High Quality Content by WIKIPEDIA articles! The Rainbow Herbicides are a group of chemicals used by the United States military in Southeast Asia during the Vietnam War. Success with Project AGILE field tests with herbicides in South Vietnam in 1961 led to the formal herbicidal program Trail Dust (1961 - 1971). Herbicidal warfare is a form of chemical warfare, in which the objective is to destroy the plant-based ecosystem of an agricultural food production and/or destroying plants which provide cover to an enemy.