MH, Maleic hydrazide

Trade name(s) Royal MH-30, Sprout Stop, Retard

Manufacturer(s) Chemtura, Drexel Chemical, UPL

Formulation(s) 1.5 lb, 2.25 lb, and 3 lb/gal soluble concentrate; 60% granule

Remarks A growth inhibitor and preemergence or postemergence selective herbicide. Inhibits cell division but not cell enlargement. Suppresses growth of grasses and some broadleaf plants. Absorption rate is greater in high humidity.

Water solubility 6,000 ppm

Storage conditions Stable.

Acute toxicity LD50 - 3,900 mg/kg

Action in plant Inhibits mitosis.

Site of action Not well understood

Chemical family None generally accepted

Koc Average is 20 mL/g (estimated) for the K salt form and 250 mL/g (estimated) for the acid. Koc was 264 mL/g for clay and 23 mL/g for sand.