Studies were aimed at evaluating the dates of appearance and intensification of major developmental stages of barnyard grass plants sown into the fodder beet, spring wheat, and faba bean canopies with mechanical and herbicide weed control. The field experiments were conducted in 2000–2002 on specific silt soil developed from light loam. It was localized in Zakrzów within Tarnobrzeg city limits. Phenological observations consisted in recording the appearance date of the following barnyard grass phonologic stages in 10-day intervals starting from the sowing date: emergence, panicle formation, flowering, fruiting, and fruit shedding. In addition, during the crop plant harvest, fruiting and fruit shedding intensities were accompanied by the percentage values. Agrotechnology for the plant was typical. Objects with herbicides were treated using the following agents: fodder beet – Buracyl 80 WP (lenacyl 80%) at 1 kg.ha-1 rate, spring wheat – Chwastox Turbo 340 SL (MCPA 30% + dicamba 4%) at 2 l.ha-1 rate, and faba bean – Afalon 50 WP (linuron 50%) at 1.5 kg.ha-1 rate. For fodder beet and faba bean, herbicide were applied just after the sowing, while spring wheat was treated at full tillering stage. Herbicides were sprayed using field sprayer working under 0.25 MPa pressure.
It was revealed that the appearance date and the advancement of studied phenological stages of barnyard grass depended on crop plant species, type of weed control, as well as weather conditions during the study. Application of soil herbicides delayed barnyard grass emergence from 10 (fodder beet) to 20 days (faba bean). Herbicides decreased the number of shed plants in faba bean and spring wheat canopies, but they invoked opposite results in fodder beet.