Predispersal seed predation of Amaranthus spp. and Chenopodium album (L)
Field studies were conducted during 1997 and 1998 to determine the role of predispersal weed seed predators in corn fields and to investigate the influence of corn row width and planting density on predispersal weed seed predation levels. 'Amaranthus' spp. ('A. retroflexus ' (L.) and 'A. powellii' (S. Wats) mixture) and ' Chenopodium album' (L.) were used as test weeds. Row width spacings used were 37.5cm. and 75cm while planting densities ranged from zero to 100,000 plants ha-1. Predispersal seed predation did occur in both groups of weeds with predation averages ranging between 0 and 40% for ' Amaranthus' spp. across both years and between 0 and 2% for ' C. album' in 1998. 'Coleophora lineapuvella' (Chambers) was observed to be the predominant seed predator of 'Amaranthus' spp. The predominant seed predator of 'C. album' was not confirmed. Seed predation of 'Amaranthus' spp. seed was higher in 37.5cm rows at low to moderate planting densities, while predation levels dropped to low levels for both 37.5cm and 75cm rows in high planting densities. PPFD transmittance was an environmental factor influencing the levels of seed predation below the canopy. Corn planting pattern did not effect levels of ' C. album' predispersal seed predation.