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Because of the burgeoning year-round demand, greenhouse growers across the United States are increasingly becoming interested in producing specialty cut flowers for local and regional markets. However, outdoor or high tunnel production is not possible year-round in northern latitudes because of low temperatures and radiation intensities experienced during the winter and early spring. Additionally, natural short days in these seasons can limit which photoperiodic crops can be grown. Thus, our objectives were to quantify the influence of the photoperiod and daily light integral (DLI) on greenhouse-grown dianthus 'Amazon Neon Cherry' and 'Amazon Rose Magic' (Dianthus barbatus interspecific) cut flowers during the young plant and finishing stages. Seeds of both cultivars were sown under 9-, 10-, 11-, 12-, 13-, 15-, or 16-hour photoperiods and a DLI of either ≈5 or 10 mol.m-2.d-1. After 4 weeks, seedlings from several young-plant photoperiods were distributed across 11-, 12-, 13-, 14-, 15-, or 16-hour photoperiods or a 4-hour night interruption (NI) under a DLI of either ≈5 (low) or 14 (moderate) mol.m-2.d-1 for finishing. The young plant photoperiod generally had a statistical, but not commercial, influence on development and finished cut flower quality, whereas a 16-h finishing photoperiod marginally hastened development compared with an 11-hour finishing photoperiod. Additionally, stems were 11 to 13 cm longer when finished under the 16-hour photoperiod compared with those finished under the 11-hour photoperiod. Day length minimally influenced the time to flower and harvest, indicating a day-neutral flowering response. However, plants finished under a moderate DLI reached visible flower bud and were harvestable 9 to 10 days earlier than those finished under a low DLI. Additionally, ≈99% of cut flowers finished under a moderate DLI were harvestable, whereas only up to 32% and 57% of dianthus 'Amazon Rose Magic' and 'Amazon Neon Cherry', respectively, finished under a low DLI were harvestable. Although finished stem lengths were comparable between DLI treatments, cut flower stems were up to 29.6% thicker under a moderate DLI. These findings indicate that high-quality greenhouse-grown dianthus 'Amazon Neon Cherry' and 'Amazon Rose Magic' cut flowers can be produced when grown under any photoperiod between 9 and 16 hours for 4 weeks (during the young plant stage) and finished under any photoperiod between 11 and 16 hours or a 4-hour NI during finishing. If longer stems are desired, then plants can be finished under a 16-hour photoperiod. Young plants should be grown under a moderate DLI $10 mol.m-2.d-1 to promote biomass accumulation and reduce the young plant crop time. Additionally, plants should be finished under a moderate DLI $14 mol.m-2.d-1 to reduce crop time and increase stem thickness and yield. [ABSTRACT FROM AUTHOR]

Cannabis sativa or hemp, defined as <0.3% total tetrahydrocannabinol (THC), is a specialty crop in the United States, of particular interest among growers in the southeastern United States to replace tobacco production. Tetranychus urticae (twospotted spider mite), Aculops cannabicola (hemp russet mite), Polyphagotarsonemus latus (broad mites), and Phorodon cannabis (cannabis aphids) are considered the most significant pests in greenhouse grown hemp. Mite and aphid injury can cause cupping and yellowing of leaves, resulting in leaf drop, and reduced flower and resin production. We sought to understand the effects of feeding by T. urticae and Myzus persicae (green peach aphid), as a proxy for P. cannabis , on the concentration of economically significant cannabinoids through a series of experiments on greenhouse grown plants. First, we compared the variability of chemical concentrations in samples collected from individual plants versus pooled samples from 5 plants, and found that chemical concentrations in single plants were similar to those in pooled plant samples. Next, we compared chemical concentrations prior to arthropod infestation and post infestation. When evaluating the mite feeding damage in 2020, cannabinoids in plants infested with high densities of T. urticae increased more slowly than in uninfested control plants or plants infested with low T. urticae densities. In 2021, the concentration of tetrahydrocannabinol did not differ significantly between treatments. Cannabidiol increased more slowly in plants with low T. urticae densities when compared to uninfested controls but did not differ from the high T. urticae densities 14 days after infestation. [ABSTRACT FROM AUTHOR]

