Bacillus spp. and Trichoderma asperellum Highly Effective Against Tomato Bacterial Wilt

A 2025 research article published in the Egyptian Journal of Biological Pest Control reports strong evidence supporting the use of beneficial microbes to combat bacterial wilt in tomatoes — one of the most destructive diseases affecting solanaceous crops worldwide. The study evaluated the biocontrol potential of Bacillus subtilis, Bacillus pumilus, Bacillus chitinosporus, and Trichoderma asperellum against Ralstonia solanacearum under both laboratory and greenhouse conditions.

Why This Matters

Bacterial wilt can cause complete plant death and severe yield losses. Chemical pesticides and resistant cultivars often fail due to variability in pathogen strains and environmental constraints. This study demonstrates that certain soil-borne antagonistic microbes can provide environmentally safe and effective alternatives.

Key Findings from the Study

1. Strong Inhibition of Ralstonia in Laboratory Tests

All four tested microbes significantly inhibited the growth of R. solanacearum in vitro.
B. pumilus showed the strongest suppression of pathogen growth among the treatments.

2. Reduced Disease Severity Under Greenhouse Conditions

In greenhouse trials spanning two growing seasons:

B. pumilus achieved the highest disease suppression (up to 62.8% efficacy).
B. subtilis also performed strongly, reducing disease severity by more than 50%.
All bioagents significantly lowered AUDPC values compared to controls.

3. Enhanced Tomato Growth and Yield

Across multiple parameters, microbial treatments improved:

plant height
chlorophyll content
number of leaves and flowers
fresh and dry weights
total yield per plant

Trichoderma asperellum consistently produced the strongest growth-promoting effects.

4. Improved Tomato Fruit Quality

Plants treated with T. asperellum produced fruits with:

larger diameter
higher TSS
increased vitamin C
improved hardness and pH stability

5. Activation of Plant Defense Genes

RT-qPCR results showed strong upregulation of PR-2 and PR-3 genes in treated plants, particularly under T. asperellum and B. pumilus treatments.
This indicates induction of systemic resistance.

Conclusion

The study concludes that Bacillus subtilis, Bacillus pumilus, Bacillus chitinosporus, and Trichoderma asperellum are promising biological control agents for managing tomato bacterial wilt. Their combined ability to suppress the pathogen, enhance plant health, and improve fruit quality positions them as valuable tools for sustainable agriculture.

Reference

Elsharkawy, M.M., Kamel, S.M., Fathallah, G. et al. Efficacy of Bacillus spp. and Trichoderma asperellum for biological control of bacterial wilt disease in tomato: in vitro and in vivo evaluations. Egypt J Biol Pest Control 35, 39 (2025). https://doi.org/10.1186/s41938-025-00877-w