The voluntary removal of arsenic acid from the commercial market has stimulated interest in new cotton (Gossypium hirsutum) defoliant/dessicant harvest-aids. CGA248757 ([[2-chloro-4-fluoro-5[(tetrahydro-3-oxo-1H,3H-[1,3,4]thiadiazolo[3,4-a]pyridazin-1-ylidene)amino]-phenyl]thio]-acetic acid methyl ester) is a low use rate post-emergent contact herbicide which inhibits protoporphyrinigen IX oxidase. Accumulation of protoporphyrins leads to radical production and cell damage. CGA248757 has low soil mobility and very short soil half-life.