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This study examined factors that shape how nursery growers perceive automated nursery technologies and evaluate how these perceptions relate to growers’ adoption. We applied Rogers’ (2003) Diffusion of Innovations to understand growers’ perceptions of automated technologies to inform Extension programming serving niche audiences in the nursery and horticulture arenas. Data were collected via a mixed-mode survey and analyzed using descriptive statistics and multiple linear regression. Nursery growers indicated fairly strong perceptions of observability, relative advantage, and compatibility. Automated nursery technologies were not perceived as being complex. Notably, perceptions of trialability were low. Compatibility, complexity, and trialability predicted growers’ current adoption of automated technologies. Relative advantage, complexity, and compatibility predicted the future adoption of automated nursery technologies. Compatibility was the most important predictor of both current use and the likelihood of adopting automated nursery technologies. Extension professionals, researchers, and others who support the nursery industry can use these findings to encourage the adoption of technological innovations. Chiefly, automated nursery technologies need to be designed with compatibility in mind (e.g., adaptable to nursery operations’ existing infrastructure, values, and goals). Uptake could be accelerated by emphasizing compatibility (e.g., conveying how these technologies can be integrated into existing systems and how the current labor force’s skillsets can be applied to new technologies). This study considered a suite of automated nursery technologies to provide a starting point in developing and diffusing these types of innovations. Future research should examine the characteristics of specific technologies to pinpoint precise strategies aimed at behavioral adoption.

HighlightsAn automated irrigation system based on a novel leachate sensor was built to schedule and deliver irrigation to a container nursery.The sensor network was designed to achieve a 0.15 leaching fraction; it maintained an actual average leaching fraction of 0.17.Water use and container effluent were reduced by 60% and 96%, respectively, without reducing crop growth. Abstract.With the aim of reducing irrigation water use, an irrigation and leachate measurement and control system was developed and evaluated to automatically schedule and actuate irrigation in a commercial nursery. Leachate and irrigation sensors were built using a tipping bucket mechanism and used to calculate the daily leaching fraction (LF) = volume leached/volume applied. For the experimental daily irrigation schedule, the previous day’s LF was used to calculate irrigation run time for the current day using a scaled multiplier, where the change in irrigation run time was proportional to the difference between the calculated LF and the target LF, 0.15. The control zone was irrigated for two hours every other day simulating the commercial nursery’s standard schedule. The irrigation control system worked as designed and correctly imposed the irrigation treatments, including correctly delaying in response to rain and actuating based on a programmed minimum runtime, when necessary. Season-long water use was 60% less for the leachate-based irrigation schedule compared to the grower’s standard irrigation schedule (p = 0.0028). The average daily LFs were 0.17 and 0.73 for the LF-based irrigation and control, respectively (p < 0.0001). Compared to the grower’s standard practice the time averaged irrigation application rate was 3.3-fold less and time averaged leaching rate was 12.1-fold less for the LF-based irrigation schedule. Substrate volumetric water content was not correlated with LF and thus was not a good predictor of leaching fraction. Growth metrics were not impacted by irrigation treatment (p = 0.1429), indicating plants received sufficient water in the LF-based irrigation system. This novel system was able to actuate and adjust irrigation run-time based on daily leaching fraction without being influenced by the lag between irrigation and leaching and had an average leaching fraction within 0.02 of the target LF. Reducing water use with this LF-based schedule has the potential to reduce agrichemical-laden nursery effluent and increase nursery irrigation capacity, i.e., their ability to expand production on the current water supply. Keywords: Container effluent, ET-based irrigation, Irrigation schedule, Leachate, Precision irrigation, Sensor-based irrigation.

Nursery producers are challenged with growing a wide range of species with little to no detectable damage from insects or diseases. Growing plants that meet consumer demand for aesthetics has traditionally meant routine pesticide application using the most time-efficient method possible, an air-blast sprayer, despite its known poor pesticide application efficiency. New variable-rate spray technology allows growers to make more targeted applications and reduce off-target pesticide loss. In this study, a prototype laser-guided variable-rate sprayer was compared with a traditional air-blast sprayer. Pesticide volume, spray application characteristics, and the control of powdery mildew were evaluated over the course of two growing seasons. Spray application characteristics were assessed using water-sensitive cards (WSCs) and DepositScan software. This prototype sprayer reduced pesticide volume by an average of 54% across both years despite being tested against a low rate (−1). In 2016, the conventional sprayer had more than double the deposit density on target WSCs among distal trees than the variable-rate sprayer; however, within proximal trees, there was no difference between the two sprayer types. In 2017, when the trees were larger, within both the distal and proximal trees, the conventional sprayer had greater deposit density on target WSCs than the variable-rate sprayer. In 2016, coverage on target WSCs was nearly 7-fold greater with the conventional treatment than with the variable-rate treatment. In 2017, when trees were larger, there was greater coverage on target WSCs in proximal trees (3.8%) compared with those in distal trees (1.0%) regardless of the sprayer type. This variable-rate spray technology provided acceptable control of powdery mildew severity on individual branches and whole trees and maintained the incidence of powdery mildew to levels comparable to that occurring among trees sprayed with a traditional air-blast sprayer. Therefore, the variable-rate spray technology has the potential to effectively control disease, dramatically reduce the pesticide footprint, and preserve natural resources such as ground and surface water, soil, and beneficial insects found within and around nurseries.

