ABSTRACT

Safflower (Carthamus tinctorius L.) is a key oilseed crop valued for its adaptability to arid conditions and its high quality oil rich in unsaturated fatty acids. However, its cultivation is significantly hampered by various plant diseases, notably leaf blight caused by Alternaria carthami. This study aimed to address critical aspects of leaf blight management, including prevalence, variability and control measures. A survey conducted during the rabi season of 2023-24 across Northern Karnataka revealed that leaf blight severity was highest in Dharwad district (33.31%) and lowest in Belagavi district (27.29%). Whereas disease severity was found maximum in Yamanur (36.25%) and minimum in Mutwad (20.42%) due to contributing factors such as the presence of initial inoculum, wet weather and high humidity.Cultural, morphological and pathogenic variability among the twelve isolates of A. carthami showed significant differences in colony characteristics and virulence. Notably, MARS, Dharwad isolate (MrD) found highly virulent.In the in vitro evaluation of fungicides, botanicals and bioagents, Mancozeb 75% WP and (Tebuconazole 50% + Trifloxystrobin 25%) 75% WG found highly effective among fungicides, with complete inhibition at specific concentrations. Trichoderma harzianum [MH027645.1 (IOF strain)] among bioagents and Azadirachtin 0.15% among botanicals exhibited the highest efficacy. Field trials confirmed that a spray schedule of Mancozeb 75% WP followed by (Tebucanazole 50% + Trifloxystrobin 25%) 75% WG was most effective, resulting in the highest seed yield of (11.10 q/ha) and benefit-to-cost ratio (1.52). Out of 38 genotypes screened one moderately resistant (ANG 10-4), three moderately susceptible, 15 susceptible and 19 highly susceptible genotypes were identified. The study concludes that integrated management involving effective fungicides, resistant genotypes and optimized spray schedules is crucial for controlling safflower leaf blight.