Weediness of oil crops in various ways of main soil processing in crop rotation

During the years 1971-2011 in the stationary experiments of VNIIMK in 4 rotations of 10-year tilled crop rotation there were studied the systems of main soil processing for oil crops (sunflower, castor, soybean, winter and spring rapeseed). Since 1971 until 2004 in oil crops (sunflower, castor and soybean) the weed was controlled with the help of soil herbicide Treflan, which resulted in the spreading of weed varieties resistant to this herbicide and their number increased, especially in the variants without soil overturning. Since 2005 the use of herbicides with high-efficiency in seedling stage of oil crops (soybean, winter and spring rapeseed) facilitated the decrease in number of weed plants of these varieties. For efficient weed control in oil crops with absence of perennial offset weed it is recommended to use the system of main soil processing, consisting in moldboard plowing at depth 20-22 cm or shallow plowing at 12-14 cm for sunflower, castor, soybean, winter and spring rapeseed and surface tillage at 8-10 cm for winter wheat after oil crops.