#SkyWatchersUnited

#OperationTrailDust
#Defoliation /ˌdiː.fəʊ.liˈeɪ.ʃən/: the process of leaves falling off a plant, or of making this happen...
#OperationRanchHand
Ranch Hand involved spraying an estimated 19 million U.S. gallons (72,000 m3) of defoliants and herbicides[1] over rural areas of South Vietnam in an attempt to deprive the Viet Cong of food and vegetation cover. Areas of Laos and Cambodia were also sprayed to a lesser extent. Nearly 20,000 sorties were flown between 1961 and 1971.[2]
The "Ranch Handers" motto was "Only you can prevent a forest"[1] - a take on the popular U.S. Forest Service poster slogan of Smokey Bear. During the ten years of spraying, over 5 million acres (20,000 km2) of forest and 500,000 acres (2,000 km2) of crops were heavily damaged or destroyed. Around 20% of the forests of South Vietnam were sprayed at least once.[3]
The herbicides were sprayed by the U.S. Air Force flying C-123s using the call sign "Hades". The planes were fitted with specially developed spray tanks with a capacity of 1,000 U.S. gallons (4 m3) of herbicides. A plane sprayed a swath of land that was 80 meters wide and 16 kilometers (10 mi) long in about 4½ minutes, at a rate of about 3 U.S. gallons per acre (3 m3/km2).[4] Sorties usually consisted of three to five aircraft flying side by side. 95% of the herbicides and defoliants used in the war were sprayed by the U.S. Air Force as part of Operation Ranch Hand. The remaining 5% were sprayed by the U.S. Chemical Corps, other military branches, and the Republic of Vietnam using hand sprayers, spray trucks, helicopters and boats, primarily around U.S. military installations.[5]
The herbicides used were sprayed at up to 50 times the concentration than for normal agricultural use.[citation needed] The most common herbicide used was Herbicide Orange, more commonly referred to as Agent Orange: a fifty-fifty mixture of two herbicides 2,4-D (2,4-dichlorophenoxyacetic acid) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) manufactured for the U.S. Department of Defense primarily by Monsanto Corporation and Dow Chemical. The other most common color-coded Ranch Hand herbicides were Agent Blue (cacodylic acid) that was primarily used against food crops, and Agent White which was often used when Agent Orange was not available.
The Agents used-known as the Rainbow Herbicides-their active ingredients, and years used were as follows:[6]
Agent Green: 100% n-butyl ester 2,4,5-T, used prior to 1966[7]
Agent Pink: 100% 2,4,5-T (60% n-butyl ester 2,4,5-T, and 40% iso-butyl ester of 2,4,5-T) used prior to 1966[7]
Agent Purple: 50% 2,4,5-T (30% n-butyl ester of 2,4,5-T, and 20% iso-butyl ester of 2,4,5-T) and 50% n-butyl ester of 2,4-D used 1961-65
Agent Blue (Phytar 560G): 65.6% organic Arsenicical (cacodylic acid (Ansar 138) and its sodium salt sodium cacodylate)[7] used from 1962 to 1971 in powder and water solution[8]
Agent White (Tordon 101): 21.2% (acid weight basis) triisopropanolamine salts of 2,4-D and 5.7% picloram used 1966-71[7][8]
Agent Orange or Herbicide Orange, (HO): 50% n-butyl ester 2,4-D and 50% n-butyl ester 2,4,5-T used 1965-70
Agent Orange II:50% n-butyl ester 2,4-D and 50% isooctyl ester 2,4,5-T used after 1968.[9][10]
Agent Orange III: 66.6% n-butyl 2,4-D and 33.3% n-butyl ester 2,4,5-T.[11]
Enhanced Agent Orange, Orange Plus, Super Orange (SO), or DOW Herbicide M-3393: standardized Agent Orange mixture of 2,4-D and 2,4,5-T combined with an oil-based mixture of picloram, a proprietary Dow Chemical product called Tordon 101, an ingredient of Agent White.[12][13]
The herbicides were procured by the U.S. military from Dow Chemical Company (all but Blue), Monsanto (Orange, Purple and Pink), Hercules Inc. (Orange and Purple), Thompson-Hayward Chemical Company (Orange and Pink), Diamond Alkali/Shamrock Company (Orange, Blue, Purple and Pink), United States Rubber Company (Orange), Thompson Chemicals Corporation (Orange and Pink), Agrisect Company (Orange and Purple), Hoffman-Taft Inc. (Orange), and the Ansul Chemical Company (Blue).[7] In April 1967, the entire American domestic production of 2,4,5-T was confiscated by the military; foreign sources were also tapped into, including the Imperial Chemical Industries (ICI).[14]
65% of the herbicides used contained 2,4,5-trichlorophenoxyacetic acid that was contaminated with 2,3,7,8-tetrachlorodibenzodioxin,[5] a "known human carcinogen...by several different routes of exposure, including oral, dermal, and intraperitoneal".[15] About 12 million U.S. gallons (45,000 m3) of dioxin-contaminated herbicides were sprayed over Southeast Asia during American combat operations.[16]