Effective Management of Cucumber Powdery Mildew with Essential Oils

Yasser S. Mostafa,Sulaiman A. Alrumman,Mohamed Hashem,El-Sayed H.E. Ziedan,Ebrahem M. Eid,Saad Alamri,Ali M. Alshehri

doi:10.3390/agriculture11111177

Yasser S. Mostafa, Sulaiman A. Alrumman + Show 5 more

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https://doi.org/10.3390/agriculture11111177

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Abstract

This research evaluated the efficacy of essential oils in the management of cucumber powdery mildew. Essential oils of lemongrass, lemon, thyme, peppermint, abundance blend, purification blend, and thieves blend were tested in vitro and under greenhouse conditions in two separate experiments. The effects of essential oils were tested against powdery mildew disease at concentrations of 1.0–2.5 mL/L, and the consequent impact of the oils on plant growth was evaluated. Powdery mildew fungus, Podosphaera xanthii, was identified using sequencing of the ITS region. The essential oils significantly reduced disease incidence up to 77.3% compared with the positive control (p < 0.5). Moreover, the essential oils increased the plant length (up to 187 cm), leaf area (up to 27.5 cm2), fresh weight (up to 123 g), dry weight (up to 22.5 g), number of flowers (16.3), and metabolite content compared with the positive control (p < 0.5). Cell membrane injury decreased significantly in the oil-treated pants (p < 0.5), indicating the protective effect of essential oils. This study recommends the application of essential oils in an appropriate dose (2.5 mL/L) to protect cucumber plants against powdery mildew. Overdose of the oils (more than 2.5 mL/L) should be avoided due to adverse effects.

Highlights

Cucumber (Cucumis sativus L.) is one of the most important and widely distributed vegetable crops due to its rapid growth and early maturity
P. xanthii KKUY-6001 was identified based on the morphology of its mycelia and conidia, consistent with Braun and Takamatsu [35], and its identity was confirmed by sequencing its internal transcribed spacer (ITS) region of DNA
Molecular identification, based on the sequences of ITS1 and ITS2 aligned with the powdery mildew fungi deposited in GenBank, confirmed the identity of the fungus as P. xanthii with a similarity level of 96.91%, and its sequence data were deposited in GenBank under accession number MG243352

Summary

Introduction

Cucumber (Cucumis sativus L.) is one of the most important and widely distributed vegetable crops due to its rapid growth and early maturity. Cucumber is produced either in protected houses or in open fields [1,2]. The global cultivation of this crop covers. 2,231,402 hectares, with production of about 87.805 tons [3]. 11,764 hectares and produces 149,074 tons, with a production rate of 1.27 tones/ha [4]. Cucumber fruit is a good source of minerals and vitamins and delivers Na, Mg, K, Ca, S, Si, F, and Fe. Cucumber contains carbohydrates, protein, thiamin, riboflavin, vitamin C, and niacin. The presence of minerals is important to maintain human blood alkalinity

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