To optimize pesticide applications to the canopies of deciduous perennial crops, spray volume should be adjusted throughout the year to match the changes in canopy volume and density. Machine-vision, computer-controlled, variable-rate sprayers are now commercially available and claim to provide adequate coverage with decreased spray volumes compared with constant-rate sprayers. However, there is little research comparing variable- and constant-rate spray applications as crop characteristics change throughout a growing season. This study evaluated spray volume, spray quality (e.g., coverage and deposit density), and off-target spray losses of variable- and constant-rate sprayers across multiple phenophases in an apple (Malus domestica) orchard and a grape (Vitis vinifera) vineyard. The variable-rate sprayer mode applied 67% to 74% less volume in the orchard and 61% to 80% less volume in the vineyard. Spray coverage (percent), measured by water-sensitive cards (WSC), was consistently greater in the constant-rate mode compared with the variable-rate mode, but in many cases, excessive coverage (i.e., over-spray) was recorded. The variable-rate sprayer reduced off-target losses, measured by WSC coverage, up to 40% in the orchard and up to 33% in the vineyard. Spray application deposit densities (droplets per square centimeter) on target canopies were typically greater in variable-rate mode. However, the deposit densities were confounded in over-spray conditions because droplets coalesced on the WSC resulting in artificially low values (i.e., few, very large droplets). Spray efficiencies were most improved early in the growing season, when canopy density was lowest, demonstrating the importance of tailoring spray volume to plant canopy characteristics.

Hydrangea macrophylla exhibiting blue sepals (versus purple or pink) have improved marketability; however, little research has been conducted to evaluate aluminum (Al), the element responsible for bluing, on crop growth, effectiveness of bluing sepals, and characteristics of flower clusters in an outdoor nursery. This study compared substrate Al availability, crop growth, flower color, number, and size over a 56-week period in two locations. A polymer coated (90-day release) or ground aluminum sulfate [Al2(SO4)3; water soluble] was either incorporated into a non-limed pine bark substrate, applied to the surface of the substrate as a top dress, or as a routinely applied Al2(SO4)3 drench (low concn.) or applied once (high concn.). In general, application of Al increased plant foliar Al concentration, but also decreased substrate pore-water pH and increased electrical conductivity (EC) with varying effects based on the applied product’s solubility and subsequent longevity. Aluminum sulfate increased the potential of Al phytotoxicity negatively affecting root morphology and creating an undesirable rhizosphere electrochemistry due to the pH being continually acidic, 1.5 mS·cm−1. These suboptimal rhizosphere conditions resulted in a lower quality or smaller plant. No plants exhibited clear, deep blue flower cluster sought by consumers. Neither the effect of pore water pH or EC could, alone or in combination, account for the lack of plant vigor or blue flower clusters when substrate and foliar Al concentrations were adequate in flowering H. macrophylla. More research is needed to investigate the effect of pore-water electrochemical properties, possible mineral nutrient co-factors that provide Al synergisms or toxicity protections, and holistic plant health on ensuring blue coloration of a vigorous H. macrophylla. Published version

HighlightsUsing leaching fraction to schedule irrigation is recommended yet no automated measurement system exists.Sensors were developed to automatically measure leachate and irrigation within a sensor network.There was no difference between sensor measured and manually captured volume for sensors deployed in a nursery.After deployment in commercial nurseries, sensors accurately measured leachate and irrigation within 10% margin.Abstract. Nursery crops are often over-irrigated, resulting in wasted water and agrochemical inputs. Irrigating based on leaching fraction is recommended, yet an automated system for measuring and recording nursery container effluent (leachate) does not exist. The objective of this research was to develop and test a sensor-based system for real-time leachate and irrigation measurement in outdoor commercial nurseries. Sensors were developed to automatically measure irrigation and leachate volume in container nurseries that use overhead irrigation with the goal of facilitating the development of an automated leaching fraction-based irrigation system. Sensors were built using readily available components, including tipping bucket mechanisms calibrated to either 4.7 or 8.2 mL per tip, and were designed and constructed to function with commonly used 3.8-, 11.4-, and 14.5-L nursery containers. Sensor networks were developed in order to collect data from the sensors. Sensors were deployed at three commercial nurseries and tested using closed- and open-loop tests. Initially, a closed-loop test was performed on a subset of the sensors to test the integrity of the sensor-container system when subjected to an overhead irrigation delivery system. Following closed-loop tests, sensors were subjected to tests utilizing directed applications of water to compare sensor measurements with the volume of water applied and to compare sensor measurements over time (pre- and post-season). There was no difference between leachate measured by sensors and leachate captured and measured manually in closed-loop tests (p = 0.0570). In directed applications, sensors measured water flow with less than 3% margin at the beginning of the season (p = 0.0485) and less than 10% margin at the end of the season (p = 0.0390) regardless of container size. Pre- and post-season comparisons showed equivalence at the 10% margin for the 4.7-mL tipping bucket size (p = 0.0043) and at 5% for those calibrated to 8.2 mL per tip (p = 0.0198). Sensors deployed in commercial nurseries accurately measured leachate and irrigation within a 10% margin in real-time, on an individual plant scale, making them a viable option for a leaching fraction-based irrigation schedule. Keywords: Container effluent, Container-grown plants, Leaching fraction, Irrigation schedule, Sensor network.

