INTRODUCTION Recently, much research has been conducted on the increased food production that will be needed for the rapidly increasing world population and on synthetic pesticides, with the goal of reducing damage to the environment and human health. Unfortunately, substantial yield losses occur due to insects and plant diseases caused by fungi, bacteria and viruses 1,2. Synthetic chemicals (e.g., herbicides, fungicides and insecticides) are widely used in the control of plant diseases, pests and weeds. However, these chemicals may cause toxic residues in treated products 3. As mentioned above, synthetic pesticides can also cause environmental pollution owing to their slow biological disruption 4,5. In addition, other disadvantages of synthetic pesticide usage are the risk of resistance development by microorganisms, weeds and insects and the high cost of the products 6-8. Antifungal and Bioherbicidal Properties of Essential Oils of Thymus fallax Fish & Mey., Origanum vulgare L. and Mentha dumetorum Schult.