In Nagano Prefecture, naturalized Brassicaceous weeds, Camelina microcarpa Andrz. ex DC., Descurainia sophia (L.) Webb ex Prantl and Thlaspi arvense L., have infested single-crop rotation wheat fields. We investigated wheat yield loss and emergence pattern in the infested fields and examined the effects of delayed seeding and selected herbicides on three weed species to establish control methods. Wheat yield decreased by about 25% in the presence of C. microcarpa and by 45% with D. sophia and T. arvense. Plant number of the three weed species peaked one month after wheat seeding in the region where snow covers the ground for two months. Whereas in the region having only a few snow days, C. microcarpa plant number peaked one month after seeding, D. sophia peaked during the winter, and T. arvense peaked one month after seeding and had a second flush after over-wintering. Delayed seeding remarkably decreased the emergence of all three weed species; however, D. sophia and T. arvense suppression was insufficient in the region with the shorter snow season. PRE application of diflufenican herbicides effectively controlled all three weed species. Residual D. sophia and T. arvense weeds in February were effectively suppressed with a foliar application of thifensulfuron-methyl.