About This File:
.
rThis file was created by scanning the printed pLiblicatiori.
Mrs. c n identifie by the software have
been corrected
: hqweyer, som
e mrstakes may remain.
- -)
TMTD Wild Mammal Repellent:
Review and Current Status
BY
M. A. RADWAN
Abstract. TMTD properties, assay methods, and use as a repellent against wild mammals
are reviewed. The review suggests that TMTD is a very useful animal repellent, although
further research is needed.
Additional key words.Tetramethylthiuram disulfide, Thiram, Arasan, seedling protection,
contact repellent.
A GREAT VARIETY of animals interfere
with forest production (Radwan 1963).
The problem is most serious in natural
and artificial regeneration areas where
deer, rabbits, hares, and other animals
cause significant damage.
Various measures to reduce browsing
and clipping injuries have been suggested,
and some of these have proven successful
against deer, rabbits, and hares (Radwan
1963). In recent years, much attention
has been given to the use of chemical
repellents. Tetramethylthiuram disulfide
(TMTD) has proven most useful.
The objectives of this paper are (1) to
summarize the properties of TMTD,
emphasizing its animal-repellent qualities
against browsing and clipping animals
and (2) to discuss limitations of the
chemical.
The Chemical
Properties
Tetramethylthiuram disulfide or, more
accurately, bis-(dimethylthiocarbamyl)
disulfide is one of the dithiocarbamate
fungicides introduced in pest control in
1934 (Tisdale and Williams 1934). The
chemical is known by various common
and trade names; these include Arasan,
Fernasan, Nomersan, Pomasol, Tersan,
Thiosan, Thiurad, Thylate, Tuads, Tuli­
san, etc. (Stecher 1960). The common
name approved by the American Phyto­
Reprinted from FOREST SCIENCE,
pathological Society is Thiram (Rohwer
1950). The chemical structure of TMTD
follows:
s
HaC
""'
s
I /
I
N-C-S-S-C-N
/
HaC
""'
CHa
CHa
The theoretical molecular weight of
the compound is 240.44. At room tem­
perature, the pure chemi.cal is a white
solid with a specific gravity of 1.29,
negligible vapor pressure, and a very
mild odor (Assoc. Amer. Pesticides Con­
trol Offic. 1966). It melts at 155 to 156° C
and then decomposes into carbon di­
sulfide, sulfur, and tetramethyl thiourea
(Kuwaoko 1943).
TMTD is soluble in chloroform; slightly
soluble in ethylene dichloride, dimethyl­
formamide, acetone, and many other
organic solvents; and very slightly soluble
in water (Assoc. Amer. Pesticides . . .
1966). TMTD is stable in weak acidic
and alkaline solutions, forms irreversible
metal complexes in the presence of metal
The author is Principal Plant Physiologist,
Forestry Sciences Laboratory, Pacific Northwest
Forest and Range Exp. Sta., Forest Service,
U. S. Dep. of Agr., Olympia, Wash. Manuscript
received July 9, 1968.
Volume 15, Number 4, December 1969 Purchased by the Forest Service, USDA, for official use, ions, and undergoes hydrolysis rapidly
in strong acids and at pH 11 and higher
(Ludwig and Thorn 1960).
Assay Methods
There are several methods for determining
TMTD in biological material; the choice
depends mainly on the amount of TMTD
in the sample, the required accuracy,
and the available equipment. Summaries
of the three principal methods follow:
Bioassay Method. This method by Leben
and Keitt (1950) is a modification of the
paper disk technique used in the assay
of antibiotics. Blotting paper disks satur­
ated with the test solutions are placed
on petri plates seeded with spores of
Glomerella cingulata. After incubation,
the diameters of the clear zones around
the disks are measured, and the concen­
tration of TMTD is obtained by referring
to a dosage-response curve drawn on
the basis of the size of clear zones pro­
duced by known amounts of TMTD.
The two most com­
monly used are (a) the carbon disulfide
evolution procedure (Pease 1957) and
(b) the colorimetric method of Keppel
(1959). In the first, TMTD in the test
sample is subjected to acid hydrolysis in a
special apparatus, and the liberated car­
bon disulfide is absorbed in Viles, reagent.
Absorbance of the resulting solution is
then determined in a suitable spectro­
photometer at 380 m , and TMTD in
the sample is found by reference to a
calibration curve.
