A Flow Visualization Study of Spore Release Using a Wind Tunnel-Mounted Laser Light Sheet.

Area of Science:

• Fluid dynamics
• Plant pathology
• Aerobiology

Background:

• Understanding airflow around plant leaves is critical for predicting pathogen dispersal.
• Previous studies have lacked detailed analysis of the micro-scale flow fields influencing spore detachment.

Purpose of the Study:

• To investigate the aerodynamic flow field surrounding individual healthy and diseased plant leaves.
• To identify vortex structures responsible for spore separation and downwind transport.

Main Methods:

• Utilized a phase Doppler anemometry system with a laser light sheet in a recirculating wind tunnel.
• Generated a turbulent boundary layer using a grid and introduced plant leaves (healthy and diseased).
• Captured and processed video of Mie-scattered light from spores using image processing software for velocity calculations.

Main Results:

• Identified three primary vortex regions around the leaf structure.
• Quantified spore velocities and analyzed their detachment dynamics.
• Correlated vortex regions with the efficiency of spore separation and downwind movement.

Conclusions:

• The identified vortex regions play a significant role in the aerodynamic detachment of spores from diseased leaves.
• This research provides a foundational understanding for modeling airborne pathogen spread in agricultural settings.