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Eastern filbert blight (EFB) and pacific flatheaded borer (PFB) are two problems of Pacific Northwest orchard and nursery production. Fungicides and insecticides used to manage these issues are typically applied to plant tissues with minimal foliage present that can result in considerable spray waste or drift. The Intelligent Spray System (ISS) is a laser-guided, variable-rate sprayer that detects objects in the target zone and releases spray volumes proportional to the density of plant tissues, thereby increasing application efficiency and reducing waste. However, the ISS has not been tested when targeting low-foliage plant tissues such as emerging shoots and trunks. Three experiments were conducted from 2018 to 2021 to evaluate the potential use of the ISS for EFB and PFB management by assessing spray coverage on emerging hazelnut shoot tips, hazelnut tree trunks, and maple tree trunks. On hazelnut shoot tips, coverage was <10% of the shoot on both adaxial and abaxial sides, with the highest coverage on the adaxial side (9.5%) resulting from spraying in standard mode (no sensors) at 3.1 kph. On hazelnut trunks, application at the slowest tested speed (3.1 kph) in intelligent mode resulted in spray coverage greater than or equal to that applied in standard mode at 5.1 kph. In addition, coverage was significantly higher on cards placed on the ground between trees when the sprayer was used in standard mode, indicating higher amounts of wasted spray and drift over intelligent mode. On maple trunks, the slowest speed tested (3.1 kph) resulted in the highest coverage of tree trunks facing the sprayer that were two and three rows away from the sprayer, with the highest coverage levels on the row of trees closest to the sprayer occurring at the highest tested speed of 6.4 kph. On cards placed on trunk sides not facing the sprayer, the slowest tested speed of 3.2 kph resulted in significantly higher coverage than both treatments at 6.4 kph and intelligent mode at 4.8 kph in the tree row closest to the sprayer. This work has demonstrated a baseline of coverage that hazelnut buds receive when spraying for EFB, illustrates that the ISS was able to effectively target trunks, and could be an alternative to drenches for PFB control.
The future of agricultural water availability is threatened by climate change, population growth, and environmental regulations. Most of the global water is being used for crop irrigation. The objective of this research was to determine optimum timer-based controller settings and controlled-released fertilizer rates for ‘American Red’ (Pelargoium ×hortorum) potted geranium plants. Fertilizer was top-dressed at 3, 6, or 9 g. Plants were irrigated by a timer-based controller set to water at 11:00 AM every other day for 2 minutes, 9:00 AM and 2:00 PM for 1 minute per day, 11:00 AM for 1 minute per day, 11:00 AM for 2 minutes per day, and a control of manual hand watering. Data regarding plant growth, soil and leaf nutrients, and water use were collected. For geranium growth factors, the total flowers per plant was greatest for irrigation at 11:00 AM for 1 minute with 6 g fertilizer. Plant height and shoot dry weight were greatest for 6 and 9 g fertilizer. The number of umbels and soil plant analysis development (SPAD) chlorophyll meter readings were greatest for 9 g fertilizer. For geranium soil nutrient content, the pH was greatest for 3 g fertilizer, whereas the electrical conductivity, potassium, nitrate, sulfate, and boron were greatest for 6 and 9 g fertilizer. Regarding the nutrient content of the leaves, total nitrogen, boron, iron, and copper were greatest for 9 g fertilizer. Water use efficiency was greatest with 6 and 9 g fertilizer and irrigation 1 minute per day at 11:00 AM. The findings indicated that using timer-based controlled irrigation systems programmed to water for 1 minute during the morning with 6 g fertilizer resulted in plants that not only reduced water consumption but also enhanced water use efficiency and overall plant quality.
