Spray Drift from Three Airblast Sprayer Technologies in a Modern Orchard Work Environment

Area of Science:

• Agricultural Engineering
• Environmental Science
• Occupational Health

Background:

• Pesticide spray drift is a major exposure route for orchard workers, leading to potential illnesses.
• Conventional axial fan airblast (AFA) sprayers, used since the 1950s, face challenges in balancing spray coverage and drift reduction.
• Emerging sprayer technologies aim to mitigate drift while maintaining efficacy in modern orchards.

Purpose of the Study:

• To compare tracer-based pesticide drift volume levels between conventional axial fan airblast (AFA) sprayers and newer airblast tower sprayers.
• To evaluate the effectiveness of directed air tower (DAT) and multi-headed fan tower (MFT) sprayers in reducing drift in orchard environments.
• To assess the potential of new sprayer technologies to meet regulatory standards for drift reduction.

Main Methods:

• Conducted comparative spray trials using tracer-based measurements in an orchard setting.
• Employed mixed-effects modeling to analyze drift volume data collected from polyester line samples on vertical masts.
• Compared drift levels at mid (26 m) and far (52 m) downwind distances for AFA, DAT, and MFT sprayers.

Main Results:

• The DAT and MFT sprayers exhibited 4-15% and 35-37% less drift, respectively, compared to the AFA sprayer.
• Statistical analysis confirmed that the MFT significantly reduced drift by 35% (P < 0.001), while the DAT showed no significant reduction (-7%, P = 0.29).
• Findings suggest MFT performance aligns with the US EPA's Drift Reduction Technology (DRT) one-star rating criteria.

Conclusions:

• Tower sprayers, particularly the MFT, show promise in decreasing pesticide drift due to directed airflow and reduced aerosol escape.
• Adoption of new technologies like MFT can lower the incidence and severity of pesticide drift exposures and related worker illnesses.
• Complementary strategies, including applicator training and application exclusion zones, are essential alongside technological improvements to minimize drift risks.