Antifungal Activity of Plant-Derived Essential Oils on Pathogens of Pulse Crops

Abstract

Pulse crops such as chickpeas, lentils, and dry peas are grown widely for human and animal consumption. Major yield and quality limiting constraints include diseases caused by fungi and oomycetes. The environmental and health concerns of synthetic fungicides use for disease management, emergence of fungicide-resistant pathogens, and demand for organic pulse crop products necessitate the search for effective alternatives. Safe and environmentally friendly plant-derived essential oils (EOs) have been reported effective against some pathogenic fungi. Growth on EO amended growth medium and an inverted Petri-plate assay were used to determine the effects of 38 oils and their volatiles on mycelial growth and spore germination of important pathogenic fungi and oomycetes: Aphanomyces euteiches, Botrytis cinerea, Colletotrichum lentis, Didymella pisi, D. rabiei, D. lentis, Fusarium avenaceum, Stemphylium beticola, Sclerotinia sclerotiorum, and Pythium sylvaticum. Palmarosa, oregano, clove, cinnamon, lemongrass, citronella, and thyme oils incorporated in media inhibited mycelial growth of all the pathogens by 100% at 1:1,000 to 1:4,000 dilution. In addition, thyme oil (1:500 dilution) showed complete inhibition of conidial germination (0% germination) of F. avenaceum, and D. pisi. All the seven EO volatiles inhibited mycelial growth of all pathogens by 50 to 100% except for B. cinerea and S. sclerotiorum. Essential oil effects on mycelial growth were fungistatic, fungicidal or both and varied by E. Essential oils show potential for management of major crop diseases in organic and conventional production systems.

Ammoides pusilla Essential Oil: A Potent Inhibitor of the Growth of Fusarium avenaceum and Its Enniatin Production

“…They are extracted from more than 17,000 aromatic plants belonging to angiosperm families: Lamiaceae, Rutaceae, Myrtaceae, Zingiberaceae and Asteraceae [14], and they have multiple antibacterial, antifungal, antiviral, antiparasitical, insecticidal, medicinal and cosmetic applications [15]. At least 16 different publications [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] presented data on EOs antifungal activities from 35 plants against F. avenaceum (Table 1). All the authors used either agar diffusion methods (paper discs or wells), or an agar dilution method.…”

“…All the authors used either agar diffusion methods (paper discs or wells), or an agar dilution method. Only one recent paper reported a method for testing the effects of the volatile components [16]. In the application of EOs for controlling the phytopathogens, the bioactivity of volatiles should widely contribute to the fungicidal or fungistatic effect and it is worthy to measure it.…”

Essential Oils of Sage, Rosemary, and Bay Laurel Inhibit the Life Stages of Oomycete Pathogens Important in Aquaculture

“…Moreover, this is the first report of the inhibitory effect of essential oils against A. astaci . Nevertheless, some authors reported a good inhibitory effect of tea tree oil against the mycelial growth of the fish pathogen A. invadans [ 28 ] and of 38 essential oils, including rosemary essential oil and essential oils from some other Lauraceae and Lamiaceae plants, against the mycelial growth of the plant pathogen A. euteiches [ 40 ].…”

“…In particular, plants from the Lauraceae and Lamiaceae families, such as Thymbra spicata and Cinnamomum zeylanicum , have been reported to inhibit pathogenic freshwater oomycetes, mostly using the mycelium and zoospores of Saprolegnia spp. as models [ 32 , 34 , 36 , 37 , 38 , 40 ]. In comparison, the inhibitory activity of essential oils and their major components against Aphanomyces spp.…”

“…In comparison, the inhibitory activity of essential oils and their major components against Aphanomyces spp. is much less studied [ 28 , 40 ]. So far, there are no reports on the inhibitory activity of essential oils against A. astaci , but some essential oils showed good inhibitory activity against the phylogenetically related plant pathogen A. euteiches and the fish pathogen A. invadans [ 28 , 40 ].…”