Determination of the effectiveness of fungicide protection systems as a reserve for sustainable sunflower production in south of Ukraine

Sunflower is a strategic crop in the agricultural sector of Ukraine, but its yield and seed quality are significantly reduced due to damage from phytopathogens. One of the main methods for their control is the use of fungicides. A study conducted in the southern regions of Ukraine established the impact of fungicide application schemes based on active substances from the classes of benzimidazoles, strobilurins, and triazoles on the spread and severity of dominant diseases and sunflower yield. The main diseases of the crop included white mold, downy mildew, black stem, and stem canker. In the absence of fungicidal protection, disease development at BBCH growth stage 91 was significant, reaching 17.5 % (white mold), 28.9 % (downy mildew), 15.3 %, and 14.5 % for black stem and stem canker, respectively. The best biological efficacy for controlling Sclerotinia sclerotiorum and Phoma macdonaldii at BBCH growth stage 16 was shown by Amistar Gold, 250 SC (1.0 l/ha) – 78.0 % and 84.3 %, respectively. Against Diaporthe helianthi and Plasmopara halstedii, the highest efficacy at the same growth stage was demonstrated by Thanos, 50 WG – 86.6 % and 92.7 %, respectively. The use of Amistar Gold, 250 SC and Acanto Plus SC at BBCH growth stage 51 showed high biological efficacy against black stem and stem canker, ranging from 88.8 % to 90.3 %. Against downy mildew, the efficacy of Acanto Plus SC was higher by 4.5 % compared to Amistar Gold, 250 SC, reaching 88.9 %. For white mold, the efficacy of these products ranged from 80.0 % to 85.7 %, with Acanto Plus SC being more effective. Alpha-standard SC did not affect the development of downy mildew and showed low efficacy against white mold – 17.1 %. For black stem and stem canker, it had average efficacy rates of 74.5 % and 77.2 %, respectively. The use of fungicide application schemes: Amistar Gold, 250 SC (BBCH 16; 51) and Thanos, 50 WG (BBCH 16) along with Acanto Plus SC (BBCH 51) provided maximum yields of 3.24 and 3.31 t/ha, exceeding the control by 1.63 and 1.99 t/ha, respectively. The recommended protection schemes using Amistar Gold, 250 SC (1.0 l/ha), Thanos, 50 WG (0.6 kg/ha), and Acanto Plus SC (1.0 l/ha) can be implemented in farms in southern Ukraine and adapted to other sunflower growing zones.