Maize crop is the most important income source to small farmers in Maranhão state due to natural consumption of spikes during whole year. However, there is few information about of weeds interferences in corn, as well as appropriate period of control. The aim of this study was to identify main weeds and to determine periods of interference in culture of green corn Al Bandeirante. The experiment was conduct in randomized complete block design with four replications in 2017. The treatments consisted of 11 growing periods of control and coexistence with weeds from planting: (0, 0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56, 0-63, 0- 70). During this periods were identified and analized crop productivity and its interference (FATHER), total period of interference prevention (PTPI), also critical period of interference prevention (PCPI). Thus, the most important weeds identified in green corn crop were Cyperus spp, Panicum trichoides, Spermacoce latifolia, Mitracarpus hirtus. As a result, the FATHER was at 16 DAE, PTPI occurred at 6 DAE, and there was no PCPI. Therefore, control of species identified in this study should be performed in any time, between emergency and 16 days of corn cycle in São Luís city, Maranhão state.