Integrating genetical and chemical control: An approach to rhizoctonia root rot disease management

Rhizoctonia root rot is a widespread and destructive disease that affects sugar beet yield in Iran and worldwide. In this study, we investigated integrated disease management methods, including the use of resistant cultivars and fungicides, to prevent the development of the disease. The present study focused on the Shokoufa susceptible cultivar and the Novodoro resistant cultivar, and tested three fungicides of Celeste, Uniform, and Maxim. The experiment was conducted under natural and artificial contamination conditions during 2022. The results showed that the Uniform fungicide effectively prevented the development of the disease on the resistant cultivar, resulting in a harvest index of 70.59%. Although this fungicide did not work as effectively on the susceptible cultivar, it still showed better performance compared to other experimental treatments. The Celeste fungicide had a disease index of 3.29 on the resistant cultivar, with 5% of the root surface having ulcers. However, it did not have a significant effect on disease control in the susceptible cultivar, which showed a sensitivity reaction. The harvest index of the resistant cultivar in this treatment was 76.47%, while the susceptible cultivar had a harvest index of 11.76%. The Maxim fungicide and control treatments had similar effects on both the resistant and susceptible cultivars in terms of disease and harvest indexes. Although the severity of the disease was lower in the resistant cultivar compared to the susceptible cultivar, both cultivars showed a low harvest index and were in the sensitive range..