Laser-guided variable-rate intelligent spray technology is anticipated to reduce pesticide use in production of crops and safeguard the environment. However, the ability of this technology to effectively control insect pests and diseases of crops must be validated before it becomes part of integrated pest management programs. Abilities of three different intelligent sprayers were tested to control pest insects and plant diseases at one fruit farm and two ornamental nurseries in Ohio during three consecutive growing seasons. The same sprayers with disabled intelligent functions were used as conventional constant-rate applications for comparisons. Test crops were apple (Malus pumila), peach (Prunus persica), blueberry (Vaccinium sect. Cyanococcus), black raspberry (Rubus occidentalis), crabapple (Malus sp.), maple (Acer sp.), birch (Betula sp.), and dogwood (Cornus florida). There were five insects and six diseases total involved in the investigations in the fruit farm and two nurseries. The field tests showed the intelligent spray applications reduced pesticide and foliar fertilizer use by ≈30% to 65% on average during the 3-year experiments. At the same time, intelligent spray technology was similar or more effective than conventional spray technology when controlling insects and diseases on a variety of crops. These results demonstrated that intelligent spray technology was environmentally friendly and more effective for control of insect and disease pests in fruit farms and ornamental tree nurseries.

Advanced variable-rate spray technology, which applies pesticides based on real-time scanning laser rangefinder measurements of plant presence, size, and density, was developed and retrofitted to existing sprayers. Experiments were conducted to characterize the application of four programmed spray rates (0.03, 0.05, 0.07, or 0.09 L·m−3 of crop geometric volume) when applied to Malus domestica Borkh. ‘Golden Delicious’ apple trees using this crop sensing technology. Water-sensitive cards (WSCs) were used as samplers to quantify spray coverage, deposits, and deposit density in the target and nontarget areas, and an overspray index based on a threshold of greater than 30% coverage was calculated. The application rate ranged from 262 L·ha−1 at the programmed spray rate of 0.03 L·m−3 to 638 L·ha−1 at the rate of 0.09 L·m−3. For a given WSC position, spray coverage and deposits increased as the spray rate increased. WSC positions 1 and 2 were oversprayed at all rates. The effect of spray rate on deposit density varied with WSC positions, with high densities achieved by low spray rates for WSCs closest to the sprayer but by high spray rates for WSCs positioned either deeper within or under the canopy. When coalescing deposits were accounted for, deposit densities met or exceeded the recommended pesticide application thresholds (insecticides 20–30 droplets/cm2; fungicides 50–70 droplets/cm2) at all WSC positions for each spray rate tested. The lowest spray rate reduced off-target loss to the orchard floor by 81% compared with the highest rate, dramatically reducing potential exposure to nontarget organisms, such as foraging pollinators, to come into contact with pesticide residues. Applying the lowest rate of 0.03 L·m−3 met deposit density efficacy levels while reducing spray volume by 83% compared with the orchard standard application of 1540 L·ha−1 and by 87% compared with the 1950 L·ha−1 application rate recommended when using the tree row volume method. Thus, there is potential for growers to refine pesticide application rates to further achieve significant pesticide cost savings. Producers of other woody crops, such as nursery, citrus, and grapes, who use air-assisted sprayers, may be able to achieve similar savings by refining pesticide applications through the use of laser rangefinder-based spray application technology.

Developing management practices that make more efficient use of irrigation is important for improving the sustainability of nursery crop production. Integrating refined irrigation scheduling with a substrate amendment like biochar can improve irrigation efficiency. The objective of this research was to evaluate the impact of biochar and need-based irrigation scheduling on gas exchange, plant water relations, and biomass gain of container-grown Hydrangea paniculata ‘Silver Dollar’ with the goal of reducing water use and maintaining or shortening production cycles. Containers were filled with pine bark and amended with either 10% or 25% by volume of hardwood biochar. Plants were automatically irrigated by one of the three irrigation schedules. The irrigation schedules were conventional irrigation, delivering 1.8 cm of water in one event each day, and two on-demand, need-based irrigation schedules. The first was based on the moisture characteristic curve for each of the three substrates developed via the evaporative method. The second was a plant physiology-based irrigation scheduling regime built on the relationship between photosynthesis and substrate moisture content. Scheduling irrigation using a plant physiology or substrate physical properties basis, in combination with biochar, reduced the water requirement for ‘Silver Dollar’ hydrangea without any negative effect on plant dry weight by maintaining sufficient plant water status and gas exchange even just prior to irrigation. Automated irrigation systems coupled with a plant physiology or substrate-based actuation and a water retentive substrate amendment have the potential to reduce nursery crops water use.

Controlling irrigation using timers or manually operated systems is the most common irrigation scheduling method in outdoor container production systems. Improving irrigation efficiency can be achieved by scheduling irrigation based on plant water needs and the appropriate use of sensors rather than relying on periodically adjusting irrigation volume based on perceived water needs. Substrate amendments such as biochar, a carbon (C)-rich by-product of pyrolysis or gasification, can increase the amount of available water and improve irrigation efficiency and plant growth. Previous work examined two on-demand irrigation schedules in controlled indoor (greenhouse) environments. The goal of this study was to evaluate the impact of these on-demand irrigation schedules and hardwood biochar on water use and biomass gain of container-grown Hydrangea paniculata ‘Silver Dollar’ in a typical outdoor nursery production environment. Eighteen independently controlled irrigation zones were designed to test three irrigation schedules on ‘Silver Dollar’ hydrangea grown in pine bark amended with 0% or 25% hardwood biochar. The three irrigation schedules were conventional irrigation and two on-demand schedules, which were based on substrate physical properties or plant physiology. Conventional irrigation delivered 1.8 cm water in one event each day. The scheduling of substrate-based irrigation was based on the soilless substrate moisture characteristic curve, applying water whenever the substrate water content corresponding to a substrate water potential of –10 kPa was reached. The plant-based irrigation schedule was based on a specific substrate moisture content derived from a previously defined relationship between substrate moisture content and photosynthetic rate, maintaining the volumetric water content (VWC) to support photosynthesis at 90% of the maximum predicted photosynthetic rate. Total water use for the substrate-based irrigation was the same as for the conventional system; the plant-based system used significantly less water. However, plant dry weight was 22% and 15% greater, water use efficiency (WUE) was 40% and 40% greater, and total leachate volume was 25% and 30% less for the substrate-based and plant-based irrigation scheduling systems, respectively, than for conventional irrigation. The 25% biochar amendment rate reduced leachate volume per irrigation event, and leaching fraction, but did not affect total water use or plant dry weight. This research demonstrated that on-demand irrigation scheduling that is plant based or substrate based could be an effective approach to increase WUE for container-grown nursery crops without affecting plant growth negatively.

