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Increased use of biopesticides has spurred demand for efficient and effective delivery systems. To this goal, laboratory tests were conducted to investigate six different classes of biopesticides discharged from five different types of flat-fan nozzles, each with three flow capacities. The biopesticide classes were horticultural oil insecticide (HOI), bacterial biofungicide (BBF), botanical extract bio-insecticide (BEBI), liquid fungal bio-insecticide (FBI-ES), wettable powder fungal bio-insecticide (FBI-WP), and mineral salt biofungicide (MSBF). Droplet size distribution, spray pattern width, spray deposition, and coverage on plant leaves and water-sensitive paper (WSP) were the spray parameters tested. These parameters varied greatly with biopesticide class, nozzle type, and nozzle flow capacity. The DV0.5 of the biopesticides ranged from 75 to 519 µm for 0.76 L min-1 nozzles, from 86 to 509 µm for 1.51 L min-1 nozzles, and from 99 to 622 µm for 2.25 L min-1 nozzles. The use of different biopesticides with the same nozzle significantly altered the spray pattern width. Compared to a water-only solution, the largest change of spray pattern width was 14.7% for the air-induction nozzle (AI11004) discharging FBI-ES. The amount of spray deposited on plant leaves for all tested biopesticides (except HOI) did not vary significantly with different nozzle types. However, the air-induction nozzles produced the most uneven spray deposition patterns. Therefore, to achieve optimal spray application efficiency and effectiveness for discharging specific classes of biopesticide, the choice of the proper nozzle type and flow capacity is critical. Keywords: Biopesticide, Crop protection, Deposition, Droplet size, Spray coverage.

Atmospheric CO2 enrichment is expected to often benefit plant growth, despite causing global warming and nitrogen (N) dilution in plants. Most plants primarily procure N as inorganic nitrate (NO3−) or ammonium (NH4+), using membrane-localized transport proteins in roots, which are key targets for improving N use. Though interactive effects of elevated CO2, chronic warming, and N form on N relations are expected, these have not been studied. In this study, tomato (Solanum lycopersicum) plants were grown at two levels of CO2 (400 or 700 ppm) and two temperature regimes (30 or 37 °C), with NO3− or NH4+ as the N source. Elevated CO2 plus chronic warming severely inhibited plant growth, regardless of N form, while individually they had smaller effects on growth. Although %N in roots was similar among all treatments, elevated CO2 plus warming decreased (1) N uptake rate by roots, (2) total protein concentration in roots, indicating an inhibition of N assimilation, and (3) shoot %N, indicating a potential inhibition of N translocation from roots to shoots. Under elevated CO2 plus warming, reduced NO3− uptake rate per g root was correlated with a decrease in the concentration of NO3−-uptake proteins per g root, reduced NH4+ uptake was correlated with decreased activity of NH4+-uptake proteins, and reduced N assimilation was correlated with decreased concentration of N-assimilatory proteins. These results indicate that elevated CO2 and chronic warming can act synergistically to decrease plant N uptake and assimilation; hence, future global warming may decrease both plant growth and food quality (%N).

Horst, L. E., Locke, J., Krause, C. R., McMahon, R. W., Madden, L. V., and Hoitink, H. A. J. 2005. Suppression of Botrytis blight of begonia by Trichoderma hamatum 382 in peat and compost-amended potting mixes. Plant Dis. 89:1195-1200. Inoculation of an industry standard light sphagnum peat potting mix with Trichoderma hamatum 382 (T382) significantly (P = 0.05) reduced the severity of Botrytis blight, caused by Botrytis cinerea, on begonia plants grown in a greenhouse. In data combined from three experiments, the degree of control provided by T382 did not differ significantly (P = 0.05) from that provided by weekly topical sprays with chlorothalonil. In addition, T382 significantly (P = 0.05) increased shoot dry weight and salability of flowering plants. Incorporation of composted cow manure (5%, vol/vol) into the light peat mix also significantly (P = 0.05) decreased blight severity while shoot dry weight and salability were increased. Blight severity on plants in this compost mix did not differ significantly (P = 0.05) from that on those in the light peat mix inoculated with T382. Finally, T382 and chlorothalonil did not significantly (P = 0.05) affect blight severity, shoot dry weight, or salability of plants grown in the compost mix. Spatial separation was maintained in begonias between the biocontrol agent T382 and the pathogen. It was concluded, therefore, that the decrease in disease severity provided by inoculation of the peat mix with T382 most likely was due to systemic resistance induced in begonia against Botrytis blight. The suppressive effect of the compost mix against Botrytis blight was unusual because composts typically do not provide such effects unless inoculated with a biocontrol agent capable of inducing systemic resistance in plants to disease.

The objective of this research was to determine the suitability of a steel slag product for supplying micronutrients to container-grown floriculture crops. Geranium (Pelargonium ×hortorum L.H. Bailey ‘Maverick Red’) and tomato (Solanum lycopersicon L. ‘Megabite’) were grown in 11.4-cm containers with a substrate composed of 85 peatmoss : 15 perlite (v/v). A group of containers referred to as the commercial control (C-control) were amended with 4.8 kg·m−3 dolomitic lime and fertilized with a commercial complete fertilizer providing macro and micronutrients (Jack’s 20N–4.4P–16.6K–0.15Mg–0.02B–0.01Cu–0.1Fe–0.05Mn–0.01Mo–0.05Zn) at a concentration of 100 mg·L−1 nitrogen (N). Another group of containers, referred to as the micronutrient control (M-control), were amended with a commercial granular micronutrient package at 0.9 kg·m−3 and dolomitic lime at 4.8 kg·m−3. The M-controls were fertilized with 7.1 mm N (100 mg·L−1 N) with ammonium nitrate and 2 mm potassium phosphate. A final group of containers were amended with 1.2, 2.4, or 4.8 kg·m−3 of steel slag and fertilized with 3.6 mm ammonium nitrate and 2 mm potassium phosphate. Both control groups resulted in vigorous and saleable plants by the conclusion of the experiment. In both crops, chlorophyll levels, root ratings, and shoot dry mass were lower in all steel slag–amended plants compared with either control groups. In geranium, foliar nutrient concentrations suggest Cu and Zn were limiting whereas B and Zn were limiting in tomato. Based on the results of this research, steel slag does not provide sufficient micronutrients, most notably B, Cu, and Zn, to be the sole source of micronutrient fertilization in container-grown crops.

Pertinent techniques for determination of plant cuticle permeability are needed to select proper doses of active ingredients and spray additives to improve pesticide application efficacy. A controlled environmental system with 100% relative humidity was developed for direct measurements of foliar uptake rates of sessile water droplets at various locations on waxy leaf surfaces during two diurnal periods between 10:30 and 13:00 (noon) and between 16:00 and 19:00 (evening) at ambient temperatures of 15 and 20°C. Sessile droplets of 340 and 540 µm in diameter were produced with a single-droplet generator. Stoma densities and osmotic pressures on leaves were also measured with a Scanning Electronic Microscope (SEM) and a vapor pressure osmometer, respectively. At 100% relative humidity inside the environmental chamber, droplets remained unchanged after they were deposited on a non-permeable glass but they penetrated leaf tissues after they were deposited on leaves. Foliar uptake time varied with droplet size, droplet deposition location on leaves, and diurnal period, but varied little with osmotic pressure and stoma density. An average uptake rate of 540 µm diameter droplets on a leaf surface at 20°C and 100% relative humidity was 0.000401 ±0.000063 µL/s which was 2.1 times the average absorption rate of 340-µm diameter droplets. The incorporation of the controlled environmental system with 100% relative humidity and the sessile droplet generator to measure foliar uptake rates of water droplets would provide a unique approach to elucidate the foliar uptake mechanism of spray droplets for efficient and effective control of target pests on specific plants.

