The possibility of biological control against potato Verticillium wilt disease using Talaromyces flavus , antagonist fungus in condition field

Potato Verticillium wilt, caused by Verticillium dahliae and Verticillium albo-atrum, possess specific importance and one of its control methods is biological control using antagonistic fungi. In this study, based on the result of a previous research project in greenhouse conditions, three isolates of Talaromyces flavus (TF-Po-V-49, TF-Po-V-50 and TF-Po-V-52) with the most inhibitory effect on Verticillium wilt disease infection index were selected for preparation of inocolums in the field. In the next step, rice bran was used for preparation of the different inoculums affected by the above-mentioned isolates. For application in the field, potato tubers were coated by tree different inoculums in terms of treatment. During 2011 and 2012, fild experiments were carried out in randomized complete block design with five treatments and four replications in the research station of Hamedan Agricultural and Natural Resources Research Center. Treatments included: 1-3: each inocolum affected by one of three isolates of T. flavus; 4: Carbendazim fungicide and 5: control without inoculum and fungicide. The efficacy of different treatments in controlling disease was evaluated based on the determination Verticillium wilt disease severiety and incidense as well as total yield. Statistical analysis of data as compound analysis showed that there was a significant decrease of disease severiety in all treatments compared to the control. However significant difference in term of disease severiety was not observed in treatments affected by antagonistic isolates compared to carbendazim treatment. The results also indicated that disease percent decresed significantly in all treatments in comparison with control. On the other hand, except TF-Po-V-49 treatment, there were not significant differences among other treatments affected by antagonistic isolates and carbendazim treatment. Statistical groups of the treatments in terms of yield average showed that the yield increased from 3.69 to 26.27% in all treatments compared to the control. Among all treatments, those affected by carbendazim and TF-Po-V-52 showed the most efficacy in increasing yield (28.74 and 26.74 ton/ha respectively) in comparison with the control (22.76 ton/ha). Based on the overall results of this study, TF-Po-V-52 was the most effective fungal antagonist in decreasing the Verticillium wilt disease severity and incidence (18.04 and 40.31% respectively) and increasing yield of potato (17.48%) and could be a potential biofungicide and biofertilizer in the fields.