THE HARMFULNESS OF RHIZOME AND CREEPING WEEDS IN CROPS OF WINTER WHEAT AND SPRING BARLEY IN THE FOREST-STEPPE SOUTH OF THE NON-CHERNOZEM ZONE

One of the reasons for the decrease in the yield of winter wheat and spring barley is the significant distribution in the crops of rhizome and root spawn weeds. The high competitiveness of weeds is largely determined by the features of their mineral nutrition. The accumulation of K2O in the Cirsium setosum and Sonchus arvensis exceeded the accumulation in cultivated plants twice. The nitrogen content in the roots and rhizomes of weeds was 1.5–2 times higher than the content of cultivated plants. The total removal of nutrients by weeds is influenced by their tier. Weed plants, intensively growing in the middle and upper tiers, contributed to a greater removal of nutrients from the soil. The removal of nitrogen was 14–43 % of the removal of cultivated plants, phosphorus – 4–12 %, potassium – up to 80 % of the removal of culture. A significant decrease (> 10 %) in yield is observed at a population density of 5–10 weeds/m2 in the lower tier. Winter wheat was more stable. A reduction of 10 % with 11–15 weeds/m2 of the lower tier. A decrease in plant productivity by 10–15 % with a population density of 5–10 weeds/m2. The calculation of the economic threshold level (ETL) at the level of 5 % yield loss for the lower tier ranged from 6–8 weeds/m2, at the level of 10 % loss to 8–12 weeds/m2. ETL (5 %) for weeds of medium and high level for Cirsium setosum in crops of spring barley – 2 weeds/m2 and in winter wheat crops – 4 weeds/m2; Equisetum arvense – 4 and 5 weeds/m2, Sonchus arvensis – 2 and 4 weeds/m2, Convolvulus arvensis – 5 and 5 weeds/m2, respectively