Efficacy of novel fungicide combinations against downy mildew in cucumber and their influence on biochemical defense mechanisms
Year: 2026
Type: article
Abstract: Downy mildew, caused by Pseudoperonospora cubensis, severely impacts cucumber (Cucumis sativus L.) in humid regions like North Gujarat, prompting evaluation of chemical fungicides as alternatives to resistant metalaxyl and copper-based options. A field trial was conducted in summer 2023 at Vegetable Research Station, Sardarkrushinagar Dantiwada Agricultural University, SDAU, used Randomized Block Design with eight treatments: Ametoctradin 27 SC + Dimethomorph 20.27 SC (0.2%), Metalaxyl 8 + Mancozeb 64 WP (0.2%), Cymoxanil 8 + Mancozeb 64 WP (0.2%), Chlorothalonil 33.1 + Metalaxyl M 3.3 SC (0.7%), Dimethomorph 50 WP (0.1%), Metiram 55 + Pyraclostrobin 50 WG (0.2%), Azoxystrobin 23 SC (0.25%) and untreated control. Sprays at 500 L/ha were applied post-disease onset, with assessments of percent disease intensity, area under disease progress curve, fruit yield (q/ha) and biochemicals (peroxidase, polyphenol oxidase, chlorophyll). Metalaxyl 8 + Mancozeb 64 WP excelled with lowest PDI (22.76%), 61.75% disease reduction, AUDPC (380.80 units) and highest yield (153.43 q/ha; 191.14% increase over control). Comparable results came from Ametoctradin + Dimethomorph (PDI 24.32%, yield 143.93 q/ha) and Cymoxanil + Mancozeb (PDI ~25%, yield 146.51 q/ha). All fungicides significantly outperformed control (PDI up to 59%, AUDPC 1007.03, yield 80.27 q/ha). Biochemical assays showed elevated peroxidase (0.18 U/g FW, Metalaxyl combo), PPO (0.18 U/g FW) and chlorophyll (1.83 mg/g FW), peaking 1-5 days post-spray before slight decline at 10 days, indicating induced defense activation. These fungicides offer sustainable management, minimizing resistance and phytotoxicity risks. Metalaxyl-Mancozeb is recommended for cucumber downy mildew control, enhancing yield and host defenses in tropical climates.
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: diamond
OpenAlex ID: W7166329456