# The Fungicidal Effect of Essential Oils of Fennel and Hops against Fusarium Disease of Pea
## 1 Introduction  
The pea (_Pisum sativum_ L., Fabaceae) is widely cultivated worldwide, mostly as an edible plant. Pea seeds contain biologically valuable protein with a desirable amino acid composition [1]. In 2021, global pea production reached about 12.4 million tons, of which 48% was produced in Europe, 21% in North America and 21% in Asia. In Europe, peas are the leading protein crop, accounting for 55.6% of total legume production. Outside Europe, soybeans are the most important protein crop, with global production exceeding that of pulses by a factor of four. Average pea yields are generally low, equivalent to about 65-70% of global soybean yields (1.72-2.04 versus 2.67-2.86 t/ha) [2]. Pea yieldsare limited by: (i) low temperatures and soil dryness during seedling emergence; and (ii) biotic factors causing plant diseases, including fungi of the genus _Fusarium_ such as _F. avenueum, F. culmorum, F. solani, F. oxysporum_ and others, which cause seedling blight and fusarium root and stem rot in the early stages of plant development and fusarium wilt in peas during flowering [3]. These pathogens colonise the seeds and are subsequently transmitted to the plants [4]. Fungi of the genus _Fusarium_ cause the most devastating plant diseases around the world [5; 6; 7]. Almost all _Fusarium_ species produce mycotoxins that have adverse health effects on humans and animals. Mycotoxins determine the progression of the disease in the early stages of infection, they accumulate in the seeds during maturation and thus affect their quality [8; 9; 10]. The following _Fusarium_ species are most frequently isolated from cultivated plants in Poland: _Fusarium oxysporum, F. avenueum, F. culmorum, F. equiseti, F. dinerum, F. solani, F. sporotrichoides, F. proliferatum_ and _F. verticillioides_[3; 11]. _Fusarium_ pathogens are mainly controlled by the use of fungicides, which, however, can have potentially harmful effects on the environment and human and animal health [8; 12]. _Fusarium_ species are characterised by high variation within and between species. The widespread use of fungicides has led to their accumulation in food, sometimes beyond the permissible residue levels [13], and it has also triggered mutations that lead to changes in the morphology, physiology and biochemical properties of the fungi. This has contributed to the development of new, highly resistant fungal races with different host plant preferences [14]. Therefore, to protect the environment and consumers, a sustainable approach to crop production is needed that includes natural alternatives that are as effective as chemical fungicides. The secondary metabolites produced by plants, such as essential oils, are generally considered safe, easy to extract, environmentally friendly, biodegradable and largely non-toxic to mammals [15]. From a chemical point of view, essential oils (EOs) are multi-component mixtures of volatile aromatic hydrophobic compounds, mostly monoter, sesquiterpenes and their derivatives [16; 17; 18]. Due to the considerable differences in their chemical composition, essential oils possess a wide range of physicochemical, sensory, biological and antimicrobial properties [19; 20]. Research has shown that some essential oils are as effective or even more effective than fungicides in inhibiting fungal growth [21; 22]. The efficacy of essential oils in inhibiting plant pathogens has been confirmed by numerous _in vitro_ studies [23; 24]. It is believed that the antifungal activity of essential oils is related to the unique properties of terpen/terpenoids. Due to their high lipophilicity and low molecular weight, these compounds are able to damage cell walls, lead to cell death or inhibit sporulation and germination of various fungal species [17; 25; 26]. In recent years, numerous studies (mostly based on _in vitro_ tests) have investigated the antifungal potential of essential oils against various pathogens, including _Fusarium_ species.