In the second method, TMTD is
extracted from the sample with chloro­
form, and extracts are treated with
cuprous iodide. Absorbance of the re­
sulting colored solution is then determined
in a colorimeter or spectrophotometer
at 440 m , and TMTD is calculated
from a standard curve. Keppel's method
is probably the most suitable assay
method for determination of TMTD in
biological material when the chemical
Chemical Methods.
440 /
Forest Sdence
is used as an animal repellent; it is fairly
simple, and moderate amounts of color
and other extracted matter from plants
and soils do not interfere. The method,
with some modification, has been used
successfully to determine TMTD in
nursery soils (Radwan 1965a) and on
Douglas-fir seedlings (Radwan 1965b,
Radwan and Dodge 1965, Radwan et
al. 1967).
Radiochemical lvfethod. This method was
developed in Belgium for the micro­
determination of TMTD (Massaux
1964b). Test solutions in chloroform are
treated with cuprous iodide and TMTD
is reduced to copper dithiocarbamate as
in Keppel's method. Solutions are then
treated with Hg203 (N03) 2, and TMTD is
determined by measuring the radioac­
tivity of the resulting mercury com­
pound in a ')'-scintillation counter.
Biological Degradation
Pure TMTD is broken down easily in
soil (Richardson 1954). As with other
dithiocarbamates, the decomposition is
complex; carbon disulfide and amines
are produced in an acid environment,
and hydrogen sulfide is formed under
alkaline conditions (Horsfall 1956). Sim­
ilarly, TMTD reaching nursery soil
during spraying is decomposed in soil;
this is shown by chemical analyses and
by recovery of soil respiration and nitri­
fication after initial inhibitions. The rate
of decomposition depends upon the
initial concentration and upon the action
of soil micro-organisms (Radwan 1965a).
Because of the acid nature of forest
soils, products of degradation are prob­
ably similar to those produced under
acid conditions.
A thin coat of TMTD repellent is
applied to seedling shoots requiring
protection from animals (see later).
Under these conditions, the chemical
is a contact repellent; it is not absorbed
or translocated by seedlings, and ap­
parently it does not decompose (Radwan
1965b). Small amounts of TMTD in
solution, however, are absorbed and
translocated by some plants. Once in
the plant, the chemical is broken down
by enzymatic action (Massaux 1964a) or
by the acid plant sap. The degradation
products have not been identified, but
it can be assumed that these products
are not as repellent as the parent com­
pound. Therefore, TMTD cannot be
used as a systemic repellent.
TMTD has been studied only in rumi­
nant animals. Robbins and Kastelic
(1961) found that rumen micro-organisms
are capable of degrading ingested TMTD
to carbon disulfide gas and probably to
hydrogen sulfide gas and dimethylamine.
They suggested that the rumen micro­
organisms' degradative ability, plus the
animals' capacity to release toxic gases
produced by belching during rumination,
may allow ruminants, as compared to
monogastric animals, to tolerate con­
siderable amounts of TMTD. This sug­
gestion may help explain why TMTD
is always less repellent to deer than to
hares and rabbits.
Toxicity
Toxicity to Animals. TMTD has low
toxicity for animals. For acute oral
toxicity, the LD5o (lethal dosage, in
milligrams per kilogram of body weight,
for 50-percent mortality) is 1,250 for
mice (Vorobeva 1964), 860 for rats, and
210 for rabbits (Assoc. Amer. Pesticides
. . . 1966).
In chronic toxicity studies, effects of
TMTD vary by the species and with
intake levels. Thus, some rats die after
consuming 1,000 parts per million (ppm)
TMTD, but other rats show no ill effects
when kept for 65 weeks on a diet con­
taining 500 ppm of the chemical (Assoc.
Amer. Pesticides . . . 1966). Similarly,
low dosages of TMTD in the diet cause
production of abnormal eggs (Swanson
et a!. 1956) and body deformities in
chicks (Waibel et a!. 1957) , functional
and inflammatory changes in the liver
and kidney of rabbits (Brieger and
Hodes 1949), and in the liver and lungs
of mice (Vorobeva 1964, 1965). However,
no toxic effects were observed with steers
in a 140-day feeding period (Thomas eta!.
1957).
TMTD also affects animals without
being ingested. Rabbits which have been
long exposed to air containing TMTD suf­
fer lung irritation (Brieger and Hodes
1949). Furthermore, the chemical ir­
ritates the skin and may cause dermatitis
in sensitive people (Assoc. Amer. Pesti­
cides . . . 1966).