The 5-day sodium carbonate-ammonium nitrate extraction assay (5-day method) has been recognized by the American Association of Plant Food Control Officials as a validated test method to identify fertilizers or beneficial substances that provide plant-available silicon (Si). The test method used the molybdenum blue colorimetric assay to quantify percentage Si; however, laboratories may use inductively coupled plasma optical emission spectroscopy (ICP-OES) for elemental analysis. To examine the use of either colorimetric or ICP-OES methods for Si determination, the 5-day method was performed on the following Si-containing compounds; wollastonite, sand, biochar, and a basic oven furnace (BOF) slag. Grow-out studies using Zinnia elegans were also performed using varying rates of the wollastonite, biochar, and BOF slag. Our results show using the 5-day method, wollastonite had the highest extracted amounts of silicic acid (H4SiO4) at 4% followed by biochar (2%), BOF slag (1%), and sand (0%). Extraction values calculated using either the molybdenum blue colorimetric assay or ICP-OES for detection of the H4SiO4 had a significant correlation, supporting the application of either detection method for this type of analysis. However, when extracted values were compared to amounts of Si taken up by the plants, the 5-day method overestimated both wollastonite and biochar. While this method is a valid indicator test for determining a soluble Si source, other plant species and methods should be perused to potentially provide more quantitative analyses for plant-available Si content of all materials.

Global warming will increase root heat stress, which is already common under certain conditions. Effects of heat stress on root nutrient uptake have rarely been examined in intact plants, but the limited results indicate that heat stress will decrease it; no studies have examined heat-stress effects on the concentration of nutrient-uptake proteins. We grew Solanum lycopersicum (tomato) at 25 °C/20 °C (day/night) and then transferred some plants for six days to 35 °C /30 °C (moderate heat) or 42 °C/37 °C (severe heat) (maximum root temperature = 32 °C or 39 °C, respectively); plants were then moved back to control conditions for seven days to monitor recovery. In a second experiment, plants were grown for 15 days at 28 °C/23 °C, 32 °C/27 °C, 36 °C/31 °C, and 40 °C/35 °C (day/night). Concentrations of nutrient-uptake and -assimilation proteins in roots were determined using protein-specific antibodies and ELISA (enzyme-linked immunosorbent assay). In general, (1) roots were affected by heat more than shoots, as indicated by decreased root:shoot mass ratio, shoot vs. root %N and C, and the level of nutrient metabolism proteins vs. less sensitive photosynthesis and stomatal conductance; and (2) negative effects on roots were large and slow-to-recover only with severe heat stress (40 °C–42 °C). Thus, short-term heat stress, if severe, can decrease total protein concentration and levels of nutrient-uptake and -assimilation proteins in roots. Hence, increases in heat stress with global warming may decrease crop production, as well as nutritional quality, partly via effects on root nutrient relations.

Use of preemergence herbicides for weed control is not always possible; some crops and many enclosed production sites are not labeled for herbicide applications. The objective of this research was to determine the utility of parboiled rice hull mulch for controlling two of the most common weeds in nursery crop production, flexuous bittercress (Cardamine flexuosa With.) and liverwort (Marchantia polymorpha L.). Two experiments were conducted to determine control of flexuous bittercress and liverwort with 0, 0.6, 1.3, or 2.5 cm (0, 0.25, 0.5, or 1.0 in) depths of rice hull mulch applied to the surface of 15 cm (6 in) diameter pots on a greenhouse bench. In both experiments, one group of containers were potted each with a single rose (Rosa ‘Radrazz’) and another group was not potted (only substrate and rice hull mulch). Flexuous bittercress seed and liverwort gemmae were applied to the surface of the substrate or mulch. Rose response and weed growth were monitored for 8 weeks in both experiments. Substrate pH, rose foliar color, and rose growth were not affected in either experiment. Flexuous bittercress and liverwort establishment and subsequent growth decreased with increasing rice hull depth. Containers with either a 1.3 or 2.5 cm (0.5 or 1.0 in) depth of rice hulls provided nearly 100% weed control. Rice hulls provided effective bittercress and liverwort control for 8 weeks with no adverse effects on roses.

Cryptococcus flavescens OH 182.9 (NRRL Y-30216) reduces Fusarium head blight (FHB) incited by Fusarium graminearum and deoxynivalenol (DON) contamination of grain. Yet little is known about the population dynamics of OH 182.9 on wheat heads and anthers. Biomass of OH 182.9 was produced in liquid culture and applied to greenhouse and field grown wheat prior to and during early anthesis. In greenhouse studies, populations of OH 182.9 were similar on anthers for heads inoculated before (Feekes 10.5) or early in flowering (Feekes 10.5.1) but were 1–3 log units lower in Feekes 10.5 inoculated wheat after 8–10 days. In greenhouse and field studies, OH 182.9 colonized anthers inside florets prior to anthesis. In the field, populations of OH 182.9 on anthers increased or, less frequently, remained stable through 12 days, regardless of application time and peaked at 1–2 log units higher than in the greenhouse. Strain OH 182.9 reduced FHB severity ( P F. graminearum that can increase DON.

Conventional spray applications in orchards and ornamental nurseries are not target-oriented, resulting in significant waste of pesticides and contamination of the environment. To address this problem, a variable-rate air-assisted sprayer implementing laser scanning technology was developed to apply appropriate amounts of pesticides based on tree canopy characteristics including tree height, width, volume, foliage density, and occurrence. The new sprayer performance was evaluated in an apple orchard by quantifying spray deposition inside canopies at three different growth stages (leafing, half-foliage, and full-foliage) with three sprayer treatments: the new variable-rate sprayer (S 1 ), the same sprayer without the variable-rate function (S 2 ), and a conventional air-blast sprayer (S 3 ). Their spray coverage and deposits inside canopies were measured and compared with water-sensitive papers and nylon screens. The three sprayer treatments provided fairly consistent spray coverage and deposits in the spray direction (or canopy depth direction) at the leafing stage. The variations in spray coverage and deposits in the spray direction increased considerably for S 2 and S 3 at the half-foliage and full-foliage stages. S 1 produced better uniformity in spray coverage and deposits across the tree height direction than S 2 and S 3 at all growth stages. Compared to constant-rate sprayers, the new variable-rate sprayer only consumed 27% to 53% of the spray mixture while still achieving adequate spray coverage inside the canopies. In addition, the spray deposition from the new sprayer was very consistent regardless of the canopy growth stage. Therefore, the new sprayer increased spray efficiency and improved spray accuracy by greatly lowering the possibility of overspray, resulting in reduced spray costs and potential reduction of environmental pollution.

