Population dynamics of capim-colchão (Digitaria horizontalis Willd.) by soil and herbicide managements

Abstract

One experiment was carried out in Londrina, PR, Brazil, in order to evaluate soil management practices to control Digitaria horizontalis Willd. (DIGHO) in soybean crop, followed by wheat, during five years. The treatments were: 1) disk plowing (DP); 2) moldboard plowing (MP); 3) scarification plus heavy disk (SHD), and 4) no-till (NT). Except for NT, managements were completed with light harrowings. Before sowing wheat, in all managements, the soil was always harrowed with heavy disk. Subplots "with and without" postemergence herbicides were established. Exponential rates of annual reductions of DIGHO seedbank, in plots with herbicides, varied between 43.2% in DP and 52.6% in NT; estimated survival periods were about 6.2 years. Higher seed concentrations were observed annually occurring at the upper soil layer of 0-10 cm, in all managements. Emergence rates of DIGHO varied with year and management, being lower in NT and greater in the other ones. Post-emergence rates of emergence varied between 0.8% and 3.5%.