Research of critical period for cotton intercropped
with maize to weed competition was
conducted in Grobogan, Central Java in crops
season 2002/2003. The purpose of this research
was to identify the critical period of cotton
intercropped with maize to weed competition.
The ten weeding periods were arranged in
Randomized Block Design with three replications.
Ten weeding periods were: 1). weedy
free first 2 weeks, 2). weedy free first 4 weeks,
3). weedy free first 6 weeks, 4). weedy free first
8 weeks, 5). weedy free full season, 6). weedy
first 2 weeks, 7). weedy first 4 weeks, 8). weedy
first 6 weeks, 9). weedy first 8 weeks, and 10).
weedy full season. The results showed that the
species of weed in cotton intercropped with
maize were Echinochloa colonum, Cynodon
dactylon, Amaranthus sp, Ageratum conyzoides,
Portulaca oleracea, Phylanthus niruri, and
Digitaria sp. The critical period of cotton
intercropped with maize to weed competition
was found at 6–8 weeks after planting. Weed
control for cotton and maize intercropping have
to be done from six to eight weeks after
planting.