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ARTICLE

Crude Extract of Ulva lactuca L., Spirulina platensis (Gomont) Geitler and Nostoc muscorum C. Agardh ex Bornet & Flahault for Mitigating Powdery Mildew and Improving Growth of Cucumber

Ahmed Mahmoud Ismail^1,*, Eman Said Elshewy², Ayman Y. Ahmed³, Hossam M. Darrag⁴

1 Pests and Plant Diseases Unit, College of Agricultural and Food Sciences, King Faisal University, Al-Ahsa, 31982, Saudi Arabia
2 Vegetable Diseases Research Department, Plant Pathology Research Institute, Agricultural Research Center (ARC), Giza, 12619, Egypt
3 Department of Mycology Laboratories, Plant Pathology Research Institute, Agricultural Research Center (ARC), Giza, 12619, Egypt
4 Research and Training Station, King Faisal University King Faisal University, Al-Ahsa, 31982, Saudi Arabia

* Corresponding Author: Ahmed Mahmoud Ismail. Email:

(This article belongs to the Special Issue: Plants Abiotic and Biotic Stresses: from Characterization to Development of Sustainable Control Strategies)

Phyton-International Journal of Experimental Botany 2025, 94(10), 3023-3045. https://doi.org/10.32604/phyton.2025.067444

Received 04 May 2025; Accepted 02 September 2025; Issue published 29 October 2025

Abstract

Powdery mildew of cucumber (Cucumis sativus L.) is a destructive disease caused by Podosphaera xanthii (Castagne) U.Braun & Shishkoff. This study aimed to investigate the antifungal effect of extracts of Ulva lactuca, Spirulina platensis, and Nostoc muscorum against P. xanthii and to improve the physiological and morphological traits of cucumber under commercial greenhouse conditions. The chemical composition of the individual extracts from U. lactuca, S. platensis, and N. muscorum was analyzed utilizing High-performance Liquid Chromatography (HPLC) and Gas Chromatography/Mass spectrometry (GC/MS). Cucumber plants were sprayed twice with 5% of the crude extracts of U. lactuca, S. platensis, and N. muscorum and their mixture (U. lactuca, S. platensis, and N. muscorum). The fungicide Topas 100 EC (Syngenta) was applied at the recommended dose (0.250 mL/L) only for comparison. The HPLC analysis indicated that the U. lactuca extract was the richest in phenolic compounds (605.84 µg g⁻¹ DW) compared to cyanobacterial extracts of S. platensis (214.77 µg g⁻¹ DW) and N. muscorum (462.97 µg g⁻¹ DW). The GC-MS spectrum analysis of methanolic extracts revealed 12 compounds in N. muscorum, 11 compounds in S. platensis and 22 compounds in U. lactuca extract. In the 1^st experiment, among treatments, the combined mixture (U. lactuca, S. platensis, and N. muscorum) and U. lactuca extract revealed the remarkable disease reduction attained 74.35% and 71.42%, respectively. However, the highest disease reduction was attributed to fungicide Topas 100 EC with value reached 85.28%. A similar pattern of results was also noted during the 2^nd experiment. In both experiments, the extract of S. platensis had the lowest effectiveness in lowering the DS and AUDPC of powdery mildew disease. The combined mixture and U. lactuca extract resulted in a substantial (p < 0.05) increase in plant lengths, fresh and dry weights, leaves number, fruit number, and weight and yield/plant. Cucumber plants treated with either the extract of U. lactuca or the combined mixture exhibited the highest activity (0.084 and 0.088 U mL⁻¹min⁻¹) for peroxidase and (1.64 and 1.62 U mL⁻¹min⁻¹) for catalase, respectively, in the second experiment. The greatest increase in total phenolic content (7.97 mg g⁻¹ FW) was noticed in plants following treatment with the combined mixture. The treatment with U. lactuca and S. platensis revealed a significant increase in carotenoids contents, reached up to 17.99 and 17.53 mg g⁻¹ FW, respectively. We, therefore, support the need for considering sustainable management of powdery mildew of cucumber using the compounds derived from U. lactuca, S. platensis, and N. muscorum and to improve cucumber growth.

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Supplementary Material

Supplementary Material File

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