There are no data in the literature on
the acute or chronic toxicity ofTMTD fot·
deer, hare, or any other forest animals
against which the chemical is now being
used. Information is also lacking on effects
TMTD may have on wild animals as
they ingest or contact seedlings treated
with the repellent.
Phytotoxicity. TMTD has successfully
controlled diseases in agricultural crops,
with little or no phytotoxic effects,
when applied at the recommended rates
(Kendrick and Zentmyer 1957). However,
greenhouse experiments with M onterey
pine showed that TMTD in soil at 62
and 125 pounds per acre has adverse
efiects on the development and shape of
mycorrhizae (Wilde and Persidsky 1956).
Furthermore, laboratory studies showed
that TMTD in solution cultures inhibits
photosynthesis and growth of some
lower plants (Lindahl 1961, 1963) and
is quite phytotoxic to tomatoes (Gross­
man 1957).
When TMTD is applied as a repellent
to protect forest trees from animals,
the chemical is applied to the shoots
and may reach the roots in amounts
and formulations different from those
used in the above-mentioned reports.
Under these conditions, there are no
data in the literature indicating phyto­
toxic effects from the chemical. TMTD
repellent, therefore, is considered non­
phytotoxic to forest seedlings, and our
unpublished data indicate no toxicity
even when the chemical is applied at
volume 15, ntnnber 4, 1969 / 441
rates much higher than those recom­
mended. Also, the repellent does not
delay bud break of Douglas-fir (Krueger
and Tsuda 1968).
Repellency
Historical Development. TMTD
and other
dithiocarbamates were introduced in pest
control by the Tisdale and Williams
(1934) patent of 1934. This patent dis­
closed the fungicidal and bactericidal
activity of this series of compounds.
Later, TMTD was found to inhibit
feeding by some insects on foliage of test
plants (Tisdale and Flenner 1942). This
information most probably marked the
discovery of the repellent properties ot
the compound.
Repellency of the dithiocarbamate
group to animals was first discovered in
1937. Both TMTD and TMTM (tetra­
methylthiuram monosulfide) had pro­
nounced repellent effects on rabbits at
the Cheyenne Horticultural Field Sta­
tion (Hildreth and Brown 1955). Later,
these same chemicals showed high re­
pellency to white rats at the Patuxent
Research Refuge (Bellack et a/. 1953)
and moderate repellency to other rodents
at the Denver Wildlife Research Center
(Welch 1954). Concurrent and followup
laboratory and field tests finally showed
that TMTD applied to forest seedlings
was effective against rabbits, hares, and
deer (Besser and Welch 1959).
Although TMTD was ex­
tensively tested in animal pens and in the
field against a variety of wild mammals,
only a few publications dealing with the
chemical's effectiveness on forest tree
seedlings are available. Much detailed
work was not published or was sum­
marized in review articles which unani­
mously recommended the treatment even
though data quantifying the protection
afforded by the chemical were often
overlooked. Also, most available infor­
mation came from work with conifers
in the Pacific Northwest, mainly due to
Effectiveness.
442 /
Forest Science
the relative importance of the species in
the region and perhaps because of the
more tolerable damage to trees elsewhere.
TMTD provides Douglas-fir seedlings
with excellent protection from hares
and rabbits. Thus, the repellent reduced
damage by 82 percent in western Wash­
ington (Besser and Welch 1959), 94 per­
cent in British Columbia (Walters and
Soos 1961), and 93 percent in north­
western Oregon (Hooven 1966). TMTD
also protects trees from deer although
its effectiveness is usually less than that
against hares and rabbits. In M aryland,
deer browsed 24 percent and 5.5 percent
of untreated and treated loblolly pine
seedlings, respectively (Little and Mohr
1961). In addition, the chemical reduced
browsing of ponderosa pine seedlings by
mule deer by 73 percent (Besser and
Welch 1959) and 78 percent (Driscoll
1963) in central Oregon, and by 84 per­
cent in Arizona (Heidmann 1963). Data
on the effect of TMTD on other wild
mammals are scarce, and although pro­
tection from meadow mice and beavers
was reported (Besser and Welch 1959),
it is doubtful that the treatment has
much practical merit against such animals.
Protection by the chemical usually
lasts through the dormant season and
up to bud break. The repellent then be­
comes ineffective, since the new growth
appearing in the spring is not protected.
TMTD, therefore, protects seedlings only
for a short time unless they are resprayed
at additional effort and expense. Conse­
quently, the chemical is considered as a
stopgap repellent until a better chemical,
preferably a systemic, is discovered, or
until other means of animal control
prove as effective at the same or lower
cost.