Container-grown nursery crops generally require daily irrigation applications and potentially more frequent applications during the hottest part of the growing season. Developing management practices that make more efficient use of irrigation water is important for improving the sustainability of nursery crop production. Biochar, a byproduct of pyrolysis, can potentially increase the water-holding capacity and reduce water and nutrient leaching. In addition, the development of sensor-based irrigation technologies has made monitoring substrate moisture a practical tool for irrigation management in the nursery industry. The objective of this research was to determine the effect of switchgrass biochar on water and nutrient-holding capacity and release in container substrates of Buxus sempervirens L. × Buxus microphylla (‘Green Velvet’ boxwood) and Hydrangea paniculata (Pinky Winky® hardy hydrangea). Containers were filled with pine bark and amended with 0%, 10%, or 25% volume of biochar. Plants were irrigated when the volumetric water content (VWC) reached the water-buffering capacity set point of 0.25 cm3·cm−3. The sensor-based irrigation in combination with the low cost biochar substrate amendment increased substrate water-holding capacity and reduced irrigation requirements for the production of hydrangea, a high water use plant. Biochar application rate influenced irrigation frequency, which likely affected plant biomass for hydrangea, but boxwood dry weight was unaffected by biochar rate. Total irrigation applied was decreased by 32% in 10% biochar treatment without reducing hydrangea dry weight. However, in the 25% biochar treatment, total irrigation applied was reduced by 72%, whereas dry weight decreased by 50%. Biochar application reduced leaching volume and leaching fraction in both plants. Leachate analysis over the course of the 8-week experiment showed that the average mass of phosphate (PO4), potassium (K), and total carbon was greater in the leachate from containers that received 25% biochar compared with those receiving 0% or 10% biochar for both plant species. For hydrangea, mass of total nitrogen (TN) and nitrate (NO3) in leachate was not significantly affected by increasing the biochar rate. However, for boxwood, the mass of NO3 and TN was greater in the 25% biochar treatment leachate, whereas the mass of ammonium (NH4) was unaffected. In hydrangea, total nutrients lost from the containers was lower in biochar-amended containers (both 10% and 25% biochar) because of receiving a lower total volume of water. Amendment with biochar also affected concentration of phosphorus (P) and K, with the highest concentration in both leaf tissue and substrate from the 25% biochar application rate.

Ornamental plant producers often rely on chemical control to manage insect pests. However, cultural practices, such as pruning, can influence plant architecture which may, in turn, affect pesticide penetration. Spray penetration was studied to determine the effect of canopy density on beneficial insect survival following insecticide application and to better understand the implications of canopy density on pest management. Regardless of canopy density or plant species, the interior position of the canopy received less than 8% spray coverage. The middle position of sparse canopies received 288 to 513% more coverage than the middle position of dense canopies. The middle and interior position of dense canopies protected greater than 50% of the convergent lady beetle (Hippodamia convergens (Guérin-Méneville) population while only the interior position of dense canopies protected greater than 50% of green lacewing (Chrysoperla rufilabris Burmeister) populations. Index words: beneficial insect, nursery crop, pesticide, plant architecture, woody ornamental. Species used in this study: China Girl® holly (Ilex ×meserveae ‘Mesog'); ‘Alice' Oakleaf hydrangea (Hydrangea quercifolia Bartr. ‘Alice'); convergent lady beetle [Hippodamia convergens (Guérin-Méneville)]; green lacewing [Chrysoperla rufilabris (Burmeister)]. Chemicals used in this study: carbaryl (1-naphthyl N-methylcarbamate, Sevin® SL, Bayer CropScience, Durham, NC).

Three, 2-day hands-on experiential learning workshops were presented in three southeastern United States cities in June 2014, by the Southern Nursery Integrated Pest Management (SNIPM) working group. Attendees were provided 4 hours of instruction including hands-on demonstrations in horticultural management, arthropods, plant diseases, and weeds. Participants completed initial surveys for gains in knowledge, skills, and abilities as well as their intentions to adopt various integrated pest management (IPM) practices after the workshop. After 3 years, participants were again surveyed to determine practice adoption. Respondents changed their IPM practice behavior because of attending the workshops. Those returning the survey set aside more time to scout deliberately for pests, plant diseases, and weeds; used a standardized sampling plan when scouting; and adopted more sanitation practices to prevent plant disease. Fewer horticultural management practices were adopted than respondents originally intended. Future emphasis should be placed on using monitoring techniques to estimate pest emergence, for example, traps and pheromone lures, as well as plant phenology and record keeping. However, more work is needed to highlight both the immediate and long-term economic benefits of IPM practice adoption in southeastern U.S. nursery production.

