title: Thymol-based submicron emulsions exhibit antifungal activity against Fusarium graminearum and inhibit Fusarium head blight in wheat.
abstract: OBJECTIVE
  Fusarium graminearum is a very destructive fungal pathogen that leads to Fusarium head blight (FHB) in wheat, a disease which costs growers millions of dollars annually both in crop losses and in remediation efforts. Current countermeasures include the deployment of wheat varieties with some resistance to FHB in conjunction with timed fungicide treatments. In this article, we introduce a fungicide based on thymol, a naturally occurring plant phenolic derived from essential oils. To overcome the hydrophobicity of thymol, the thymol active was incorporated into a low-surfactant submicron emulsion with and without a carrier oil.
  
  
  RESULTS
  The minimum fungicidal concentration of F. graminearum was found to be both 0·02% for thymol emulsions with and without an oil component. Time-to-kill experiments showed that thymol emulsions were able to inactivate F. graminearum in as little as 10 s at concentrations above 0·06%. Spraying the thymol emulsions (~0·1% range) on the wheat variety Bobwhite demonstrated significant reductions in FHB infection rate (number of infected spikelets). However, with 0·5% thymol, the wheat heads exhibited premature senescence. Transmission and scanning electron micrographs suggest that the mechanism of antifungal action is membrane mediated, as conidia exposed to thymol showed complete organelle disorganization and evidence of lipid emulsification.
  
  
  CONCLUSIONS
  The collective experimental data suggest that thymol emulsions may be an effective naturally derived alternative to the current thymol treatments, and chemical fungicides in ameliorating FHB.
  
  
  CONCLUSIONS
  This is the first thymol-derived nanoemulsion particles resuspended into water and not DMSO, exhibiting the same antibacterial/antifungal activity as previously described thymol and thyme oil treatments. This drastically reduces the environmental footprint thymol will leave if utilized as a fungicide treatment on field crops.
authors.affiliation: Department of Agronomy, College of Agriculture, USDA-ARS Purdue University, West Lafayette, IN, USA. tagill@ufl.edu.
authors.forename: T A
authors.initials: TA
authors.lastname: Gill
authors.affiliation: Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN, USA.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN, USA.
authors.forename: M
authors.initials: M
authors.lastname: Saenger
authors.affiliation: Department of Agronomy, College of Agriculture, USDA-ARS Purdue University, West Lafayette, IN, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Scofield
mesh_terms: D004655:Emulsions / Q000494:pharmacology; D005659:Fungicides, Industrial / Q000494:pharmacology*; D005670:Fusarium / Q000187:drug effects* / Q000254:growth & development; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control*; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development; D013943:Thymol / Q000494:pharmacology*; D014908:Triticum / Q000382:microbiology*
chemical_list: D004655:Emulsions; D005659:Fungicides, Industrial; D013943:Thymol
keywords: Fusarium graminearum; antifungal; biocide; thymol; wheat