The objective of this work was to assess the effect of rape and black oats as cover crops on chemical weed control timing in corn under no-till. The experiment was arranged in a complete block design, with the treatments in subplots and four replications. The main treatment plots were cover crops and the subplots the chemical weed control timings, according to corn growth stages (1, 2, 3, 4, 5 and 6 leaves). Two control plots, one with and the other without total weed control were added to the experiment. Weed chemical control was performed in postemergence with the association of the herbicides nicosulfuron + atrazine (Sanson 0.8 L ha-1 + Primóleo 0.3 L ha-1). When chemical control was applied, the cover crop black oat showed to be more efficient on corn grain yield. Rape was found to require more criterion as to the correct timing for weed control, while black oat allowed more flexibility. The best time for herbicide application ranged from the corn growth stages of two to three leaves.
Avena strigosa; Raphanus sativus; mulching; no-till