Mode of Action. The manner in which
TMTD repels animals is still unknown;
however, one or more of the known
properties of the compound or its degra­
dation products may account for its
repellent activity. These properties in­
clude: (a) irritation of skin and external
sensitive tissues (Assoc. Amer. Pesticides
1966), (b) inhibition of micro­
organisms (Tisdale and Flenner 1942)
(possibly in animals), (c) inhibition of
some enzymes (Owens 1953), (d) reaction
with essential cell constituents such as
glutathione (Johnston 1953), and (e)
toxic effects of hydrogen sulfide and
carbon disulfide gas which are probably
produced during degradation of TMTD in
animals. Properties as yet unknown may
also be important. Clearly, identification
of the main properties which determine
the repellency of TMTD will probably
make it possible to devise means to
increase the effectiveness of the chemical
and to develop other more effective
repel!ents.
Use on Forest Seedlings
Formulations
Repellent TMTD formulations are com­
mercially available. These are combi­
nations of aqueous suspensions of TMTD
(the active ingredient) and an adhesive
(sticker) and small amounts of thickening
and defoaming agents. Other formula­
tions are easily prepared from such
ingredients by use of the following in­
formation:
The Active Ingredient. The main sources
for TMTD are Arasan 42-S, Arasan 75,
and Arasan SF-X. Arasan 42-S in liquid
form is the preferred source.
The Adhesive. Many adhesives have been
tested for use with TMTD. Rhoplex
AC-33 and Dow Latex 512-R are recom­
mended adhesives. Although their rela­
tive effectiveness has not been accurately
determined, Rhoplex AC-33 is more
commonly used in the Pacific Northwest.
Ideally, TMTD formulations contain­
ing Rhoplex AC-33 should be sprayed
when relative humidity is low, seedlings
are dry, and air temperature is about
70° F (Duffield and Eide 1962). In the
Pacific Northwest, such ideal conditions
are rather rare during the spraying
season which begins as soon as the
seedlings become dormant late in the
fall. Even under the best spraying con­
ditions, the repellent film is not ade­
quately bound to the seedlings and much
TMTD is lost due to weathering, hand­
ling of seedlings, and cold storage
(Radwan 1965b, Radwan et a/. 1967). On
the other hand, earlier spraying may
injure the growing seedlings and will
not protect postspraying growth. Rhoplex
AC-33, therefore, is not the best ad­
hesive for spraying dormant forest seed­
lings, and, although a recent attempt to
replace it was not successful (Bullard and
Campbell 1968), the search for a suitable
substitute should continue.
Other Additives. Three other ingredients
now used in TMTD formulations are:
(a) a thickening agent such as Methocel,
(b) a defoaming agent such as normal
octyl alcohol, and (c) a surfactant
(spreader) such as Triton (B-1956, X151,
or X171).
Methods of Application
TMTD formulations are applied to
seedlings by dipping or by spraying
with any sprayer which allows dispersion
of the repellent at a uniform controllable
rate. Treatment is usually in the nursery
with power equipment used for large­
scale operations and a dipping or spraying
method for limited applications. Sprayers
of the knapsack type, however, are
most practical for spraying individual
seedlings in the field, especially when
repeated applications are required.
The use of aircraft to spray plantations
with TMTD has been considered. Such
blanket application with quantities of
TMTD sufficient to protect forest tree
seedlings seems uneconomical and also
might be hazardous to man and wildlife.
With all types of sprayers now in use,
much TMTD reaches the soil during
spray operations. Effects of the chemical
in the soil are not serious, and under some
conditions benefits may even be ob­
tained (Radwan 1965a). However, de-
volume 15, number 4, 1969 / 443
velopment of new spray equipment to
minimize TMTD losses, especially in
nursery applications, seems desirable,
if only for economic reasons.
Rates ol Application
In most early tests, attention was cen­
tered primarily on percent strength of
TMTD in formulations applied by dip­
ping or spraying; little regard was given
to the rate of application. It soon became
apparent that concentration alone was
meaningless. Following treatment, seed­
lings became repellent to animals in
pen or field tests only if sufficient repellent
had been uniformly applied and retained.
Such effective amounts of TMTD are
conveniently expressed in terms of rate
of application, which becomes meaningful
only when percent strength of the formu­
lation, method of application, and species
and size of seedlings are specified.
