Location: Application Technology Research2016 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.
Data was analyzed for the evaluation of commercially available esterified seed oil surfactant and petroleum oil surfactant reported in the 2015 progress report. These surfactants were tested for modifying spread areas and fading times of water and herbicide droplets. A manuscript was written to report the findings and was published in a scientific journal. Direct measurements of foliar uptake rates of sessile water droplets at various locations on waxy leaf surfaces reported in the previous progress report were analyzed and summarized. A manuscript was written to report the findings and was published in a scientific journal. Data collected for the dynamics of impact and spread of water droplets on soybean leaf surfaces reported in the previous progress report were analyzed and summarized. Variables included droplet diameters ranging from 185 to 693 µm, impact speeds from 1.85 to 6.4 m s-1, impact angles from 28 to 75°, and two soybean leaf surface orientations (horizontal and 30° inclination). Investigations were conducted with two high-speed digital video cameras and a mono-sized droplet generator under laboratory-controlled conditions. A manuscript was written to report the findings and was published in a scientific journal. Spray additives including spreader stickers, activator, surfactant oil concentrate, and silicone surfactant were evaluated to improve spread areas and fading times of water and pesticidal droplets on Cucurbitaceous leaves and aluminum discs. The aluminum discs were used as a control. Tests were conducted with 450 µm sessile droplets at ambient temperature of 32°C and relative humidity of 30%, 50% and 70% inside a controlled environmental chamber. The sessile droplets were produced with a single-droplet generator. Images of the sessile droplets on leaf surfaces and discs were acquired through an image acquisition unit. The coverage area of a droplet on the leaf surface following deposition was analyzed with an image analytical program. Droplet fading times were computed using the timed interval and the total number of sequential images from the start of droplet deposition to its disappearance. Comparisons of spray deposition and coverage inside tree canopies discharged from a newly developed intelligent sprayer and a conventional air-blast sprayer were conducted in an ash tree field. Spray drift and ground loss at five different distances from the tree row sprayed by the intelligent and conventional air-blast sprayers were also investigated. Nylon screens, water sensitive papers and plastic plates were used as artificial targets to quantify spray deposits, coverage, airborne spray drift, and ground loss. A fluorescent tracer was mixed with water to quantify the amount of spray deposits on the artificial targets. Field tests were conducted for a newly developed laser-guided air-assisted variable-rate sprayer to control aphids, pod gall midges, and pear sawflies on crabapple, honey locust and cherry trees, respectively in three commercial nurseries in Ohio and Oregon. Efficacy of pest control treatments applied by the laser-guided sprayer was compared with those from two conventional air-assisted tower sprayers and an axial-fan radial air-blast sprayer. During the tests, the spray volume discharged from the laser-guided sprayer was adjusted automatically based on the plant presence, canopy volume and foliage density. The application rates for the conventional sprayers were determined with the tree row-volume method to comply with best pest management practices. A sophisticated strategy was developed to integrate intelligent spray control functions onto conventional sprayers based on the success of previous intelligent sprayer development. The critical component of the strategy was the versatile algorithm that was able to comply with a high-speed laser scanning sensor, a non-contact Doppler radar travel speed sensor, a custom-designed nozzle flow rate controller, and an embedded computer to control outputs of individual nozzles on conventional air-assisted sprayers. A computer program was written in C++ language for the algorithm to determine the presence of a tree canopy, map the canopy structure, estimate the foliage density, calculate the sectional canopy volume and spray volume designated to individual nozzles, and manipulate variable numbers of nozzles to discharge variable spray rates to match tree structures. As a result, the flow rate of each nozzle was automatically optimized to cover different parts of canopies at different travel speeds in real time. Release rates of two types of spruce budworm lures were measured with an environmentally-controlled precision system at ambient temperatures of 20, 25, 30, 35 and 40 °C and relative humidity of 50%. The measurements will be used for future development of mathematical models to precisely manage spruce budworm lures.
