In vitro Efficacy of Selected Fungicides Against Pestalotiopsis telopeae Isolate 2A6 Associated with Leaf Spot Disease on Photinia × fraseri ‘Red Robin’
In the present study, fungicide sensitivity of Pestalotiopsis telopeae isolate 2A6, identified as the causal agent of leaf disease on Photinia × fraseri ‘Red Robin’ in outdoor ornamental plant nurseries in Sakarya, Türkiye, was evaluated under in vitro conditions. The active ingredients azoxystrobin, captan, difenoconazole, tebuconazole, and thiophanate methyl were evaluated at concentrations of 1, 3, 5, 10, 30, 50, and 100 µg mL–1 on potato dextrose agar medium. The highest inhibition rates of mycelial growth of P. telopeae isolate 2A6 were 99.23%, 91.83%, and 81.20% for fungicides tebuconazole, difenoconazole, and captan, respectively, at 100 µg mL–1. Lower inhibition rates were observed for the active ingredients azoxystrobin and thiophanate methyl compared to the other fungicides tested. Consistent with these findings, the EC50 values obtained from Probit analysis confirmed that difenoconazole and tebuconazole exhibited the highest antifungal activity among the tested active ingredients. The results of the present study provide preliminary insights for future research on the control of leaf spot diseases caused by P. telopeae in outdoor ornamental plants. This study serves as a preliminary in vitro screening to establish baseline fungicide sensitivity for P. telopeae in Türkiye.