Common Cocklebur (Xanthium strumarium L.) is an emerging aggressive & invasive weed in crop fields in the Khyber Pakhtunkhwa (KP) Province of Pakistan. Among the crops, maize has been severely affected by X. strumarium in the region. In order to evaluate the competitive ability of X. strumarium in maize, field experiments were conducted at Agricultural Research Farm, KP Agricultural University Peshawar, Pakistan during 2006 and 2007 using a Randomized Complete Block Design with split plot arrangement, replicated three times. The main plots comprised of four varying maize densities: 5, 7.5,...