Phase sensitivity of perennial dicotyledonous weed species to Flex herbicide

The Far Eastern Research Institute of Plant Protection - Branch of Federal State Budget Scientific Institution “Federal Scientific Center of Agricultural Biotechnology of the Far East named after A.K. Chaiki”, 42-a, st. Mira, p. Kamen-Rybolov, Khankaysky District, 692682 Primorsky Territory, Russia

^* Corresponding author: dalniizr@mail.ru

Abstract

Phase sensitivity to Flex herbicide, BP (active ingredient fomesafen 250 g/l) of seven perennial weed species common in soybean crops in the south of the Far East was studied in 2022-2023 under vegetation house conditions: bristly thistle Cirsium setosum (Willd.) Bieb., perennial sowthistle Sonchus arvensis L., corn mint Mentha arvensis L., common mugwort Artemisia vulgaris L., rough hedge nettle Stachys aspera Michx., curly dock Rumex crispus L. and rough potato Metaplexis japonica (Thunb.) Makino. The herbicide treatment of weeds was carried out in three terms in different stages of their growth and development. The preparation was applied in six rates of consumption - 0.75; 1.0; 1.0; 1.25; 1.5; 1.8 and 2.0 litres/ha. The degree of herbicidal effect of Flex was assessed by the decrease in height and weight of above-ground organs of experimental plants in comparison with the control (without treatment). It was found that Flex completely destroys plants of all species studied at the early stages of growth and development (2...5 leaves). When treating weeds in subsequent phases (4...10 leaves), the drug retains very good to good effectiveness against corn mint, bristly thistle, rough potato, and rough hedge nettle. The activity of the herbicide is significantly reduced when it is applied to overgrown weeds. Only corn mint retains high sensitivity to fomesafen after treatment.