Sustainable Application of NATIVO 300 SC Fungicide (Tebuconazole 200 g/L +Trifloxystrobin 100 g/L) in the Control of Brown Spot (Bipolaris oryzae) in Strict Rainfed Rice Cultivation in Côte d’Ivoire

Rice brown spot is a devastating disease caused by Bipolaris oryzae. Various fungicide formulations are used against this phytomycosis, which occurs in all ecologies in Côte d'Ivoire. This study aimed to rationalize the application of a fungicide effective against brown spot in strict rainfed rice cultivation. The experimental design was a Fisher block with three replications. It was carried out in strict rainfed ecology at Biankouma between July and November 2023. The fungicide used was NATIVO 300 SC (Tebuconazole 200 g/L + Trifloxstrobin 100 g/ L). Five different treatments were tested (T0: no fungicide treatment; T1: NATIVO 300 SC at a dose of 350 ml.ha-1, every 10 days interval from the initial appearance of brown spot symptoms until 50% heading stage; T2 : NATIVO 300 SC at a dose of 350 ml.ha-1, at the seedling (4 to 5 leaves), booting and complete heading stages; T3: NATIVO 300 SC at a dose of 350 ml.ha-1, at seedling (4 to 5 leaves), maximum tillering and complete heading stages; T4: NATIVO 300 SC at a dose of 350 ml.ha-1, at early tillering (2 to 3 stems visible), maximum tillering and complete heading stages). Data on disease severity of brown spot and agronomical parameters were recorded ans statistically analysed using SAS 9.4 software. The results proved that treatments T1 and T4 proved more effective, with leaf severity indices of 2.0±0.98 and 3.52±0.78 versus 6.52±0.66 for the control, and yield gains of 67.69 and 60.09% respectively. In conclusion, application of NATIVO 300 SC fungicide at a dose of 350 ml/ha can be recommended at the early tillering, maximum tillering and complete heading stages of rice for effective management of brown spot.