Benomyl is a chemical that was created by Hein L. Klopping in July, 1959, and was marketed as the fungicide Benlate.  Benomyl became one of the best selling fungicides due to its low toxicity to mammals and effecivness towards microorganisms and invertibrates.

How Did Benomyl Work?

Benomyl, whose chemical formula is C14H18N4O3, works by binding to microtubules, a part of cells that are important for mitosis, meiosis, and other cellular activities.  Benomyl interferes with these cell functions, and is selective towards fungal microtubules rather than mammalian microtubules.

Benomyl was used before harvest or after harvest to kill fungal diseases in vegetable crops, various fruits, nuts, and turf.

Why is Benlate no longer available?

Benlate started having issues when Dupont issued a recall in 1991 due to some of its Benlate 50DF being contanimated with the herbicide Atrazine.  This contamination was blamed for destroying millions of dollard of crops, and Dupont hit with hundreds of lawsuits.  Dupont eventually paid out about $750 million dollars in damages before data suggested that Benomyl was not the cause of the crop damages.  In 1995, a Florida Judge rejected a complaint from the Florida Department of Agriculture that Benomyl was the cause of these crop damages.

Unfortunately, this was not the end of the lawsuits.  In 1996, a mother who was exposed to Benomyl while pregnant due to her job successfully sued Dupont for $4 million.  Her child was born without eyes.  Other birth defect claims against Benlate were also filed.

Due to these lawsuits and other business reasons, Dupont stopped selling Benlate worldwide in 2001.  Benomyl is still sold through many companies through the world.