Essential oils (EOs) are products of plant origin and include mixtures of different chemical compounds. These volatile substances have many interesting properties, including antifungal properties. Fungi may develop under field conditions on crops such as wheat or corn and are able to synthesize mycotoxins, which adversely affect livestock and human health. In the present study, selected EOs were used to inhibit the growth of Fusarium graminearum and F. culmorum and reduce the concentrations of mycotoxins in wheat grain. The EOs significantly inhibited the growth of tested Fusarium species (90.99–99.99%), as determined based on ergosterol quantitative analysis. Only the addition of orange oil to F. culmorum exhibits a different inhibition capacity (68.13%). EO application resulted in a large reduction in zearalenone content (99.08–99.99%); only in the case of orange oil application was the reduction estimated at approximately 68.33%. However, all EOs provided a significant reduction in the concentration levels of group B trichothecenes (94.51–100%). It can be concluded that EOs inhibit the growth of fungi of the genus Fusarium and reduce concentration levels of the mycotoxins zearalenone and group B trichothecenes.

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Antifungal activity of selected essential oils against Fusarium culmorum and F. graminearum and their secondary metabolites in wheat seeds.

The current study aimed to evaluate the negative allelopathic effect of Eucalyptus citriodora essential oil on some of the most noxious weeds in Algeria (Sinapis arvensis, Sonchus oleraceus, Xanthium strumarium and Avena fatua). Gas chromatography-flame ionization detector (GC-FID) and GC/mass spectrometry (MS) were used to define the chemical composition of the oil. Citronellal (64.7%) and citronellol (10.9%) were the major essential oil compounds. Three concentrations of the oil were used for laboratory (0.01, 0.02 and 0.03%) and greenhouse (1, 2 and 3%) experiments. Seed germination and seedling's growth were drastically reduced in response to the oil concentrations where at 0.01 and 0.02% the oil drastically affects the seed germination of the tested weeds and at 0.03% the oil suppresses completely the germination of S. arvensis. The oil also exhibited strong allelopathic effect on the 3 - 4 leaf-stage plants 1 and 6 days after treatment. A completely death of S. arvensis, S. oleraceus and A. fatua and severe injuries on X. strumarium appeared at 3% of the oil. Chlorophyll content and membrane integrity were significantly affected after treatment of the plant weeds representing a severe reduction in total chlorophyll and cell membrane disruption. The study concludes that E. citriodora essential oil might has the potential use as bioherbicide and can constitute an alternative process of weed control.

Allelopathic Effect of Eucalyptus citriodora Essential Oil and Its Potential Use as Bioherbicide.

Recent research demonstrates that the number of virulent phytopathogenic fungi continually grows, which leads to significant economic losses worldwide. Various procedures are currently available for the rapid detection and control of phytopathogenic fungi. Since 1940, chemical and synthetic fungicides were typically used to control phytopathogenic fungi. However, the substantial increase in development of fungal resistance to these fungicides in addition to negative effects caused by synthetic fungicides on the health of animals, human beings, and the environment results in the exploration of various new approaches and green strategies of fungal control by scientists from all over the world. In this review, the development of new approaches for controlling fungal diseases in plants is discussed. We argue that an effort should be made to bring these recent technologies to the farmer level.

Recent Approaches towards Control of Fungal Diseases in Plants: An Updated Review.

Development of eco-friendly nanoemulsions of some natural oils and evaluating of its efficiency against postharvest fruit rot fungi of cucumber

Essential oils are complex mixtures of odorous principles stored in different parts of special plants that play an important role in plant defense mechanisms against pathogenic fungi. They are composed of different chemical compounds which have various biological activities and therapeutic effects that can be used in different industries as well as control molds and various fungi such as food-borne and phytopathogenic fungi which cause different postharvest diseases and animal and human disorders. The antifungal activity of essential oil is associated with phytochemical components. In addition to this, percentage inhibition of mycelia growth depends on some other factors such as the antifungal activity method, the day of observation, oil concentration, and examined fungal species. In order to reduce the hazardous effects of synthetic fungicidal products, the increasing interest in the possible application of essential oils for pathogen management has induced to investigate new sources of biologically active natural products in antifungal therapy.

Mohamed A. Abdel Wahab

Papers

In vitro Antifungal Activity of Some Plant Essential Oils