Talaromyces pinophilus inhibits Pythium and Rhizoctonia-induced damping-off of cucumber

This study examined the biocontrol potential of 39 fungal isolates obtained from the rhizosphere of tomato and cucumber in Oman against Pythium aphanidermatum and Rhizoctonia solani, major causal agents of damping-off of cucumber. Soil samples were collected from the rhizosphere of cucumber and tomato and the direct plating technique was used for isolating fungi from soil samples. In vitro screening of the 39 fungal isolates against P. aphanidermatum and R. solani was performed by the dual culture method. Among the 39 isolates, TT266 was found to be the most effective in interfering with growth of P. aphanidermatum and R. solani. Bioassay experiments showed that isolate TT266 significantly improved the survival of cucumber seedlings from 8% when inoculated with Pythium to 38% when TT266 was used (P < 0.05). TT266 also significantly improved the percentage of cucumber survival inoculated with R. solani from 15 to 69%. The biocontrol agent did not have any negative effects on the survival, root length, shoot length or dry weight of cucumber seedlings. Identification of TT266 to the species level using sequences of the ITS region showed that it was Talaromyces pinophilus. This is the first report of Talaromyces pinophilus as a potential biocontrol agent for Pythium and Rhizoctonia damping-off of cucumber. The study also confirms that fungal isolates present in the rhizosphere of vegetable crops can be potential biocontrol agents for soil borne diseases.