Abstract

The phenology and growth of A. theophrasti in competition with cotton, and the influenced of weed sowing time and
weed plant density on phenology and growth were examined in several field studies conducted over the period
2000–2002. A. theophrasti was found to produce three cohorts that emerged in a staggered manner from April 21 to
June 20. The first cohort emerged simultaneously with cotton under a plastic cover and the second by the time cotton
plants had 5–6 true leaves. Flowering in these two cohorts started at 572–594 growing degree-days (GDD), boll
ripening (stage H) at 800–885 GDD and boll drying at 1020–1037 GDD.
Velvetleaf and cotton cotyledons were formed simultaneously at all weed sowing densities. Also, plant height of A.
theophrasti increased with increasing density, whereas cotton height decreased due to shad and competition.

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