## 1 Introduction  
The control of fungal pathogens and pests has vital importance for the protection of crops and food provision worldwide. Organic compounds are still the major active components of plant protection products. Although pesticides in agronomy exert powerful effects on disease control management, the long-term their unreasonable use led to serious environmental problems inducing successive pesticide-resistant pathogen development, disrupting soil ecological balance, and causing environmental and human health. There are among the most common pollutants in one-fifth of the Earth's land. Plant protection products pollute terrestrial and aquatic ecosystems, and every year millions of people are exposed to pesticides [1]. Daily exposure to pesticides has numerous consequences for human health. Pesticide exposure has numerous health consequences. Pesticides could induce tumors in the liver, lungs, stomach, kidneys, skin, and stomach [2, 3]. Also, exposure to pesticides has been associated with dermatological, gastrointestinal, neurological, respiratory, reproductive, and endocrine symptoms of diseases [4]. Drug resistance and environmental and health hazards indicate the urgent need for novel active compounds. These compoundsmust be highly specific with a broad-spectrum mode of action, as well as environmentally and toxicologically acceptable [5]. In order to limit pesticide harmful effects, the European Parliament and the Council issued Directive 2009/128/EC that promotes integrated pest management with priority for plant protection products. This Directive has the fewest side effects on human health, non-target organisms, and the environment [6]. Coumarins are secondary plant metabolites widely distributed in higher plants, bacteria, fungi, and sponges [7]. Depending on the substitution of the 1-benzopyran-2-one skeleton, coumarins can be divided into several types: simple coumarins, furanocouramis, pyranocoumarins, and other coumarins (Figure 1). This great structural diversity of these natural compounds and their synthesized derivatives enables their wide range of pharmacological activities, such as antioxidant [8; 9; 10]; antibacterial [11; 12; 13; 14; 15; 16; 17]; antifungal [18; 19; 20]; anti-human immunodeficiency virus (HIV) infection [21; 22]; anti-tubercular [23]; cytotoxicity [24]; and anti-cancer activities [25; 26; 27; 28; 29]. There are also many reports about their effectiveness against plant pathogenic pests. These secondary metabolites are natural protection agents against environmental enemies and competing plants, therefore they are called allelochemicals. Allelicomicals are biocomunicators that act in a natural mixture of active components, while single compounds are not active [7; 30; 31]. Coumarin derivatives have been reported as strong agents against phytopathogen fungi, such as: _Botrytis cinerea_[32]; _Moniliophthora pernicosa_[33]; _Colletotrichum gloeosporoides_, _Fusarium oxysporum_, _Valsa mali_[34]; _Macrophonina phaseolin_ and _Sclerotiniia sclerootrium_[35; 36]. Coumarins have also antimicrobial potential against phytopathogens: _Ralstonia solanacearum_[37]; _Agrobacterium tumefaciens_[38]; _Pseudomonas aeruginosa_[39]. Nematicidal activity has been demonstrated for several simple coumarins, furanocouramis, and dicoumarols, and their skeletons have been used for the development of new efficient nematicides against plant parasitic nematodes: _Meloidogyne incognita_, _Ditylenchus destructor_, _Bursaphelenchus xylophilus_, _Bursaphelenchus mucronatus_, and _Aphelenchoides beseygi_[40; 41]. Despite numerous pieces of evidence in the literature about coumarins' biological effects on plant pathogenic pests, there is still scarce information about their practical applications in agriculture. In addition, there is scarce information about their effects on beneficial soil organism populations [35; 36]. The traditional approach to plant protection product discovery is an expensive and time-consuming process.