The only available information on
the minimum effective rates of application
based on detailed experimentation are
for 2-0 Douglas-fir seedlings. These
rates are (a) 1 gal of 6-percent TMTD
per 2,000 seedlings when the dip method
is used (Dodge et a!. 1967) and (b) 1 gal
of 10-percent TM TD per 5,000 seedlings
(9 gal/1,000 sq ft of average-stocked
seedbed area) for spraying in the nursery
(Radwan and Dodge 1965). Appropriate
rates for larger seedlings and for seedlings
of other species can be calculated by
extrapolation and by assuming that
the minimum effective amount of TMTD
for individual 3-gram (dry-weight) seed­
lings is 11 to 22 mg (Radwan 1965b).
The same information can also be used
to calculate rates for spraying with
hand sprayers if TMTD loss to the soil
is determined.
Literature Cited
AssociATION oF AMERICAN PEsTICIDES CoNTROL
O FFICIALs, INc. 1966. Pesticide chemicals official
compendium. Kansas State Board Agr, Topeka.
1297 p.
BELLACK, ERviN, ]AMEs B. DEWITT, and RAY
T REICHLER. 1953, Relationship between chemical
444 /
Forest Science
structure and rat repellency. Nat Res Counc,
Chem-Biol Coord Center, Rev 5:48-156.
BESSER, JEROME F., and JAcK F. W ELCH. 1959.
Chemical repellents for the control of mammal
damage to plants, N Amer Wildlife Conf Trans
24:166-173.
BRIEGER, HEINRICH, and WILLIAM A. HoDEs.
1949. Toxicity of dithiocarbamates and the
hazard from exposure to these compounds.
Proc Ninth lnt Congr Ind Med London 1948:
598-602.
B uLLARD, RoGER W., and DAN L. CAMPBELL,
1968. Evaluation of adhesives for foliar appli­
cation of chemicals. Forest Sci 14:39-44.
DoDGE, W. E., C. M. LovELEss , and N. B. KvERNO.
1967. Design and analysis of forest-mammal
repellent tests. Forest Sci 13:333-336.
DRISCOLL, RicHARD S. 1963. Repellents reduce
deer browsing on ponderosa pine seedlings.
U S Forest Serv Res Note PNW-5, 8 p. Pacif
Nthwest Forest Range Exp Sta.
DuFFIELD, JoHN W., and REx P. EmE. 1962.
Application of rabbit repellent to coniferous
planting stock in the Pacific Northwest. J
Forest 60:109-111.
GRossMAN, F. 1957. Untersuchungen iiber die
innertherapeutische Wirkung organischer Fungi­
cide. I. Thiocarbamate und Thiurame. Z Pllan­
zenkr Pllanzenschutz 64:718-728.
HEIDMANN, J. J. 1963. Deer repellents are effective
on ponderosa pine in the Southwest. J Forest
61:53-54.
HILDRETH, A. C., and G. B. BRowN. 1955. Re­
pellents to protect trees and shrubs from damage
by rabbits. US Dep Agr Tech Bull ll34 , 31 p.
HoovEN, EDWARD F. 1966. A test of Thiram on
two rabbit-infested areas of Oregon. Tree
Planters' Notes 79:1-3.
HoRSFALL, J. G. 1956. Principles of fungicidal
action (p 176-181). Chron Bot Co., Waltham,
Mass. 279 p.
JoHNSTON, CARTER D. 1953. The in vitro reaction
between tetraethylthiuram disulfide (Antabuse)
and glutathione. Arch Biochem Biophys 44:
249-251.
KENDRICK, J. B., JR., and G. A. ZENTMYER. 1957.
Recent advances in control of soil fungi. In
Advances in Pest Control Research I. P 219-275.
Interscience Publishers, Inc., New York.
KEPPEL, GEORGE E. 1959. Report on the determi­
nation of tetramethylthiuram disulfide (Thiram)
on corn and apples. J Assoc Offic Agr Chern
42:545-548.
KRUEGER, K ENNETH 'vV., and ALBERT H. TsuDA.
1968. Bud break of Douglas-fir seedlings not
delayed by spring treatment with TMTD or
ALAR. Tree Planters' Notes 19:11-12.
KuwAoKo, YATAKA, 1943. Tetramethylthiuram
disulfide and its derivatives. I. Thermal decompo­
sition of tetramethylthiuram disulfide and its
decomposition products. J Soc Rubber Ind,
Japan 16:322-326 (No. 1739g in Chern Abstr
44, 1950).
