Biological effectiveness of herbicides in winter wheat crops of autumn sowing

An effective measure for controlling the most harmful wintering and winter weed species, such as Apera spica-venti, Galium aparine, Veronica persica, Consolida regalis, Capsella bursa-pastoris, Descurainia Sophia, Vicia villosa, etc. in winter wheat crops is the autumn application of herbicides, especially in the early stages of crop development, starting from the seed germination stage, when it is most sensitive to their presence. The study presents the results of two-year studies on the biological effectiveness of applying the herbicide Pledge 50, WP in different stages of development of winter wheat (BBCH 00, 11, 12, 14, and 16) independently and in a mixture with herbicides partners: Zenkor Liquid 600, SC, Marathon, SC, Granstar Gold 75, WG, Grodil Maxi 375, OD, and adjuvant Skaba, EC. As a result, it is identified that the biological effectiveness of the drugs under study against Apera spica-venti and other winter and wintering weeds substantially differed depending on the phase of development of winter wheat during the period of herbicide application. Pre-emergence application of herbicides does not ensure proper control of Apera spica-venti and other winter and wintering weeds. In particular, during the spring resumption of vegetation, the control of Apera spica-venti with the use of 0.1 kg/ha Pledge 50, WP was 69.0%, with an overall efficiency of 68.0%. Application of 0.4 l/ha Sencor Liquid 600, CS provided indicators of 66.1 and 71.4%, respectively. The introduction of 0.1 kg/ha of Pledge 50, WP in the BBCH 11 development phase provided high efficiency in controlling Apera spica-venti and all weeds in general with indicators of 91.2 and 87.6%, respectively. The use of a reduced rate of 0.08 kg/ha Pledge 50, WP in the BBCH 12 phase did not reduce both the overall effectiveness against weeds – 87.4%, and Apera spica-venti in particular – 93.1%. The use of Pledge 50, WP (0.1 kg/ha) in the BBCH 16 phase had a worse, but acceptable effect with efficiency indicators of 84.2% against Apera spica-venti and 83.6% overall. The best control of Apera spica-venti and all weeds, in general, was obtained by using a mixture of Pledge 50, WP + Granstar Gold 75, WG + adjuvant Skaba, EC (0.06 kg/ha + 0.025 l/ha + 0.05 l/ha) in the BBCH 14 phase – 97.5 and 99.2%, which is at the level of Sencor Liquid 600, SC + Grodil Maxi 375, OD (0.35 l/ha + 0.11 kg/ha). The highest yield of winter wheat in the experiment was obtained by applying a mixture of Pledge 50, WP + Granstar Gold 75, WG + adjuvant Skaba, EC (0.06 kg/ha + 0.025 l/ha + 0.05 l/ha) in the BBCH 14 phase – 7.56 t/ha, which is 59.8% better than the control