Determination of the effects of Thiram applied to seed with organic solvent infusion technique on sugar beet root rot pathogen Pleospora betae

Şeker pancarı (Beta vulgaris var. saccharifera), a major industrial crop contributing significantly to global sugar beet production and serving as a crucial source of income for farmers in Turkey. Pleospora betae is a significant pathogen transmitted through seeds, causing damage to sugar beet plants. In Turkey, the recommended approach to combat the disease involves the use of Thiram at a rate of 400g/100 kg of seeds. However, the high rate of seed infection and deep-seated infections pose challenges to disease management. This study investigates the effectiveness of Thiram applied with acetone using the organic solvent infusion technique to prevent seed infections caused by P. betae in Aranka and Terranova varieties. Moist chamber tests revealed that acetone at rates of 70% and 99% did not cause significant germination loss in seeds. While no significant changes were observed in germination rates with Thiram applications in conjunction with acetone, the development of the pathogen on the seeds was significantly reduced, though not entirely prevented. Experiments conducted in pots showed that the application of Thiram with 70% acetone caused significant reductions in emergence rates in high-disease Aranka cv. seeds, leading to a substantial decrease in disease incidence in emerging plants. However, in Terranova cv. seeds with a lower infection rate, no significant changes in germination rates were observed. Furthermore, the study explored the application of fungicides Penthiopyrad (125 and 250 ml/100kg) and Fluxapyroxad (75 and 150 ml/100kg) to seeds. While these fungicides significantly reduced disease development on seeds in moist chamber tests, they did not exhibit a significant inhibitory effect on disease in pot experiments.