Project Number: 3607-21620-008-00
Project Type: Appropriated

Start Date: Dec 11, 2008
End Date: Dec 10, 2013

Objective:
Develop precision sprayers that can continuously match canopy characteristics to deliver agrichemicals and bio-products accurately to nursery and fruit crops. Identify and characterize factors that have the greatest impact on foliar pesticide spray application efficiency: determine how water droplets amended with spray additives, relative humidity and the morphological surfaces of leaves affect the droplet evaporation time, spread factor and residual pattern on leaves; determine how the droplet size and velocity, spray formulation, and morphological surface of leaves affect spray impact, retention and coverage. Identify and evaluate agrichemicals and bio-products that can be precisely delivered through drip irrigation systems.

Approach:
Precision sprayers with wide range controllable flow rate, multi-jet nozzles will be developed to reduce the amount of pesticides required by matching spray characteristics to specific types of ornamental nursery and fruit trees. Fast response, high resolution, non-contact sensors will be used to detect the plant size, shape, density and position. Based on the plant structure data from the sensors, air velocity, spray application rate and number of jets will be determined to control the spray outputs as needed. All these operations will occur as the sprayer moves past the plant, providing uniform spray coverage with minimum off-target loss. Evaporation time, spread factor and chemical residual pattern area of individual droplets containing spray additives on leaves will be measured via sequential imaging under controlled conditions. Droplets will be placed inside an environmental-controlled chamber under a stereomicroscope and a high definition digital camera. A large database will then be developed including droplet evaporation time, and deposit pattern area on leaves with different surface characteristics, droplet sizes, chemical formulation components, and relative humidity conditions. A laboratory system will be developed to determine dynamic effects of spray characteristics on spray impact, retention and coverage on fine surface structure plants. All individual pesticide spray application variables will be controlled under laboratory conditions. The system contains a turntable, a mono-disperse droplet generator and uniform air carrier to deliver droplets onto leaves or selected polymer targets with defined surface properties. Droplet impact and rebound velocity will be measured with a particle/droplet laser image analysis system. A cold field emission scanning electron microscope (CFESEM) and a variable pressure scanning electron microscope will be used to determine leaf surface fine structure, droplet coverage area, residue deposit form and composition, and distribution of active ingredients on leaf target surfaces. Variables will be droplet size, droplet velocity, travel speed, type of liquid formulation, physical properties and concentration of spray additives, leaf orientation, leaf deformation, leaf wax and leaf roughness. Relationships among the spray droplet retention, distribution and coverage area on leaf surfaces with the variables will be determined and documented in a large database as a guideline to choose the optimum operational parameters. An engineering testing system for delivering agrochemicals and bio-pesticides through drip irrigation will be developed. All individual delivery variables will be controlled in the system. The distribution uniformity of agrochemicals and bio-pesticides with different physical properties and particle sizes throughout drip lines and in the soilless substrates and soil will be investigated. Tests will also include determination of emitter sizes and amounts of water needed to diffuse bio-pesticides in the soilless substrate in various size containers. A new injection unit will be developed to precisely deliver suspendable bio-pesticides through drip irrigation.