Maleic hydrazide (1,2-dihydro-3,6-pyridazinedione) (MH) was first disclosed as a chemical compound in the dissertation of a German doctoral candidate in chemistry in 1894, but no one suggested a use for the chemical and it remained virtually unmentioned in the literature for over 50 years. 1 In 1947, scientists of the U.S. Rubber Company (now Uniroyal) "rediscovered" MH and observed its growth-regulating activity on tomato (Lycopersicon esculentum Mill.). 1 A patent was issued to Uniroyal in 1952, and MH was registered for use on tobacco in the same year. 1 About the same time, it was found to have growth-regulating properties on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb.), smooth bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), redtop (Asrostis alba L.), timothy (Phleum pratense L.), and several other grasses. 3