Spray drift and off-target losses are inherent problems of conventional air-assisted sprayers; consequently, their low efficiencies cause environmental pollution and public anxiety. A new drift reduction technology incorporating laser scanning capabilities with a variable-rate air-assisted sprayer was developed to address these problems. This new sprayer, the same sprayer with the variable-rate function disabled, and a conventional constant-rate air-blast sprayer were tested for comparison of spray drift and off-target losses in an apple orchard. Tests were conducted at three different growth stages: trees just beginning to leaf (leafing), half foliage, and full foliage. Spray deposits from spray drift and off-target losses were collected within tree rows at ground level, above and behind the sprayed trees, in the spaces between trees, and from 3.2 m tall poles at 5, 15, and 35 m from the tree rows. Compared to the constant-rate sprayers, the laser-guided variable-rate sprayer reduced average spray losses on the ground by 68% to 90% and around tree canopies by 70% to 92%, reduced airborne spray drift by 70% to 100%, and most importantly, reduced the spray volume by 47% to 73%, while spray deposition quality inside the canopy for these sprayers was comparable. These results demonstrate that the variable-rate sprayer incorporating the innovative laser scanning technology reduced spray drift and off-target losses of pesticides, was environmentally sustainable, and was economically beneficial to growers.

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.

Larvae of scarab beetles (Coleoptera: Scarabaeidae) are important contaminant and root-herbivore pests of ornamental crops. To develop alternatives to conventional insecticides, 24 plant-based essential oils were tested for their acute toxicity against third instars of the Japanese beetle Popillia japonica Newman, European chafer Rhizotrogus majalis (Razoumowsky), oriental beetle Anomala orientalis (Waterhouse), and northern masked chafer Cyclocephala borealis Arrow. Diluted solutions were topically applied to the thorax, which allowed for calculating LD50 and LD90 values associated with 1 d after treatment. A wide range in acute toxicity was observed across all four scarab species. Of the 24 oils tested, allyl isothiocyanate, cinnamon leaf, clove, garlic, and red thyme oils exhibited toxicity to all four species. Allyl isothiocyanate was the most toxic oil tested against the European chafer, and among the most toxic against the Japanese beetle, oriental beetle, and northern masked chafer. Red thyme was also comparatively toxic to the Japanese beetle, oriental beetle, European chafer, and northern masked chafer. Interspecific variability in susceptibility to the essential oils was documented, with 12, 11, 8, and 6 of the 24 essential oils being toxic to the oriental beetle, Japanese beetle, European chafer, and northern masked chafer, respectively. Analysis of the active oils by gas chromatography-mass spectrometry revealed a diverse array of compounds, mostly consisting of mono- and sesquiterpenes. These results will aid in identifying active oils and their constituents for optimizing the development of plant essential oil mixtures for use against scarab larvae.

Atmospheric CO

Xylosandrus germanus (Blandford) and Xylosandrus crassiusculus (Motschulsky) (Coleoptera: Curculionidae: Scolytinae) are two of the most damaging nonnative ambrosia beetle pests in ornamental plant nurseries. Adult females tunnel into the stems and branches of host plants to create galleries with brood chambers. Hosts are infected with symbiotic Ambrosiella spp. fungi that serve as food for the larvae and adults. Plants can also become infected with secondary opportunistic pathogens, including Fusarium spp. Both X. germanus and X. crassiusculus have broad host ranges, and infestations can result in "toothpicks" of extruded chewed wood and sap flow associated with gallery entrances, canopy dieback, stem and trunk cankers, and plant death. Beetles efficiently locate and preferentially attack living, weakened plants, especially those physiologically stressed by flooding, inadequate drainage, frost injury, or winter injury and low temperature. Maintaining plant health is the foundation of a management plan. Vulnerable hosts can be partially protected with preventive pyrethroid applications in the spring before peak flight and attack, which are monitored using ethanol-based trapping tactics. Floriculture and Nursery Research Initiative (USDA-FNRI); Horticultural Research Institute (HRI); USDA-ARS National Program 304-Crop Protection and Quarantine [3607-22000-012-00D]; American Nursery and Landscape Association; USDA-Animal and Plant Health Inspection Service; Virginia Nursery and Landscape Association We thank Jenny Barnett (USDA-ARS), Betsy Anderson (USDA-ARS), Helene Doughty (VT-HRAREC), Elizabeth Barekzi (VT-HRAREC), and Elizabeth Gliem (VT-HRAREC) for technical assistance. We also thank two anonymous reviewers for providing useful comments on an earlier version of the manuscript. This project was funded by the Floriculture and Nursery Research Initiative (USDA-FNRI), Horticultural Research Institute (HRI), USDA-ARS National Program 304-Crop Protection and Quarantine (Project 3607-22000-012-00D), American Nursery and Landscape Association, USDA-Animal and Plant Health Inspection Service, and the Virginia Nursery and Landscape Association. Mention of proprietary products or companies does not imply any endorsement or preferential treatment by the USDA-Agricultural Research Service, The Ohio State University, Virginia Tech, Tennessee State University, North Carolina State University, Clemson University, or the University of Maryland.

Pine bark (PB) is currently imported from southern U.S. states to nursery growers in the upper midwest and northeast United States. Alternatives to PB that are regionally abundant and sustainable are needed for nursery substrates. The objective of this research was to determine the influence of pine wood (PW), which consisted of chipped and hammermilled pine trees (excluding branches and needles) on substrate physical properties when substituted partially or wholly for PB in substrates typical of Ohio. Four cooperating nursery sites, each with unique substrates comprised primarily of PB, were recruited to use PW as a substitute for 0%, 50%, or 100% of the PB fraction in their substrate. All other physical and chemical amendments used traditionally at each site were incorporated. Physical properties including particle size distribution (PSD), air space (AS), container capacity (CC), total porosity (TP), unavailable water (UAW), bulk density (Db), and moisture characteristic curves (MCC) were determined for each substrate at each cooperator site. Pine wood was generally more coarse than all but one of the PB materials used by the four cooperating sites. Amendment with PW did not have any consistent or predictable effect on AS, CC, TP, or Db of the resultant substrates. Pine wood had little identifiable effect on plotted MCC, although it reduced calculated easily available water in one substrate. It was concluded that substitution of PB with PW can result in changes to substrate physical properties that might lead to irrigation management changes, but none of these changes were considered negative or drastic enough to cause physical properties to be outside of acceptable ranges.

Alternatives to pine bark for nursery crop substrates have been proposed, including the use of straw materials such as switchgrass. While straw substrates can be developed with suitable physical properties measured immediately after mixing, little is known about how the physical properties of straw-based substrates change over time. The objective of this research was to measure the change in air space (AS), container capacity (CC), total porosity (TP), and bulk density (Db) over time of a switchgrass-based substrate compared to a pine bark substrate. Switchgrass and pine bark substrates were packed into 15 cm (6 in) tall aluminum cores and placed in a production greenhouse with or without a single hibiscus plant. Physical properties of the substrates were measured at the beginning of the experiment and 9 to 10 weeks later when the plants were nearly too large for their containers. Air space decreased over time, primarily as a function of root growth and shrinkage. Container capacity increased slightly across all treatments over time. Bulk density changed very little over time. The switchgrass substrate was more prone to shrinkage than the pine bark substrate, although vigorous hibiscus root growth reduced shrinkage in switchgrass substrates.

