Determination of some fungicides efficasy and resistancy into citrus brown spot diseases Alternaria alternata f.sp. citri isolates

In this study, the effects of seven fungicides belonging to four different groups on mycelial growth of 12 isolates of Alternaria alternata f.sp. citri and resistance situations were investigated in vitro. The highest effects on mycelial growth were showed by iprodione, pyroxymidone, propiconazole and propineb. Especially, iprodione was highly effective on isolate on 17-1 at 5ppm and above concentrations. However, very frequent use of these fungicides in the growing season has led to the problem of development of resistance. There were no significant effect of Metiram-komplex, trifloxystrobin and kresoxim-methyl fungicides on the a mycelial development. Results showed that the different active ingredients were included in effective fungicide spray program started with iprodione, propiconazole, proxymidone and propineb which have resistance problem and may not be used in a season frequently.Key words: Alternaria alternata f.sp. citri, Minneola tangelo, chemical