As wildfires increase in extent and severity in the western United States, land managers need new tools to stabilize and rehabilitate impacted hillslopes. One potential tool is the use of three disturbance‐adapted mosses Ceratodon purpureus (Redshank), Funaria hygrometrica (Cord moss), and Bryum argenteum (Silvergreen moss), collectively known as fire mosses. By growing and adding vegetative propagules in the form of gametophyte fragments to burned hillslopes, land managers could potentially increase the rate of moss colonization and stabilize soils. A first step in developing a native plant materials rehabilitation technique is overcoming propagule limitations using ex situ cultivation. We focused on greenhouse cultivation of moss gametophyte fragments allowing us to grow vegetative propagules with control over atmospheric, edaphic, and hydrologic conditions. In this experiment, we grew fire mosses using an easily scalable technique and commercially available materials. We demonstrated repeated success growing these species in the greenhouse and fine‐tuned harvesting techniques to increase productivity. We found that fire moss achieved high cover in 2 months when grown on organic substrate with constant wicking hydration and a protective shade covering, but growth was not favored by addition of burned materials. We successfully upscaled our growing technique, and developed efficient harvest methods. This success overcomes an initial barrier to testing and developing fire mosses as a novel rehabilitation technique. [ABSTRACT FROM AUTHOR]

Controlled environment (CE) food crop production has existed in the United States for many years, but recent improvements in technology and increasing production warranted a closer examination of the industry. Therefore, our objectives were to characterize historical trends in CE production, understand the current state of the U.S. hydroponics industry, and use historical and current trends to inform future perspectives. In the 1800s, CE food production emerged and increased in popularity until 1929. After 1929, when adjusted for inflation (AFI), CE food production stagnated and decreased until 1988. From 1988 to 2014, the wholesale value of CE food production increased from $64.2 million to $796.7 million AFI. With the recent increase in demand for locally grown food spurring an increase in CE production, both growers and researchers have been interested in using hydroponic CE technologies to improve production and quality. Therefore, we surveyed U.S. hydroponic food crop producers to identify current hydroponic production technology adoption and potential areas for research needs. Producers cited a wide range of technology utilization; more than half employed solely hydroponic production techniques, 56% monitored light intensity, and more than 80% monitored air temperature and nutrient solution pH and electrical conductivity. Additionally, the growing environments varied from greenhouses (64%), indoors in multilayer (31%) or single-layer (7%) facilities, to hoop houses or high tunnels (29%). Overall, producers reported managing the growing environment to improve crop flavor and the development of production strategies as the most beneficial research areas, with 90% stating their customers would pay more for crops with increased flavor. Lastly, taking historical data and current practices into account, perspectives on future hydroponic CE production are discussed. These include the importance of research on multiple environmental parameters instead of single parameters in isolation and the emphasis on not only increasing productivity but improving crop quality including flavor, sensory attributes, and postharvest longevity. [ABSTRACT FROM AUTHOR]

Most of fresh tomatoes sold in the United States (US) are grown using protected agriculture. The risk of contamination and severe disease outbreaks in humans due to foodborne pathogens linked to fresh produce are a constant threat to the public and the industry. To date, there are limited tools to prioritize food safety management practices in commercial greenhouses to reinforce food safety in a timely manner. One rapid cost effective approach, originally applied in education and healthcare, is the Delphi method that uses expert opinion to quantify and rank priorities. An iterative systematic Delphi expert elicitation approach was used to prioritize management factors for the reduction of foodborne pathogen contamination in tomato greenhouses in the US. A validated online survey addressing eight thematic areas (water management, workers, environment and greenhouse design, equipment sanitation, waste management, animal intrusion, traceability, and propagation) was discussed among 20 individuals internationally recognized as experts in fresh produce production in protected agriculture, foodborne pathogens, and food safety theory and practice. Consensus rankings of activities and practices most likely contributing to microbial contamination and its mitigation were determined. Food safety priorities to prevent contamination of greenhouse tomatoes, in order of significance ( i.e, ranking scale, weighted average; 1 lowest, 5 highest), included handwashing (4.67), environmental controls (4.32), enforceable worker health policy (3.94), cleaning and sanitation of reusable plastic containers (3.94), reused retail-ready containers (3.89), and irrigation water testing for human pathogens (3.84) to prevent contamination of greenhouse tomato. The majority of experts indicated that contaminated greenhouse surfaces that are in contact (direct or indirect) with the fruits are important sources of pathogen transfer to fresh tomatoes, highlighting the need for environmental controls in greenhouses. Importance of adequate worker management practices including handwashing and health policy highlights the role of worker education in reducing the risks of foodborne outbreaks linked to greenhouse grown produce. This report illustrates the benefits of using Delphi approach to improve food safety in greenhouses. The provided priority list can be used by growers to guide the routine food safety practice implementation procedures. [ABSTRACT FROM AUTHOR]

