Weed seed loss due to predation in Michigan maize fields

The influence of weed seed predation by invertebrates and vertebrates was examined in relation to distance from hedgerows in maize fields of southwestern Michigan. Experiments were conducted in spring and winter and included five common weed species, i.e., velvet-leaf (Abutilon theophrasti), redroot pigweed (Amaranthus retroflexus), common lamb's-quarters (Chenopodium album), fall panicum (Panicum dichotom~florum), and yellow foxtail (Setaria lutescens). In the spring post-tillage study, treatments excluding invertebrates, vertebrates, invertebrates + vertebrates plus no exclusion controls were established at 5 and 100 m from the hedgerow. Seeds were placed into the field in trays filled with sterilized soil at low densities to avoid creating a 'super stimulus' for seed predators. The trays were placed in the field for 3-4 weeks and then placed in a heated greenhouse and seed loss was estimated from the number of seedlings that emerged. The design of the winter study was similar except that only control and vertebrate exclusion treatments were used and seeds were left in the field from December to mid-April. Significant differences among exclusion treatments were found in spring in terms of seed loss. Seed loss was lowest in the treatments that excluded both vertebrates + invertebrates and highest under no exclusion. There was some evidence of preferential predation by vertebrates upon seeds of A. retroflexus and C. album. In winter, significant seed predation by vertebrates on all species except A. retrqflexus were detected. In both seasons, seed predation was highly patchy among and within fields and there was no consistent effect of distance from hedgerow. © 1997 Elsevier Science B.V.