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).Д«iological 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 macroвЂ“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

Screening of biocontrol agents bacteria