Effectiveness of soil herbicides in sunflower crops grown by direct seeding technology

Relevance and methods. Sowing of agricultural crops using direct seeding technology is becoming more widespread in the fields of the Stavropol Territory and other regions of our country. In the first years of the development of this technology, changes in the species composition of weed vegetation and increase the infestation of cropsare possible, in this regard, effective protection of crops from weed vegetation plays an important role in increasing the yield and economic efficiency of crop cultivation. In 2018–2020, at the experimental field of the North Caucasus Federal Scientific Agricultural Center, located in the zone of unstable moisture of the Stavropol Territory on ordinary chernozem, studies were conducted to identify the effectiveness of the use of soil herbicides in sunflower crops sown at various times (April 5–10, April 25–30 and May 15–20) using direct seeding technology. In the experiment, the sunflower was sown in the studied time with the use of only a continuous herbicide 5–7 days before sowing and with the use of the same continuous herbicide in combination with the introduction of soil herbicides after sowing. Results. On average, over the years of research, it was found that the use of a continuous herbicide is most effective 5–7 days before sowing, followed by the use of a tank mixture of soil herbicides in the post-sowing period when sowing the crop in the second decade of May. This scheme of herbicide application, combined with the postponement of the sowing period to May 15–20, reduces the number of growing weeds in crops during the growing season to 8–19 pcs./m 2 and increases the yield to 2.32 t/ha.