Recently, plant essential oils (EOs) have attracted special attention in plant disease control and food preservation. Since ancient times, essential oils extracted from plants have exhibited many biological characteristics, especially antimicrobial properties. Recent studies have described the potentials of EOs and derivatives to inhibit the growth and reproduction of microorganisms, mainly in response of overwhelming concerns of consumers about food safety. In the context of returning to nature, with the advancement of science and technology and improved living standards, people have begun to seek solutions for food hygiene without chemical additives. Therefore, biological pesticides and plant-oriented chemicals have received special attention from scientists because they are environmentally friendly and nonhazardous, sustainable, and effective alternatives against many noxious phytopathogens. Present study is intended to appraise the fungicidal properties of ginger EOs to combat leaf blight disease of taro, which threatens global taro production. Farmers often hinge on extremely toxic synthetic fungicides to manage diseases, but the residual effects and resistance of chemicals are unavoidable. The microwave-assisted hydrodistillation method was used for ginger EOs extraction and an FTIR (ATR) spectrometer was used to evaluate their chemical composition and citral was identified as most abundant compound (89.05%) in oil. The pathogen isolated from lesions of diseased taro plants was identified as Phytophthora colocasiae and used as test fungus in the present study. Ginger EO was evaluated in-vitro for antifungal properties against mycelium growth, sporangium production, zoospore germination, leaf, and corm necrosis inhibition. Repeated experiments have shown that the concentration of ginger essential oil (1250 ppm) proved to be the lowest dose to obtain 100% inhibition of fungal growth and spore germination, sporangia formation and leaf necrosis assessment. These results are derived from this fungal species and a hypothesis that involves further research on other plant pathogens to demonstrate the overall potency of essential oils. This study references the easy, economic, and environmental management and control of plant diseases using essential oils and byproducts.

Background: Taro leaf blight, caused by a severely destructive oomycete fungusPhytophthora colocasiae, is responsible for threatening yield loss worldwide. The pathogen has the ability to germinate and spread rapidly to other plants during favorable conditions resulting in acute decline and even death, causing 100% crop loss. Farmers usually rely on highly toxic systemic fungicides to control the disease, which is effective, but residual effects and resistance of these agrochemicals is still a concern. Recently as returning to nature people tend to use chemical-free products, especially edible stuff produced in organic agriculture. Therefore, the use of bio-pesticides and phytochemicals is gaining special attention by scientists as they are ecofriendly non-hazardous, sustainable, and potent alternatives to control many virulent plant pathogens The present research was conducted to assess the antifungal potential of cinnamon essential oils againstP.colocasiae.Materials and methods: The essential oils from cinnamon bark were extracted using microwave-assisted hydrodistillation equipment, and then their chemical constituents were evaluated using ATR FTIR spectroscopy. The antifungal potential of essential oil was assessed against mycelium, sporangia, zoospore, leaf necrosis, and corms lesions under laboratory conditions at, 0.156, 0.312, 0.625, 1.25, 2.5, 5.0 mg/mL concentrations. Hymexazol was used as positive control and no essential oil as negative control, while each treatment have three replications and experiment repeated twice.Results: The main component of oil was identified as cinnamaldehyde. The pathogen isolated from infected taro leaves was identified asP.colocasiaeand then was used as a test fungus in the current study. Repeated experiments show maximum inhibition percentage of mycelial growth, zoospore germination, and sporulation of the fungus were observed at 0.625 mg/mL, whereas leaf necrosis was 100% inhibited at 1.25 mg/mL concentration.Conclusion: This research can be a reference for easy, cost-effective and environment-friendly management and control of taro leaf blight with phytochemicals and plant essential oil derivatives.Graphic

In order to illustrate their tolerance mechanism, four leading cultivars of Brassica napus (Mianyou 15, Guohaoyou 8, Yiyou 21, and Mianyou 16) were investigated to study the effects of Clopyralid, Benazolin, and Clethodium on physio-chemical and ultrastructural attributes of Brassica napus at during seed germination stage, by various concentrations (0.0, 0.5, 0.7, 1.0, 1.3 μg/10 mL) of Clopyralid, Benazolin, and Clethodium to rape seedlings in terms of various physiological and biochemical measurements and microscopic analysis. The main results were as follows: low concentration (0.5 μg/10 ml) of Clopyralid, Benazolin, and Clethodium had no significant effect on Brassica napus CVS. It was found that with the increasing of treated concentrations, the growth of Brassica napus was inhibited more when the concentration of Clopyralid, Benazolin, and Clethodium was higher than 1.3 μg·L-1. It inhibited the net photosynthetic rate, chlorophyll content, chlorophyll fluorescence value, and anti-enzyme activities of Brassica napus. Moreover, it increased lipid peroxidation, accumulated reactive oxygen species, and damaged the ultrastructure of chloroplasts and mitochondria in mesophyll cells. In addition, the ability of resistance to the stress of Clopyralid, Benazolin, and Clethodium in all cultivars shows higher sensitivity which is more effective. Therefore, this study defined the effect of selected herbicides on Brassica napus, and the findings have great significance in extending the calculation by field application of those herbicides.