Determination of Optimum Nativo SC 300 (Trifloxystrobin 100g/l + Tebuconazole 200g/l) Spray Frequency for Control of Rust (Puccinia allii Rudolphi) on Garlic in the Highlands of Bale, South Eastern Ethiopia

Garlic (Allium sativum L.) is one of the major allium crops grown in the highlands of Bale, southeastern Ethiopia. Rust, caused by Puccinia allii, is the most important disease affecting garlic in these areas. This study investigates the optimum spray frequency of the fungicide Nativo SC 300 (Trifloxystrobin 100g/l + Tebuconazole 200g/l) for effective control of this pathogen. Conducted at the Sinana Agricultural Research Center in Ethiopia, the experiment employed three different spray frequencies: five times at weekly intervals, three times bi-weekly, and twice every three weeks, starting at disease onset. Utilizing a Randomized Complete Block Design with three replications, the study found that the lowest rust severity (1%) was observed in plots treated weekly, while maximum severity (83.3%) occurred in untreated plots. Fungicide-treated plots yielded significantly higher total bulb yields than untreated controls. Notably, the highest yield (13.92 t/ha) and net benefit were achieved with three applications at 14-day intervals. This suggests that applying Nativo SC 300 thrice bi-weekly from the onset of rust results in optimal yield and economic return.