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Neem Essential Oil as an Antifungal Agent against Phyllosticta citricarpa

Summary

Citrus fruits are susceptible to a serious fungal disease called black spot that prevents them from being exported to certain countries. This study tested neem oil, a natural plant extract, as a replacement for chemical fungicides currently used to clean citrus fruits. The researchers found that neem oil was just as effective as the standard copper-based treatments at killing the fungus and preventing the disease, and it worked by breaking down the fungus cell membranes. This natural alternative could help farmers and fruit companies maintain food safety while using more eco-friendly solutions.

Background

Citrus black spot (CBS) caused by Phyllosticta citricarpa is a quarantine phytopathogen that significantly impacts citrus fruit quality and export potential. Current sanitation methods use copper oxychloride or sodium hypochlorite, but alternative organic sanitizers are needed. Neem essential oil (NEO) has demonstrated antimicrobial properties against various pathogens but has not been evaluated against P. citricarpa.

Objective

To evaluate the antifungal efficacy of neem essential oil against P. citricarpa and assess its potential as an alternative sanitizer for citrus fruits in packinghouses. The study aimed to determine inhibition concentration, mechanism of action, and in vivo effectiveness compared to copper oxychloride.

Results

NEO at 100 μL·mL⁻¹ inhibited 89.68±1.14% of fungal mycelium growth, equivalent to copper oxychloride. Fluorescence microscopy showed NEO disrupted cytoplasmic membranes of fungal hyphae within 30 minutes. GC-MS/MS identified phenolic compounds (syringol, 2,6-dimethoxyphenol, phenol, 2,4-bis-1,1-dimethylethyl) as primary antifungal agents. In vivo assays reduced microorganisms by 93.00±3.88% and completely eliminated P. citricarpa propagules.

Conclusion

Neem essential oil effectively serves as an alternative sanitizer against P. citricarpa, with efficacy equivalent to copper oxychloride. The mechanism of action involves cytoplasmic membrane disruption through phenolic compounds. NEO shows promise for sanitizing citrus fruits in packinghouses and potentially other fruits against various phytopathogens, offering an eco-friendly alternative to conventional chemical sanitizers.
  • Published in:International Journal of Microbiology,
  • Study Type:Experimental Study,
  • Source: PMID: 39071039, DOI: 10.1155/2024/6251407
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