US Patent 6,185,865
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
A method of clearing fungal spores from seed by immersing the seed in an aqueous solution including dissolved inert gas and sonicating the seed at a frequency preferably of between about 15 kHz and about 30 kHz and an energy density of between about 1 watt/cm2 and about 10 watts/cm2 for a period of between 0.1 minute and about 15 minutes.
Soll, David R. and Daniels, Karla J. Method for clearing of fungal spores from seed by ultrasound. US Patent 6,185,865 filed January 26, 1998 and issued February 13, 2001. https://ir.uiowa.edu/patents/256