Extension and research professionals in the southeastern United States formed the Southern Nursery Integrated Pest Management working group (SNIPM) to foster collaboration and leverage resources, thereby enhancing extension programming, increasing opportunity, and expanding the delivery of specialized expertise to nursery crop growers across a region. Building a productive and lasting working group requires attracting a group of research and extension faculty with complementary expertise, listening to stakeholders, and translating stakeholder needs into grant priorities to help solve problems, all hallmarks of effective teamwork principles. SNIPM has now grown to include 10 U.S. states and 11 institutions and has been awarded seven grants totaling $190,994 since 2009. A striking benefit of working group membership was observed over time: synergy. Greater awareness of individual expertise among SNIPM members, each of whom were focused on different aspects of the nursery production system stimulated multistate extension publications, electronic books (eBooks), mobile device applications (apps), popular press articles, and spin-off research projects when separate foci were combined and directed toward complex challenges. Deliverables achieved from this faculty collaboration include nine peer-reviewed publications, four manuals and books and 23 book chapters, and a combined total of 11 abstracts, conference proceedings and extension publications. To date, the return on investment for SNIPM is one deliverable produced to every $2265.89 in grant funding. SNIPM has also been honored with multiple American Society for Horticultural Science publication awards as well as the Southern Region Integrated Pest Management Center Bright Idea Award for the quality and originality of their project outputs. Continuing to work together toward common goals that bridge technology and serve the nursery industry while supporting each individual member’s program will be crucial to the long-term success of this working group.

In 2014, the Southern Nursery Integrated Pest Management (SNIPM) Working Group published both print and electronic versions of IPM for Shrubs in Southeastern U.S. Nursery Production: Volume I. Five hundred print books (of 3000 copies) were distributed to commercial ornamental growers and extension educators in return for their participation in a follow-up survey. The survey was administered to determine the value of book contents, savings that growers realized from using the book, perceived value of the book had users been asked to pay for it, and demographic information. The survey response rate was 46.2%, with respondents from 18 states. Of 243 respondents, 194 (79.8%) had used the book. Entomology information was most used and most useful, followed by plant pathology, weed science, and cultural information. Collective savings attributed to book use totaled $408,832/year for the 194 nurseries that used the book. Applying the use rate (79.8%) identified in this survey, this represents $5.62 million in savings per year for the 3000 printed books, of which 2394 are estimated to have been used. Savings varied by the type and size of operation. Larger operations had greater savings per year. Container growers saved $44.15/acre and field growers $28.37/acre. The price that growers were willing to pay for the book also varied by operation type and size. Extension educators and growers were willing to pay an average of $41.20, with an additional $0.063/acre for container growers and $0.126/acre for field growers. Return on investment for the U.S. Department of Agriculture grant funding for the project was $187.60 per dollar of funding. This survey demonstrates that collaborative efforts can produce high-value deliverables with significant regional and/or national impact.

Two sensor-based irrigation scheduling systems were compared for water use and plant growth in container-grown Green Velvet boxwood (Buxus sempervirens L. × B. microphylla Siebold & Zucc. var. koreana ‘Green Velvet’) and slender deutzia (Deutzia gracilis Siebold & Zucc). These crops were chosen because they have different water requirements during production. The two sensor-based irrigation systems included a physiological-based on-demand (OD) irrigation system where the set point was derived from the relationship between substrate moisture and photosynthetic rate. The second system was a daily water use (DWU) method where the amount of water used by the crop was replaced each day. The objective of the study was to evaluate and compare water use and growth metrics using the OD and DWU irrigation scheduling regimes for two container-grown woody plants that differed in their water consumption. There were no differences in root and shoot biomass or growth index due to the irrigation schedule employed for either boxwood or deutzia. For boxwood plants, OD irrigation reduced water consumption by 35.5% and enhanced water use efficiency (WUE) by 54.5% compared with DWU. Total water use of deutzia in OD zones was reduced by 26.5% compared with DWU. DWU offers the labor scheduling advantage of irrigation occurring at a set time of day, and OD offers the advantage of watering as required, potentially reducing water stress as the season progresses and as the plant size and atmospheric demand increase.

Water resources can be used more efficiently by including sustainable substrate components like coir that increase water-holding capacity. The first objective of this study was to evaluate the impact of coir amendment rate on plant available water and plant gas exchange, with the goal of optimizing substrate available water and determining the optimum coir amendment rate in a greenhouse environment. The second objective was to establish the optimum method of determining plant available water using either plant gas exchange parameters or substrate physical properties. Greenhouse experiments were conducted with Hydrangea paniculata &lsquo, Jane&rsquo, (Little Lime&reg, hardy hydrangea) potted with one of five different coir rates (0%, 10%, 25%, 40% and 65%) mixed with pine bark on a volume basis. Plant gas exchange parameters and substrate water content were measured daily over a range of increasingly drier substrate moisture contents. Actual photosynthetic rates increased with increasing coir amendment rate and were highest with 65% coir amendment. Amending pine bark with coir increased the water storage capacity, plant available water, and plant gas exchange parameters. Results suggest that 65% coir amendment rate was the optimum amendment rate among those tested in a greenhouse environment and plant photosynthetic rate was the better method of determining plant available water.

Budget reductions for the Cooperative Extension Service have made traditional extension programming (face-to-face, live programming) difficult for extension professionals. Attending traditional extension programming can also prove to be challenging for industry practitioners due to the need to delay or reschedule work activities and the need to travel to participate. The Tennessee Master Nursery Producer program (TMNP) is a professional development extension program designed to enhance the sustainability of the Tennessee nursery crops industry. The TMNP was first offered as a traditional extension program in 2012. Although the program was successful, it demanded substantial time from faculty and staff to coordinate the program, prepare presentations, and travel. Recurring travel expenses required a significant financial commitment from both extension personnel and participants. An asynchronous online program was developed to address these challenges and to increase accessibility, exploit the economies of scale, and standardize curriculum. The objective of this article is to describe the advantages and disadvantages that were identified offering nursery production subject matter as a traditional live classroom and subsequently as an asynchronous online program in terms of development cost, administrative and technological requirements, and economic impacts.