One-year-old, container-grown seedlings of red maple (Acer rubrum L.) and yellow-poplar (Liriodendron tulipirera L.) were treated with Hydretain ES (HydES) or Ecosential (ECOS) applied as a soil drench. A progressive drought cycle was imposed after treatment and, as each seedling wilted, the leaves and roots were harvested. For both species, foliar growth was unaffected by HydES or EcoS, but root growth (surface area of roots < 1mm diameter; fine root:coarse root ratio; root area index) was less for seedlings grown in humectant-treated media. These data, along with soil moisture measurements taken during the dry down period (which showed a consistently higher water content in the humectant-treated substrate), suggest that drought-induced fine root growth in humectant-treated media was slower since there was less need for these roots to extend and proliferate to access additional soil moisture sources. In a study conducted the following year, HydES and ECOS were applied as a soil drench to one-year-old, container-grown seedlings of red maple and river birch (Betula nigra L.) prior to withholding irrigation. In these studies, each time an untreated seedling wilted, measurements of chlorophyll fluorescence, leaf gas exchange and xylem water potential were taken on the wilted seedling along with similar measurements taken on a HydES-and an EcoS-treated seedling. These data indicate that the level of physiological activity (chlorophyll fluorescence and net C02 exchange) was greater for seedlings grown in HydES-treated media than for seedlings of the same species grown in EcoS-treated media, a condition attributed, at least in part, to a lower level of water stress (lower xylem water potential) in the HydES-treated seedlings.

Quinoclamine is used in Europe, and was under evaluation in the Unites States for the control of liverwort in nursery crops. Liverwort is a nonvascular, chlorophyll-containing plant that can be problematic in greenhouse and nursery crops. POST-applied quinoclamine controls liverwort. However, liverwort structures vary in their sensitivity to POST-applied quinoclamine. Specifically, archegonial receptacles (female) are much more tolerant of quinoclamine than either antheridial receptacles (male) or thalli (leaflike structures). A series of studies were conducted to, first, document the degree of differential sensitivity between tissues to quinoclamine, and second, to determine the basis of this differential sensitivity. The dose that results in 50% of the population being controlled (I50) of antheridial receptacles and juvenile thalli were estimated to be 1.60 and 1.27 kg·ha−1, respectively. TheI50of archegonial receptacles could not be estimated, but exceeded 10.45 kg·ha−1. Chlorophyll content varied between liverwort tissues, but the content did not correlate to quinoclamine sensitivity. Absorption of14C after application of radiolabeled quinoclamine was less in archegonial receptacles than in either antheridial receptacles or thalli. Scanning electron microscopy of the surface of the liverwort tissues revealed that archegonial receptacles had smaller pores (equivalent to stomata in higher plants) than either antheridial receptacles or thalli. The tolerance of archegonial receptacles to quinoclamine can be partially, but not exclusively, attributed to reduced absorption. This reduced absorption may be attributed to the limited pore size and less total pore area of the archegonial receptacles.

Current label recommendations of pesticides for arthropod pests and plant diseases in the nursery and green industry are vague and frequently result in excessive pesticide use. The objective of this research was to demonstrate that modifications of spray application techniques with current spray equipment in ornamental nursery production could reduce pesticide use. The efficacy of half rates and full rates of both active ingredients and carrier was investigated in commercial nurseries with air-assisted sprayers in two tests and a state inspector survey for the control of arthropod pests and plant diseases. Sprayers were optimized with properly sized nozzles and properly calibrated operating parameters. In Test 1, treatments were conducted in approximately 0.5 ha (1.2 A) plot each in three commercial nurseries for control of arthropod pests and diseases, and in Test 2, the same treatment for aphid control was evaluated in a birch tree plot. The survey was a compilation of the pests and diseases that were diagnosed by state inspectors in over 2,800 plant varieties and species from two commercial nursery fields [total about 280 ha (692 A)] after the spray treatments in six growing seasons. Crop damage by 49 insects and 40 diseases were surveyed for different application rates. The studies revealed that insect and disease control using 50% of the label rates was as effective as full rates when quality spray coverage on targets was achieved, resulting in real cost benefits to producers, consumers and the environment.

The genome of the floriculture pathogen Dahlia mosaic caulimovirus (DMV) encodes six open reading frames. Generally, caulimovirus gene VI products (P6s) are thought to be multifunctional proteins required for viral infection and it is likely that self-association is required for some of these functions. In this study, yeast two-hybrid and maltose binding protein (MBP) pull-down assays indicated that full-length DMV P6 specifically self-associates. Further analyses indicated that only the DMV P6 N-terminal region, consisting of 115 amino acids, interacts with full-length P6 and with itself. This distinguishes the DMV P6 from its Cauliflower mosaic virus counterpart, which contains four regions involved in self-association. Thus, our results suggest that each caulimovirus P6 may possess a unique pattern of protein–protein interactions. Bioinformatic tools identified a putative nuclear exclusion signal located between amino acid residues 10–20, suggesting another possible function for the P6 N-terminal region.

Spray deposition and coverage at different application rates for nursery liners of different sizes were investigated to determine the optimal spray application rates. Experiments were conducted on 2- and 3-year-old ‘Autumn Spire’ red maple (Acer rubrum) liners. A traditional hydraulic sprayer with vertical booms between tree rows was used to apply the spray applications. Application rates were 10, 20, 30, and 40 gal/acre for the 2-year-old liners and were 20, 40, 60, and 80 gal/acre for the 3-year-old liners. Nylon screens were used to collect spray deposition of a fluorescent tracer dissolved in water, and water-sensitive papers were used to quantify spray coverage inside canopies. Spray deposition, coverage, and droplet density inside both 2- and 3-year-old liner canopies increased as the application rate increased. The minimum rates to spray 6.6-ft-tall, 2-year-old ‘Autumn Spire’ red maple liners and 8.7-ft-tall, 3-year-old liners were 20 and 40 gal/acre, respectively. An exponential equation was derived from these results to estimate the spray application rate required for different tree liner heights and to minimize excessive chemical use in rapidly growing tree liners.

Background Adjuvants can improve pesticide application efficiency and effectiveness. However, quantifications of the adjuvant-amended pesticide droplet actions on foliage, which could affect application efficiencies, are largely unknown. Results Droplet evaporation rates and spread on waxy or hairy leaves varied greatly with the adjuvant types tested. On waxy leaves, the wetted areas of droplets containing crop oil concentrate (COC) were significantly smaller than those containing modified seed oil (MSO), non-ionic surfactant (NIS) or oil surfactant blend (OSB), whereas the evaporation rates of COC-amended droplets were significantly higher. On hairy leaves, COC-amended droplets remained on top of the hairs without wetting the epidermis. When the relative concentration was 1.50, the wetted area of droplets with NIS was 9.2 times lower than that with MSO and 6.1 times lower than that with OSB. The wetted area increased as the adjuvant concentration increased. MSO- or OSB-amended droplets spread extensively on the hairy leaf surface until they were completely dried. Conclusion These results demonstrated that the proper concentration of MSO, NIS or OSB in spray mixtures improved the homogeneity of spray coverage on both waxy and hairy leaf surfaces and could reduce pesticide use. This article is a US Government work and is in the public domain in the USA.

