Impact of drilling date on Apera spica‐venti L. and Alopecurus myosuroides Huds, in winter cereals

Summary The impact of drilling date on Apera spica‐venti and Alopecurus myosuroides in winter cereals was investigated in field trials in 1991 and 1992. Two drilling dates were considered with an inter val of 14 to 16 days between dates. Generally, drilling date had an inconsistent effect on weed plant populations in spring, but seedling emerg ence of both species appeared to be delayed at the later drilling compared with the earlier date. This delay may partly explain the reduced com petitive ability of A. myosuroides in wheat in 1991 and 1992 and of A. spica‐venti in wheat in 1991 at the later drilling date. The seed popula tion per plant of both species was lower at the later date in some instances, whereas in others drilling date had no effect. Reduced seed produc tion was mainly caused by a reduction of the number of inflorescences per plant. The poten tial of utilizing drilling dates as a cultural control measure against grass weeds is discussed.