Sustainable Chemistry and Pharmacy 15 (2020) 100219 Available online 28 January 2020 2352-5541/© 2020 Elsevier B.V. All rights reserved. Phytotoxic potential of selected essential oils against Ailanthus altissima (Mill.) Swingle, an invasive tree ☆ Erna Karalija a , Sabina Dahija a , Adisa Pari�c a , Sanja � Cavar Zeljkovi�c b, c, * a Laboratory for Plant Physiology, Department of Biology, Faculty of Science, University of Sarajevo, Zmaja od Bosne 33-35, 71 000, Sarajevo, Bosnia and Herzegovina b Centre of the Region Han� a for Biotechnological and Agricultural Research, Department of Genetic Resources for Vegetables, Medicinal and Special Plants, Crop Research Institute, � Slechtitelů 29, 78371, Olomouc, Czech Republic c Centre of the Region Han� a for Biotechnological and Agricultural Research, Department of Phytochemistry, Palacky University, � Slechtitelů 27, 78371, Olomouc, Czech Republic A R T I C L E INFO Keywords: Allelopathy Essential oil Medicinal plants Germination assay Seedling growth GC-MS ABSTRACT Ailanthus altissima (Mill.) Swingle, tree of heaven, is an exotic tree introduced as a horticultural tree in Europe and America in 18th Century. Now it is aggressively invading ecosystems. This study was aimed to estimate phytotoxic potential of essential oils (EOs) from fourteen industrial, aromatic and medicinal crops, such as Thymus sp., Pinus sp., Origanum sp. etc. against this invasive species. The phytotoxic potential was assessed through three different doses of EOs by a germination bioassay and the effects on seedling growth. Analysis of seedling growth revealed that seven EOs (Petasites hybridus, Thymus serpyllum, Thymus vulgaris, Rosmarinus officinalis, Helichrysum italicum, Matricaria chamomilla, Origanum vulgare) exhibit high phytotoxic effect resulting in 95–100% seedling mortality. Moreover, detailed GC-MS analysis of these oils showed that they are mostly comprised either of oxygenated monoterpenes or sesquiterpene hydrocarbons, which are already known as compounds with allelopathic effects. Presented results indicate these essential oils might be used as natural herbicides by foliar application of oils on young plants of Ailanthus altissima. 1. Introduction The invasion of exotic plants that used to be separated by biogeo- graphical barriers has recently become a great problem (Medina-Villar et al., 2017). Ailanthus altissima (Mill.) Swingle (family Simaroubaceae), is a deciduous tree plant native to Southeast Asia, and is one of the most widespread invasive plant species in Europe and North America (DAI- SIE, 2014). Highly invasive potential is caused by its tolerance to various ecological conditions and even pollution, high reproduction rate, growth and regeneration rate. The growth rates are different in high-light and low light environments, with increasing growth rate in correlation to light intensity. Nevertheless, small seedlings and saplings will survive under a closed canopy and low-light conditions (Kota et al., 2007). In most cases females do not produce seed until they are small trees (Wickert et al., 2017), but both sexes will activly spread via root sprouts. After stem and root damage vegetative growth of this species will increase (Kowarik and S€ aumel, 2007). This species also produce a wide span of secondary metabolites with herbicidal and insecticidal activities (Sladonja et al., 2015). Moreover, A. altissima also affects human health, causing allergies, dermatitis, and even myocarditis (Kowarik and Saumel, 2008). Such properties of this tree inhibit post-disturbance succession through cre- ation of toxic soil environment (Lawrence et al., 1991; Sladonja et al., 2015). Its eradication is difficult, as it has a high regenerative capacity (Sladonja et al., 2015). Currently, the only way to effectively control A. altissima is the application of herbicides after mechanical treatment (Badalamenti and LaMantia, 2013). In a search for an alternative to the intensive use of synthetic chemical pesticides, scientists are focusing on natural products, with essential oils as the most prominent candidates (Synowiec et al., 2017). In recent years, extensive research regarding fungicidal (Kumar et al., 2014), insecticidal (Isman et al., 2011; Abbad et al., 2014) and ☆ Key Message: Selected commercially available essential oils might be used as natural herbicides by foliar application of oils on young plants of Ailanthus altissima, which is known as highly invasive tree plant. * Corresponding author. Centre of the Region Han� a for Biotechnological and Agricultural Research, Department of Genetic Resources for Vegetables, Medicinal and Special Plants, Crop Research Institute, � Slechtitelů 29, 78371, Olomouc, Czech Republic. E-mail addresses: zeljkovic@vurv.cz, sanja.cavar@upol.cz, sanjacavar.sc@gmail.com (S. � Cavar Zeljkovi�c). Contents lists available at ScienceDirect Sustainable Chemistry and Pharmacy journal homepage: http://www.elsevier.com/locate/scp https://doi.org/10.1016/j.scp.2020.100219 Received 14 November 2019; Received in revised form 17 January 2020; Accepted 22 January 2020