In vitro Evaluation of Native Trichoderma Species against Pythium aphanidermatum, the Causal Agent of Ginger Rhizome Rot

Abstract

Background: Ginger rhizome rot, caused predominantly by Pythium aphanidermatum, is a destructive soil-borne disease that can substantially reduce ginger productivity under favourable conditions. Biological control using native Trichoderma isolates offers a potentially sustainable approach for suppressing the pathogen and reducing reliance on chemical fungicides. Aims: This study aimed to isolate and identify native Trichoderma spp. from rhizosphere soils and to evaluate their in vitro antagonistic potential against Pythium aphanidermatum, the causal agent of ginger rhizome rot. Study Design: Completely Randomised Design (CRD). Place and Duration of Study: Department of Plant Pathology, College of Agriculture, Latur, Maharashtra, India. The study was carried out during 2025–2026. Methodology: Rhizosphere soil samples were collected from different agricultural fields in the Latur and Ch. Sambhajinagar districts for the isolation of native Trichoderma spp. Seven isolates were purified and identified based on their cultural and morphological characteristics. Pythium aphanidermatum was isolated from naturally infected ginger rhizomes and its pathogenicity was confirmed under screen house conditions using the sick soil method. The antagonistic activity of the Trichoderma isolates was evaluated against P. aphanidermatum using the dual culture technique. Radial mycelial growth of the pathogen and percentage inhibition were recorded at 3, 5, and 7 days after inoculation. Results: Seven native Trichoderma isolates belonging to four species (T. virens, T. harzianum, T. koningii, and T. hamatum) were obtained from ten rhizosphere soil samples. All isolates significantly inhibited the mycelial growth of P. aphanidermatum compared with the untreated control. Among them, Trichoderma virens (LTv-1) showed the highest antagonistic activity, recording the lowest pathogen growth (14.93 mm) and the highest mycelial growth inhibition (83.41%) at 7 days after inoculation. This was followed by T. koningii (LTk-1) and T. virens (LTv-2), which recorded 76.48% and 75.97% inhibition, respectively. Statistical analysis indicated significant differences among the treatments according to the CD test (P ≤ 0.01). Conclusion: The study demonstrated that native Trichoderma isolates effectively suppressed the growth of Pythium aphanidermatum under in vitro conditions. Among the tested isolates, T. virens (LTv-1) exhibited the greatest biocontrol potential and may serve as a promising eco-friendly biological control agent for the management of ginger rhizome rot. However, further field evaluation is required to validate its effectiveness under natural conditions.