Why Bacterial Biocontrol Often Fails in the Field: Insights from Tomato Bacterial Disease Management in Tropical Systems with Emphasis on Vietnam

Biocontrol using antagonistic bacteria is considered a promising and sustainable approach for managing tomato bacterial diseases. Many antagonistic bacterial strains show strong activity under laboratory conditions, but their performance in greenhouse and field conditions is often unstable. This discrepancy is commonly described as the “translation gap”, meaning the gap between laboratory/greenhouse success and inconsistent field performance. This review examines the main causes of this gap. The analysis indicates that inconsistent field performance is not caused by a single factor, but by the combined effects of limited ecological fitness, environmental variability, formulation and delivery problems, and differences in agricultural management practices. Laboratory and greenhouse systems often simplify plant–bacteria–pathogen interactions and do not fully reflect the complexity of field environments. As a result, they may overestimate the practical potential of bacterial biocontrol agents. A conceptual framework is proposed to link biological, environmental, technical, and operational constraints and to explain why bacterial biocontrol often fails under practical conditions. Special attention is given to tropical tomato production systems, with emphasis on Vietnam, where high temperature, rainfall, humidity, intensive cultivation, and limited field-based evidence further increase the difficulty of achieving consistent disease control. Overall, this review highlights the need to move beyond simple antagonistic activity-based screening and to give greater attention to ecological fitness, rhizosphere colonization, stress tolerance, formulation quality, and compatibility with local farming practices.