فهرست مطالب razak mahdizadehnaraghi

Two field experiments were conducted and executed during 2015 and 2016 to evaluate the effectiveness of six newly developed fungal bioformulations in controlling garlic white rot disease caused by Sclerotium cepivorum. The bioformulations were developed using three antagonistic fungi including Trichoderma harzianum, T. asperellum and Talaromyces flavus and rice bran as an organic carrier. They were selected based on their performance in the greenhouse conditions in a previous study, where they effectively controlled and reduced the garlic white rot disease. Field trials were conducted in a randomized complete blocks design with eight treatments (six bioformulations, an untreated control and a Carbendazim fungicide) each with four replicates. The garlic seeds (bulbs) were coated with each bioformulation and were sown in the field soil preinoculated with S. cepivorum. The incidence and the index of white rot disease severity were then determined in different treatments 90 days after sowing. Results showed that in the first year field experiment, most bioformulations were effective and reduced both disease factors significantly in comparison with the untreated control. The biofomulations R.B-T.h-1 and R.B-T.h-2, with 9.11% and 13.50% disease incidence, respectively, reduced the disease significantly and were as effective as the fungicide. However, in the second year due to the higher soil inoculum density, four out of the six applied bioformulations performed effectively in controlling the disease. The overall results of this study suggest that these newly developed bioformulations could replace harmful chemical fungicides in managing white rot disease in the garlic fields.

White rot caused by Sclerotium cepivorum (Berk).is one of the most widespread and damaging fungal diseases of garlic This diseas causes significant losses to garlic crops in Iran including Hamadan province evey year. At the present, the most common control control method of the disease is the use of chemical fungicides. This control measure is costly and contaminates the agricultural environment. Moreover, since the pathogen is soil-borne, this control method is not quite effective in controlling the disease. In this study, the effects of two antagonistic fungi including Trichoderma and Talaromyces as bio-control agents in the control of the causal fungal pathjogen were investigated under laboratory and greenhouse conditions. For this purpose, ten isolates of the antagonistic fungi, four isolates of T. harzianum (Th), two isolates of T. asperellum (Ta) and four isolates of T. flavus (Tf) were selected. The effects of antagonistic agents on the growth of the pathogen were evaluated in in vitro using dual culture method. Moreover, the impact of the volatile and non-volatile metabolites of the antagonistic agents on growth of the pathogen was also investigated. The results of the laboratory experiments showed that six isolates (two isolate from each species) significantly reduced the pathogen growth. Several new bioformulations were then developed and prepared using rice bran (RB) as an organic carrier and the most effective antagonistic isolates. The effectiveness of the developed bioformulations in controlling the white rot disease of garlic was studied under green-house conditions. The experiment was conducted as completely randomized design consisted of nine treatments (six bioformulations, one fungicide and two controls) each with four replications. The results of the greenhouse experiments indicated that regarding disease incidence and severity, there were significant differences among the treatments (P<0.05). The highest infection rate (53.82%) was observed in the positive control (treatment without biological agent or fungicide). The lowest infection rates were belonged tohealthy control (9.24%), fungicide (11.23%), RBTh1 (11.33%), RBTa2 (11.37%) and RBTh2(11.42%) respectively which were placed in the same statistical group.These overall results indicate that the biological control of Allium white rot disease using antagonistic fungi is possible as an effective alternative method.