Phase distribution of airborne chemicals is important because intake and uptake mechanisms of each phase are different. The phase distribution and concentrations are needed to determine strategies of exposure assessment, hazard control, and worker protection. However, procedures for establishing phase distribution and concentration have not been standardized. The objective of this study was to compare measurements of an airborne semivolatile pesticide (chlorpyrifos) by phase using two different procedures. Six pesticide applications in two facilities were studied and at each site, samples were collected for three time slots: T1, the first 1 or 2 hr after the commencement of application; T2, a 6-hr period immediately following T1; and T3, a 6-hr period after the required re-entry interval (24 hr for chlorpyrifos).Two phase-separating devices were co-located at the center of each greenhouse: semivolatile aerosol dichotomous sampler (SADS) using flow rates of 1.8 l.min−1and 0.2 l.min−1, corresponding to a total inlet flow rate of 2.0 l.min−1with a vapor phase flow fraction of 0.1; and an electrostatic precipitator (ESP), along with a standard OVS XAD-2 tube. Chlorpyrifos in vapor and particulate form in a SADS sampling train and that in vapor form in an ESP sampling train were collected in OVS tubes. Chlorpyrifos in particulate form in the ESP setting would have been collected on aluminum substrate. However, no chlorpyrifos in particulate form was recovered from the ESP. Overall (vapor plus particle) concentrations measured by OVS ranged 11.7 – 186.6 μg/m3at T1 and decreased on average 77.1% and 98.9% at T2 and T3, respectively. Overall concentrations measured by SADS were 66.6%, 72.7%, and 102% of those measured by OVS on average at T1, T2, and T3, respectively. Particle fractions from the overall concentrations measured by SADS were 60.0%, 49.2%, and 13.8%, respectively, for T1, T2, and T3. SADS gives better guidance on the distribution of chlorpyrifos than does the ESP, although the accuracy of the concentration distribution cannot be verified in the absence of a standardized procedure for determining phase division. [ABSTRACT FROM AUTHOR]

Organic and heirloom tomatoes are high-value products with growing demand but there are many challenges to successful cultivation. A systems comparison study was carried out to evaluate the production of the popular heirloom tomato 'Cherokee Purple' (Solanum lycopersicum L.) under high tunnel and open field systems in North Carolina from 2007 to 2008. Management of the high tunnel (i.e., temperature and irrigation), weather events as well as pest and disease pressure influenced crop quality and yield. The high tunnel and field systems achieved similar total yields (100 t·ha -1) the first season but yields were 33% greater in the high tunnel system than the field system in the second year (100 100 t·ha -1 and 67 100 t·ha -1, respectively). Both years, the tomatoes were planted in high tunnels 1 month earlier and harvested 3 weeks earlier than the field. The accumulation of ≈1100 growing degree-days (GDD) was required in both systems before 50% of the fruit was harvested. Fruit cracking, cat-facing, blossom-end rot, and insect damage were the major categories of defects in both systems. Incidence of both Tomato Spotted Wilt Virus (TSWV) and Gray Leaf Spot (GLS) were lower in the high tunnel compared with the field in 2007 and 2008, respectively. Results of this study suggest that with proper management techniques, high tunnels can optimize yields, increase fruit quality, and provide season extension opportunities for high-value horticultural crops. [ABSTRACT FROM AUTHOR]

In winter months, U.S. domestic strawberry supply is low and demand is high, and unit price for strawberries is at its highest point during the year. Forcing strawberries in high tunnels during this time might capture this niche market. Since yields are much lower in forced systems, enhancing the light environment to increase yield with colored nets (ChromatiNets; distributed by Polysack, Inc., San Diego, CA) was attempted in 2007-2008 (previously published) without success. In the second year of field experiments in 2008-2009, the experiment was repeated with some modifications. 'Sweet Charlie' plugs were conditioned from September 5 to September 26 at 24°C on a 12-hr day/night cycle and were planted September 28 in fertilized plots in a high tunnel (29.3-m long × 4.3-m wide × 3.1-m high). Conditioned plants were also planted outside on mulched, drip-irrigated beds as a control. Red, yellow, and pearl ChromatiNets (24% shade factor, lowest intensity possible) were installed over the top of the high tunnel in 7.3-m wide swathes and a nonnetted plot included. Plants were fertigated weekly with about 3.2 kg N/hectare per week from 15 N-30 P2O4-15 K2O. High tunnels were vented to maintain day temperatures in the range of 25 to 30°C. In the second year's work, marketable berry production began November 21, 2008, and continued until February 27, 2009, without any yield advantage for ChromatiNets. In March, plants appeared exhausted; therefore, the high tunnel was opened and plants were allowed to acclimate to outside temperatures. By April, the outside plots were in full production, yielding more than any high tunnel treatments. In the high tunnel, however, yields resumed, with the red nets tending to yield more than the pearl; no-net control and yellow net yielded similarly, but slightly less, than red. In May, all high tunnel treatments and outside berries yielded similarly. Over all harvest periods, there were no differences in total yields with nets in the second year, similar to the first year. It is probable that in winter, the ChromatiNet shading factor overwhelmed any light quality enhancement, and in longer, warmer, and brighter days, the ChromatiNets may show an advantage. [ABSTRACT FROM AUTHOR]

