Management of grape powdery mildew with an intelligent sprayer and sulfur

Wine grapes are an important agricultural commodity in the Pacific Northwest where grape powdery mildew (GPM) is one of the main disease problems. The efficacy of different sulfur concentrations and different output volumes from an air blast sprayer retrofitted with the Intelligent Spray System (ISS) were evaluated for the management of GPM. The ISS consists of a LiDAR sensor, Doppler speed sensor, embedded computer, flow controller, and individual pulse-width-modulation solenoid valves at each nozzle. GPM cluster severity ranged from 55% to 75% across all trials in the study when using the ISS at its default spray rate of 62.5 ml m-3 and micronized sulfur at 6 g L-1, which was significantly higher than all other fungicide treatments, but lower than non-treated controls. Similarly, leaf incidence values were highest on non-treated vines, followed by micronized sulfur at 6 g L-1 applied at 62.5 ml m-3 , with all other fungicide treatments being significantly lower in all trials. Using the ISS at the 62.5 ml m-3 rate and a rotation of locally systemic fungicides resulted in the lowest observed GPM leaf incidence, and average cluster severity of 11% in both 2019 and 2020, the lowest cluster severity of all fungicide treatments tested. GPM control using the ISS and micronized sulfur was equivalent to a constant-rate air blast treatment at 6 g L-1 when the spray rate of the ISS was increased to 125ml m-3, or if the concentration of sulfur was increased to 24 g L-1. In those cases, the amount of sulfur applied to vines was at or above the minimum label rate from bloom until the end of the season, or the entire season, respectively. This study has shown that sufficient disease control cannot always be expected when mixing pesticides at the same rate as would be used for a constant-rate sprayer in a variable rate sprayer, especially when using contact fungicides like sulfur . With appropriate adjustments, the variable-rate ISS can be a useful tool to reduce pesticide quantities, water required for mixing, and as a result labor, as fewer trips to refill for a given spray event are required.

Deposition of sprayed drops in soybean in function of sowing spacing

To reach all parts of the plants can be a difficult achievement faced by the drops in several crops. Strategies in crop management such as an increment in the plant spacing can contribute to the spray application's success. This study aimed to evaluate the droplets deposition in soybean, using three different spray nozzles and application rate, in two soybean rows spacing. The experimental design used was the randomized blocks, with treatments arranged in a split-plot scheme. The plots were the interrow spacing (0.45 and 0.76 m), the subplots were the spray nozzles (JA-2 and Magno 11002 BD), and the sub-subplots were the application rate (120, 200 and 280 L ha-1). Droplets coverage was evaluated in the upper, middle and lower thirds of soybean plants. Water-sensitive papers were installed in the adaxial part of plant leaves to analyze the spray technology and evaluated using E-Sprinkle® software. Spraying was performed in plants at the R5.3 soybean stage. This experiment evaluated the following parameters: the volume median diameter, the density of droplets per cm2, the droplet coverage area, and the droplet percentage less than 150 µm. The increase in the soybean row spacing combined with the spray volume increase provided greater droplet coverage in the middle third in soybean crop. The Magno 11002 BD droplet nozzle provided the higher droplet coverage in the row spacing of 0.76 m. The spray rate of 280 L ha-1 provided the highest density of droplets per cm2 in the lower third and greater coverage in the middle-third.

Computational optimization for the deposition of bioconvection thin Oldroyd-B nanofluid with entropy generation

The behavior of an Oldroyd-B nanoliquid film sprayed on a stretching cylinder is investigated. The system also contains gyrotactic microorganisms with heat and mass transfer flow. Similarity transformations are used to make the governing equations non-dimensional ordinary differential equations and subsequently are solved through an efficient and powerful analytic technique namely homotopy analysis method (HAM). The roles of all dimensionless profiles and spray rate have been investigated. Velocity decreases with the magnetic field strength and Oldroyd-B nanofluid parameter. Temperature is increased with increasing the Brownian motion parameter while it is decreased with the increasing values of Prandtl and Reynolds numbers. Nanoparticle’s concentration is enhanced with the higher values of Reynolds number and activation energy parameter. Gyrotactic microorganism density increases with bioconvection Rayleigh number while it decreases with Peclet number. The film size naturally increases with the spray rate in a nonlinear way. A close agreement is achieved by comparing the present results with the published results.

Fungicide management in the Asian soybean rust

Asian soybean rust is the major crop disease and the management of the use of the fungicide is important for effective control. The objective of this work was to evaluate the management of fungicides with sequential applications to control Asian soybean rust. The experimental design used was a randomized block with four replications and eight treatments with different combinations of fungicides from the following chemical groups: triazole, strobilurin, carboxamide, and dithiocarbamate. The applications were carried out with backpack spray equipment at constant pressure (CO2) and a spray rate of 200 L ha-1. The severity of rust, the area under the disease progress curve, control efficiency, mass of 1,000 grains, and productivity were evaluated. The protective fungicide mancozeb, in mixtures with systemic fungicides, were more effective for the control of Asian soybean rust than the systemic fungicides applied without the protective fungicide.

