Estimation of critical period for weed control in sesame (Sesamum indicum L.) in northern Ethiopia

Abstract

A field experiment was conducted for three consecutive cropping seasons (2006, 2007 and
2008) to estimate the critical period of weed control and yield loss in sesame at Humera
Agricultural Research Center, Northwestern Ethiopia. Quantitative series of both increasing
duration of weedy and weed free periods were compared with complete weed free and
weedy check. The experimental design used was RCBD with three replications. The results
indicated that the experimental field was infested both with broadleaved (90.1%) and grassy
(9.9%) weeds. Three years pooled data revealed that, Ocimum basilicum, Corchorus trilocularis,
Corchorus orinocensis and Hibiscus trionum were among the dominant broadleaved weeds
where as Digitaria abyssinica and Digitaria ternata, were the dominant grassy weeds. Significant
difference in dry weed biomass was observed both under early and late competition periods
in all the three years. Uninterrupted weed growth caused a reduction of 82.9%, 82.5% and
86.3% in 2006, 2007 and 2008 respectively, in yield as compared to complete weed free. On the
other hand, the yield loss from weedy up to 14 and weed free up to 28 or more days after crop
emergence were less than 10% and hence, the critical period of weed control in sesame at
Humera area was found to be between 14 and 28 days after crop emergence with duration of
14 days.