Iprodione Resistance of Alternaria Alternata F.sp. Citri Minneola Tangelo Isolates in Turkey

Abstract

In this study, isolates of Alternaria alternate f.sp. citri, cause of citrus brown spot, were obtained from Minneola tangelo orchards in Çukurova Region where disease appeared and after pathogenicity tests their resistance to iprodione was investigated. Five of 35 isolates recovered from different orchards were observed as iprodione-resistant. The ED50 values of these resistant isolates ranged from 61.89 to 109.21 μg/ml, but the average ED50 value of iprodione-sensitive isolate was less than 1 μg/ml. When the orchards where from iprodione-resistant isolates collected were checked in terms of fungicide application program in recent years, it was noticed that iprodione application was much more than others. When Iprodione-sensitive isolates were subcultured on PDA supplemented with iprodione, they developed resistance starting after second subculture, ED50 values continued to increase after each subculture.