Table 1: Environmental conditions and plant size for preemergence and postemergence applications for field research in 2002 and 2003.

Application 2002 2003 Preemergence      Date 19 April 2 May  Air temperature (°C) 22 18  Soil temperature (°C) 18 16 Postemergence      Date 6 June 27 June  Height (cm) 5–25 5–20  Leaf number 6–10 4–12  Population (no/m2) 419–586 382–528  Cloud cover (%) 5 8  Relative humidity (%) 33 57  Air temperature (°C) 30 25