Inspired by Louis Pasteur‘s ideas on microbial infection, the English doctor Joseph Lister demonstrated in 1865 that use of carbolic acid on surgical dressings would significantly reduce rates of post-surgical infection. Lister’s work in turn inspired St. Louis-based doctor Joseph Lawrence to develop an alcohol-based formula for a surgical antiseptic that also included eucalyptol, menthol, methyl salicylate, and thymol. (Its exact composition was a trade secret.) Lawrence named his antiseptic “Listerine” in honor of Lister.
The discovery –that essential oils or aromaric oils used in perfumes were very effective broad spectrum bactericides changed the world of medicine. Years later, the manufacturer of Listerine would advertise that it kills 99.99% of the germs in your mouth on contact. The key germ killer was thymol or thyme oil.
After so many years of using synthetic chemistries, these natural essential oil extracts are making a comeback in agriculture, as they possess properties similar to synthetics and are extremely effective in the right concentrations. Their molecular structures start with a benzene ring – a six carbon ring (represented by a hexagon) which includes three double bonds. Each of the carbons represented by a corner is also bonded to one other atom. The result is a benzyl alcohol, a form of alcohol that is far more effective in killing bacteria than isopropyl alcohol, the alcohol that a nurse would use prior to giving you a shot. Phenols, compounds with a hydroxyl group (one hydrogen and one oxygen) attached to the six-membered aromatic ring, are very effective bactericides, fungicides, insecticides and virucides.
Essential oils also have terpenes, which are not based on the benzene ring and are insecticidal. Terpenes are very effective in controlling small sucking insects – thrips, aphids, mites, whitefly, etc. They destroy the trachea and eggs and impact the insects’ GABA, which regulates neurotransmitters.
Refinements of these essential oils has produced a single product that has multiple applications as a fungicide, bactericide, insecticide and virucide. The products are safe and effective to use (they are exempt from EPA registration), there is no Pre Harvest Interval (PHI) or Maximum Residue Limits (MRL), you can apply a pick simultaneously, and they don’t harm pollinators.
These products offer a new, clean and safe way to address disease and insect problems and, because of their new chemistry, have no built up pathogen resistance to overcome. They provide growers with an organic solution (although they are mostly used on conventional farms) that is as effective as their conventional-chemistry counterparts.
Andaman Ag offers Thyme Guard, derived from thymol, a product that Dr. Lister would be very pleased to know exists in the agricultural market today!