COMPARATIVE EFFICACY OF SELECTED FUNGICIDES AGAINST CUCUMBER FRUIT ROT DISEASE UNDER FIELD CONDITIONS

Abstract

Cucumber (Cucumis sativus L.) production in Nigeria is constrained by fruit rot disease, which reduces yield and market quality under field conditions. This study evaluated the comparative efficacy of selected fungicides and their residue levels in cucumber. Field experiments were conducted at the Teaching and Research Farm of the Federal University of Agriculture, Abeokuta, Ogun State, during the 2023 late and 2024 early planting seasons using two hybrid varieties Amarisa Super F1 and Oliver Bold F1. Three fungicide treatments, Five Star (azoxystrobin 200 g/L + difenoconazole 125 g/L SC), Dew Force (pyraclostrobin 40 g/L + dimethomorph 72 g/L EC), Ridomil Gold (metalaxyl 40 g/kg + mancozeb 640 g/kg), and an untreated control, were evaluated in a randomized complete block design with three replications. Fungicides were applied weekly from two weeks after sowing. Disease incidence, severity, and yield were analyzed using ANOVA, while residue levels were determined by UV-visible spectrophotometry and compared with the Codex maximum residue limits. Season significantly influenced disease development, with higher incidence (34.38%) and mean severity score (1.31) in the late season. Fungicides reduced disease. Five Star recorded the lowest incidence (15.00%), severity (0.67), and highest yield (10,539 kg/ha), followed by Ridomil Gold (25.75%, 0.69, 7,973 kg/ha) and Dew Force (28.86%, 1.11, 7,913 kg/ha) compared with the control (37.94%,1.42, 5,133.75 kg/ha). Variety significantly influenced yield, with Amarisa Super F1 (9,706 kg/ha) outperforming Oliver Bold F1 (6,073 kg/ha). Residues were metalaxyl (0.000068–0.000071), mancozeb (0.000047–0.000049), azoxystrobin (0.000046–0.000049), difenoconazole (0.000032–0.000034), pyraclostrobin (0.000051–0.000053), and dimethomorph (0.000036–0.000038 mg/kg), below Codex MRLs of 0.5, 2.0, 1.0–3.0, 2.0, 0.5, and 1.5 mg/kg, respectively. Five Star provided superior control without compromising food safety.