Integrated Management and Fungicide Efficacy of Foliar Diseases in Spring Wheat in Kazakhstan

Spring wheat (Triticum aestivum L.) is a key economic crop in Kazakhstan. This study aimed to identify genetic sources conferring resistance to major foliar diseases and to quantify the contribution of fungicide application to yield stability. Field experiments conducted in 2024 assessed the resistance of 36 spring wheat genotypes, 17 common wheat and 19 durum wheat (T. durum Desf.), to major foliar and stem diseases under natural infection conditions. Two genotypes, nos. 513 and 545, exhibited superior resistance, with incidences of leaf rust, stripe rust, and leaf blotch complex ranging from 0-3%, markedly lower than those of standard cultivars. These genotypes combined high disease resistance with favorable spike characteristics, underscoring their breeding potential. Application of the fungicide Kolosal PRO (0.5 L ha⁻¹) effectively suppressed Puccinia striiformis (13.4-fold reduction) and improved spike length, grain weight, and the number of productive tillers. Integrating genetic resistance with targeted fungicide use reduced disease variability by 35-45% and enhanced yield stability by 20-25%. Correlation analysis revealed a moderate positive relationship between productive tiller number and grain weight (r = 0.47). Overall, the results demonstrate that combining durable host resistance with optimized chemical protection enhances the resilience and productivity of spring wheat under variable pathogen pressures in Kazakhstan.