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ARS Home » Midwest Area » Wooster, Ohio » Application Technology Research » Research » Research Project #425625

Research Project: Improved Pest Control Application Technologies for Sustainable Crop Protection

Location: Application Technology Research

2018 Annual Report

Objective 1: Establish comprehensive ground-based strategies to increase foliar retention of pesticide spray for traditional and specialty crops produced in greenhouses and the field. Sub-objective 1.1: Determine the influence of spray parameters including droplet size, formulation physical properties, ambient air conditions, and plant surface morphology on the droplet behavior, evaporation, absorption, and residual pattern on plant surfaces. Sub-objective 1.2: Determine the influence of droplet size and velocity, travel speed, spray formulation physical properties, crop characteristics, leaf surface morphology, and leaf surface orientation on spray droplet dynamic impact, retention, rebound and coverage. Objective 2: Develop intelligent-decision spraying systems to increase spray application efficiency and reduce off-target losses. Sub-objective 2.1: Develop advanced sensor-based intelligent decision systems that can be adapted for different types of sprayers. Sub-objective 2.2: Investigate spray deposition uniformity, off-target losses and pesticide savings with intelligent-decision controlled sprayers. Sub-objective 2.3: Develop drift reduction technologies (DRT) with intelligent decision systems to aid in reducing off-target losses and enabling development of sustainable production programs. Objective 3: Develop ground-based methods for improving delivery of weed management materials to nursery containerized production systems. Sub-objective 3.1: Optimize application factors such as droplet size, spray volume and irrigation volume to improve delivery efficiency of herbicides through a nursery crop canopy to the substrate surface. Sub-objective 3.2: Determine the influence of delivery and plant parameters such as air-assistance, travel speed, irrigation volume, and canopy structure on deposition of granular materials on container substrates. Objective 4: Develop alternative delivery methods for agrochemicals and bio-products. Sub-objective 4.1: Develop mechanical delivery devices to apply entomopathogenic nematodes. Sub-objective 4.2: Develop methods and strategies for efficiently applying pheromones.

This project envisions that research on intelligent spray technologies, efficient applications of bio-products as alternative pesticides, and coordinated strategies can enhance pesticide application efficiency for efficacious and affordable control of insects, diseases and weeds. The research will focus on delivery systems in conjunction with spray droplet transport, fate of spray droplets upon target impact, epidemiology of pests and pathogens, pesticide formulation, and microclimatic conditions. Selective approaches to achieve the objectives will be to: (1) establish comprehensive ground-based strategies to increase pesticide retention on specialty and traditional crops in greenhouse and field environments; determine the influence of spray parameters such as droplet size, formulation physical properties, ambient air conditions, and plant surface morphology on the droplet impaction, rebound, retention, spread, evaporation, absorption, and residual pattern on plant surfaces under the conditions that individual parameters can be controlled separately; (2) innovate advanced intelligent-decision spraying systems to increase spray application efficiency; investigate spray deposition uniformity, spray drift, off-target losses and pesticide savings for ornamental nurseries, orchards and other specialty crops with intelligent-decision controlled sprayers; develop drift reduction technologies with intelligent decision systems to aid in enabling development of sustainable production programs; (3) develop methodologies to improve herbicide applications for containerized nursery production systems; optimize application factors such as droplet size, spray volume and irrigation volume to improve delivery efficiency of herbicides through a nursery crop canopy to the substrate surface; determine the influence of delivery and plant parameters such as air-assistance, travel speed, irrigation volume, and canopy structure on deposition of granular herbicides on container substrates; (4) develop mechanical delivery devices to apply new agrochemicals and bio-products for pest control; discover innovative techniques for accurate delivery of entomopathogenic nematode infected insect larvae to effectively control soil pests; develop methods and strategies for efficiently applying pheromones by designing new dispensers with controlled evaporation rates.