Automatic variable-rate sprayers require accurate measurement of canopy size. An estimate of canopy size is made by measuring the distance to the canopy at several elevations above the ground; an ultrasonic sensor was used to determine canopy distance in this study. It is sometimes necessary to conduct spray operations during harsh operating conditions. In this study ultrasonic sensors were subjected to simulated environmental and operating conditions to determine their durability and accuracy. Conditions tested included exposure to extended cold, outdoor temperatures, cross winds, temperature change, dust clouds, travel speeds and spray cloud effects. The root mean square (RMS) error in a series of measurements of the distance to a simulated plant canopy was used to test for significant difference among treatments. After exposure to outdoor cold conditions for 4 months, the RMS error in distance measured by the ultrasonic sensor increased from 3.31 to 3.55cm, which was not statistically significant. Neither the presence of dust cloud nor the changes in cross-wind speeds over a range from 1.5-7.5m/s had significant effects on the mean RMS errors. Varying sensor travel speed from 0.8 to 3.0m/s had no significant influence on sensor detection distances. Increasing ambient temperature from 16.7 to 41.6^oC reduced the detection distance by 5.0cm. The physical location of the spray nozzle with respect to the ultrasonic sensor had a significant effect on mean RMS errors. The mean RMS errors of sensor distance measurements ranged from 2.3 to 83.0cm. The RMS errors could be reduced to acceptable values by proper controlling the sensor/spray nozzles spacing on a sprayer. In addition, multiple-synchronized sensors were tested for their measurement stability and accuracy (due to possible cross-talk errors) when mounted on a prototype sprayer. It was found that isolating the pathway of the ultrasonic wave of each sensor reduced detecting interference between sensors during multiple sensor operation. Test methods presented herein may be useful in the design of standardized testing protocols for field use distance sensors.

Switchgrass (Panicum virgatum) biomass is being evaluated as a potential alternative to pine bark as the primary potting component in containerized nursery crops. Substrates composed entirely of switchgrass have higher pH than what is considered desirable in container substrates. The objective of this research was to evaluate the influence of elemental S, sphagnum moss, and municipal solid waste compost (MSC) as amendments for reducing substrate pH and buffering it against large changes over time. Three experiments were conducted; the first two experiments were conducted using annual vinca (Catharanthus roseus ‘Pacifica Blush’) to quickly assess how pH was affected by the three amendments, and the final experiment was conducted with blueberry (Vaccinium corymbosum ‘Duke’) to assess the long-term effects of substrate amendments. Summarizing across the three experiments, elemental S was effective in reducing substrate pH; however, rates 1 lb/yard3 or greater reduced pH below the recommended level of 5.5 and lower S rates did not maintain lowered pH over time. Sphagnum moss and MSC together at 20% and 10% (v/v), respectively, were effective at reducing substrate pH and buffering against change. Sphagnum moss and MSC provided the additional benefit of improving physical properties of the switchgrass substrates.

The use of an appropriate adjuvant for pesticide applications is a critical process to improve spray deposit characteristics on waxy leaves and to reduce off-target losses. After deposition and evaporation, residue patterns of 500 ° m sessile droplets that incorporated four classes of adjuvants on five different waxy plants were investigated. Droplets were generated with a single-droplet generator and deposited on target leaves placed in an environmentally controlled chamber at 60% relative humidity and 25°C ambient temperature. Adjuvants tested were two oil-based types (crop oil concentrate, or COC; and modified seed oil, or MSO), a nonionic surfactant (NIS), and a mixture (oil surfactant blend, or OSB). Water-only droplets were also tested for comparative purposes. The five waxy plants were difficult to wet and had a water contact angle greater than 90°. The water-only droplets did not spread at all and formed extremely small wetted areas on the leaf surface. The addition of an adjuvant to the spray solution significantly reduced the contact angle and increased the wetted area, but the change or improvements varied with the plant species and adjuvant class. In general, MSO and NIS enhanced the droplet spread and maintained the droplet evaporation time on the waxy leaf surfaces. After evaporation, the residues formed patterns of "coffee rings". Droplets with oil-based adjuvants had more uniform residual distribution in the deposition patterns than droplets with the surfactant adjuvant. Results of this study demonstrated that selection of the appropriate class of adjuvants significantly improved deposit formation on waxy leaves, leading to more effectiveness of pesticides.

Understanding the performance characteristics of application equipment is important for helping make the most efficacious applications. While handguns making high volume applications are common in greenhouse production, it is difficult to achieve uniform distribution of product in a timely manner. Broadcast applications made using air-assistance can help aid canopy penetration and the volume of carrier required to make applications. The objectives of this research were to determine how air-assist sprayer application parameters influence spray deposits on the undersides of leaves in a mature poinsettia canopy. Bench-top trials were conducted using a motorized boom inside a greenhouse to treat a mature and dense poinsettia canopy. Sprayer treatments applied a tank mix of water and fluorescent tracer. Nylon screen targets were secured to the underside surfaces of leaves in the upper and lower elevation of target plants. A five-port, air-assist nozzle with flat fan nozzle tips was used to make the applications. Three air outlet speeds, two travel speeds, and three nozzle flow rates were evaluated. Each treatment was replicated three times. Spray deposits were highly variable. Upper elevation spray deposits were significantly greater than lower elevation deposits. Individually, higher air outlet speed (36.0 m s-1), slower travel speed (3.2 km h-1), and higher nozzle flow rate (1.17 L min-1) tended to produce higher sprayer deposits on the underside surfaces of leaves. The combination of travel speed and nozzle flow rate that produced the highest application rate (900 L ha-1) also produced the highest deposits. There was a 500% increase in underside leaf surface deposits in the lower canopy area for a corresponding 500% increase in application rate. However, the main effects produced no significant differences in spray deposits in the lower canopy area. Further improvements in directing sprays or providing canopy turbulence are necessary to improve deposition and management of insect pests feeding on the underside of poinsettia leaves.

