Dispersal and deposition of pollen of creeping bentgrass (Agrostis stolonifera L.) was estimated through the use of CALPUFF, a complex model originally developed to simulate dispersal of particulates and other air pollutants. Rate and diurnal pattern of pollen emission, as well as pollen survival characteristics, were determined in field experiments. Peak pollen emission rates were 0.2 to 5 X 106 pollen grains per min per m2 of a bentgrass stand. Peak pollen emission occurred between 10 AM and noon. Pollen survival under outdoor conditions was well described by a negative exponential, with 1% surviving for 2 h and none for 3 h. CALPUFF simulations produced deposition of 100,000 viable pollen grains per m2 at distances of 2 to 3 km from the source field, and deposition of 1 pollen grain per 10 m2 at distances of 4.6 to 6.7 km from the source field. Amount, extent and pattern of simulated deposition varied with weather conditions and, to a lesser extent, source field size. Simulation of a dust devil scenario, in which a small thermal vortex lifted pollen from the field, produced deposition of 1 pollen grain per m2 and 1 grain per 10 m2 at distances of 9.5 and 15.3 km, respectively, from the source field. Fertilization rates can not be estimated directly from pollen deposition estimates, because fertilization also depends on pollen competition at the recipient plants. However, the deposition modeling results suggest that pollen-mediated gene flow is likely at distances of at 2 to 3 km from a source field, and possible at distances of 15 km or more.
