Determination of Seedling Root Rot Fungal Pathogens and Disease Prevalence Rates in Cotton (Gossypium hirsutum L.) Fields of the Tigris Basin

This study was conducted to identify the fungal pathogens responsible for seedling root rot in cotton (Gossypium hirsutum L.) cultivated in the Tigris Basin, to determine their prevalence, to characterize these pathogens at morphological and molecular levels, and to assess their pathogenicity in order to contribute to the development of effective disease management strategies. In this study, during the growing season 2021-2022 surveys were conducted on May and June along the Tigris Basin, where cotton is intensively cultivated. Diseased cotton samples were collected from a total 79 separate cotton fields. Fungal agents causing seedling root rot, including Fusarium species (Fusarium spp., Fusarium oxysporum, F. solani, F. moniliforme (verticillioides), F. chlamydosporum, F. proliferatum, F. acuminatum), R. solani, Macrophomina phaseolina, Phytium spp., Alternaria spp., Ulocladium sp., Cladosporium spp., Chaetomium spp., Thielaviopsis basicola, Phoma spp., Phymatotrichopsis omnivora, Sclerotinia sp., and Sordaria tomentoalba were isolated. As a result of pathogenicity tests among the agents causing seedling root rot, Thielaviopsis basicola, Alternaria spp., Fusarium moniliforme, Fusarium oxysporum and Fusarium solani were determined to be highly pathogenic. The disease rate of fields in the study was between %2-16. The prevalence of the disease in the studied fields was %100. In the region, it is essential to implement sustainable approaches for managing fungal diseases, including raising awareness among growers, using resistant cultivars, reducing pesticide use, ensuring proper field drainage, practicing crop rotation, and adopting biological control methods.