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Multiple-row container-grown trees require specially designed sprayers to achieve efficient spray delivery. A five-port air-assisted sprayer with both automatic and manual control modes was developed to discharge adequate spray deposition inside multiple-row trees. The sprayer resulted from integration of a high-speed laser-scanning sensor with a sophisticated nozzle flow control system, an embedded computer with a touch screen, a Doppler speed sensor, a specially-designed algorithm and an air-assisted sprayer base. It was able to detect target tree presence and measure target tree size, shape and leaf density. The sprayer then controlled the spray output of each nozzle to match tree structures. The sprayer was tested for its sprayer deposition quality inside canopies in a four-row sterling silver linden (Tilia tomentosa 'Sterling Silver' Moench) field and another six-row northern red oak (Quercus rubra L.) field. Tests were conducted with the sprayer in variable-rate application (VRA) and constant-rate application (CRA) modes. The average spray deposit on foliage of trees was 1.37±0.47 μL cm−2 from VRA and 1.29±0.42 μL cm−2 from CRA in linden, and was 2.15±0.57 μL cm−2 from VRA and 2.72±0.94 μL cm−2 from CRA in red oak, respectively. In comparison, spray coverage on foliage of trees was 19.8±3.0% from VRA and 20.9±4.3% from CRA in the linden trial, and was 27.9±3.7% from VRA and 30.5±5.4% from CRA, respectively, in the red oak trial. The newly developed air-assisted sprayer in both VRA and CRA modes would be able to discharge adequate spray deposition inside multiple-row tree plants while conserving pesticide. Index words: environmental protection, pest control, pesticide, precision sprayer, spray coverage. Species used in this study: sterling silver linden (Tilia tomentosa 'Sterling Silver' Moench), northern red oak (Quercus rubra L.).

Better management of nutrient applications during a growing season is needed to economically produce marketable container-grown ornamental shade trees. Fertilizer practices were used to test the growth of Acer rubrum ‘Red Sunset’ trees in two commercial nursery fields (each containing four plots) that were irrigated with either city or pond water. In each field, the same 16 treatments were replicated. Two slow-release granular fertilizers (18-5-12 and 12-0-42) were applied separately or together by incorporation, topdress or both to a potting mix for trees grown in 26 liter (7 gal) containers and placed above or below ground. Trees irrigated with pond water also received supplemental liquid nutrients throughout the growing season along with nitric acid to lower the pH of the potting substrate. Tree growth was assessed by stem diameter (caliper), height, canopy size, leaf color and root measurements. Significant higher caliper increases occurred in trees treated with 18-5-12 fertilizer and irrigated with either pond or city water than trees treated with the 12-0-42 fertilizer. Significantly higher percent increases in caliper also occurred for trees irrigated with pond water and top-dressed with 18-5-12 fertilizer than trees with incorporated 18-5-12 fertilizer. With the same slow-release fertilizer applications, trees irrigated with pond water and supplemental nutrients had greater percent increases of caliper, larger canopy areas and better root systems than trees irrigated with city water. The differences in tree height increase were not as great as the caliper increases. However, tree growth irrigated with pond water required additional inputs with extra nutrients and labor costs throughout the growing season.

In nursery production, knowledge of water quality and quantity is needed to improve irrigation and fertilizer application efficiency as it relates to potential for soil and groundwater contamination. Water and fertilizer use and loss as well as tree growth were investigated for Red Sunset maple (Acer rubrum 'Franksred') trees in a pot-in-pot system with two different potting media and one coal ash based medium. The coal ash based medium (Mix #1) was mainly composed of biosolids, flue gas desulfurization gypsum, and coal combustion bottom ash. The two potting media mainly composed of aged pine bark and steamed composted nursery trimmings as well as left-over potting medium from commercial nurseries, but one with low initial amendments (Mix #2) and the other one with high initial amendments (Mix #3). Trickle irrigation was applied to each tree with an automatic control system. Watering trees started when the medium moisture was below 30%, and stopped when the moisture was 42%. During two-year tests, the amount of water including irrigation and rainfall applied to each tree with Mix #1, #2 and #3 was 741, 910 and 950 L, respectively. The amount of water loss through drainage for each tree with Mix #1, #2 and #3 was 107, 147 and 112 L, respectively. Among the tree media, Medium #3 produced the highest tree growth rate, followed by the Mix #2. The coal ash based medium had great potentials to be used for nursery production.

Information on better utilizing airblast sprayers to achieve high pesticide spray application efficiency in nursery tree production is needed. Foliar spray deposition and coverage at different heights inside crabapple tree canopies were investigated for a conventional airblast sprayer operating at four different application rates ranging from 230 to 900 liters/ha [24 to 94 gallons per acre (GPA)]. Deposition on the ground at various distances from the sprayer was also measured at the 700 liters/ha (73 GPA) application rate. Foliar deposition and coverage on targets below 2.6 m (8.5 ft) inside tree canopies increased as the application rate increased, but the increase in the coverage was much lower than the deposition. For trees taller than 2.6 m (8.5 ft), the sprayer could not deliver uniform spray deposition and coverage across the tree height. The portion of trees below 2.1 m (6.9 ft) was well covered by the spray deposits with 230 liters/ha (24 GPA) application rate while higher application rates resulted in over spray application. Less than 30% of total spray volume was deposited on target trees while over 34% of the total spray volume was lost on the ground. The tree-row volume method should include foliage density and tree-row gaps to avoid excessive estimation of spray application rates for nursery tree crops.

