Location: Pollinator Health in Southern Crop Ecosystems Research
Project Number: 6066-21000-001-026-T
Project Type: Trust Fund Cooperative Agreement
Start Date: May 1, 2023
End Date: Oct 31, 2024
Objective:
1. To estimate the pesticide and adjuvant exposure to insect pollinators from spray drift.
2. To analyze the droplet spectrum of different spray nozzles and estimate their potential to control spray drift.
Approach:
Eight experimental cotton plots measuring 100’ x 100’ will be set up. Two wildflower plots of 20’ x 400’ on two sides of cotton plots (20% of the area of cotton plots) will be established to capture pesticide spray drift and analyze the pesticide and adjuvant exposure to insect pollinators. We will sow a mixture of wildflower seeds in the wildflower plots. Two plots of 20’ x 400’ (20% of the area of cotton plots) will be planted with conventional corn/soybean to visually look at how far the spray drift goes. We will plant cotton in the middle of May and harvest it by late October. The crop will receive one preemergent herbicide and two postemergent herbicide applications. Three to four insecticide applications are planned. Of these, one/two pesticide applications will be carried out using aerial delivery (by commercial ag pilots) depending on availability. Water-sensitive cards will be used to collect data on spray drift. We also plan to collect drifted droplets less than 50 microns using a filter paper/cloth/wire mesh sampler that will be placed at different heights in the downwind direction. The data collected on water-sensitive cards will be analyzed with DepositScan software, which provides results on the tank mix deposited per unit area (µL/cm2) of card and parameters such as DV10 (the diameter for which 10% of the total spray volume is made up of droplets of equal or lesser diameter), DV50, DV90, relative span, % coverage along with the diameter of each droplet deposited on the water-sensitive card. The quantity of pesticides/adjuvants deposited on the flowers will be estimated based on (i) weight and (ii) using the established standard operating procedure to recover the pesticide/adjuvant from the collection medium. A similar approach will be followed for the finer drifted droplets (<50 µm diameter) collected on filter paper/cloth/wire mesh. Instantaneous weather observations will be monitored using the Vantage Pro2 weather station and related to spray drift.
To test the medium droplet size nozzles and air induction nozzles in the lab, we will use the spray chamber setup (DeVries Manufacturing, MN). The spray chamber setup has an automated travel and spray system. However, the travel speed, spray height, and nozzle type can be changed. We plan to use a P15 image analyzer (Oxford Laser, UK) to look at the droplet spectrum. Several typical medium droplet size and air induction spray nozzles used in tractor booms will be procured. They will be mounted in the spray chamber one after the other and tested for spray pattern and droplet spectrum for different pressures, travel speeds and spray heights. The P15 image analyzer with the spray chamber provides information on DV10, DV50, DV90, relative span and droplet velocity. For field testing of nozzles, we have a dedicated 45-gal tank sprayer that can be mounted on our Kubota gator. We have access to a wide variety of boom sprayers mounted in tractors.The drift potential of each nozzle will be analyzed by looking at the droplet spectrum data collected in the spray chamber testing. In the field, the drift potential will be analyzed based on the data collected in the water sensitive card/mylar.
