Efficacy of different bio-control agents for managing Colletotrichum leaf blight of large cardamom in Taplejung, Nepal

Large cardamom (Amomum subulatum) is a high-value spice crop primarily grown in the mid-hills of Nepal, providing significant economic benefits to smallholder farmers. However, the crop faces substantial threats from Colletotrichum blight, which has led to severe yield losses, prompting the need for effective disease management strategies. This study was conducted in Phungling-06, Taplejung district, within the cardamom cultivation zone, to evaluate the efficacy of various biocontrol agents in managing Colletotrichum blight. Using a randomized complete block design (RCBD) with five treatments, the study applied three foliar sprays of biocontrol agents (Trichoderma harzianum, Trichoderma viride, Pseudomonas fluorescens, Pseudomonas fluorescens + Bacillus subtilis, and a control). Disease severity and AUDPC scores were measured over a period of four weeks. The results demonstrated that Trichoderma harzianum significantly reduced disease severity and AUDPC, followed by Trichoderma viride. Additionally, Pseudomonas fluorescens and its combination with Bacillus subtilis showed promising effects compared to the control. These findings suggest that biocontrol agents can provide an eco-friendly and sustainable alternative to chemical fungicides in large cardamom production. Future research should focus on optimizing the application techniques and exploring the long-term benefits of these biocontrol strategies in integrated pest management systems for large cardamom cultivation.