Search

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

Laser-guided variable-rate intelligent spray technology is designed to significantly reduce pesticide use with a positive impact on the environment. However, there have been no reports on applying this technology to commercial fruit farms. Comparative experiments of intelligent variable-rate and conventional constant-rate spray applications for pesticide use and pest control were conducted at a fruit farm in Ohio during two consecutive growing seasons. Apple (Malus pumila), peach (Prunus persica), blueberry (Vaccinium section Cyanococcus), and black raspberry (Rubus occidentalis) were used for the tests. Pest severity of codling moth (Cydia pomonella), oriental fruit moth (Grapholitha molesta), scab (Venturia inaequalis), and powdery mildew (Podosphaera leucotricha) in apple; oriental fruit moth, brown rot (Monilinia fructicola), and powdery mildew (Podosphaera pannosa) in peach; spotted wing drosophila (Drosophila suzukii), mummy berry (Monilinia vaccinii-corymbosi), and phomopsis (Phomopsis vaccinii) in blueberry; and anthracnose (Elsinoe veneta) in black raspberry were assessed. There was equal severity of pests between intelligent and conventional spray applications, whereas the intelligent spray reduced pesticide use by 58.7%, 30.6%, 47.9%, and 52.5% on average for apple, peach, blueberry, and black raspberry, respectively. These results illustrate that intelligent spray technology is more environmentally friendly than conventional standard spray technology and equally or more effective for control of insect and disease pests in fruit production.

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

To improve the precision spraying strategy and reduce excessive pesticide application in orchards, an air-assisted sprayer integrated with a laser-scanning system was developed to realize the toward-target variable-rate spraying. In the spray control system, a method of calculating canopy gridding volumes was designed to ensure that the canopy was divided into a uniform grid size, a variable-rate spray model was used in the flow rate decision software to control the spray output according to the canopy gridding volumes and travel speed, and a method of saving and accessing spray data was used to control the spray delay. The effects of different grid sizes and travel speeds on the spray performance were evaluated by quantifying spray coverage uniformity inside tree canopies. The results showed that spray coverage uniformity declined with increasing grid width from 0.14 to 0.28 m although the mean spray coverage on each target location showed no significant differences. Additionally, there were no significant variations in mean spray coverage at speeds of 1.0, 1.2 and 1.4 m/s for a tested tree of 1.6 m width and at any experimental speeds for a tested tree of 1.3 m width, which indicated that the variable-rate sprayer could provide good spray coverage uniformity under various travel speeds with a canopy size limitation. Compared with the same sprayer without the variable-rate spray function, the intelligent sprayer prototype realized effective toward-target spraying and avoided overspraying while providing sufficient spray coverage. [ABSTRACT FROM AUTHOR]

Conducting on-farm evaluations of pest control and economic feasibility is a necessary procedure to ensure successful adoption of new spray technologies by commercial horticulture enterprises. A newly developed laser-guided variable-rate air-assisted sprayer was tested for control of spirea aphids (Aphis spiraecola), pod gall midges (Dasineura gleditchiae), and pear sawflies (Caliroa cerasi) on crabapple (Malus species), 'Sunburst' honey locust (Gleditsia triacanthos inermis), and 'Mazzard' cherry (Prunus avium) trees, respectively, in three commercial nurseries in Ohio and Oregon. The efficacy of the laser-guided sprayer for pest control treatment was compared with the efficacy of two types of conventional constant-rate air-assisted sprayers. During the tests, the variable rate from the laser-guided sprayer was achieved automatically based on plant presence, canopy structure, and foliage density. The application rates for the conventional sprayers were determined to comply with best pest management practices. Compared to the conventional constant-rate sprayers with comparable and effective insect control, the laser-guided sprayer reduced the spray volume rate to control aphids by 60% and 36% in nurseries 1 and 2, respectively. Similarly, in nursery 3, the laser-guided sprayer used 77.6% and 29.7% less spray volume and chemicals to control pod gall midges and sawflies, respectively. Thus, the new variable-rate spray system reduced pesticide use, increased pesticide spray application efficiency, and improved profitability, thereby offering an economically and environmentally responsible approach to controlling insect pests. [ABSTRACT FROM AUTHOR]

Sensors that can accurately measure canopy structures are prerequisites for development of advanced variablerate sprayers. A 270° radial range laser sensor was evaluated for its accuracy in measuring the dimensions of target surfaces with complex shapes and sizes. An algorithm for data acquisition and three-dimensional (3-D) canopy image construction were designed and processed with an embedded computer. Test targets included three beach balls at three heights, a rectangular box, a cylinder, two artificial trees, and three field-grown ornamental trees. Other variables included 2, 3, 4, and 5 m detection distances and sensor travel speeds of 3.2, 4.8, 6.4, and 8.0 km h-1. The laser sensor measurements of the test targets were statistically similar with the actual measurements. The average root mean square error (RMSE) and coefficient of variation (CV) varied slightly with detection distance and travel speed. Among all the dimension measurements in the ranges of 0.58 to 2.54 m in the X direction, 0.58 to 2.54 m in the Y direction, and 0.58 to 2.94 m in the Z direction, the highest average RMSE of 68 mm occurred in the Z direction and the highest average CV of 8.6% occurred in the Y direction. Similarity of paired images from the laser sensor and a camera was greater than 0.85 for all targets. These tests confirmed the capability of the laser sensor and the algorithm to accurately measure complex-shaped targets, offering potential for integration of the sensor and algorithm into sprayers that would make real-time adjustment of spray outputs to match plant structures and travel speeds. [ABSTRACT FROM AUTHOR]

