Trichoderma Fungi Can Control Blue Mold Rot in Onions Across Pakistan

**New Study Demonstrates Powerful Biocontrol of Onion Blue Mold Using Trichoderma Species in Pakistan**

A newly published study in the Egyptian Journal of Biological Pest Control reports promising results for the biological management of blue mold rot in onions—a destructive postharvest disease caused by Penicillium expansum. The research, conducted across storage facilities in Sindh and Balochistan, confirms that Trichoderma harzianum and T. viride are effective antagonists against the pathogen.

Blue mold rot poses a serious challenge to onion production in Pakistan, where onions are stored, transported, and marketed over long distances. The disease is characterized by blue-green fungal growth caused by P. expansum, leading to rapid deterioration of onion bulbs and major economic losses.

In this study, researchers isolated P. expansum from infected onions and confirmed its identity through morphological and molecular techniques. The team then screened four Trichoderma species—T. harzianum, T. viride, T. virion, and T. hamentum—to evaluate their antagonistic abilities.

Key Findings

In vitro inhibition:
T. harzianum and T. viride suppressed the radial mycelial growth of P. expansum by approximately 63%, outperforming other tested species.
In vivo performance on onion bulbs:
- T. harzianum reduced blue mold rot severity to 37.3%.
- T. viride achieved 51% rot severity.
- The untreated control group showed a much higher 86.7% rotting.

These results show that T. harzianum is the most potent biocontrol agent among the species tested, reducing rot severity by 64%, while T. viride achieved a 41% reduction.

Implications for Agriculture in Pakistan

The authors recommend the use of these Trichoderma species as postharvest biocontrol agents to manage blue mold rot in onions stored in Pakistan. This approach provides an environmentally friendly alternative to chemical fungicides, aligning with sustainable agricultural practices.

The study highlights the need for further work on formulation development and large-scale implementation to ensure practical field application.

Reference

Waris, M., Abro, M., Hajano, JUD. et al. Biological control of blue mold rot of onion using Trichoderma species in pakistan. Egypt J Biol Pest Control 35, 37 (2025). https://doi.org/10.1186/s41938-025-00875-y