Loblolly pine (Pinus taeda L.) bark is the primary component of nursery container substrates in the eastern United States. Shortages in pine bark prompted investigation of alternative substrates. The objective of this research was to determine if ground switchgrass (Panicum virgatum L.) could be used for short production-cycle woody crops. Two experiments were conducted using ‘Paprika’ rose (Rosa L. ‘ChewMayTime’) potted in 15-cm tall and wide containers. In Expt. 1, substrates were composed of coarse-milled switchgrass (processed in a hammermill with 1.25- and 2.5-cm screens) amended with 0%, 30%, or 50% peatmoss and fertilized with 100, 250, or 400 mg·L−1 nitrogen (N) from ammonium nitrate. In Expt. 2, substrates were composed of coarse-milled (similar to Expt. 1) or fine-milled switchgrass (processed through a single 0.48-cm screen), amended with 0% or 30% peatmoss, and fertilized with the same N rates as in Expt. 1. Summarizing across both experiments, coarse switchgrass alone had high air space and low container capacity. Fine switchgrass had physical properties more consistent with what is considered normal for nursery container substrates. Switchgrass pH was generally high and poorly buffered against change. Fine switchgrass had higher pH than coarse switchgrass. Tissue analysis of rose grown in switchgrass substrate for 7 to 9 weeks revealed low to moderate levels of calcium and iron, but all other nutrients were within acceptable ranges. Despite varying substrate physical properties and pH levels, all roses at the conclusion of the experiment were of high quality. Switchgrass processed to an appropriate particle size and amended with typical nursery materials should provide a suitable substrate for short production-cycle woody crops.

Applying pesticides uniformly to the target area with drip irrigation systems is essential for achieving effectiveness of efficient insect or disease control and for the sustainability of a safe environment. The uniformity and recovery rate of water-soluble and insoluble materials of chemical and microbial pesticides with different physical properties discharged from emitters throughout driplines was evaluated. The materials were a water-soluble fluorescent tracer (BSF), a flowable water-dispersible insecticide (Imidacloprid), a suspendible microbial entomopathogenic fungus (EPF), a suspendible microbial soil fungicide (SF), and microbial entomopathogenic nematodes. Treatments also included three different flow capacities of emitters with nominally rated flow capacities of 1.9, 3.8, and 7.6 L h-1, respectively. Although all materials were readily deliverable through the drip irrigation system, the uniformity of the materials discharged varied with the material formulations and emitter flow capacity. For all emitter flow capacities, BSF had the lowest coefficient of variation, followed by nematodes, Imidacloprid, SF, and EPF. Conversely, the recovery rate of the five materials was in the reverse order. Emitter flow capacity affected the recovery rates of Imidacloprid and SF discharged from the emitters, but not of BSF, EPF and nematodes. Drip irrigation was demonstrated as a viable alternative for application of water-soluble and insoluble materials; however, the discharge rates of EPF and SF must first be determined to compensate for their non-uniformity of delivery and low recovery rates from emitters.

Silicon (Si) detection, distribution, and quantification in plants was compared using electron beam analysis (EBA; scanning electron microscopy coupled with energy dispersive X‐ray analysis), colorimetric analysis, and inductively coupled plasma–optical emission spectroscopy (ICP‐OES) in 14 economically important floriculture species. Using EBA, Si was identified most commonly around the base of trichomes and along the leaf margins. The ICP‐OES processing and analysis for Si using sodium hydroxide (NaOH) resulted in damaged torches and microwavable Teflon® vessels that required expensive replacement at the end of each run, but this was not the case in the colorimetric method or with a potassium hydroxide (KOH)–based matrix in the ICP‐OES. The results of these analyses suggest there is agreement between quantification methods, and EBA has a lower detection limit of about 300 mg kg−1 dry weight of Si. Several new floriculture species (zinnia, impatiens, verbena, and calibrachoa) were identified that take up...

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.

Conventional boom sprayers usually are not effective in delivering droplets to inner parts of dense target canopies, such as soybeans at growth stages from R3 to R5. An experimental mechanical canopy opener was developed with the assistance of mathematical models and attached to a conventional boom sprayer to increase spray deposition and coverage inside soybean canopies. The opener consisted of a 2.5 cm diameter metal pipe to push canopies forward, and a frame for connecting the pipe to the spray boom. Field experiments were conducted to determine the amount of spray deposition and percentage of spray coverage on artificial targets at the middle and lower portions of soybean canopies with three opener depths (7.5, 15, and 22.5 cm), three opener widths (15, 25, and 35 cm), and two different sizes of flat-fan nozzles. Additional field experiments were conducted to compare spray deposition and coverage inside soybean canopies among treatments using an air-assisted sprayer, the conventional boom sprayer with the opener, and the boom sprayer with a conventional flat-fan nozzle and a dual-pattern nozzle assembly without the opener. At the time of experiments, the soybean plants were at R5 growth stage with an average height of 1.06 m. An opener width of 25 cm or larger significantly increased the spray deposition and coverage inside the canopies. An opener depth from 7.5 to 15 cm had better spray coverage than the 22.5 cm opener depth. The boom sprayer with the opener produced no significant difference in spray deposition and coverage at the middle of canopies compared to the air-assisted sprayer, but it did produce significantly lower spray deposition and coverage at the lower portions of canopies than the air-assisted sprayer. With assistance from the opener to push the top of canopies, spray deposition and coverage on targets inside soybean canopies by the boom sprayer was improved.

Pelargonium was a priority genera collected by the Ornamental Plant Germplasm Center (OPGC) until a recent reorganization. To preserve genetic diversity for future breeders, OPGC collects heirloom cultivars, breeding lines, and wild species. The current Pelargonium collection at OPGC consists primarily of cultivars originating from P. ×hortorum and P. ×domesticum. Target region amplification polymorphism (TRAP) has the advantage of producing a large number of markers through use of sequence information that is already available. Our first goal was to determine the feasibility of TRAP for the analysis of this large collection, so that in the future the most diverse genotypes may be retained. To achieve this goal, we first modified existing DNA extraction techniques to account for the high levels of phenolic compounds present in some Pelargonium species by combining several washes to remove the phenolics with the addition of high levels of antiphenolic compounds. Second, we evaluated the TRAP procedure using the DNA isolated from 46 accessions. For 44 accessions, one or two primer combinations generated enough fragments to discriminate each of the accessions, and similar clades were produced by cluster analysis of the polymorphic fragments amplified by different primer combinations. All the scorable fragments were polymorphic, for one primer combination there were 148 markers from one image and the other produced 160 markers on two images. These results demonstrate that TRAP is an effective method for molecular characterization of ornamental collections.

Plant performance and appearance in deficient and toxic levels of nutrients are well characterized. However, less is known about the potential subtleties of plant growth, form, development, nutrient uptake, and biotic stress tolerance in the broad tolerable range. Begonia [Beg (Begonia × tuberhybrida Voss)] and new guinea impatiens [NGI (Impatiens hawkeri Bull.)] were grown over a wide range of N (from 1.78 to 57.1 mm NH4:NO3 ratio at a 1:1 ratio supplied as nutrient solution) in a peat:perlite soilless substrate in greenhouse conditions. Plant growth, development, chlorophyll content, leaf angle, nutrient uptake, tissue caloric value, and susceptibility to Botrytis cinerea Pers.:Fr. disease were evaluated in two experiments. Elevated N supply resulted in decreased plant height (16% in Beg and 7% to 16% in NGI), flower count (3% to 48% in Beg and 7% to 49% in NGI), bud numbers (23% to 80% in Beg), canopy area (11% to 33% in NGI), and mass (21% to 33% in Beg and 18% to 58% in NGI). Chlorophyll content saturated at an N supply of 28.6 mm. N uptake efficiency, shoot N use efficiency, and shoot N utilization efficiency decreased with increasing N supply. Elevated levels of N supply from 7.15 to 57.1 mm also increased the susceptibility of Beg to B. cinerea disease by 10% to 80% in stems and 3% to 14% in leaves. The increase in susceptibility also corresponded with increased tissue energy content (kJ·g−1) and altered leaf orientation. This study indicates many plant changes occur between nutrient extremes that can have a significant impact on growth, development, and the ability to withstand disease.

