WEED CONTROL Herbicide Residue Assert (imazamethabenz) may have a residue the year following application to wheat, barley or sunflower. Rotational crop restrictions for Assert are found on page 64 of the 1996 North Dakota Weed Control Guide in the table, "Rotation Restrictions for Crops Grown in North Dakota". All other rotational crops not listed can be seeded 15 or more months after application. Following rotational directions will usually result in normal growth of rotational crops; however, various environmental and agronomic factors make it impossible to eliminate all risks associated with Assert. Injury to rotational crops is always possible.