Control of Cucumber Powdery Mildew Using Resistant Cultivars and Organic Agricultural Materials

Abstract

This study evaluated the efficacy of various inorganic materials, biological control agents, organic agricultural materials (OAMs), and essential oils for controlling cucumber powdery mildew (CPM) under greenhouse conditions. Treatments included silicate, bicarbonate, copper sulfate, sulfur-based compounds, Bacillus subtilis KB-401, Bacillus amyloliquefaciens M27, Bordeaux mixtures, chitosan combined with oxidated copper salt, chitooligosaccharides, and essential oils such as castor and rapeseed oil with lecithin. Results demonstrated that Bordeaux mixtures, particularly Bordeaux Mixture I, and sulfur-based compounds provided the most reliable CPM control among inorganic materials. Bacillus strains KB-401 and M27 achieved sustained disease suppression, suggesting their value in integrated pest management (IPM). Chitosan combined with oxidated copper salt showed high efficacy, making it a promising candidate for long-term control. Among OAMs, loess-sulfur mixtures proved especially effective in preventive applications, achieving comparable results to resistant cultivar 'Saronsamcheok'. Essential oils, including castor and rapeseed oil, also exhibited significant CPM suppression potential, although repeated applications may be necessary for sustained control. These findings highlight the potential of these environmentally friendly treatments as viable components of an IPM strategy for managing CPM in cucumber crops. Further studies are recommended to optimize combinations and application timing for enhanced efficacy.

Keywords: Bordeaux mixture; cucumber resistant cultivar; garlic extract; loess-sulfur mixture; powdery mildew.

Fig. 1. Preventive and curative effect of foliar-sprayed organic materials on the disease severity of cucumber powdery mildew (CPM) in the greenhouse.

Cucumber used in this study was a susceptible cultivar ESBD for CPM. Error bars indicate standard deviation (n = 10) and different letter above the column indicates significant difference at 5% level by Duncan’s multiple range test.

Fig. 2. Disease severity of cucumber powdery mildew on resistant cultivar (CPM, bar 1) and susceptible cultivar (bar 2 to 11) for CPM sprayed at different application times with/without three organic materials in the plastic film house in Wanju County.

Error bars indicate standard deviation (n = 30) and different letter above the column indicates significant difference at 5% level by Duncan’s multiple range test. Note: 1, Resistant cultivar ‘Saeronsamcheok’; 2, susceptible cultivar ’Misobaekdadagi (MBDD)’; 3, MBDD+ single application of Bordeaux mixture; 4, MBDD+two times application of Bordeaux mixture, 5, MBDD+three times application of Bordeaux mixture; 6, MBDD+single application of sulfur-loess mixture; 7, MBDD+two times application of sulfur-loess mixture, 8, MBDD+three times application of sulfur-loess mixture; 9, MBDD+single application of sodium bicarbonate; 10, MBDD+two times application of sodium bicarbonate; 11, MBDD+three times application of sodium bicarbonate.