Biocontrol of White Mold caused by Sclerotinia Sclerotiorum in Cucumber using Trichoderma Aggressivum, Bacillus Paralicheniformis, and Earthworms: First Study in Iraq

Abstract

Sclerotinia sclerotiorum causes white mold in crops, leading to severe yield losses in cucumber and many vegetables. This study evaluated the biocontrol potential of the Trichoderma aggressivum, Bacillus paralicheniformis, and earthworms Aporrectodea trapezoides against this pathogen. The pathogen was isolated from infected plants and evaluated for pathogenicity in pots experiments. In vitro, T. aggressivum showed strong antagonism (Bell’s scale grade 2), B. paralicheniformis inhibited fungal growth by 89.7% and earthworms consumed 80% of hydrated sclerotia. Under plastic house conditions, all treatments reduced disease incidence (T. aggressivum: 76.67%, B. paralicheniformis: 83.33%, Earthworms: 86.67%) and severity (AUDPC: 82.2, 99.03, 116.48 respectively). They also increased peroxidase activity (79.77, 65.8, 62.03 ΔAbs/min/g) and phenolic content (118.1, 101.5, 96.5 mg/g).