TY JOUR TI EFFECT OF CRUDE OIL CONTAMINATION ON SPRING RAPE VULNERABILITY BYDOWNY MILDEW IN FOREST GRAY SOIL KW gray forest soil KW crude oil contamination KW spring rape KW contamination level KW downy mildew KW disease abundance and development KW yield JO Vestnik of Kazan State Agrarian University AU Osipova, R.A. AU Gilyazov, M.. PY 2021 IS 16 PB Kazan state agrarian University