MA Monachesi1, JA Lobo2, LG Huvierne2, C Joya1 and RP Bertani2
1Instituto de Tecnología Agroindustrial del Noroeste Argentino (ITANOA), Estación Experimental Agroindustrial Obispo Colombres (EEAOC) – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), CCT NOA Sur – Las Talitas, Tucumán, R. Argentina, T4101XAC; mmonachesi@eeaoc.org.ar
2Estación Experimental Agroindustrial Obispo Colombres (EEAOC) – Las Talitas, Tucumán, R. Argentina, T4101XAC
Red stripe disease (RS) in sugarcane [Acidovorax avenae subsp. avenae (Aaa)] has gained importance in the last decade in Tucumán, the leading sugarcane-producing province in Argentina, but several aspects of this disease are still unknown. The objectives of this research were to: 1) evaluate the prevalence of RS in Tucumán, Argentina; 2) determine the behavior of the main commercial varieties against RS, both in the field and under controlled conditions; and 3) investigate the possible presence of other Aaa morphologies as causal agents of RS in Tucumán, Argentina. During four successive sugarcane seasons, RS prevalence and incidence were recorded across Tucumán’s sugarcane area. Symptomatic leaves were collected, isolations were performed, and PCR (RS-ITS-F1/RS-ITS-R1) was used to confirm the presence of Aaa. Assays under controlled conditions involved inoculating seedlings of TUC varieties with Aaa suspension; RS severity was evaluated, and the Area Under the Disease Progress Curve (AUDPC) was calculated. Between 2021 and 2024, RS prevalence in Tucumán ranged from 11% to 51%, with TUC00-19 having the highest prevalence. TUC02-22 showed the highest values of leaf incidence in 2021/2022 season and TUC06-7 in both 2022/2023 and 2023/2024 seasons. Only TUC00-19 and TUC06-7 varieties exhibited top rot symptoms in all seasons. TUC95-10, TUC03-12 and TUC00-65 showed the lowest RS incidence levels. In controlled-conditions assays, TUC00-19 and TUC06-7 showed the highest AUDPC values after bacteria inoculation, while TUC02-22 and TUC03-12 were the least affected. TUC95-10 remains resistant to RS, while TUC00-65 showed as resistant in the field but showed high AUDPC values after artificial inoculation. Cream-white and yellow Aaa colonies were isolated from RS-symptomatic leaves. These isolates were used for inoculations in controlled conditions and all plants exhibited RS symptoms. This study enhances understanding of TUC varieties’ resistance to RS and confirms yellow and cream-white Aaa colonies as causal agents of RS in Argentina.