Classical aminoglycoside antibiotics are obsolete or hampered by the emergence of drug resistant bacteria. Recent discoveries of antifungal amphiphilic kanamycins offer new strategies for reviving and repurposing these old drugs. A simple structural modification turns the clinically obsolete antibacterial kanamycin into an antifungal agent. Structure-activity relationship studies have led to the production of <b>K20</b>, an antifungal kanamycin that can be mass-produced for uses in agriculture as well as in animals. This review delineates the path to the discovery of <b>K20</b> and other related antifungal amphiphilic kanamycins, determination of its mode of action, and findings in greenhouse and field trials with <b>K20</b> that could lead to crop disease protection strategies.