Biological effectiveness of using fungicides and IFO PZN suspension in combination with fungicides against yellow rust and powdery mildew diseases of winter wheat

In this study, effective protection methods were applied against fungal diseases commonly found in soft winter-sown wheat grown in the foothill regions of the Kashkadarya region, using fungicides and suspensions. The research identified the impact of these treatments on plant health and the progression of disease development. During the 2019–2020 growing season, in untreated control plots, the average number of wheat plants per 1 m² was 410, with the initial incidence of yellow rust (Puccinia striiformis) affecting 230 plants (infection rate: 56.1%). During the disease’s peak and decline phases, infection rates increased to 73.41% and 76.1%, respectively, with 301 and 312 infected plants. Between 2020 and 2022, disease severity increased significantly. For instance, during the epidemic stage of 2020–2022 and 2021–2022, infection levels rose by 2.43% to 5.72% compared to 2019–2020, and by 1.65% to 4.24% in the final stage, with yields reduced by 1.5 to 3.2 c/ha. In field trials, the biological effectiveness of combining fungicides (Duazol 40% EC at 0.25 l/ha (reference), Bi- Kanazol 400 g/l at 0.3 l/ha, AZOTE 320 SC 32% SC at 0.3 l/ha, Rauma 490 EC at 1.25 l/ha, Alta Super 40% at 0.3 l/ha, Altus Duo 32.5% at 0.3 l/ha) with IFO PZN suspension (3.0 l/ha) was tested against yellow rust and powdery mildew (Erysiphe graminis). Results showed that disease incidence in untreated control plots ranged from 74.2% to 54.4%, while combining AZOTE 320 SC and Rauma 490 EC with IFO PZN reduced disease levels to 0.8% and 0.5%, respectively. Biological effectiveness reached 98.6– 99.1% against yellow rust and 99.0% against powdery mildew. Thus, using a combination of IFO PZN suspension with AZOTE 320 SC or Rauma 490 EC fungicides is recommended for chemical control of these diseases in winter wheat. The combined application enhances chlorophyll content and improves biochemical composition in plant tissues, increasing resistance to both diseases and environmental stress. These methods contribute to high- quality yields and effective disease prevention in wheat production.