Efficacy of Gliocladium roseum against dry rot of potato caused by Fusarium sambucinum

Abstract

Aim of the study: Fusarium dry rot of potato is a major disease and caused by several Fusarium species with Fusarium sambucinum Fuckel being the most aggressive species in worlwide, including Turkey. Several fungal biocontrol agents have been used for achieving plant disease control, amongst them Gliocladium group has been found effective against tuber pathogens. Gliocladium roseum, a filamentous fungus which is widely distributed in soil and decaying vegetation. It is commonly considered a contaminant and has never been found to be a pathogen in animals or humans. It has ecologically relevant not only in the protection of plants against pathogens, producing a wide range of antibiotic substances and parasitizing other fungi, but also in the stimulation of plant growth. Moreover, these species of fungi can grow on cellulose and produce hydrocarbon and derivatives that look much like diesel. Aim of this study was to determine the efficiency of G. roseum against Fusarium sambucinum caused dry rot of potato. Material and Methods: This study was carried out in two phases: In vitro and In vivo conditions. In first phase, the effect of Gliocadium roseum was studied against three isolates of F. sambucinum (Fs2, Fs3 and Fs4) in vitro conditions in PDA medium by dual culture technique and incubation at 22 ± 24ºC. In the second phase, Potato tubers, CV. Desire were wounded and inoculated with 500 µl of Gliocladium roseum suspensions (107 spores mL-1), 24 h prior inoculation by F. sambucinum and reductioa rate of dry rot in tubers recorded 5-6 weeks incubation at 20-24 ºC in comparison with control treatments. Parameters of dry rot caused maximal width (w), depths (d) were noted, and tubers were calculated by applying the following formula (Lapwood et al. 1984). Penetration (mm): [w/2 + (d-6)]/2.Results: In vitro results showed that G. roseum was moderate mycoparasitism when compared to other antagonist microorganisms, G. roseum growth slowly on the colony of pathogen. But it had been found that G. roseum was very strong to penetre and coiling on pathogen. In vivo results showed that tuber dry rot was reduced by G. roseum with different rates. Penetration measure for F. sambucinum Fs2, Fs3 and Fs4 was 9,58, 8,66 and 14,50 respectively. When compared to treated control (+), F. sambucinum (Fs2, Fs3 and Fs4) isolates were inhibited by G.roseum with the rate of 50,08 %, 56,82 % and 39,10 % respectively.