Competition of late-emerging weeds with sugarbeets.
Weed-free sugar-beets growing at a spacing of 60 cm (half the normal stand) yielded the same weight of roots as those spaced 30 cm (full stand) while those spaced 90 cm (1/3 normal stand) yielded about 90% as much. Annual weeds that emerged after 1 July were suppressed and killed by competition from sugar-beets of normal vigour in a full stand but became competitive when the sugar-beets were spaced at half or one-third of the full stand. Competition from Echinochloa crus-galli and a mixture of Amaranthus retroflexus and A. powellii (which reached a height of 150 cm) reduced root yields by 5-39% in the half stands and by 19-49% in the one-third stands compared with weed-free sugar-beets in the same stand. Solanum sarachoides was also abundant but did not grow higher than the crop and had no measurable effect on yields. From summary.