Spray drift potential, spray coverage, droplet size, and spray pattern width for various sizes of air induction and conventional flat-fan nozzles with equivalent orifice areas were investigated and compared under laboratory conditions. Droplet sizes were measured with a laser imaging system; spray coverage on water-sensitive paper (WSP) was evaluated with a boom sprayer at a constant travel speed in a greenhouse, and ground and airborne spray deposits were determined in a wind tunnel at two wind velocities (2.5 and 5.0 m/s). Tests were also conducted to evaluate the effect of air-intake holes being sealed or open on spray characteristics of air induction nozzles. With the equivalent nominal flow rate, air induction nozzles had approximately 2.1 to 2.75 times larger exit orifice areas than the conventional nozzles. With the equivalent orifice area and equal liquid flow rate, there was no significant difference in droplet size, spray pattern width, spray coverage, ground spray deposit, and airborne deposit among regular air induction nozzles, air induction nozzles with two sealed air-intake holes, and conventional flat-fan nozzles. Spray characteristics of air induction nozzles could be achieved by conventional nozzles with the equivalent orifice size operated at the reduced operating pressure.

The amount of water and major nutrients lost through drainage from a nursery container substrate treated with different amounts of nitrogen (N), phosphate (P), and potassium (K), and potted with butterfly bush plants were investigated. The substrate was mainly composed of aged pine bark and steamed composted nursery trimmings as well as leftover potting mix from a commercial nursery. Plastic containers with nominal capacity of 3.8 L were equally divided into 10 groups containing the substrate with or without plants, and treated with different amounts of N, P, and K applied to the surface of the substrate. A total of 4.8 L of water was applied to the substrate in each container during a 28-day period of the test. There was 48.4% of NO3-N and 6.3% of P leached away when 0.8 g of NO3-N and 0.4 g of P were applied to the substrate in the container with plants during the test. The amount of nutrients in the substrate with the greatest plant growth and the lowest nutrient loss through drainage was 0.44 g for N and 0.18 g for P. Substrate with plants had less water drainage and nutrient loss than the substrate with no plants. When the substrate moisture content was below 25%, the maximum amount of water that could be added into the substrate with plants before drainage was 257 mL of water/L of the substrate. Excess fertilizers applied to the container plants resulted in high nutrient loss and low plant growth rate. Current fertilizer use rates should be reduced to improve nursery production efficiency.

A conventional, axial-flow, air-blast orchard sprayer was used to make applications to the outside row of a semi-dwarf apple block. Fluorescent tracer was applied at the same rate using either disc-core nozzle sets or air-induction nozzles fitted with flat-fan tips. The experiment included measuring the percent area of spray coverage on leaves after three variations in spray application method. Each of the variations used a different type of nozzle on the same conventional, axial-fan orchard sprayer. The three nozzle variations were a Spraying Systems D3-25 nozzle set, a Spraying Systems D4-25 nozzle set, and a TurboDrop 02 (TD02) air-induction nozzle set. Canopy spray deposits, downwind sedimentation, and airborne spray losses were also measured following treatment on the inside half of the outside row using D4-25 nozzles or TD02 nozzles. The small droplet spectrum D3-25 nozzle set produced the highest leaf surface coverage on both upperside and underside surfaces at 2.0 and 3.0 m heights in the canopy. The upperside leaf surface coverage produced by the D3-25 nozzle was only somewhat greater than the TD02 nozzle. It was, however, significantly higher than the D4-25 nozzle set at the 3.0 m height. Conversely, the underside leaf surface coverage produced by the D3-25 was significantly greater than the TD02 nozzle set at both 2.0 and 3.0 m heights and not statistically different from the D4-25 nozzle set at the lower sampling height. There were relatively few differences in canopy spray deposits between the D4-25 and TD02 nozzle sets. The TD02 treatment produced the lowest downwind sedimentation deposits on targets 8 to 32 m from the edge of the orchard. The D4-25 produced approximately three times higher deposits up to 9 m above the ground than the TD02 treatment on passive nylon screens located 8 m downwind from the edge of the orchard. The D4-25 treatment produced significantly higher airborne deposits on elevated, high-volume, air sampler filters out to 64 m. At 128 m, sedimentation and airborne deposits were similar for the D4-25 and TD02 treatments.

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.

Information is lacking on spray techniques to improve deposit uniformity within nursery canopies and reduce off-target loss on the ground and via spray drift from the treated area. Spray deposits at various elevations within crabapple trees and on the ground were investigated with an air blast sprayer equipped with conventional hollow-cone nozzles, air-induction nozzles, and conventional hollow-cone nozzles with a drift retardant in a commercial nursery field. Airborne deposits at three elevations on sampling towers and on the ground at several distances from the sprayer were also investigated with the three spray treatments in an open area without trees. 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 without air assist. Droplet size distributions across spray patterns without air assist were measured with a laser particle/droplet image analysis system. In general, there was no significant difference for deposits within nursery tree canopies and on the ground with three different spray techniques. At the 700 L/ha application rate, which was 360 L/ha lower than the rate typically used in nursery application, the tree canopies received over 4 to 14.5 times as much spray deposit as actually needed from all treatments, and a large portion of spray volume deposited on the ground. Compared with conventional hollow-cone nozzles, drift reduction from air-induction nozzles or the spray mixture with drift retardant treatment was significant in wind tunnel tests but was not significant in field tests.

New sprayers are needed to deliver droplets uniformly within dense nursery crops to obtain healthy and marketable plants in the nursery industry. An air-assisted sprayer with five-port nozzles was developed and investigated to improve spray penetration into dense nursery canopies. Spray deposits at the top, middle, and bottom of canopies were characterized using fluorescence detection, and were compared at three nozzle heights in a commercial nursery field. Dynamic air velocities corresponding to the deposit sampling locations inside and outside the canopy were measured at the time when the sprayer passed over the canopies. Air jet velocity profiles from nozzle outlets to 0.79 m below the nozzles were determined experimentally and mathematically. The measured air jet velocity decreased from 40.1 to 19.4 m/s when the distance from the orifice increased from 0.33 to 0.79 m. The peak velocities at the top and middle elevations for both inside and outside the canopy decreased as the nozzle height above the ground increased, but the peak velocities at the bottom elevation for both situations were not significantly decreased as the nozzle height increased. The average period of time for dynamic air velocities higher than 1 m/s inside the canopy was 1.9 s at the bottom, 3.8 s at the middle, and 1.1 s at the top of canopies. The mean spray deposit inside taxus canopies with leaf area index of 5.96 increased in an exponential function as the peak air velocity increased. The spray penetration capability and spray deposition uniformity inside taxus canopies were greatly improved with the five-port air-assisted sprayer.