Progress Report
A universal intelligent spray control system was modified as a retrofit kit for conventional orchard sprayers. The retrofit kit was mounted on nine growers’ sprayers used in nurseries, fruit and nut orchards, and vineyards in Ohio, Oregon, Tennessee, South Carolina, Texas and Australia. With the retrofit, these conventional sprayers were upgraded to perform intelligent functions in controlling spray outputs to match canopy presence, size and leaf density in real time. Total sixteen sprayers equipped with the intelligent spray technology were on-farm tests for their efficacy, efficiency and reliability. An additional sprayer retrofitted with the intelligent spray control kit was adapted by a sprayer company for demonstrations of the new spray technology in workshops, trade shows and other educational programs. A decision support system (DSS) complying with weather stations was evaluated in seven nursery, grape and fruit farms in Ohio to manage pesticide spray application schedules to control diseases and pest insects. On-site weather stations were installed to transmit data to the web via a wireless or cellular connection. Information gathered from the individual insect pest and disease models was combined for future development of a consensus model for spray application recommendations. Investigations were conducted to determine effects of anti-evaporation adjuvants mixed with two commonly used plant cell growth disruption and restriction herbicides on the coverage area and fading time of droplets deposited on climbing annual weed leaves. Test data were statistically analyzed for development application strategies to improve herbicide droplet performance. Bio-pesticides of six different classes were tested with three flow capacities of five different types of hydraulic nozzles under laboratory conditions. The six classes of bio-pesticides were horticultural Oil, mineral, bacterial, fungal, and insecticidal growth regulator. Droplet size spectrum, spray pattern uniformity, and spray deposition of the bio-pesticides discharged from different nozzles were quantified. Release rates of eleven different classes of semiochemical dispensers at ambient temperatures of 20, 25, 30, 35 and 40 °C and relative humidity of 50% were determined and analyzed for development of prediction models to manage forestry pests. A portable electronic nose system equipped with a sophisticated sensor array was investigated and modified to detect volatile organic compounds released from tomato plants infested with aphids and whiteflies. Gas chromatography mass spectrometry was used to verify the accuracy of the electronic nose system. Potentials of using the system for future development of plant health indicators to manage greenhouse pests were examined. The accuracy of an inexpensive indoor-use laser scanning sensor combined with a specially-designed plant surface mapping algorithm was evaluated in detection of complex-shaped object surfaces and sizes. Test variables included detection heights, sensor travel speeds, and horizontal distances to the sensor. Potential adaptations of this laser scanning sensor to measure complex-shaped plants were analyzed for future development of automatic spray systems to achieve variable-rate functions in greenhouse applications. Effects of droplet contact angle with the leaf contact angle hysteresis, leaf thickness and toughness, and surface roughness due to venation and trichome density on spreading and adhesion were examined for understanding of droplet impaction, retention, or rebound on leaf surfaces. Droplets were produced by a mono-sized droplet generator and were released at different heights relative to the leaf. Droplet motion and surface interactions were recorded with two ultrahigh-speed cameras and analyzed with 3-D motion analysis software. Contact angle and contact angle hysteresis were measured by the sessile drop method. Leaf surface and cuticle properties were determined through SEM and GC-MS. Leaf toughness was measured with an optical filmetrics profiler. Test results on different plant leaves were analyzed and summarized. This is a summary of the progress reports for the life time of this 5-year project which will expire 10/28/2018 and will be replaced with a bridging project: An experimental system was developed and then modified to investigate droplet dispersion and evaporation process on plant surfaces under controlled environmental conditions. A high-speed imagery system was developed and was used to determine dynamic effects of spray characteristics on spray impact, retention and coverage onto plant leaves. A database was established for the evaporation rate, retention rate, spread factor and chemical residual pattern coverage area of individual droplets with different chemical formulations on waxy, semi-waxy and hairy leaf surfaces. Systematic investigations of the dynamic impact, retention, rebound, spread pattern and evaporation and absorption process of pesticide droplets on leaf surfaces have developed new knowledge of relationships between pesticide delivery systems and biological effects on the pest management. The accomplishments have established scientific approaches to quantitatively elucidate the fate of droplets on different plant surfaces, and demonstrated that spray applications for optimal biological effect must be specifically tailored for different plant surfaces and spray systems. An intelligent spray control system was invented as a retrofit kit for conventional air-assisted sprayers to implement variable-rate functions. Field tests for sprayers with and without intelligent decision control modes were conducted to compare spray deposition uniformity inside canopies, spray volume and off-target losses for the plants at different growth stages in nurseries, orchards and vineyards. Effectiveness of the new intelligent sprayer to control pests was also investigated for specialty crop production. The experimental intelligent variable-rate sprayer technology was developed to control spray outputs to match canopy presence, size, shape and leaf density in real time. The accomplishments have demonstrated the new technology could reduce pesticide use by 46% to 70%, reduce airborne spray drift by up to 87%, and reduce spray loss on the ground by 68% to 93%, resulting in significant cost savings and environmental stewardship for specialty crop production. Continuous discovery of this technology will ultimately lead to the new generation of pesticide application equipment and strategies to achieve real cost benefits to producers, consumers and the environment, and safer and healthier conditions for workers and public. A light small-scale delivery system was developed and tested to apply nematode-infected cadavers as biological insecticides to limit pest insect populations in the soil. A sophisticated device integrated with a environmentally-controlled system was developed to investigate release rates of pheromone dispensers as biological pesticides to control forest pest insects. Investigation and development of application systems to efficiently deliver bio-pesticides have increased growers’ flexibilities to choose alternative pest control bio-products to enhance efficacy and reduce production costs with minimal environmental impact.