Nursery and greenhouse producers, research and extension faculty, and representatives from allied fields collaborated to formulate a renewed vision to address water issues affecting growers over the next 10 years. The authors maintained the original container irrigation perspective published in “Strategic vision of container nursery irrigation in the next ten years,” yet broadened the perspective to include additional challenges that face nursery crop producers today and in the future. Water availability, quality, and related issues continue to garner widespread attention. Irrigation practices remain largely unchanged due to existing irrigation system infrastructure and minimal changes in state and federal regulations. Recent concerns over urbanization and population growth, increased climate variability, and advancements in state and federal regulations, including new groundwater withdrawal limitations, have provided an inducement for growers to adopt efficient and innovative practices. Information in support of the overarching issues and projected outcomes are discussed within.

An experiment was conducted to determine which of five substrate-moisture sensor placements best estimates volumetric water content (VWC) for 11.4 L containers filled with Hibiscus moscheutos ‘Pink Elephant,’ as well as the effect of low VWC on sensor measurements. Five sensor placements were tested; three sensors were horizontally inserted into the sidewall at 5, 10, and 15 cm from the base of the container and the other two placements were inserted into the substrate surface either vertically or diagonally. All positions showed a strong linear relationship (r2> 0.92) with VWC determined gravimetrically, indicating they all are appropriate models of container substrate moisture. Sensors placed 15 cm above the base had a y-intercept closer to zero than sensors at 5 cm from the base, vertical and diagonal, but the slope was less accurate (farther from 1, P-value 0.0148) than the vertical placement. Vertical placement had a more accurate slope than 15 cm from the base, but the y-intercept was further from zero. The substrate was dried to 0.11 m3·m-3 during the experiments and became hydrophobic. This substantially decreased the amount of water that could be held at effective container capacity and decreased sensor accuracy. For this species and container size, no probe placement proved superior to the other placements, but choosing a horizontal placement was most practical for pesticide applications, pruning and hand weeding while surface installed placements may be most practical for sensor calibration and ease of installation, and removal.

The genus Vaccinium represents an increasingly important group of plants for the U.S. green industry. In 2012, blueberries (Vaccinium sp.) ranked the second most important berry crop in the U.S. with a total crop value over $780 million. The popularity of blueberries creates opportunities as well as challenges for nursery crop producers. This article presents a review of current nursery production practices of blueberry and explores the challenges and opportunities for nursery crop producers, including pesticide use during nursery production of an edible crop, and discusses current research relevant to the green industry. Needs for additional research and opportunities for breeding are presented. Blueberries are Ericaceous plants and have very specific cultural requirements. This review presents the culture, as well as insect, mite, and disease control from an integrated pest management (IPM) approach for several blueberry species. A serious threat to the blueberry market, spotted wing drosophila (Drosophila suzukii Matsumura) is discussed to provide information needed by commercial producers and landscape managers to address client and customer questions. This review also highlights the most relevant blueberry selections for container production in the southeastern United States.

Market researchers have found that nursery and greenhouse production practices that reduce plastic use can increase consumer interest. However, there are broader crop performance, production efficiency, and environmental factors that must be considered before adopting containers made with alternative materials. This review highlights current commercially available alternative containers and parent materials. In addition, findings from recent and ongoing nursery, greenhouse, and landscape trials are synthesized, identifying common themes, inconsistencies, research gaps, and future research needs.

Chemical pesticides can efficiently control insect pests and are often relied upon by nursery producers. With increased consumer concerns regarding insecticides, growers may choose to limit insecticide applications by incorporating natural enemies into their pest management program. This study assessed the effects of commonly used contact (bifenthrin and carbaryl) and systemic (imidacloprid and dinotefuran) insecticides on adult Chrysoperla rufilabris (Burmeister), adult Hippodamia convergens (Guerin-Meneville), and adult Orius insidiosus (Say) to evaluate their safety for use with natural enemies. Insects were confined in experimental arenas either with leaves sprayed to provide insecticide residues or leaves treated with only water and then air-dried prior to use. Both systemic and contact insecticides caused mortality in all three insect species. The contact insecticide bifenthrin was the least toxic to C. rufilabris, and the systemic insecticide, dinotefuran, was not toxic to H. convergens. ...

Cutting-propagated ‘Alice’ oakleaf hydrangea (Hydrangea quercifolia Bartr.) often produces a few vigorous branches with apical dominance, thus suppressing growth of other branches. As a result, the maturing canopy is sparse and develops asymmetrically, rendering plants unappealing to customers. For this reason, growers prune or apply plant growth regulators (PGRs) to encourage more branching, thereby producing a more desirable product. Propagation through tissue culture may provide another option to increase branching as an outcome of habituation. Habituation occurs when plant cultures continue to respond to a hormone that is no longer being supplied and, in turn, frequently leads to more branching. We evaluated oakleaf hydrangea growth as affected by propagation technique [tissue-cultured (TC) and cutting-propagated (CUT)] and PGR (cyclanilide and benzyladenine) application during container production. Nontreated TC plants had more branches longer than 15.2 cm (6 in) compared to nontreated CUT plants in 2008, although not in 2010. In both years, single applications of cyclanilide did not affect total branch number but two applications increased total branch number compared to nontreated plants, averaged over propagation technique. Plants treated with benzyladenine had similar or fewer total branches compared with nontreated, hand-pruned, and cyclanilide-treated plants (one or two treatments). Propagation technique did not consistently influence response to PGRs.