An experimental cross-flow (CF) fan sprayer and a conventional, axial-fan (AF), orchard sprayer were used to treat multiple rows consisting of four year old, multi-stem, red maple trees, Acer rubrum L. and Turkish filbert trees, Corylus colurna L. The effects of sprayer type, fan orientation, application volume, and ground speed on canopy and ground spray deposits and canopy spray coverage across multiple target rows were evaluated. Variations in deposits and coverage across the canopies were generally smaller for the CF sprayer than the AF sprayer. The AF sprayer produced the highest overall deposits in the first row nearest the sprayer. Reducing fan speed kept more material in the tree row adjacent to the sprayer while decreasing spray volume did not affect the spray deposits in that row. Tower sprayer fan orientation did not affect canopy deposits but could be used to minimize spray drift. These results indicate that the most uniform spray distribution in a tree canopy is obtained by treating the canopy from each side. These findings also suggest growers should experiment with different spray volume and speed settings that can provide efficacious applications more efficiently.

Two types of air-assist sprayers were used to treat, from one side only, a single row of hedge-pruned, red maple (Acer rubrum L. ‘Red Sunset’) trees in a commercial Ohio nursery. A traditional orchard type sprayer and a prototype air curtain sprayer using crossflow fans and hydraulic nozzles were evaluated for differences in canopy deposits, spray coverage, and downwind ground deposits. The air curtain sprayer produced more uniform deposits vertically but not higher mean deposits than the traditional orchard type sprayer. The air curtain sprayer also produced somewhat higher ground deposits downwind of the treatment area. There were no differences in spray coverage between sprayers despite differences in the droplet spectrum produced by each sprayer. Evidence from the coverage and ground target samples indicate that slower fans on the air curtain sprayer might be needed to reduce air speed to retain more spray within the tree canopy. As operated, neither of the sprayers can be expected to produce uniform spray deposits around the nursery stock if treatments are made from one side of the row only. Canopy and ground target deposits indicate that alternate row spraying will not necessarily produce uniform deposits across two tree rows as planted at the test site.

In pot-in-pot nursery production, information on the amount of drainage water loss from the pots due to irrigation and rainfall is beneficial to improving irrigation water use efficiency and optimizing nutrition management. An experimental field site was established to determine drainage water loss from pot-in-pot container nurseries with micro-irrigation. The site consisted of 50 container-grown trees, 10 tipping-bucket rain gauge units, and a portable weather station. Rain gauge units were calibrated four different ways to determine repeatability and reliability for real-time measurement of the drainage water. Volume of water was calculated from the product of number of tips and volume per tip. Accuracy of measurements was verified by the amount of drainage water collected weekly in collection buckets located under rain gauge units for various irrigation applications and rainfall events. The maximum difference in the weekly amount of drainage water collected with the collection buckets and measured with the rain gauge units was 1.215 L (or 5.3% error) when the daily irrigation application to five trees was 15.5 L. The system reported real-time measurement of drainage water due to irrigation and rainfall, and provided a research tool to evaluate strategies for nurseries to better manage irrigation schedules.

Spray penetration and off-target loss from a conventional, air-assist, axial-fan sprayer and a high-clearance, boom-type sprayer were investigated in Honey Locust (Gleditsia triacanthos) and Canadian Hemlock (Tsuga canadensis) trees located in two different production nurseries. Aqueous tracer solutions of either Ca(NO3)2 foliar fertilizer or Cu(OH)2 fungicide were used in the experiments. Spray deposition distributions within canopies and off-target loss to drift and the ground were assessed via residues collected on foliage, electron microscope stubs, artificial plates, vertical and ground-level profile plastic tapes, and high-volume air samplers. Electron beam analysis (EBA) was used to assay residues on stubs, leaves, and needles placed and collected at several locations and heights in the canopy. Plastic tape samples were evaluated with a laboratory spray deposit analyzer using a conductivity detector. Both assessment methods used in the present study were useful for detection and quantification of Ca or Cu spray penetration within nursery canopies. The average spray deposit on upper surfaces of leaves was three times that deposited on lower surfaces within the Honey Locust trees. Spray deposit at the top of Canadian Hemlock tree canopies was 14 times higher than that at the middle and bottom of canopies. Spray deposit on ground targets greatly decreased as the distance from the spray path increased in both nurseries; however, airborne spray deposits did not decrease as much with increasing downwind distance as ground deposits.

Information is lacking on spray techniques to reduce off-target loss on the ground and via spray drift from the treated area in nursery applications. Airborne deposits at three elevations on sampling towers and on the ground at several distances from the sprayer were investigated with the three spray treatments in an open field without crops. Tests were conducted with an air blast sprayer equipped with conventional hollow cone nozzles (HC), low drift nozzles (AI), and conventional hollow cone nozzles with a drift retardant (HCDR) in an open field without crops. To compare field test results, wind tunnel experiments were conducted to assess spray deposits on the floor beyond 0.4 m downwind distance from the nozzles and airborne deposits at 2.1 m downwind from the spray discharge point with the three spray techniques. Droplet size distributions across spray patterns were measured with a laser particle/droplet image analysis system. There was no significant difference in airborne deposits for the three elevations at both 15 and 30 m downwind from the sprayer between AI and HC methods except for 3.05 m elevation at the 15 m distance although the average airborne deposits with AI were lower than that with HC. The downwind spray deposits on the ground at 15 and 30 m from the sprayer with AI were higher than that with HC and HCDR. Compared with conventional hollow cone nozzles, drift reduction from air induction nozzles or the spray mixture with drift retardant was significant in wind tunnel tests but was not significant in field tests.