The residual effects of clomazone, metazachlor and their mixtures on re-sown crops were studied in field experiments carried out during 1997-2000 on leached brown soil in Poland. Two-factor experiments were established in 4 replications for the following crops. The treatments consisted of herbicides and the method of pre-sowing soil tillage (pre-sowing ploughing or reduced soil tillage). In autumn, after sowing of winter oilseed rape, Command 480 EC (clomazone) was applied to soil at 0.2 litre/ha (96 g a.i./ha) alone and as a mixture with Butisan 400 SC (metazachlor) at 2.5 litre/ha (1000 g a.i./ha). Butisan 400 SC was applied twice at 1.5 litre/ha (600 g a.i./ha) at the cotyledon stage of weeds. The following crops were re-sown in spring: spring barley, spring wheat, oat, pea and sugarbeet. The frosty winter enhanced the residual effects of the herbicides on the re-sown crops, injuries were much more visible, and the yields of the re-sown crops were decreased. Generally, reduced tillage presown harrowing with disc harrowing did not affect the phytotoxicity of the herbicides. Oat was as susceptible to the herbicides as the other spring cereals.