Experimental Observation of a Regression Dependence for Hydrodynamic Performance of the Regular Packing

The investigational studies of regression dependence of the new efficient regular packing bed’s flow friction on gas velocity and liquid spray rate has been carried out. The tests were made by the procedure of a complete two-factor experiment. On account of experiment design matrix, there are four tests to be made to determine the regression dependence. It is found that the packing bed’s flow friction builds up along with increase of superficial gas velocity and liquid spray rate. The regression dependence that puts packing bed’s flow friction in touch with superficial gas velocity and liquid spray rate is procured. The specific dependence is valid for air velocity 1.21-3.12 m/sec and liquid spray rate 0.0080-0.0304 m3/(m2 sec). The conclusion on significance of regression dependencies has been made in terms of Student’s t-test. The sufficiency of regression equation has been inspected via the Fisher’s criterion. The resulting regression equation can be utilized in the design and engineering process of absorbers with the shock-spray packing.

Advancing Sustainability in Tree Crop Pest Management: Refining Spray Application Rate with a Laser-guided Variable-rate Sprayer in Apple Orchards

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

Rate response of select grass weeds to pinoxaden

Pinoxaden is a POST acetyl coenzyme A carboxylase (ACCase) inhibitor in the phenylpyrazolin chemical family and is labelled for turfgrass use at broadcast rates of 35.5 to 71 g ai ha−1 and spot spray rates of 156 to 310 g ai ha−1. A greenhouse rate-response study was conducted to characterize the efficacy of pinoxaden against common grassy weeds. Weed species examined in this study were yellow foxtail, southern sandbur, annual bluegrass, roughstalk bluegrass, large crabgrass, dallisgrass, bahiagrass, goosegrass, and perennial ryegrass. Nonlinear regressions were modelled to determine visible injury rates (the application rate at which 50% of the weed species were injured and the 90% [I90] rate) and weight reduction rates (the application rate at which there was a 50% reduction in fresh weight and 90% reduction [WR90]) for each weed species. Only annual bluegrass, bahiagrass, and goosegrass had visible injury I90 values greater than the maximum labelled spot spray rate of 310 g ai ha−1. Annual bluegrass, bahiagrass, southern sandbur, and goosegrass all had WR90 values greater than the maximum labelled spot spray rate of 310 g ai ha−1. Results from this study indicate that the evaluated weed species can be ranked, according to visible injury I90 values, from most to least susceptible: perennial ryegrass > yellow foxtail > dallisgrass > large crabgrass > southern sandbur > roughstalk bluegrass > bahiagrass > goosegrass > annual bluegrass.

Production and Characterization of Controlled Release Urea Using Biopolymer and Geopolymer as Coating Materials

Synthetic polymers-based controlled release urea (CRU) leaves non-biodegradable coating shells when applied in soil. Several alternative green materials are used to produce CRU, but most of these studies have issues pertaining to nitrogen release longevity, process viability, and the ease of application of the finished product. In this study, we utilized tapioca starch, modified by polyvinyl alcohol and citric acid, as coating material to produce controlled release coated urea granules in a rotary fluidized bed equipment. Response surface methodology is employed for studying the interactive effect of process parameters on urea release characteristics. Statistical analysis indicates that the fluidizing air temperature and spray rate are the most influential among all five process parameters studied. The optimum values of fluidizing air temperature (80 °C), spray rate (0.13 mL/s), atomizing pressure (3.98 bar), process time (110 min), and spray temperature (70 °C) were evaluated by multi-objective optimization while using genetic algorithms in MATLAB®. Urea coated by modified-starch was double coated by a geopolymer to enhance the controlled release characteristics that produced promising results with respect to the longevity of nitrogen release from the final product. This study provides leads for the design of a fluidized bed for the scaled-up production of CRU.

OPTIMIZATION OF AQUEOUS-BASED FILM COATING PROCESS PARAMETERS CONTAINING GLUCOSAMINE SULFATE POTASSIUM CHLORIDE

Objective: The aim of the present work was to prepare film coated tablet of glucosamine sulfate potassium chloride and study the effect of coating process parameters which implicate more significant effects on an aqueous-based film coating process of tablets. Methods: The different batches of uncoated tablets were prepared by wet granulation method. Aqueous film coating was carried out by using opadry®II white 85F18422. A 32 full factorial design was employed to study the effect of spray rate (X1) and inlet air temperature (X2) on coating uniformity, coating process efficiency and % loss on drying. The surface characteristics of the aqueous based film coated tablet were studied using a SEM. Check point batch was prepared to validate the evolved model. Results: Preliminary trials indicated that individually process parameters affected the quality of coated tablets. Hence, studied the combined effect of these factors on the coating process required and 32 full factorial design was applied. In this study, it was seen that spray rate and inlet air temperature had a major effect on tablet coating process. It was observed from factorial batch that maximum drug release was found in batch F5. Conclusion: The results of full factorial design indicate both parameters spray rate (X1) and inlet air temperature (X2) have significant effect on coating process and batch F5 is stable for 3 mo at accelerated condition.

Investigation of the regularity of sedimentation of liquid droplets during field crop spraying

Purpose. Improving the quality of spraying field crops, reducing losses of chemicals of spraying and improving the environmental safety. Methods. Analytical and experimental. Results. Analytical dependences are obtained, which make it possible to determine the droplet velocity depending on their diameter and working pressure. Conclusions. With increase in diameter of the droplet and the liquid pressure in the spray increases the time during which it reaches the speed of hovering and increases the path which will pass a drop until its speed reaches the hovering velocity. These data can be used to justify the rational parameters of the sprayer. Keywords: dispersion of spray, meteorological factors, spraying, droplet settling, spray, rate hovering.