An appropriate blend of growing media components increases water holding capacity and reduces irrigation frequency. Synthetic commercial materials, referred to as hydrogels, have remarkable hydrating properties, but can add significantly (about 15%) to the cost of growing media. The literature generally states that the physical characteristics of hydrogels, such as polyacrylamide (PAM), are altered by the presence of divalent cations (Ca2+ and Mg2+). Few studies, however, have simultaneously investigated plant growth and development and media characteristics on a daily basis throughout plant production. Thus, the mechanisms explaining the reported beneficial and/or detrimental effects from PAM incorporation remain hidden. In this study, canopy ground cover of two species [pansy (Viola ×wittrockiana Gams) and new guinea impatiens (Impatiens hawkeri Bull)] was measured daily, from transplanting to marketable size, using digital imaging to determine growth differences of plants grown in media containing different amounts of PAM. Media water content was determined with time-domain reflectance probes every 10 minutes in media treatments. Total number of irrigation events, time between irrigation events, root development after 4 and 8 weeks of growth, flower number, flower longevity, and dry masses of the shoot were also measured. Scanning electron microscopy revealed significant structural differences in hydrated PAM depending on water quality. The pansy canopy coverage was significantly greater with hydrogels, and root growth early in production was enhanced with PAM. No such effect was observed for new guinea impatiens. Total flower numbers and flower longevity of new guinea impatiens decreased with increasing amount of PAM (16.7% or higher) in the media. PAM incorporation reduced the need for irrigation early in production for both species, but by the end of production, those new guinea impatiens plants were smaller (less shoot dry mass) and required irrigation as often as plants grown without PAM. This effect coincided with reduced media volume, air capacity, and total porosity in PAM-containing media. Theoretical analysis of the potential benefits from hydrogels confirms the potential benefit early in production with little to no benefit later in production and in post-production. These data will assist growers in determining if the benefits derived from the use of PAM justify the added cost of medium.

Techniques are needed to monitor nursery production practices for proper use of water resources and nutrient management. An experimental system to examine water quality, irrigation efficiency and drainage from pot-in-pot nursery container production was established in a commercial nursery. The system mainly consisted of 50 pot-in-pot containers with 50 trees irrigated with micro spray stakes, drainage water measurement devices, container-substrate moisture probes, thermocouples, a weather station, and data loggers. Tests indicated the system was capable to measure irrigation and rainfall inputs, drainage water loss, container substrate moisture content and temperature, leachate of nitrogen, phosphate and potassium in drainage water, and tree growth in pot-in-pot nursery production. The system provided a method to not only monitor the loss of water and nutrients but also continuously monitor the substrate temperature and moisture content during four seasons of a year to evaluate potentials of winter injury or summer heat damage to roots for pot-in-pot nursery production.

Stable analysis of fluorescence is essential to ensure accurate evaluation of pesticide spray application efficiency when fluorescent tracers are used to quantify deposition and drift. The fluorescent intensity of five fluorescent tracers commonly used for the quantitative assessment of spray deposition and off-target loss was investigated with wash solutions over pH conditions from 6.86 to 10.4. The tracers selected in the tests were Acid Yellow 7, Eosin, Fluorescein, Pyranine, and Tinopal. The fluorescence of Pyranine was the most sensitive to the solution pH conditions, followed by Fluorescein and Tinopal. Acid Yellow 7 and Eosin had a nearly constant fluorescent intensity over the pH range from 6.86 to 10.40. The fluorescent strength of Fluorescein increased 1.3 times, Tinopal 1.25 times, and Pyranine 3.0 times as the pH value increased from 6.86 to 8.43, but it became nearly constant when pH value was greater than 8.43. However, Pyranine, Fluorescein, and Tinopal showed much stronger fluorescence than Acid Yellow 7 and Eosin with the same concentrations. A solution containing Fluorescein at pH 8.43 and higher demonstrated 124 times greater fluorescent intensity than the solution containing the same amount of Acid Yellow 7. The fluorescent strength should be examined not only with purified distilled water but also under various wash solution pH conditions during the selection of tracers for pesticide spray deposition and drift trials.

Exposure to hydrodynamic stresses during flow through a hydraulic nozzle can cause permanent damage to biological pesticides during spray application. Aqueous suspensions of a benchmark biological pest control agent, entomopathogenic nematodes (EPNs), were passed through three different hydraulic nozzles (standard flat fan, Spraying Systems XR8001VS; hollow cone, Spraying Systems TXA8001VK; and full cone, Spraying Systems FL5-VS) within an experimental, opposed-pistons flow device. Computational fluid dynamics (CFD) was used to numerically simulate the internal flow within the XR8001VS and TXA8001VK nozzles, and important flow field parameters from the CFD simulations were compared to the observed EPN relative viability after treatment. Overall, greater reductions in EPN relative viability were observed for the flat fan (9.5%) compared to the cone type nozzles (

Three sprayers were evaluated for their affect on retention and efficacy: a carbon dioxide powered high-volume sprayer, a DRAMM coldfogger, and an Electrostatic Spraying Systems (ESS) sprayer with air-assistance. The active ingredients used were spinosad and azadirachtin. The plant canopy was constructed in the greenhouse using potted soybeans (Glycine max (L) Merrill cr Pioneer 9392). Application efficacy with spinosad was assessed using thrips [Western flower thrips, Frankliniella occidentalis (Pergande)] and mite (two-spotted spider mite, Tetranychus urticae Koch) abundance on shoots and leaves. Application efficacy with azadirachtin was assessed using thrips and aphid (soybean aphid, Aphis glycines Matsumura) abundance on shoots and leaves. The atomization characteristics of each sprayer were measured using an Aerometrics phase/Doppler particle analyzer (PDPA) 100-1D. The results of four tests are presented. Two tests used each sprayer according to manufacturer recommendations. These are 'recommended volume' tests that confound differences in toxicant distribution caused by the sprayer with differences caused by changes in application volume. The other two tests were 'constant volume' tests in which all three sprayers were used to deliver the same application volume. Both types of test gave differences between sprayers in retention of toxicant, but only the recommended volume tests showed significant effects of the sprayers on pest abundance. We attribute this difference to the role played by changing application volumes in the dose-transfer process. The constant-volume tests showed that application equipment influences efficacy.

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.

Third instar European chafer (EC), Rhizotrogus majalis (Razoumowsky), were found to be killing field-grown Rhododendrons ‘P.J.M.’ and Eastern hemlocks in two commercial nurseries in northeastern Ohio. Apparently, 1 or 2 grubs per plant were sufficient to severely damage young plants (rhododendrons). Subsurface applications of Dursban TNP were tested as rescue treatments against the grubs in these fields. Three novel single-point subsurface applicators were tested for delivery of Dursban in the rhododendron trial. A subsurface treatment of Dursban TNP was compared to surface applied drench treatments of Dursban TNP and Dylox 80 T & O in the hemlock trial. We found that EC grubs killed young plants of both species by removing most of the fibrous roots and/or girdling the stems. The subsurface treatments of Dursban TNP, significantly reduced (95%) the number of EC grubs compared to untreated hemlocks and rhododendrons when treatments were applied early or late fall, respectively. There were no differences in suppression of grubs among the applicators in the rhododendron trial.

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.