Vol. 9, Special Issue 12, Part H (2025)

The recent surge of Fusarium infections has made it increasingly difficult to cultivate healthy small‑cardamom (Elettaria cardamomum) plants. In the field, the pathogen manifests as capsule rot, seed decay, seedling wilt, stem rot and lodging, rhizome and root‑tip rot, and leaf yellowing. To address this, a field trial was carried out in Santhanpara, Vandanmedu, Parathode and Kattappana. The objective was to assess the individual and combined effects of several biocontrol agents Pseudomonas fluorescens (Strains IDK‑S‑1, IDK‑V‑2, IDK‑P‑3, IDK‑K‑4), Bacillus subtilis (strains IDK‑S‑1, IDK‑V‑2, IDK‑P‑3, IDK‑K‑4), Trichoderma harzianum (strains IDK‑S‑1, IDK‑V‑2, IDK‑P‑3, IDK‑K‑4) and arbuscular mycorrhizal fungi (AMF; strains IDK‑S‑1, IDK‑V‑2, IDK‑P‑3, IDK‑K‑4) on plant growth, yield and suppression of Fusarium wilt. The causal agent of wilt was identified as Fusarium oxysporum Schlecht. Five native bacterial antagonists and one fungal antagonist were isolated from forest soil and from healthy cardamom plantations in different regions.

Under field conditions, a combined foliar spray and soil drench of P. fluorescens (Pf‑IDK‑S‑1) together with B. subtilis (Bs‑IDK‑V‑2) reduced the pathogen’s mycelial growth by 60 % relative to single‑strain applications. These two strains were compatible. The greatest disease reduction, however, was achieved by a soil application of P. fluorescens (IDK‑S‑1) together with T. harzianum (IDK‑P‑3). Moreover, plots treated with the P. fluorescens + B. subtilis mixture showed a significant increase in plant height and a yield gain of up to 27 % compared with untreated control plots.