The preferential design for variable-rate orchard and nursery sprayers requires that the sprayers are able to control the liquid and air flow rates based on the canopy structure in real time. Demand for this advanced feature has increased rapidly with the public demand for reductions in pesticide use. A variable-rate, air-assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the capability of varying the airflow rate by changing the fan inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various locations inside tree canopies of three different sizes and foliage densities. Air jet velocities were adjusted by changing the sprayer fan inlet diameter with an airflow regulator and measured with a constant-temperature anemometer coupled with hot-wire probes. Peak air velocity and airflow pressure decreased with foliage density and canopy depth. For the 0.34 m fan inlet diameter, the airflow pressure ratio of the front portion to the back portion of the canopies was 2.45 for a 1.65 m tall and 13.4 leaf area index (LAI) Tsuga canadensis (Tree 1), 1.43 for a 2.35 m tall and 2.5 LAI Ficus benjamina (Tree 2), and 1.64 for a 3.0 m tall and 1.5 LAI Acer rubrum (Tree 3). Similarly, the front-to-back peak air velocity ratios were 8.55, 1.59, and 1.89 for Tree 1, Tree 2, and Tree 3, respectively. Variations were significant for peak air velocities and airflow pressures among the three different tree volumes and foliage densities. Increasing the fan inlet diameter from 0.13 to 0.34 m increased average airflow pressure from 2.84 to 4.01 kg m-2, from 3.88 to 5.82 kg m-2, and from 2.46 to 3.75 kg m-2 inside the canopies of Tree 1, Tree 2, and Tree 3, respectively, while it also increased average peak air velocity from 2.6 to 4.5 m s-1, from 5.5 to 9.1 m s-1, and from 3.0 to 5.2 m s-1 inside the three tree canopies. Therefore, the new sprayer design with an airflow regulator to alter the fan inlet diameter was able to provide variable airflow for different canopy sizes and foliage densities and offered a potentially effective approach to discharge uniform airflow profiles to carry droplets with efficient spray penetration into plant canopies. [ABSTRACT FROM AUTHOR]

Precision modulation of nozzle flow rates is a critical step for variable-rate spray applications in orchards and ornamental nurseries. An automatic flow rate control system activated with microprocessors and pulse width modulation (PWM) controlled solenoid valves was developed to control flow rates of multi-channel nozzles independently for variable-rate sprayers. The system consists of a data acquisition module, a data processing module, and a flow rate control module. An embedded computer along with a touch screen was used to process control algorithms and allowed communication between the sprayer operator and the control system. The flow rate control module was designed with multichannel driver circuits for activating the solenoid valves and driver protection circuits for avoiding surge voltages due to frequent on/off actions of the solenoid valves. Laboratory tests were conducted to verify the accuracy of the control system with three nozzles (0.530 to 1.703 L min-1) at four different operating pressures (138 to 345 kPa) and ten duty cycles (10% to 100%). The microcontroller-controlled circuit precisely produced PWM signals with desired pulse widths to match the duty cycles, and linear spray outputs were achieved accurately with the duty cycles of the PWM-controlled solenoid valves. With the protection circuit for the solenoid valve drivers, the longevity of the solenoid valves increased from 350 to 2,426 h. The system offers flexibility in choosing the number of connection channels needed for the number of nozzles individually or in a group on sprayers. Accordingly, together with canopy structures and travel speeds from laser scanning or other sensors, this compact control system is capable of performing variable flow rate functions for multiple nozzles separately. [ABSTRACT FROM AUTHOR]

Efficient and effective precision spray equipment and strategies are in high demand to reduce pesticide use in tree crop production. An experimental variable-rate air-assisted sprayer implemented with a high-speed laser scanning sensor was developed to control the spray output of individual nozzles in real time. The sprayer consisted of a laser scanning sensor control system and an air and liquid delivery system. Each nozzle in the delivery system, coupled with a pulse width modulated (PWM) solenoid valve, achieved variable-rate delivery based on occurrence, height, and width of the target tree and its foliage density. Other components of the sensor control system included a unique algorithm for variable-rate control that instantaneously processed measurements of the canopy surfaces. To determine system delay time, a high-speed video camera was used to record the time period between sensor detection of the canopy and nozzle activation. Spray deposition uniformity inside canopies was verified by quantifying spray coverage inside four ornamental nursery trees of different sizes and canopy densities at 3.2 and 6.4 km h-1 travel speeds. Test results demonstrated that differences in spray coverage inside the canopies of these four trees in the spraying direction were not statistically significant, even though these trees had different structures, canopy volumes, and foliage densities. The canopy volume and foliage density measured with the algorithm developed for the laser sensor-controlled detection system exhibited little variation between the two travel speeds. Design criteria for the sensor-controlled system in the experimental sprayer were acceptable for variable-rate application, having great potential for spray volume and drift reduction, and thus reducing environmental impact. [ABSTRACT FROM AUTHOR]