a b s t r a c t Independently controlled irrigation plots were designed to test two container nursery irrigation regimes on oakleaf hydrangea (Hydrangea quercifolia 'Alice') in both nursery and controlled greenhouse environ- ments. The experiments were conducted in both 3.8 and 11.4 L containers. Plants were automatically irrigated by one of two soil moisture sensor-based regimes: (1) a daily water use (DWU) system that delivered the exact amount of water that had been lost in the previous 24 h and (2) an on-demand (OD) irrigation system based on a specific substrate moisture content derived from the relationship between substrate moisture and photosynthetic rate. In this system, irrigation was applied when the substrate

The genus Viburnum encompasses a group of about 150 species of evergreen, semi-evergreen or deciduous trees and large shrubs. Viburnums are native to temperate, subtropical and tropical areas of southeastern Asia, eastern North America, Central America, the Caribbean and parts of South America. Native and nonnative Viburnum species have become prominent landscape plants in the southeastern United States due to their beauty, utility, relative ease of maintenance and broad adaptability to the region's climate and soils. Efficient management of viburnum pests to maintain healthy viburnum plants in nurseries and landscape settings is crucial for sustaining the economic competitiveness and profitability of green industry professionals competing in the horticulture marketplace. Diversity of species within the genus, however, is vast, and can contribute to many host-pest complexes that differ among growing environments and cause severe economic or aesthetic losses. Additionally, some abiotic disorders may mimic biotic damage or may render viburnum more susceptible to pests and diseases. This review focuses on viburnum culture in production and landscape settings with an emphasis on major insect and mite pests, plant diseases and abiotic disorders affecting management of Viburnum species in nursery and landscape settings.

Pruning is commonly performed during production of nursery crops to produce symmetrical, compact plants that are pleasing to the consumer’s eye. To achieve the desired results, nursery growers hand prune or apply plant growth regulators (PGRs). However, hand pruning is expensive and is not always effective, and efficacy of PGRs can depend on cultural practices, environmental conditions, irrigation, cultivar, and rate. Therefore, the objective of these experiments was to evaluate the effect of dikegulac sodium applied to pruned or unpruned ‘Limelight’ hardy hydrangea (Hydrangea paniculata). Plants were grown at two locations, Tennessee (TN) and Mississippi (MS). The pruned treatment consisted of hand pruning, leaving three nodes followed by applications of dikegulac sodium (400, 800, or 1600 ppm). Applications of dikegulac sodium to pruned or unpruned plants were made the same day using a carbon dioxide backpack sprayer. There were two additional control treatments: hand-pruned untreated (hand-pruned) and unpruned untreated (untreated). Plants were grown outdoors under full sun in TN and under 40% shade in MS. Data were collected at the close of the experiment on the number of branches over 1 inch, final growth index (FGI), floral attributes, branch symmetry, and phytotoxicity. At both locations, pruned and unpruned plants treated with 800 or 1600 ppm dikegulac sodium had more branches than the hand-pruned and unpruned plants. Flower number and size tended to be greater for unpruned plants than pruned plants. Phytotoxicity was observed at 2 and 6 weeks after treatment (WAT). For plants grown in TN, symptoms were more pronounced on plants following treatment with 800 (pruned plants) and 1600 ppm (pruned and unpruned) dikegulac sodium compared with the untreated plants. There were no visible phytotoxicity symptoms at 6 WAT for plants grown in MS, regardless of treatment.

With increased mobile device usage, mobile applications (apps) are emerging as an extension medium, well suited to “place-less” knowledge transfer. Conceptualizing, designing, and developing an app can be a daunting process. This article summarizes the considerations and steps that must be taken to successfully develop an app and is based on the authors’ experience developing two horticulture apps, IPMPro and IPMLite. These apps provide information for major pests and plant care tasks and prompt users to take action on time-sensitive tasks with push notifications scheduled specifically for their location. Topics such as selecting between a web app and a native app, choosing the platform(s) for native apps, and designing the user interface are covered. Whether to charge to download the app or have free access, and navigating the intra- and interinstitutional agreements and programming contract are also discussed. Lastly, the nonprogramming costs such as creating, editing, and uploading content, as well as ongoing app management and updates are discussed.

Mobile device applications (apps) have the potential to become a mainstream delivery method, providing services, information, and tools to extension clientele. Testing, promoting, and launching an app are key components supporting the successful development of this new technology. This article summarizes the considerations and steps that must be taken to successfully test, promote, and launch an app and is based on the authors’ experience developing two horticulture apps, IPMPro and IPMLite. These apps provide information for major pests and plant care tasks and prompt users to take action on time-sensitive tasks with push notifications scheduled specifically for their location. App testing and evaluation is a continual process. Effective tactics for app testing and evaluation include garnering focus group input throughout app development and postlaunch, in-house testing with simulators, beta testing and the advantages of services that enhance information gained during beta testing, and postlaunch evaluations. Differences in promotional and bulk purchasing options available among the two main device platforms, Android and iOS, are explored as are general preparations for marketing the launch of a new app. Finally, navigating the app submission process is discussed. Creating an app is an involved process, but one that can be rewarding and lead to a unique portal for extension clientele to access information, assistance, and tools.

