Heuberger, Shannon Ellers-Kirk, Christa E. Tabashnik, Bruce Carrière, Yves Diagram of rings drawn around a hypothetical cotton field. <p>The first ring is 250 m from the field edge, and each subsequent ring increases in radius by 250 m. The area of non-Bt and Bt cotton was measured at each increasing scale. Light and dark gray represent non-Bt and Bt cotton, respectively, and the black rectangle represents a monitored non-Bt cotton field. For actual monitored fields, some rings overlapped those of nearby monitored fields.</p> rings;drawn;hypothetical 2013-02-20
    https://plos.figshare.com/articles/figure/_Diagram_of_rings_drawn_around_a_hypothetical_cotton_field_/486061
10.1371/journal.pone.0014128.g001