Effects of wheat residues on dicotyledonous weed emergence in a simulated no-till system

It is presently not known what effect wheat root residues have in regulating dicotyledonous (dicot) weed emergence in no-till management systems. past research has focussed almost entirely on the role of shoot residues, while the role of root residues in weed control has been essentially ignored. This field study was designed to determine the respective effects of wheat shoot and root residues in regulating the emergence of three dicotyledonous weed species (morning-glory, pigweed and prickly sida). Glyphosate desiccated wheat plots and fallow plots were surface seeded with morning-glory, pigweed and prickly sida during the spring of 1996 and 1997. Weed seedling emergence was determined for two months during each experimental period in plots with or without wheat shoot and/or root residues. The resulting data suggested that: a) the closer desiccation of the wheat cover crop Occurred to the initial emergence of pigweed seedlings, the lower the emergence of that weed, b) the effects of wheat shoot and/or root residues on dicot weed seedling emergence vary considerably for the different weed species ranging from stimulation to inhibition and c) the role of root residues appear to be much more important to regulating weed emergence than that of surface shoot residues, Differences in soil moisture and temperature associated with the presence or absence of wheat residues could not be used to explain the observed treatment effects.