Effects of tree and crop residue mulches and herbicides on weed populations in a temperate agroforestry system

Field studies were conducted in southern Ontario in 1994 and 1995 to (1) compare and evaluate the influence of poplar-leaf (Populus spp. DN 177) and wheat-straw (Triticum aestivum L.) mulches and herbicides (glyphosate and imazethapyr) on weed suppression and emergence patterns in tree rows of a temperate intercropped plantation and to (2) document the relative abundance, life cycles and distribution of weed species in four tree-based intercropped fields in southern Ontario.;Wheat-straw mulch application significantly reduced weed emergence and biomass over poplar-leaf mulch in roto-tilled and no-till plots, in both years of the study.;Glyphosate reduced perennial weed populations by 70%. Imazethapyr was the most effective in reducing both weed emergence and biomass.;The most 'widespread and abundant' weed species recorded in the survey included Taraxacum officinale Weber., Elytrigia repens (L.) Beauv., Trifclium spp., Erigeron spp., Cerastium vulgatum L., Panicum capillare L., Setaria spp. and Chenopodium album L.