This result suggests that a reliable leaf N assessment can be performed in a rapid, nondestructive way in apple orchards.
Ariana P. Torres, Susan S. Barton and Bridget K. Behe
As more individuals use the Internet for business and leisure, the opportunities for firms to promote products and services and to communicate with consumers online increases. The objective of this study was to investigate green industry managerial decisions to engage in online advertising and how much to invest while determining the main drivers contributing to these decisions. A double-hurdle model analyses of 1735 responses to the 2014 National Green Industry Survey, which gathered information on business practices, showed >40% of green industry business invested in online advertising. Typically, businesses investing in online advertising spent more than 43% of all advertising expenditures in online methods, including websites, social media, and newsletters. Furthermore, the decision to engage in online advertising was driven by the percentage of wholesale and contract sales, market access, firm size, product mix, and business owners’ perceptions. Results also showed that the amount of dollars invested in online advertising depended on firm size, tools used to find customers, location, and business owners’ perceptions. Our findings can help extension personnel and policymakers with the design and deliver social media training and educational events. Our findings can also help green industry businesses understand the two-step nature of the decision to invest in online advertising.
Mitchell Eicher-Sodo, Robert Gordon and Youbin Zheng
Hydrogen peroxide (H2O2) is an oxidizing agent used to disinfect recirculated irrigation water during the production of organic crops under controlled environmental systems (e.g., greenhouses). To characterize the phytotoxic effects and define a concentration threshold for H2O2, three microgreen species [arugula (Brassica eruca ssp. sativa), radish (Raphanus sativus), and sunflower (Helianthus annuus ‘Black Oil’)], and three lettuce (Lactuca sativa) cultivars, Othilie, Xandra, and Rouxai, were foliar sprayed once daily with water containing 0, 25, 50, 75, 100, 125, 150, or 200 mg·L−1 of H2O2 from seed to harvest under greenhouse conditions. Leaf damage was assessed at harvest using two distinct methods: 1) the percentage of damaged leaves per tray and 2) a damage index (DI). Applied H2O2 concentrations, starting from 25 mg·L−1, increased the percentage of damaged leaves in every species except ‘Black Oil’ sunflower, which remained unaffected by any applied concentration. Symptoms of leaf damage manifested in similar patterns on the surface of microgreen cotyledons and lettuce leaves, while mean DI values and extent of damage were unique to each crop. Fresh weight, dry weight, and leaf area of all crops were not significantly affected by daily H2O2 spray. Identifying how foliar H2O2 damage manifests throughout the crop, as well at individual cotyledon or leaf surfaces, is necessary to establish an upper concentration threshold for H2O2 use. On the basis of the aforementioned metrics, maximum recommended concentrations were 150 mg·L−1 (radish), 100 mg·L−1 (arugula) for microgreens and 125 mg·L−1 (‘Othilie’), 75 mg·L−1 (‘Rouxai’), and 125 mg·L−1 (‘Xandra’) lettuce.
Derald Harp, Gaye Hammond, David C. Zlesak, Greg Church, Mark Chamblee and Steve George
Landscaping today involves the struggle to balance aesthetically pleasing plants while minimizing the impact on the environment, reducing water usage, decreasing fertilizer use, and eliminating or significantly reducing pesticide usage. Roses (Rosa sp.), although seen as challenging plants, remain the most popular flowering shrub in the United States. The identification of new cultivars that combine beauty, pest and disease resistance, and drought tolerance are important to Texas landscapes. Sixty roses were assessed over a 3-year period to determine flowering, drought tolerance, disease resistance, and overall landscape performance in minimal-input gardens in north central Texas. Atypical weather during the study had a significant impact on performance. A 2-year drought (2010–11) was accompanied by the hottest summer on record (2011), which included a record number of days of at least 100 °F or higher. As a result, supplemental irrigation was provided three times both summers. Roses generally fared well under these conditions and survived the drought. Flowering was most abundant during the spring and fall, and it was least abundant in the summer. Powdery mildew [PM (Sphaerotheca pannosa var. rosae)] was a minor problem. Nine of 60 cultivars developed no visible symptoms of PM during the study. Most PM occurred in Spring 2010, with very little found after June; none was found in 2011. Black spot [BS (Diplocarpon rosae)] was serious for some cultivars, but most were BS-free; RADrazz (Knock Out®) and Lady Banks White had no observed BS during the study. BS occurred mostly in May, June, and November. Overall landscape performance ratings were high, with 23 cultivars having a mean landscape performance rating equal to or better than the Belinda’s Dream standard. The best-performing cultivars were RADrazz (Knock Out), RADcon (Pink Knock Out®), RADyod (Blushing Knock Out®), WEKcisbaco (Home Run®), and Alister Stella Gray. This study was able to identify many other highly performing roses in north central Texas.
