THE INFLUENCE OF HERBICIDE APPLICATION TIME AND HARROWING ON WEEDINESS AND ECONOMIC EFFICIENCY OF WINTER WHEAT

Abstract

A two-factor field experiment was conducted in 2023–2024 on the farm of farmer Algirdas Aukselis in Joniškis district. Experimental treatments: Factor A – herbicide application time: 1) not applied (N), 2) only in autumn (A), 3) only in spring (S), 4) in autumn and spring (A+S); and Factor B – crop harrowing: 1) not harrowed, and 2) harrowed (H). With dicotyledonous weeds prevailing in the winter wheat crop, the herbicide DIFLANIL 500 SC (0.2 L ha^-1, active ingredient diflufenican) was used for autumn spraying. In spring, a mixture of HERBISTAR 200 EC (0.6 L ha^-1, active ingredient fluroxypyr) and AXIAL 50 EC (0.6 L ha^-1, active ingredient pinoxaden) herbicides was sprayed. It was found that the time of herbicide application and harrowing had a significant impact on the weediness of the crop. When spraying with herbicides, weediness of winter wheat crops in autumn decreased by 52.7–66.6 % compared to unsprayed  fields. Spring harrowing significantly (1.3–1.7 times) reduced the weediness of crops. During spring harrowing, the efficiency of herbicide spraying reached 45.0–47.5 %. When applying a combined weed control strategy – spraying with herbicides (S+A, and S) together with harrowing, a greater effect on total profit was found compared to herbicides used separately at different times. Harrowing of crops increased total profit from EUR 16.0 ha^-1 (in unsprayed fields) to EUR 228.0 ha^-1 (in fields sprayed in autumn and spring).