Model of creation of productive agrocenosis of Echinacea Sergey Pospelov, Viacheslav Zdor, Oleg Mishchenko, Anna Pospelova and Ninel Kovalenko E3S Web of Conf., 222 (2020) 02048 Published online: 22 December 2020 DOI: 10.1051/e3sconf/202022202048