1. Precise manipulation of variable-rate sprayer outputs. Successful use of precision pesticide sprayers is of great importance to ensure a bountiful and high quality of plant products in crop production. Development of variable-rate sprayers capable of delivering variable amounts of pesticide to match crop structures has gained great attentions recently. To achieve variable spray rates, nozzles used on sprayers are manipulated by pulse-width-modulated solenoid valves. However, flow rates of these nozzles vary with operating pressures when the sprayers are discharging variable outputs. In this research, variations in the total flow rate of multiple solenoid valve controlled nozzles were quantitatively determined, and two-variable linear regression equations for the total flow rate with number of active nozzles were established to predict spray outputs under varied and constant pressure conditions. Consequently, this information will be used to develop a feedback control system for future intelligent sprayers to further improve their chemical delivery accuracy.

2. Characterization of biological pesticide deliveries. Efficient delivery of biopesticides is one of the most challenging processes in their applications and requires different application systems to achieve effectiveness. Hydraulic nozzles were investigated to address the question whether they could provide high spray quality for newly released biopesticides on targets. Test results demonstrated that droplet sizes and spray pattern widths varied significantly with the biopesticide class, nozzle type, and nozzle flow capacity. Based on the findings, biological control evaluations were recommended to verify the effectiveness of these biological pesticides discharged through flat-fan pattern nozzles under field conditions. A scientific basis was also constructed for choosing nozzles and operating parameters that could efficiently and effectively deliver biopesticides with controlled spray application characteristics. Consequently, these practical strategies will assist growers to choose convenient and inexpensive spray systems to apply selective biopesticides for crop protection without risks of accumulation of pesticides in the environment.

3. Decision support systems for nursery plant disease and insect management. Decision-support systems are tools that can help growers to choose pest management options to make spray decisions. To date, no decision-support systems have been developed to aid in the management of pest insects and diseases for commercial nursery production. As the development and implementation of decision-support systems takes considerable time and resources, four decision-support systems originally developed for orchards were reviewed and proposed for their capacity to be adapted for use in commercial nursery production. Additionally, the development of a consensus forecast model was proposed by combining the information generated from multiple independent models into a single spray-decision recommendation. The model will assist nursery managers, extension agents, consultants, and other agricultural clientele in the management of plant diseases and insect pests to solve problems under complex and uncertain conditions.

4. Computer simulation of spray droplet movements in orchards. Assessing the spray deposition quantity on target trees in orchards can assist to configure sprayer settings and guide application practices to increase spray efficiency and minimize drift mitigation. A comprehensive computational fluid dynamics (CFD) model was developed to simulate the movements of spray droplet clouds discharged from air-assisted sprayers through multiple rows of tree canopies in apple orchards. The CFD model accuracy was validated with experimental measurements of spray deposits inside canopies and off-target losses to the ground and air at three different growth stages. Fate and transport of spray droplets and mass balance of pesticide spray were analyzed under regular and worst scenarios of weather conditions. This CFD simulation will provide a new economic approach to predict spray deposition and off-target losses including spray drift for crops with complex architectures and leaf densities in orchards, and will provide a new approach to improve sprayer operation performance.

Review Publications
Wallhead, M.W., Zhu, H. 2018. Decision support systems for plant disease and insect management in commercial nurseries in the Midwest: A perspective review. Journal of Environmental Horticulture. 35(2):84-92.
Shen, Y., Zhu, H., Liu, H., Chen, Y., Ozkan, E. 2017. Development of a laser-guided embedded-computer-controlled air-assisted precision sprayer. Transactions of the ASABE. 60(6):1827-1838.
Wallhead, M.W., Zhu, H., Broders, K. 2017. Hyperspectral evaluation of Venturia inaequalis management using the disease predictive model RIMpro in the northeastern U.S. Agricultural Sciences. 8:1358-1371.
Zhu, H., Liu, H., Shen, Y., Zondag, R. 2017. Spray deposition inside multiple-row nursery trees with a laser-guided sprayer. Journal of Environmental Horticulture. 35(1):13-23.
Hong, S., Zhao, L., Zhu, H. 2018. CFD simulation of pesticide spray from air-assisted sprayers in an apple orchard: tree deposition and off-target losses. Atmospheric Environment. 175:109-119.
Yeary, W., Fulcher, A., Zhu, H., Klingeman, W., Grant, J. 2018. Spray penetration and natural enemy survival in dense and sparse plant canopies treated with Carbaryl: implications for conventional and biological control. Journal of Environmental Horticulture. 36(1): 21-29.
Hong, S., Zhao, L., Zhu, H. 2018. CFD simulation of airflow inside tree canopies discharged from air-assisted sprayers. Computers and Electronics in Agriculture. 149: 121-132.
Cui, S., Ling, P., Zhu, H., Keener, H. 2018. Plant pest detection using an artificial nose system: A review. Sensors. 18(2):378-396.