# The Fungicidal Effect of Essential Oils of Fennel and Hops against Fusarium Disease of Pea
## 3 Results and discussion
### Determination of Antifungal Activity Ex Vitro  
#### 3.2.1 Results of the Pot Experiment  
The results of the pot experiment in which pea plants were artificially inoculated with _F. culmorum_ spores showed that both FEO and HEO provide protection against Fusarium wilt (Figure 1). The subsequent test was carried out with _F. culmorum_, as it is an important pathogen under Polish conditions, causing late blight of pea, as well as stem base rot, root rot and Fusarium wilt of pea plants. Disease progression was inhibited in pea plants sprayed with both essential oils 24 h before artificial inoculation. An assessment of the health status of the pea plants 14 days after the fungal spores were applied to the soil also confirmed that both essential oils reduced the severity of Fusarium wilt compared to the positive control. Fennel essential oil was a more potent antifungal than HEO. When applied at a lower concentration (500 ppm), FEO reduced infection by 40.4% (DI = 37.3%) and HEO by 25% (DI = 52%) (Figure 1). At a concentration of 2000 ppm, HEO inhibited the progression of Fusarium wilt by 43% (DI = 34%) and FEO by 60.4% (DI = 17.3 %), relative to the positive control (DI = 77.7%) (Figure 1). Plants that were not inoculated with _F. culmorum_ were healthy. In other studies, fennel essential oil also inhibited the progression of fungal diseases. [PERSON] et al. [67] reported that application of 1 mL FEO at a concentration of 500 \(\mu\)L/mL suppressed Fusarium wilt in tomato plants both one week before and two weeks after artificial inoculation with _Fusarium oxysporum_ f. sp. _Icyopersici_ spores. An _ex vitro_ experiment conducted by [PERSON] et al. [68] showed that essential oils of fennel and Syrian oregano (_Origanum syriacum_ subsp. _bewnii_ ([PERSON]) [PERSON] and [PERSON]) promoted the survival of tomato seedlings grown on soil infected with _S. sclerotium_. In the _in vitro_ experiment, FEO was a more effective antifungal agent, while in the _ex vitro_ experiment Syrian oregano oil protected the tomato seedlings better against fungal infection. The survival rate of tomato seedlings increased from 26.6% to 69.8% and 63.3%, respectively, after treatment with Syrian oregano oil and FEO at the highest concentration (3.2 \(\mu\)g/mL) compared to control plants treated with _S. sclerotium_ spores. The antiviral effect of FEO was also confirmed against courgette yellow mosaic virus and its vector _Aphis gossypii_[69]. The antifungal activity of essential oils extracted from other plant species has been investigated in numerous studies [49; 70; 71; 72; 73; 74; 75]. Different ways of applying essential oils to plants are also used, e.g., dipping the seeds in the tested essential oils for 24 h reduces the Fusarium wilt and seedling rot and improved the survival of pea plants [76]. Seeds preserved with cumin oil had better aroma and flavour than those treated with a synthetic fumigant [77]. In artificially inoculated wheat grain (_Triticum aestivum_ L.), herbal application of essential oils of fennel, cinnamon tree (_Cinnamomum_ [PERSON]), oregano (_Origanum vulgarae_ L.), palmarosa leaves (_Cymbopogon martini_ (Roxb.) [PERSON]), spearmint (_Mentha viridis_ L.), bitter orange peel (_Citrus_\(\times\)_autantium_ L.), thymne hyemalis leaves and flowers ([PERSON]) and rosewood (_Aniba rosaeodora_ [PERSON]) inhibited ergosterol production by almost 100% and thus strongly inhibited the growth of _F. graminearum_ and _F. culmorum_. The essential oils studied also significantly reduced the concentrations of fungal mycotoxins, zeaeralenoene and group B trichothecenes, in wheat grains [71]. The inhibitory effect of essential oils on the biosynthesis of mycotoxins was also described by [PERSON] et al. [78], [PERSON] et al. [79] and [PERSON] et al. [80]. Mycotoxin contamination was not investigated in the present study, but a significant decrease in the concentration of _F. culmorum_ DNA was observed in pea plants treated with both FEO and HEO.