The conception of environmental quality is common used in our society. Ecological farming is one of the most quality orientated agricultural system. The experiment was conducted in the Kazliskiai ecological farm of Lithuanian University of Agriculture. There were different kind of investigation determined earlier on the farm, but there were no investigation made on the influence of weedy trench to winter-wheat field. The aim of this work is to determine how weedy trench influences segetic flora and its botanical structure in winter- wheat agrophytocenozis. The tasks, which help to gain the aim: 1. To analyze how the amount of weeds change receding from weedy trench; 2. To analyze how the botanical structure of weeds change receding from weedy trench; 3. To evaluate interrelationship between amount of weeds and their botanical structure due to weedy trench. The object of the research work – the winter-wheat field segetic flora of Kazliskiai ecological farm. The following methods were used in this work: • The analysis of scientific literature; • The calculation of segetic flora amount and its botanical structure in workspaces; • The statistical analysis using EXCEL, DISPERS programs. The results of this work show: The weedy trench has a positive influence on the amount of segetic flora. It is 2-4 times bigger nearby weedy trench than in the middle of the field. The botanical structure changes only in autumn but not numerously.