1. Determination of effective combinations of herbicides and spray additives to control paddy melon weeds. Paddy melon is an exotic weed and a major competitor of crops for water and nutrients in semi-arid areas. Various practices with combinations of herbicides and surfactants have been recommended to control paddy melons, but it is unclear if these practices are efficient and effective. In this research, ARS researchers at Wooster, Ohio investigated deposition patterns and fading times of herbicidal droplets with different formulations on weed leaves at a microscopic level. Test results demonstrated that droplet coverage areas were increased by over 2.3 times with addition of the seed oil surfactant into the water-only solution but were not affected with addition of the petroleum oil surfactant. Both seed oil surfactant and petroleum oil surfactant enhanced the droplet penetration into plant tissues while the former could have slower evaporation rates for better droplet transport to targets under hot and dry weather conditions. Knowing these behaviors of droplets on weeds will assist to develop better application practices for utilization of systemic herbicides to increase foliar application efficiency.
2. Determination of the most efficient fertilizer practices and nutrient applications to produce fast container-grown trees with low nutrient leaching. Because of vast varieties and species in nurseries, scientific guidelines are lacking for growers to improve their nutrition practices based on their specific production circumstance. Fertilizer practices with topdressing, incorporating and liquid feeding methods can cause substantial labor cost and excessive nutrient drainage loss. To provide solutions to this problem, ARS researchers at Wooster, Ohio compared 16 fertilizer practices and nutrient applications by determining the tree growths and the amounts of nutrient leachate (N, P, K, EC, pH) for the Acer rubrum grown in above- or below-ground containers and irrigated with city water or recycled and buffered pond water. The comparison also included fertilizer practices with fertigation and with the container substrate that had nutrients incorporated, top-dressed or both with two slow-release granular fertilizers. Test results demonstrated that shortening tree production time and saving labor costs with minimum nutrient leachate could be achieved by maximizing the one-year growth of container-grown trees through the optimal fertilizer practices.
3. Direct measurement of foliar uptake rates of water droplets on waxy leaves to improve systemic pesticide efficiency. Knowledge is lacking on the plant cuticle permeability of systematic compounds to control target pests. In this research, ARS researchers at Wooster, Ohio pioneered a direct measurement of foliar uptake rates of droplets at various locations on waxy leaf surfaces with their sophisticated unique controlled environmental system. They discovered that droplets penetrated leaf tissues after they were deposited on leaves while remained unchanged on a non-permeable glass. Foliar uptake time varied with droplet size, droplet deposition location on leaves, and diurnal period, but varied little with osmotic pressure and stomatal density. These discoveries will assist researchers and spray applicators to properly select chemical doses and spray additives to improve pesticide application efficiency.
The floral and nursery grower industry needs timely weather data to aid decision making in crop management and protection. This information also benefits small farms and nurseries with less than $250,000 annual gross receipts. Research weather stations have been developed and upgraded cooperatively with The Ohio State University/Ohio Agricultural Research and Development Center and commercial nurseries in northern Ohio. Web pages have been developed to report charts on wind speed and azimuth, solar radiation, atmospheric temperature and relative humidity, precipitation, leaf wetness, barometric pressure, soil temperatures, soil moisture contents at depths from 10 to 100 cm below the soil surface, and interrelationships among variables related to leaf wetness. In addition to application technology research, data and summaries are available in real time to the grower industry via web sites to aid in crop management and protection decisions and irrigation scheduling.
Hadlocon, L., Zhao, L., Wyslouzil, B., Zhu, H. 2015. Semi-mechanistic modelling of ammonia absorption in an acid spray wet scrubber based on mass balance. Biosystems Engineering. 136:14-24.
Gao, J., Zhu, H., Horst, L., Krause, C.R. 2015. Determination of foliar uptake of water droplets on waxy leaves in controlled environmental system. Transactions of the ASABE. 58(4):1017-1024.
Jia, W., Zhu, H. 2015. Dynamics of water droplet impact and spread on soybean leaves. Transactions of the ASABE. 58(4):1009-1016.
Zhu, H., Zondag, R., Merrick, J., Demaline, T., Krause, C.R. 2015. Nutrient leaching from container-grown ornamental tree production. Journal of Environmental Horticulture. 33(2):76-83.
Zhu, H., Lin, J. 2016. Coverage area and fading time of surfactant-amended herbicidal droplets on cucurbitaceous leaves. Transactions of the ASABE. 59(3): 829-838.