Plant Science Laboratories

Site 21
Location: Fort Gordon, Augusta, Georgia
Fort Chaffee, Fort Smith, Arkansas
Apalachicola National Forest, Sopchoppy, Florida
Date → July 1967 – October 1967
Activity Description: During the period December 1966 to October 1967, the
newly named “Plant Science Laboratories” at Fort Detrick initiated a comprehensive
short-term project to evaluate desiccants and herbicidal mixtures as rapid-acting
defoliants. The objectives of this study were to evaluate rapid-acting desiccants as
defoliants and to assess the defoliation response of woody vegetation to mixtures of
herbicides and/or desiccants. The criteria for assessment was based principally on
rapidity of action, but included other features such as safety and ease of handling,
compatibility with dissemination systems, and low toxicity to man and wildlife.
The approach to the objective of an improved rapid-acting defoliant involved three
phases: (1) evaluation of commercially available rapid desiccants or contact herbicides;
(2) evaluation of improved formulations of rapid desiccants developed under industry
contacts and by in-house effort; (3) development and evaluation of desiccant-herbicide
mixtures containing the rapid defoliant characteristics with the sustained long-term
effects of Orange and other Tactical Herbicides. The project required an immediate
access to a diversity of woody vegetation. Accordingly, Fort Detrick arranged for test
locations at Fort Gordon near Augusta, Georgia; Fort Chaffee near Fort Smith, Arkansas,
and Apalachicola National Forest near Sopchoppy, Florida.
The Georgia site was described as a warm temperate, humid, moderate rainfall climate
with deep, well-drained sands in rolling topography. The vegetation type was an oakhickory-
pine forest. The Arkansas site was described as a temperate continental,
moderate rainfall climate with fine sandy loam soils in rolling topography. The
vegetation type was an oak-hickory forest. The Apalachicola National Forest site was
described as a subtropical, humid, moderate precipitation climate with sandy soils in a
flat poorly drained topography. The vegetation type was described as a Southern mixed
forest. All sites were selected because of their isolation from any local human
populations, e.g., in Florida, the site was a ridge located in a swamp forest.
Assessment: The desiccants selected for evaluation included Herbicide Blue (a
tactical herbicide), and the commercial desiccants diquat, paraquat, dinitrobutylphenol
50
(DNBP), pentachlorophenol (PCP), hexachloroacetone (HCA), and monosodium
methanearsonate (MSMA), pentachloro-pentenoic acid (AP-20), endothall, and various
mixed formulations of these desiccants. The systemic herbicides included the two tactical
herbicides Orange and White; the potassium salt, triisopropanolamine salts, and the
isooctyl ester of picloram; and, a ethylhexyl ester of 2,4,5-T mixed with HCA. Mixtures
of propanil, nitrophenol, linuron, and silvex were also evaluated. All chemicals were
furnished by Fort Detrick.
Aerial application at these three sites were made with a Bell G-2 helicopter equipped with
two 40-gallon tanks and a 26-foot boom with 6-inch nozzle positions adaptable for
volume deliveries of 3, 6, or 10 gallons per acre in a 50-foot swath. Spray equipment,
pilot, and support were furnished under contract with Allied Helicopter Service of Tulsa,
Oklahoma. Aerial applications were made on duplicate 3-acre plots, 200 by 660 feet in
dimension. A sampling and evaluation trail was established in each plot on a diagonal
beginning at 100 feet from one corner. Major species were marked along 500 feet of this
transect and individual plants were identified by combinations of colored plastic ribbons.
A minimum of 10 individuals of each species was marked unless fewer were present.
Evaluations were made at 1-, 5-, 10-, 30-, and 60-day intervals by experienced Fort
Detrick personnel. At each evaluation period the identical marked individuals of the
major species were rated for defoliation and desiccation. At each location, approximately
475 gallons (~10 drums) of Herbicide Blue, 95 gallons (~2 drums) of Herbicide Orange,
and 6 gallons of Herbicide White were expended.
The assistance of Department of Army forestry personnel at Fort Gordon, Fort Chaffee,
and the 3rd and 4th Army Headquarters were acknowledged in the report for their support
in the selection and preparation of sites in Georgia and Arkansas. The land and facilities
for the Florida tests were provided by the Supervisor, Apalachicola National Forest,
Tallahassee, Florida. Personnel from the Physical Sciences Division, Fort Detrick
assisted in the development of formulations and preparations of field test mixtures. They
also provided the data on the physical characteristics of the candidate tactical defoliants
and mixtures.
Sources: Darrow RA, Frank JR, Martin JW, Demaree, KD, Creager RA (1971): Field
Evaluation of Desiccants and Herbicide Mixtures as Rapid Defoliants. Technical Report
114, Plant Sciences Laboratories, Fort Detrick, Frederick, Maryland. Document
unclassified but subject to special export control. Available from the Defense
Documentation Center, Accession Number AD 880685.DOD PDF

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