In June to Oct. 2008, a U.S. floriculture survey was conducted to examine the factors affecting growers' willingness to adopt sustainable practices. The factors affecting adoption of sustainable practices were evaluated in five areas: environmental regulations, customer value, growers' attitudes toward sustainability, age, and operation size. A logistic regression model was used to examine factors affecting growers' adoption of sustainable practices. Nearly two-thirds (65.2%) of respondents thought sustainability was very important to the environment. Similarly, more than half (63%) of the respondents had sustainable practices in their operations. Although respondents had positive attitudes toward sustainability and the environment, these positive attitudes alone were unable to predict adoption behaviors. The two most important factors that affected adoption of sustainable practices were the concerns about implementation and the risk perceived by growers, Neither perceived customer value nor the stringency of state regulations affected the adoption of sustainable practices. The results from this study provide original insight into growers' views of sustainability and identify the educational assistance needed by growers to overcome the factors affecting their adoption of sustainable practices. [ABSTRACT FROM AUTHOR]

Abstract: Million year-scale (3rd-order) depositional sequences (few 10s to ~100 m-thick) are common in the Devonian marine record and are correlated between sedimentary basins and across widely separated continents implying a eustatic origin. Tectonically driven changes in mid-ocean ridge spreading rates/lengths are too slow to account for the calculated 3rd-order rise/fall rates and typical orbital frequencies (~20–400 ky) are too fast. We analyzed oxygen isotopes from conodont apatite to evaluate if Early–Middle Devonian 3rd-order sea-level changes were controlled by paleoclimatically driven ice volume (glacio-eustasy) and seawater temperature change (thermo-eustasy). Two successive depositional sequences in the western U.S. (Nevada) and Czech Republic (Prague Basin) were sampled. The δ18O values range from 17.8‰ to 20.2‰ (SMOW) and show similar trends across the Emsian–Eifelian boundary with increasing and peak values in the lower costatus, decreasing values in the mid costatus, and increasing values in the upper costatus to australis zones. The similarities between these widely separated localities indicate that the isotopic trends are global rather than controlled by local variations in seawater temperature, evaporation/freshwater influx, or diagenesis. In the Nevada section, where the sea-level history is the most complete and best understood, the isotopic values increase and peak in late highstand and lowstand system tracts and decrease to the lowest values in the transgressive and maximum flooding intervals suggesting the My-scale sea-level changes were paleoclimatically controlled. The magnitude of isotopic shift from lowstand to maximum flooding intervals ranges from 0.8‰ to 1.5‰ and occurred over time spans of <1.7 My. The only known mechanism to explain such large and rapid isotopic shifts is glacio-eustasy. If a reasonable range of My-scale subtropical sea surface temperature changes are assumed (~1–3 °C), then this requires glacio-eustatic sea-level changes of >35 m to explain the remaining isotopic shifts. These amplitudes imply that significant continental ice sheets grew and melted on the <1.7 My time scales during the Early–Middle Devonian and, like recent reports for the mid-Cretaceous and early Eocene, challenge previous assumptions of ice-free greenhouse climates. A plausible climate driver for these My-scale paleoclimate changes is long-period eccentricity (~2.4 My) and obliquity (~1.2 My) variations. [Copyright &y& Elsevier]

