At twice the canopy height, the pollen concentration decreased considerably to about 30% of the canopy height
values. During the mornings, pollen was emitted in large quantities while during the afternoons, airborne pollen concentrations decreased and no significant atmospheric pollen was measured from about 2 h prior to sunset until sunrise the next morning. The actual time that airborne pollen was first recorded differed from day-to-day and depended on the time required for the anthers to dry and open, as well as there being sufficiently strong winds to entrain the pollen away from the plants