A method of applying stretch film wrapping to an agricultural bale (10) which is of rectangular cross section and using a bale wrapper apparatus which comprises: a table which supports the bale (10) and which operates to rotate the bale generally about its longitudinal axis (11) during a wrapping cycle; a dispenser reel arrangement (12, 13, 16, 17, 20, 21, 24, 25) from which stretch film wrapping is withdrawn so as to form successive overlapping windings of film which cover the bale; and means which applies relative rotation between the table and the dispenser reel arrangement about a second axis (14) which extends substantially perpendicular to said first axis during the wrapping cycle; in which: each winding of film includes a longitudinal edge strip portion and an adjoining longitudinal strip portion; and the longitudinal edge portion has different deformation properties from the deformation properties of said adjoining portion so as to be more readily extensible under a given load than said adjoining portion, and thereby to enable the winding to tighten itself around each corner (15) of the bale (10) and thereby at least minimize the generation of creases or wrinkles in the film winding at each corner region of the bale.