Investigation of the effects of some fungicide applications against wheat rust diseases on urediniospor density and thousand-grain weight

Rust pathogens (Puccinia spp.), which cause significant yield losses in wheat production areas, have become one of the major diseases throughout the period from the domestication of wheat to the present day. These pathogens (yellow, brown, and black rust) appear during different stages of wheat development. They can cause significant yield losses by forming blisters called pustules, especially on leaves, leaf sheaths, stems, and heads. Today, various methods are used to manage these factors, including cultural measures, the use of resistant varieties, and chemical control. This study aims to investigate the effects of applying fungicides containing active ingredients from different groups once or twice on the formation of rust diseases and on thousand-grain weight. For this purpose, in vivo trials were conducted in the districts of Adana, İmamoğlu, and Ceyhan, where four original fungicides and their various combinations were tested both as single and double applications. In in vitro trials, the urediniospore density on the treated wheat leaves and the thousand-grain weights of the harvested wheat were examined. In areas with high disease pressure, a single application of fungicides was insufficient to control the disease; however, trials with two fungicide applications prevented rust diseases at rates of up to 100%. In urediniospore counts, a single application of fungicide resulted in a density of 120700 spores/cm², compared to 40225 spores/cm² for Radius and 47750 spores/cm² for Quake, demonstrating that these two fungicides were the most effective in reducing urediniospore counts. No urediniospore formation was observed in areas where two applications were made. In thousand-grain weight assessments, a single application did not show a significant increase in thousand-grain weight. In contrast, thousand-grain weight increased significantly in plots where fungicide was applied twice. These results suggest that a single application may be insufficient in years with high disease pressure, and that two applications can completely prevent urediniospore formation, demonstrating that the number of applications is critically important for effective disease management.