In winter months, the U.S. domestic strawberry supply is low, demand is high, and unit price for strawberries is at its highest point during the year. Forcing strawberries in high tunnels during this time might capture this niche market. 'Sweet Charlie' plugs were conditioned from 24 Aug. to 12 Sept. at 24 oC on a 12-hour day/night cycle, and were planted on 12 Sept. in fertilized plots in a high tunnel (29.3 m long × 4.3 m wide × 3.1 m high). Conditioned plants were also planted outside on mulched, drip-irrigated beds as a control. Red, yellow, and pearl ChromatiNets (24% shade factor: lowest intensity possible) were installed over the top of the high tunnel in 7.3 m wide swathes, and a no-net control plot was included. Plants were fertigated weekly with about 3.2 kg N/hectare per week from 15 N-30 P2O4-15 K2O. High tunnels were vented to maintain day temperatures in the range of 25 to 30 oC. Runners were removed and counted beginning 24 Sept. until 17 Nov. when runnering stopped. Runner production was 59% greater with yellow and pearl nets compared with the no-net controls. In contrast, the red nets produced 38% fewer total runners and runners per plant than the yellow and pearl nets, but red nets produced 34% more runners than the no-net controls. Runner production of no-net plants in high tunnels was 20% greater in contrast to the plants growing outside. Yield data from fall/winter forcing and residual spring harvests did not show any great advantage to marketable weight and numbers with ChromatiNets. Marketable berry production began on 31 Oct., with berry production slowing in November and missing the Thanksgiving market window, with negligible production in December. The plants began to produce heavily in January, with greater yields with red nets and no-net controls along with significant reductions with yellow and pearl nets. In February, all three ChromatiNets yielded less than the no-net controls. In March, plants appeared exhausted; therefore, the high tunnel was opened and plants were allowed to acclimate to outside temperatures. By April, the outside plots were in full production, yielding more than any high tunnel treatments. In the high tunnel, however, yields resumed with the no-net control and yellow net yielding similarly, but red and pearl nets yielding less than the no-net controls. In May, all high tunnel treatments yielded less than the outside plots. The no-net control produced greater total yields of all net treatments and apparently, the ChromatiNets suppressed overall yield. It is probable that in winter, the ChromatiNet shading factor overwhelmed any light quality enhancement and in longer, warmer, and brighter days, the ChromatiNets may show an advantage. [ABSTRACT FROM AUTHOR]

Tomato transplants are the primary means of establishing commercial tomato production fields in the eastern United States. Transplants are often suspected as the source of inoculum for major outbreaks in production fields of bacterial spot of tomato (BST) caused by Xanthomonas perforans ( Xp ). A combination of high plant densities with overhead irrigation, high humidity, and high temperatures are conducive to BST outbreaks during transplant production. In addition to chemical control, transplant growers use roguing to remove diseased transplants, as a primary way to manage BST during transplant production. The value of roguing is often questioned, because information about the rate of pathogen spread and the incubation period between infection and symptom development is limited. In this study, we evaluated the extent of X. perforans spread on tomato transplants relative to symptom development by using a rifampicin-resistant X. perforans strain and conducting experiments in an environmentally controlled greenhouse simulating grower practices and also at a commercial transplant facility in Florida. BST symptom development typically lagged behind X. perforans dispersal by at least 5 to 7 days depending on environmental conditions. Furthermore, X. perforans was capable of aerosolization, which resulted in long-distance dispersal of ≤2 m under highly favorable conditions. Growers should rogue diseased plants and surrounding nonsymptomatic plants by >1 and ≤3 m, depending on outbreak severity, to limit disease spread. As a result, proper disease management should reduce introduction of nonsymptomatic transplants into the field and subsequently reduce pesticide applications.

Understanding human behavior is a complicated and complex endeavor. Academicians and practitioners need to understand the underlying beliefs and motivations to identify current trends and to effectively develop means of communication and education that encourage change in attitudes and behavior. Sociological research can provide information about how and why people make decisions; this information impacts the research and extension community, helping them formulate programs and present information in a way that increases adoption rates. Life cycle assessment can document how plant production impacts the environment. Production of ornamental plants (greenhouse, container, and field produced flowers trees and shrubs) accounted for 4.4% of the total annual on-farm income and 8.8% of the crop income produced in the United States in 2017, representing a substantial portion of farmgate receipts. Greenhouse and nursery growing operations can use this information to increase production and water application efficiency and decrease input costs. Information related to the environmental impacts of plant production, derived from life cycle assessment, can also inform consumer purchase decisions. Information from water footprint analysis quantifies the relative abundance and availability of water on a regional basis, helping growers understand water dynamics in their operation and informing consumer plant purchases based on water availability and conservation preference. Economics can motivate growers to adopt new practices based on whether they are saving or making money, and consumers modify product selection based on preference for how products are produced. Specialty crop producers, including nursery and greenhouse container operations, rely heavily on high quality water from surface and groundwater resources for crop production; but irrigation return flow from these operations can contribute to impairment of water resources. This review focuses on multiple facets of the socioeconomics of water use, reuse, and irrigation return flow management in nursery and greenhouse operations, focusing on grower and consumer perceptions of water; barriers to adoption of technology and innovations by growers; economic considerations for implementing new technologies; and understanding environmental constraints through life cycle assessment and water footprint analyses. Specialty crop producers can either voluntarily adapt practices gradually to benefit both economic and environmental sustainability or they may eventually be forced to change due to external factors (e.g., regulations). Producers need to have the most current information available to inform their decisions regarding water management. [ABSTRACT FROM AUTHOR]