First Report of Alternaria alternata and Rhizopus arrhizus Causing Drooping and Death on Sunflower Sprouts (Helianthus annuus) in Kazakhstan

This study presents the first confirmed report of Alternaria alternata and Rhizopus arrhizus as causative agents of seedling wilt and death in sunflower (Helianthus annuus) in Kazakhstan. During phytopathological examination of seeds from four sunflower hybrids, characteristic fungal colonies were identified through morphological and molecular methods, including ITS sequencing and PCR amplification of Alt a1 and calmodulin genes. Symptoms of brown spots, desiccation, and gray mold were observed, with re-inoculation tests confirming pathogenicity. Phylogenetic analysis revealed a 91-98% similarity with known Alternaria and Rhizopus species. This research emphasizes the importance of monitoring imported seed material and implementing integrated disease management strategies. The findings contribute to understanding phytopathogen diversity in the region and inform recommendations for disease prevention in sunflower cultivation.