Pawpaw (Asimina triloba) is a fruit-bearing tree native to North America, and nurseries have a strong public demand for grafted trees. Most nurseries currently propagate pawpaw cultivars clonally through chip budding and whip-and-tongue grafting, both onto pawpaw seedling rootstock. Flexibility in successful grafting and budding techniques can optimize the type and quality of available scionwood while using the available labor. In an initial experiment, a range of pawpaw selections were subjected to grafting and budding techniques that indicated candidate cultivars and advanced selections for further examination. Therefore, the objective of this study was to determine the optimal method of propagating the pawpaw cultivars, KSU-Atwood™, KSU-Chappell™, and the advanced selection Hi7-1 using chip budding, whip and tongue, T-budding, and a cleft grafting tool. Additional trees, each of KSU-Atwood™ and KSU-Chappell™, were also subjected to green budding in the summer with the current season’s scionwood. Whip and tongue grafting was the most successful method, with a scion survival rate (SSR) of 95.8%, followed by the cleft grafting tool (SSR = 66.7%) and chip budding (SSR = 50.0%), then T-bud grafting (SSR = 25.0%), and lastly green bud grafting (SSR = 0.0%). There were no cultivar differences for the grafting techniques used. The whip-and-tongue method had the highest scion survival rate; however, cleft grafting and chip budding can be effective propagation methods for nurseries if scionwood quality does not support the whip-and-tongue grafting technique. In addition to whip-and-tongue grafting, the cleft grafting tool is a viable option for grafting pawpaw for use by personnel with less grafting experience or skill.
‘Marquette’ is a cold-hardy hybrid grape cultivar that has received increased attention for its use in wine production in the upper midwestern and northeastern United States since it was released in 2006. However, ‘Marquette’ is an early budburst cultivar susceptible to spring freeze damage. We examined the influence of high wire bilateral flat cane (HWC) and four-arm Kniffin (4AK) training systems on young ‘Marquette’ performance during a year with spring freeze damage (2017) and the subsequent season without frost events (2018). In 2017, there were two consecutive spring frost events at the experimental site approximately 2 weeks after the vines reached 50% budburst, which damaged more than 70% of the shoots. The percentage of freeze-damaged shoots and the severity of freeze damage to green tissues did not differ between training systems, but 4AK vines had higher yield at harvest (5.16 kg/vine or 3.12 tons/acre) than HWC vines (3.45 kg/vine or 2.10 tons/acre) because of the greater number of buds retained at winter pruning. There was no freeze damage close to budburst in 2018, and the yield of 4AK vines was still higher (11.74 kg/vine or 7.08 tons/acre) than that of HWC vines (8.20 kg/vine or 4.98 tons/acre). In 2018, the Ravaz index (yield-to-pruning weight) values were lower for HWC vines (3.41) than for 4AK vines (5.39), but the training system did not consistently affect fruit composition in either vintage. Within the 4AK system, shoots that emerged from the lower cane had more freeze damage than those of the upper cane and produced lower crop yield and fruit with lower soluble sugars in both vintages. Our results suggest that ‘Marquette’ vines can be grown on a training system with high cropping potential, such as a divided canopy system or a single canopy, with a higher number of buds and shoots than that of our study. Among divided canopy systems, 4AK might not be the best option for vigorous ‘Marquette’ vines because, in addition to greater susceptibility to freeze damage, the lower cane of 4AK was highly shaded by the upper highly vegetative canopy, which might have caused its lower productivity and soluble sugars at harvest compared with those of the upper cane.
Fresh eucalyptus stems can be preserved via systemic absorption of glycerin, but the optimal rate of glycerin and its effect on foliage color and stem pliability during holding have not been well-described. We harvested stems of Eucalyptus pulverulenta ‘Baby Blue’ and treated them in solutions of 0% (control), 25%, 50%, and 75% glycerin:reverse-osmosis water for 2 weeks. Leaf greenness was measured nine times during this period; the change in stem weights and solution uptake were measured as well. Stem pliability was evaluated after 2 weeks in solution as well as 1 week after holding the stems dry. The 25% and 50% glycerin treatments increased stem weight, whereas the control and 75% treatments decreased stem weight. The glycerin treatments absorbed less than 50 mL solution per three stems during 2 weeks, whereas those in the control absorbed >270 mL water. The color of foliage was similar during the first 5 days in treatment solutions, but stems in 25% and 50% glycerin treatments were less green than those in the control and 75% treatments by day 6, and this trend continued. No difference occurred in stem pliability among treatments after 2 weeks in glycerin solutions; however, after 1 week of holding, the top 9 cm of stems in glycerin treatments were more pliable than those in the control. Based on these results, we recommend a rate of 25% glycerin to preserve eucalyptus foliage for use in botanical artistry.
