Eco-friendly management of papaya collar rot: A biocontrol approach in nurseries using antagonistic bioagents

Collar rot, a devastating nursery disease in papaya (Carica papaya), caused by Pythium aphanidermatum, severely compromises seedling establishment and crop productivity. This study, conducted at Sylhet Agricultural University, Bangladesh, evaluated the biocontrol potential of three antagonistic bioagents—Trichoderma solid (T2), Bioderma solid (T1), and Bioderma powder (T3)—against the pathogen, compared to an untreated control (T0). Morphological characterisation confirmed P. aphanidermatum as the causal agent. Trichoderma solid (T2) emerged as the most effective treatment, achieving 84.8% disease suppression, the highest seedling vigour index (1592.2), and superior germination (88.9%), alongside enhanced shoot (9.1 cm) and root growth (8.8 cm). Bioderma solid (T1) ranked second in efficacy, while Bioderma powder (T3) significantly reduced disease incidence and promoted vegetative development. In contrast, the control (T0) exhibited severe collar rot (70.1% incidence) and the lowest vigour (321.4). The results demonstrate that Trichoderma-based formulations act as potent antagonists against P. aphanidermatum, offering a sustainable alternative to synthetic fungicides. This study underscores the integration of biocontrol agents into papaya nursery management to mitigate soil-borne pathogens, reduce agrochemical dependency, and enhance seedling resilience. These findings advocate for scaling biocontrol strategies to safeguard papaya cultivation, a critical crop for tropical agro-economies and nutrition security.