Yuxiang Wang, Liqin Li, Youping Sun and Xin Dai
Spirea (Spiraea sp.) plants are commonly used in landscapes in Utah and the intermountain western United States. The relative salt tolerance of seven japanese spirea (Spiraea japonica) cultivars (Galen, Minspi, NCSX1, NCSX2, SMNSJMFP, Tracy, and Yan) were evaluated in a greenhouse. Plants were irrigated with a nutrient solution with an electrical conductivity (EC) of 1.2 dS·m−1 (control) or saline solutions with an EC of 3.0 or 6.0 dS·m−1 once per week for 8 weeks. At 8 weeks after the initiation of treatment, all japanese spirea cultivars irrigated with saline solution with an EC of 3.0 dS·m−1 still exhibited good or excellent visual quality, with all plants having visual scores of 4 or 5 (0 = dead, 1 = severe foliar salt damage, 2 = moderate foliar salt damage, 3 = slight foliar salt damage, 4 = minimal foliar salt damage, 5 = excellent), except for Tracy and Yan, with only 29% and 64%, respectively, of plants with visual scores less than 3. When irrigated with saline solution with an EC of 6.0 dS·m−1, both ‘Tracy’ and ‘Yan’ plants died, and 75% of ‘NCSX2’ plants died. ‘Minspi’ showed severe foliar salt damage, with 32% of plants having a visual score of 1; 25% of plants died. ‘Galen’ and ‘NCSX1’ had slight-to-moderate foliar salt damage, with 25% and 21%, respectively, of plants with visual scores of 2 or less. However, 64% of ‘SMNSJMFP’ plants had good or excellent visual quality, with visual scores more than 4. Saline irrigation water with an EC of 3.0 dS·m−1 decreased the shoot dry weight of ‘Galen’, ‘Minspi’, ‘SMNSJMFP’, and ‘Yan’ by 27%, 22%, 28%, and 35%, respectively, compared with that of the control. All japanese spirea cultivars had 35% to 56% lower shoot dry weight than the control when they were irrigated with saline irrigation water with an EC of 6.0 dS·m−1. The japanese spirea were moderately sensitive to the salinity levels in this experiment. ‘Galen’ and ‘SMNSJMFP’ japanese spirea exhibited less foliar salt damage and reductions in shoot dry weight and were relatively more tolerant to the increased salinity levels tested in this study than the remaining five cultivars (Minspi, NCSX1, NCSX2, Tracy, and Yan).
Alex J. Lindsey, Joseph DeFrank and Zhiqiang Cheng
The use of nonpotable water for irrigation on various sport venues has led to an increased use of seashore paspalum (Paspalum vaginatum) turf in Hawaii. An ongoing challenge many seashore paspalum turf managers struggle with is bermudagrass (Cynodon dactylon) infestations. Herbicide efficacy studies were conducted at the Hoakalei Country Club [‘SeaDwarf’ seashore paspalum (fairway cut)] and the Magoon Research Station [‘SeaStar’ seashore paspalum (grown in container)] on the island of Oahu in Hawaii. Spray applications of the herbicides mesotrione, topramezone, metribuzin, and ethofumesate were evaluated alone and in tank mixtures for bermudagrass suppression and seashore paspalum injury. At the Hoakalei Country Club, maximum bermudagrass injury with minimal seashore paspalum discoloration was obtained with tank mixes of mesotrione (0.06 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.02 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre). Unacceptable seashore paspalum turf injury was obtained in all treatments that did not include metribuzin. At the Magoon Research Station, maximum selective bermudagrass suppression was achieved with tank mixes of topramezone (0.01 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.01 lb/acre) + metribuzin (0.09 lb/acre) + ethofumesate (1.00 lb/acre). The addition of metribuzin and/or ethofumesate to the tank mix safened (reduced turf discoloration) seashore paspalum to topramezone or mesotrione foliar bleaching. Tank mixes of mesotrione, topramezone, metribuzin, and ethofumesate have the potential for bermudagrass suppression and control of other grassy weeds in seashore paspalum turf.