Phytosanitary condition of soybean crops under different fungicide protection

The article presents the results of determining the phytosanitary condition of soybean crops under different fungicide protection. The research was conducted in 2021-2023 in the conditions of Savarske LLC, Kyiv region. Experimental design: Factor A. Varieties. «Amadea», «Aurelina». Factor B. Fungicides. Control (treatment of seeds and plants with water), «Maxim Advance 195 FS», «TH» (1.25 l/t) (seed treatment before sowing), «Vaibrans RFC», t.n. (1 l/t) (seed treatment before sowing), «Selest top 312.5 FS», «TH» (1 l/t) (pre-sowing seed treatment), «Standak Top» (2 l/t) (pre-sowing seed treatment), «Abacus» (2 l/ha) (during the growing season), «Maxim Advance 195 FS», «TH» (1. 25 l/t) + «Abacus» (2 l/ha), «Vaibrans RFC», t.n. (1.25 l/t). n. (1 l/t) + «Abacus» (2 l/ha), «Seleste top 312.5 FS», «TH» (1 l/t) + «Abacus» (2 l/ha), «Standak top» (2 l/t) + «Abacus» (2 l/ha). It was found that at the stage of the first pair of true soybean leaves (BBCH10-12) in the control plots without fungicides using the most common diseases were alternaria – 34.2 %, ascochyta – 30.2 % and fusarium – 24.5 %. During the flowering period (BBCH 65), the percentage of fusarium (20.5%) and ascochyta (28.3 %) decreased and the percentage of alternaria (35.7%) increased, while the percentage of Septoria was 3.1% in the first period and 5.4 % in the second period. In the varieties «Amadea» and «Aurelina» at the stage of BBCH 12 the prevalence of fusarium, alternaria and ascochitosis were on average 2.2 and 2.7%, 3.7 and 3.0% and 2.7 and 2.1%, respectively, and the disease intensity development was 3.8 and 4.0%, 3.1 and 3.6% and 3.1 and 2.2%, respectively. The efficacy of pre-sowing soybean seed treatment with fungicides reduced the development of Fusarium by 83.3–88.9%, Alternaria by 85.5–90.3% and Ascochitosis by 80.2–89.7% on average in the soybean varieties tested. At the BBCH 65 stage (flowering) in soybean varieties «Amadea» and «Aurelina» the prevalence of fusarium, alternaria and ascochitosis were on average 2.4 and 2.7%, 3.5 and 3.4%, 3.2 and 2.6%. The most effective system for protecting soybean crops against fusarium, alternaria and ascochyta was the combined using of a pre-sowing seed treatment with the fungicides «Maxim Advance 195 FS», «TH» (1.25 l/t), «Vaibrans RFC», t.n. (1 l/t), «Selest Top 312.5 FS», «TN» (1 l/t) and «Standak Top» (2 l/t) and the application of «Abacus» (2 l/ha) during the growing season. Key words: soybean, variety, fungicides, seed treatment, disease extend, intensity of disease development, preparations efficiency.