Data were collected from four plant materials courses over the span of 20 years. Two classes were at the undergraduate level, Trees and Shrubs for Sustainable Built Environments (HORT 306) and Plants for Sustainable Landscapes (HORT 308), and two classes were at the graduate level, Plants for Landscape Design (HORT 608) and Plants for Landscape Design II (HORT 609). Data from these courses were analyzed to determine trends in student performance and benchmarks that might be associated with student success. Data included student enrollment, midterm course grades, final course grades, number of unexcused absences, student-reported study times for various activities, student major, student experience (class rank), whether the courses were required, and perceived difficulty levels of the courses. Trends in grade distributions were fairly stable until the last 3 to 4 years before COVID-19, when mean final grades and the frequencies of A or B grades increased. Midterm grades were strongly positively correlated with final course grades across majors in all four courses before COVID-19 (R 2 = 0.90, 0.74, 0.72, and 0.54 for HORT 306, HORT 308, HORT 608, and HORT 609, respectively; P ≤ 0.001) and continued to be positively correlated after COVID-19. The number of unexcused absences was negatively significantly correlated with final course grades across majors (R 2 = −0.69, −0.63, −0.21, and −0.45 for HORT 306, HORT 308, HORT 608, and HORT 609, respectively) before COVID-19 (P ≤ 0.001) and continued to be similarly correlated after COVID-19. Fewer reductions from midterm to final grades were observed for fall courses than for spring courses, particularly for seniors. Self-reported time spent studying all aspects of the courses was either not significantly correlated (P ≤ 0.05) or surprisingly slightly negatively correlated with the final course grades for all four courses. Perceptions of courses as moderately difficult (range, 7.0–8.0 out of 10.0) were remarkably stable overall but varied considerably by major (range, 5.0–8.3) and experience (range, 7.5 for seniors to 8.1 for freshman). More than 96% of enrollment in the graduate courses both before and after COVID-19 comprised Horticulture and Landscape Architecture majors, whereas undergraduate enrollment included a wide diversity of majors; however, the majority of those students were horticulture or landscape architecture majors. Biological science students or students who were architectural design majors were the top-performing students in both undergraduate courses, whereas undeclared majors, social science majors, and those in probationary major categories were among the lower-performing students in both undergraduate courses.
As the demand for locally grown specialty cut flowers increases, cultivars of Pycnosorus globosus and Caryotperis incana are becoming more available for growers to produce as cuts. However, protocols for year-round greenhouse production are limited. Therefore, our objective was to determine if the photoperiod influences flower induction and development, time to harvest, yield, and morphology of billy buttons (Pycnosorus globosus) ‘Paintball Globe’ and ‘Paintball Poppy’ and bluebeard (Caryopteris incana) ‘Pagoda Lagoon’ and ‘Pagoda Dark Pink’ to facilitate commercial greenhouse production. Shoot-tip cuttings were rooted and transplanted into bulb crates and placed in a greenhouse with a mean daily air temperature of 20 °C and 9-, 10-, 11-, 12-, 13-, 14-, 15-, or 16-hour photoperiods or a 9-hour short day (SD) with a 4-hour night interruption (NI) from 2200 to 0200 HR for 11 weeks. Billy buttons initiated inflorescences and developed flowers under all daylengths; however, the greatest stem lengths were recorded under long days (LDs). Bluebeard inflorescences initiated under all daylengths were tested. Time to visible inflorescence and flower was hastened under daylengths ≤14 hours, whereas inflorescences under the 16-h photoperiod or 4-h NI never fully developed. For ‘Pagoda Lagoon’ and ‘Pagoda Dark Pink’, the critical daylengths for flower development were 14 hours and 15 hours, respectively. On average, only bluebeard ‘Pagoda Lagoon’ harvested under photoperiods ≥10 hours developed marketable stem lengths (>40 cm). To hasten time to visible inflorescence and harvest and ensure marketable stem lengths, billy buttons should be grown under daylengths ≥13 hours. Based on these results, we recommend growing bluebeard under a 16-hour photoperiod or NI for 4 to 6 weeks to promote vegetative growth, followed by an 11- to 14-hour photoperiod for flower induction and development. We classify billy buttons as a day-neutral plant for flower induction and a facultative LD plant for flower development. Similarly, bluebeard can be classified as a facultative SD plant for flower induction and an obligate SD plant for flower development.