The microorganisms operating for biocontrol of phytopathogens have different modes of action (Nega 2014). Understanding the mechanisms in the biological control process can allow the establishment of favorable conditions in the interaction between phytopathogen and biocontrol agent that is important in performing a successful biological control strategy in a specific pathosystem (Handelsman and Stabb 1996). 2 Mechanisms of biocontrol agents for the management of phytopathogensĪ key factor for attaining an effective prevention of phytopathogens in their hosts is the knowledge about their mechanism of action. The current study is a comprehensive review of applying fungal and bacterial antagonists for biological control of various plant diseases caused by fungal, bacterial, and nematodes in Iran during a period of 26 years. Furthermore, because of increasing the stability of biological agents, the bioformulation progress has recently been evaluated in Iran (Karimi and Sadeghi 2015). 2016 Khaledi and Taheri 2016 Abdoli et al. 2010 Khalighi and Khodakaramian 2012 Naeimi and Zare 2013 Azizpour and Rouhrazi 2016 Karimi et al. Trichoderma, Pseudomonas, and Bacillus species have mostly been used for biological control of phytopathogens in Iran (Peyghami and Nishabouri 1998 Shahiri Tabarestani et al. A large number of fungal and bacterial biocontrol agents have been found as the most important agents for plant disease management with identification of their role in plant pathogen management (Ramadan et al. In the twenty-first century, with the improvement of biological control of plant pathogens throughout Iran, different biocontrol agents have been applied against the various pathogens in vitro, in greenhouse and field conditions. were the first biocontrol agents applied against Athelia rolfsii ( Sclerotium rolfsii), Rhizoctonia solani, and Fusarium solani, the causal agents of diseases on groundnut, bean, and apple, respectively (Asghari and Myee 1992 Bazgir et al. The first published studies on biological control of plant pathogens in Iran were presented in 1992. The advantages of beneficial microbes for associated plants are establishment of antagonistic microorganisms, prevention of phytopathogens, overall improvement of plant health, plant growth promotion, enhanced nutrient availability and uptake, and increased resistance to both biotic and abiotic stresses in the hosts (Vinale et al. Biocontrol agents either with antagonistic activities, or modifying effects on plant physiology and anatomy, mostly reduce the negative effects of pathogens. 2009).īiological control, which attracted broad considerations in the past few decades, is defined as a bioeffector strategy that uses other living organisms for controlling insects, mites, weeds, and phytopathogens (Flint et al. These problems make enhanced attempts for developing ecofriendly microbe-based pesticides or biopesticides which use biological control agents (BCAs) as active ingredients and basically act different from common chemical pesticides (Sindhu et al. Therefore, growers have generally concentrated on the intensive use of chemicals for the management of pests and diseases which induce several problems, including resistance to pesticides, hazardous effects on human health, loss of beneficial soil microorganisms, entrance of residual toxic material in the food chain, and reduction in macro–microorganism biodiversity (Sindhu et al. Furthermore, different pests and diseases cause annual economic losses (20 to 40%) in agricultural products by decreasing the crop yield, destroying the quality, and pollution of products with toxic chemicals (Guo et al. Increasing human population in the world demands more food (70 to 100%) by 2050 to supply human needs (Godfray et al. Keywords: biological control Trichoderma Pseudomonas Bacillus 1 Introduction