VALOR™ Herbicide (flumioxazin), formerly known as V-53482, is a new herbicide being developed by Valent USA Corporation for burndown and residual control of broadleaf weeds in cotton. Registrations are pending for soybeans and peanuts. It is also being evaluated for use in sugarcane and turfgrass. Flumioxazin is a N-phenylphthalimide derivative, which is a new chemistry for cotton. The mode of action of this family is inhibition of protoporphyrinogen oxidase (PPO). Porphyrins accumulate in susceptible plants causing photosensitization, which leads to membrane lipid peroxidation. The peroxidation of membrane lipids leads to irreversible damage of membrane function and structure in susceptible plants.