The objective of these experiments was to evaluate the response of Little Lime™ hardy hydrangea (Hydrangea paniculata ‘Jane’) across two seasons in response to single foliar applications of three plant growth regulators (PGRs) at two rates: dikegulac sodium at 800 or 1600 ppm, benzyladenine at 300 or 600 ppm, or ethephon at 500 or 1000 ppm. There were two additional treatments: a hand-pruned control leaving three nodes and an unpruned water control (untreated) applied the same day as the PGR applications. To evaluate PGR efficacy, vegetative growth, floral attributes, branch symmetry, and phytotoxicity were assessed. Dikegulac sodium significantly increased branch number (BN) compared with all other treatments. Branch symmetry was greater in dikegulac sodium (800 or 1600 ppm) and hand-pruned treatments compared with the untreated and other PGR treatments (2011 and 2012). Flower number was greater in all PGR treatments compared with hand-pruned plants (2011 and 2012). The only treatment that promoted more symmetrical branching without reducing flower count was dikegulac sodium (800 or 1600 ppm). Phytotoxicity was observed in both seasons; however, no injury symptoms were evident 16 weeks after treatment (WAT), the termination of the experiment.

Favored for their rapid growth and brilliant fall color, maple ( Acer spp.) trees are among the most commonly grown deciduous shade trees in urban landscapes and commercial production nurseries. Many maple species used as ornamental plants share a suite of important arthropod pests that have the potential to reduce the trees' economic and esthetic value. We review the biology, damage, and management for the most important pests of maples with emphasis on integrated pest management (IPM) tactics available for each pest. Unfortunately, the biology of some of these pests is not well studied. This knowledge gap, paired with the low esthetic threshold for damage on ornamental plants, has hindered development of IPM tactics for maple pests in nurseries and landscapes. Maples will likely remain a common landscape plant. Therefore, our challenge is to improve IPM of the diverse maple pest complex.

The genus, Magnolia, encompasses a group of about 240 species of evergreen or deciduous trees and large shrubs. Magnolias are native to temperate, subtropical and tropical areas of southeastern Asia, eastern North America, Central America, the Caribbean and parts of South America. Native and nonnative Magnolia species have become prominent landscape plants in the southeastern U.S. due to their beauty, utility, relative ease of maintenance and broad adaptability to the region's climate and soils. Species introductions, breeding and selection programs over the last 50 years have produced superior selections with improved flowering, new flower colors and ornamental foliage and buds often featuring brown, copper or gold indumentum. Magnolia health and pest management is sometimes overlooked in both landscape and production settings because magnolia is considered to have relatively few pest and disease problems. Some abiotic disorders may mimic biotic damage or may render magnolia more susceptible to pests and diseases. When they occur, abiotic disorders, pests or diseases on magnolia can cause significant economic or aesthetic losses. This review focuses on magnolia culture in production and landscape settings with an emphasis on major pests, plant diseases and abiotic disorders affecting management of Magnolia species.

Genetic engineering of nitrogen assimilation has received considerable attention for its improvement of nitrogen use efficiency in crops. Overexpression of maize Dof1 (ZmDof1), a plant-specific transcription factor, has been reported to promote nitrogen assimilation and growth under low-nitrogen conditions in transgenic Arabidopsis and rice. The present study explored its application in Populus by overexpressing the ZmDof1 gene. Contrary to the results in Arabidopsis and rice, introduction of the ZmDof1 gene did not improve growth of transgenic Populus under different low-nitrogen conditions both in vitro and in greenhouse. Expressions of genes that are involved in nitrogen assimilation and carbon fixation were not induced in ZmDof1-transgenic Populus. Nitrogen/carbon concentrations and photosynthesis rate were not increased in the ZmDof1-transgenic Populus. The results in transgenic Populus overexpressing the ZmDof1 gene indicated that ZmDof1 did not play an important role in nitrogen assimilation under low nitrogen condition in woody Populus plants as it did in annual Arabidopsis and rice plants.

Extension and research professionals worked with a focus group of 10 nursery owners and managers across a five-state region (Georgia, Kentucky, North Carolina, South Carolina, Tennessee) in the southeastern United States to prioritize diverse nursery pests and production issues that are related to container and field production. A second focus group meeting, focused on technology, was followed by a survey that asked nursery growers to prioritize potential inputs and uses of information technology and the features they most valued, for example, that might be included within a nursery-specific mobile device application. The resulting prioritization highlights common challenges faced by growers across the southeastern United States in managing major plant diseases, arthropod pests, and weeds; as well as documenting emerging critical issues of nonpest related production issues, regulatory constraints, and technological needs. The focus group and survey format effectively identified grower needs that will help inform nursery producers and guide university Extension and research professionals, university administrators, industry associations, and state and federal government officials toward efficient resource allocation. These prioritizations explain the current state-of-need across a diverse agricultural industry segment and will help further refine future strategic action plans for nursery integrated pest management (IPM) and emerging critical nursery crop pest issues.

A demand-based irrigation system was developed for Hibiscus rosa-sinensis ‘Cashmere Wind’ based on the relationship between photosynthesis and substrate moisture level (moisture response curve). An experiment was conducted to evaluate the premise that biomass would decrease only when substrate moisture levels caused a significant reduction in photosynthetic rate. Irrigation set points were based on the moisture response curve and corresponded to 49, 41, 30, and 22 m 3 m −3 volumetric water content (89–61% container capacity). Gas exchange and leaf water potential were greater for plants in the three wettest irrigation treatments. Plants under these treatments used 1.4, 1.2, and 1.05 times more water during the experiment than plants in the driest treatment. Biomass metrics were generally unaffected by treatments or were greater for one or both intermediate treatments. This research demonstrates that a demand-based irrigation system with a physiological basis (predicated on the relationship between photosynthesis and substrate moisture potential) could be an effective biorational approach for scheduling irrigation and reducing water consumption in container-grown nursery crops.