Alternaric acid is an antifungal metabolite isolated from Alternaria solani by Brian and co-workers at ICI’s Butterwick Labs, Welwyn, England in 1949. Over 40 years later its stereochemistry was solved by Ichihara and co-workers at Hokkaido University, Japan. Alternaric acid is a selective antifungal agent with no antibiotic activity but does elicit selective herbicidal activity. Alternaria solani is the cause of early blight disease in potato and tomato plants and alternaric acid is considered the causative agent.