Differential Efficacy of Fungal and Bacterial Antagonists against Fusarium verticillioides, Macrophomina phaseolina, and Dickeya zeae: Stalk Rot Pathogens of Maize

Abstract

Aim: This study evaluated the in vitro antagonistic efficacy of selected fungal and bacterial bioagents against the major maize stalk rot pathogens Fusarium verticillioides, Macrophomina phaseolina, and Dickeya zeae. Study Design: The experiment was arranged in a completely randomised design. Place and Duration of Study: The study was conducted at the Agricultural Research Station, Peddapuram, ANGRAU, Andhra Pradesh, India, during 2025–26. Methodology: Six bioagents, namely Trichoderma harzianum, T. asperellum, T. koningiopsis, Pseudomonas fluorescens, P. chlororaphis, and Bacillus subtilis, were tested. Antagonism against the fungal pathogens was assessed by the dual-culture technique, whereas activity against D. zeae was evaluated through an inhibition-zone assay. Mycelial growth inhibition, inhibition-zone diameter, and reduction in sclerotial production were recorded and statistically analysed. Results: The bioagents differed in their activity against the tested pathogens. Trichoderma koningiopsis and T. asperellum were the most effective against F. verticillioides and M. phaseolina, producing 56.67–71.25% inhibition over the control. Fungal bioagents also reduced sclerotial production of M. phaseolina more effectively than the bacterial bioagents. Bacillus subtilis and P. chlororaphis showed moderate, broader antagonistic activity against the fungal and bacterial pathogens, with inhibition generally ranging from 36.67% to 46.67%. Conclusion: The findings indicate that T. koningiopsis, T. asperellum, B. subtilis, and P. chlororaphis merit further validation as components of integrated maize stalk rot management under greenhouse and field conditions.