Molecular characterization of Fusarium oxysporum f.sp. dianthi and evaluation of fungicides against Fusarium wilt of carnation under protected cultivation

Abstract

Fusarium wilt, caused by Fusarium oxysporum f.sp. dianthi (FOD), is one of the most devastating carnation diseases globally, resulting in significant crop loss (40-70%). The purpose of this study was to determine the efficacy of several fungicides against Fusarium wilt of carnation in vitro and in vivo under protected cultivation. The disease infected plant samples were collected, and pathogen isolates were confirmed through morphological and molecular techniques. The rDNA sequences of isolates had 97-100% similarity with other sequences of FOD available in Genbank and the isolates were identified as Fusarium oxysporum f.sp. dianthi. Phylogenetic analysis of rDNA sequences revealed 62-99% sequence similarity among the isolates. Further, we evaluated nine different fungicides against the virulent pathogenic isolate CFODTNAU1 under in vitro and in vivo. Three different concentrations such as 500, 1000 and 1500 ppm were evaluated on mycelial growth of the pathogen under in vitro and percent inhibition over control was calculated. Among the fungicides, three of them namely, tebuconazole 50% + trifloxystrobin 25% WG, tebuconazole 25.9% SC and azoxystrobin 23% EC completely inhibited (100% inhibition) the mycelial growth of the fungus in vitro. Under protected cultivation, application of tebuconazole 50% + trifloxystrobin 25% WG through root dipping and soil drenching @ 1.0 g/L recorded 11.11% of wilt incidence compared to control (29.71% wilt incidence), which was 59.99% reduction over control. Besides, this fungicide also increased the stem length, earliness of flowering and yield than the control and other treatments. Thus, the fungicide tebuconazole 50% + trifloxystrobin 25% WG can be used for amelioration and control of wilt disease in carnation.