Sensitivity of Argentine Pyrenophora Teres F. Teres Isolates to Different Fungicide Mixtures

Net blotch disease, caused by Pyrenophora teres f. teres (Ptt), is one of the most serious diseases of barley in Argentina. The in vitro sensitivity profile of Ptt to different fungicide mixtures currently used in Argentina was determined in isolates from different localities. Mycelial growth inhibition was measured, and the 50% inhibitory concentration (EC50) was estimated by simple logarithmic regression. In addition, the in vivo sensitivity of Ptt to the application of fluxapyroxad 5% + epoxiconazole 5% + pyraclostrobin 8.1% (FEP) was evaluated in greenhouse and field trials. The EC50 values ranged from 0.004 to 0.527 mu g/mL, indicating that the fungicide mixtures tested were highly fungitoxic to all Ptt isolates tested. The in vivo and field fungicide efficacy averaged 99.9% and 79.5%, confirming a correlation between in vitro and in vivo sensitivity. The fungicide mixtures evaluated here were all highly fungitoxic and efficient for managing net blotch.