In the present investigation, the antifungal activity of essential oil emulsions and nanoemulsions of sweet basil (Ocimum basilicum L.), marjoram (Majorana hortensis Moench), peppermint (Mentha piperita L.), spearmint (Mentha spicata L.) and thyme (Thymus vulgaris L.) were evaluated against Fusarium oxysporum isolated from infested cumin and geranium plants. Essential oils were obtained by hydrodistillation and analyzed by gas chromatography. The nanoemulsion was formulated using the essential oils, non-ionic surfactant (Tween 80) and water by ultrasonication method for 30 min and characterized by particle size analyzer and transmission electron microscope. Essential oil emulsions were prepared as mentioned above without sonication. The transmission electron micrograph showed that the essential oil nanoemulsions were spherical in shape and moderately mono or di-dispersed. The droplet size was correlated well with the results obtained from droplet size analysis showing that droplets are present in the nanometer range, with particle size of less than 100 nm and were stable after 3 months of storage under room temperature (27 °C). Four concentrations of the emulsions and nanoemulsions were used to evaluate the anti-fusarium activity in vitro. The results showed that maximum inhibition against Fusarium oxysporum. f.sp. cumini was resulted by thyme essential oil nanoemulsion and emulsion at 2000 ppm and sweet basil essential oil nanoemulsion at 4000 ppm. Also, maximum inhibition against Fusarium oxysporum isolated from geranium plant resulted by thyme essential oil nanoemulsion and emulsion at 2000 ppm. All essential oil nanoemulsions exhibited higher activities compared to emulsions against fungal growth at all concentrations. Treating cumin seeds with each of the concentrations of essential oil emulsions did not affect germination, while seed germination percentage sharply decreased at high concentrations of nanoemulsions treatments. The results suggest the potential effects of thyme and sweet basil essential oil nanoemulsions as novel fungicide agents against Fusarium spp.

otrytis blight was observed in Egypt (Nov., 2016) on Poinsettia (Euphorbia pulcherrima) that caused small light brown spots at the edge of leaves and enlarged to include the whole leaf. The isolated fungus was identified as Botrytis cinerea based on its morphological and cultural characteristics. In greenhouse, artificial inoculation of plants developed blight symptoms. The effect of ultrasonication on the particle size of lemongrass and citronella essential oil nanoemulsions was determined. The results showed that the particle sizes from sonication for 30 minutes were around 90.6 and 79.8 nm, and TEM study revealed the spherical shape. Changes in the essential oil emulsions components were observed in the nanoemulsions compared with the original as the size of the oil particles become small, the stability and main component of the emulsion were significantly improved. In vitro, the nanoemulsion at different concentrations (1000-8000 ppm) were capable of adversely affecting the mycelial growth of Botrytis cinerea. In greenhouse experiment, poinsettia plants were sprayed with the two essential oils (emulsion and nanoemulsion) and the fungicide carbendazim 50% WP (as additional control), after and before inoculation by the fungus. The disease severity was decreased by the treatments compared to the untreated control. The lowest disease severity, being 10.0 and 13.0% with nanoemulsion of lemongrass, before and after inoculation by the fungus, respectively. The results indicate an increase in the concentrations of active substances in essential oils due to their exposure to ultrasonication and their conversion to nanoemulsions, as the results suggest the potential effects of lemongrass essential oil nanoemulsion as a novel fungicide agent against Botrytis cinerea.

Three biocontrol agents i.e., Bacillus subtilis, Pseudomonas fluorescens, Trichoderma harzianum, were evaluated for their efficacy in controlling powdery mildew on squash plants. In greenhouse experiment, the highest inhibition of disease severity percentage was achieved by P. fluorescens, B. subtilis and T. harzianum, and application of Amistar 250 SC on squash plants resulted significant reduction of disease severity. The bacterial bioagents, i.e. P. fluorescens, and B. subtilis exhibited the highest reduction in disease severity. On the other hand, T. harzianum gave the lowest reduction in the disease severity. All resistance inducers (i.e., potassium nitrate (KNO3), potassium phosphate monobasic (KH2PO4), potassium phosphate dibasic (K2HPO4 and salicylic acid) treatments resulted in significant reduction in disease severity under greenhouse conditions. Under field conditions, similar reduction in disease severity of powdery mildew was observed in treated plants. All treatments significantly increased squash yield per plant. More than 75% increase in yield was observed in treated plants with (KNO3 at 100 mM).

This study was carried out at the Experimental Farm of Medicinal and Aromatic Plants Research Department in El Kanater El Khairia, HRI, ARC, during the two successive seasons of 2016 and 2017 to study the effect of some microorganisms (Bacillus subtilis, Trichoderma harzianum, Pseudomonas fluoroscens and Streptomyces griseus) on suppressing of damping-off disease of basil seedling, vegetative growth, oil production and chemical constituents of sweet basil (Ocimum basilicum L.) plants. The plants treated with any of the bioagents, showed highest effect in controlling damping-off and increased basil productivity compared with control plans. The results showed that, all bioagents treatments significantly increased vegetative growth (plant height, number of branches, fresh and dry weights (g/plant), oil percentage, oil yield, chemical constituents (chlorophyll (a), (b) and carotenoids contents as well as total carbohydrates percentage) compared with control plants. Streptomyces griseus gave the best effect against damping-off disease and all plant characteristics compared with control plants in the first season while, in the second season, Pseudomonas fluorescens increased plant protection and all plant characteristics. GC analysis of sweet basil essential oil of all treatments identified nine components. The major component of the essential oils was Linalool.