Pre- and post-dispersal weed seed predation and its implications to agriculture

We investigated pre- and post-dispersal seed predation to determine whether they would reduce weed seed populations and whether the intensity of preda tion could be manipulated by altering tillage or cultural practices. Both p re- and post-dispersal predation significantly decreased weed seed density. Pre-dispersal predation was variable and reduced seed production of Amaran thus retroflexus and A. powellii by 3 to 40% in 1998. Post-dispersal predat ion reduced seed density of Echinochloa cnrs-galli and Chenopodium album by 3% per day. The combination of pre- and post-dispersal seed predation may therefore be a significant broad-spectrum form of biological weed control. Furthermore, these high levels of predation may account for some of the pat chiness observed in the distribution of annual weeds. This has implications for precision agriculture which focuses primarily on soil characteristics to explain weed distribution.