Evaluating the biocontrol efficacy of beneficial soil microbes against the Fusarium wilt disease of tomato

Abstract

Tomato is one of the most important agricultural crops in the world as it is a rich source of vitamins A and C. The quality and the quantity of tomato fruits is severely affected by the fungal plant pathogens.  Fungal diseases are among the most dangerous biological stresses that cause severe damage to tomato crops in many countries. Fusarium wilt disease in tomato caused by Fusarium oxysporum f. sp. lycopersici, become a major concern of yield loss worldwide. This study evaluated the efficacy of multiple antagonistic biocontrol agents, including Trichoderma species and non-pathogenic F. oxysporum, in mitigating Fusarium wilt. Pathogenic F. oxysporum strains were isolated from diseased tomato plants, while biocontrol agents were cultured from rhizosphere soil of healthy tomato plants. In vitro dual-culture assays demonstrated that non-pathogenic F. oxysporum inhibited pathogenic strains by 86.8% (±4.8) at 7 days post-inoculation (dpi), significantly higher than T. harzianum, which achieved 62.8% (±6.2) inhibition (p < 0.01). Other Trichoderma strains, such as T. viride and T. asperellum, showed moderate inhibition levels of 54.3% (±2.3) and 51.9% (±5.9), respectively. Greenhouse pot trials reinforced these in vitro results, with non-pathogenic F. oxysporum achieving a significant disease reduction of 77.0% (±3.0) in Fusarium wilt incidence, followed by T. harzianum at 64.8% (±2.7) (p < 0.01). Statistically significant improvements in plant growth were also recorded in treated plants. T. harzianum increased shoot length by 25.6% (±3.1) and root weight by 22.4% (±2.9) compared to control plants, while non-pathogenic Fusarium enhanced root length by 30.2% (±3.4) and overall biomass by 28.7% (±3.8) (p < 0.01). Data were analyzed using ANOVA, followed by LSD for pairwise comparisons, confirming the efficacy of these biocontrol agents in reducing disease incidence and promoting plant growth. These findings underscore the potential of antagonistic biocontrol agents as viable, sustainable alternatives to chemical fungicides for managing Fusarium wilt in tomato production systems, supporting both plant health and environmental resilience.