LEBEN, CuRT, and G. W. KEITT, 1950. Bioassay
for tetramethylthiuram-disulfide. Phytopathology
40:950--954.
LINDAHL, P. E. Bjorn. 1961. Inhibition of growth
and photosynthesis in submerged plants with
tetramethylthiuram disulphide and sodium di­
methyldithiocarbamate and reversal of this
inhibition of photosynthesis. Nature 191:51-53.
----, 1963. The effect of sodium dimethyldi­
thiocarbamate and tetramethylthiuram disul­
phide on photosynthesis and endogenous respira­
tion in Enteromopha linza (L.). J Agr Physiol
Plantarum 16:644-660.
LITTLE, S., and MoHR, J. J. 1961. Tests of deer
and rabbit repellents on planted loblolly pines
in eastern Maryland. Tree Planters' Notes
48:17-19.
LuDWIG, R. A., and G. D. THORN. 1960. Chemistry
and mode of action of dithiocarbamate fungicides.
In Advances in Pest Control Research III.
P 219-252. Interscience Publishers, Inc., New
York.
MAssAux, FREDDY. 1964a. The penetration and
transport
of tetramethylthiuram disulfide
(TMTD) in plants. Bull Soc Roy Sci Liege
33:206-213 (No. 4708g in Chern Abstr 61, 1964).
----. 1964b. Microdetermination of TMTD
(tetramethylthiuram disulfide) using Hg203, Bull
Inst AgronSta Rech, Gembloux, Belg 31:563-569
(No. 6796c in Chern Abstr 62, 1965).
OwENS, RoBERT G. 1953. Studies on the nature of
fungicidal action. I. Inhibition of sulfhydryl-,
amino-, iron-, and copper-dependent enzymes
in vitro by fungicides and related compounds.
Contrib Boyce Thompson Inst 17:221-242.
PEAsE, H. L. 1957. Determination of dithiocarba­
mate fungicide residues. J Assoc Offic Agr Chern
40:1113-1118.
RADWAN, M. A. 1963. Protecting forest trees and
their seed from wild mammals (A review of the
literature). U S Forest Serv Res Pap PNW-6
28 p. Pacif Nthwest Forest Range Exp Sta.
. 1965a. Persistence and effect of TMTD
on soil respiration and nitrification in two
nursery soils. Forest Sci 11:152-159.
. 1965b. Determining minimum amounts
of TMTD rabbit repellent needed to protect
Douglas-fir planting stock. Tree Planters' Notes
70:16-20.
---
---
----, and WENDELL E. DoDGE. 1965. Effective
application rates of TMTD rabbit repellent to
Douglas-fir seedlings in the nursery. Tree Planters'
Notes 72:7-9.
----, W. E. DoDGE, and H. S. WARD. 1967.
Effect of storage on subsequent growth and
repellency of Douglas-fir seedlings sprayed
with TMTD. Tree Planters' Notes 18:10-13.
RicHARDSON, L. T. 1954. The persistence of Thiram
in soil and its relationship to the microbiological
balance and damping-off control. Can J Bot 32:
335-346.
RoBBINs, RALPH, and JoE KAsTELic. 1961. Rumen
degradation of fungicides. Fate of tetramethyl­
thiuram disulfide in the digestive tract of the
ruminant animal. J Agr Food Chern 9:256-260.
RoHWER, S. A. 1950. Common names for five
commercially-available fungicidal chemicals. Phy­
topathology 40:118.
STECHER, PAUL G. (Ed.). 1960. The Merck Index of
chemicals and drugs. Merck and Co, Inc.,
Rahway, New Jersey. 1642 p.
SwANsoN, M. H., P. E. WAIBEL, N. V. HELBACKA,
and E. L. JoHNSON. 1956. Shell egg quality as
affected by Arasan in the diet. Poultry Sci
35:92-95.
THoMAs, W. DowE, J. MATSUSHIMA, and V. H.
ARTHAUD. 1957. The effects of corn treated
with fungicides upon performance of fattening
steers. J Animal Sci 16:93-99.
TisDALE, W. H., and A. L. FLENNER. 1942. Deriva­
tives of dithiocarbamic acid as pesticides. Ind
Eng Chern 34:501-502.
TisDALE, WENDELL H., and IRA \VILLIAMS. 1934.
Disinfectant. (U S Patent No. 1,972,961). U S
Patent Off.
VoROBEVA, R. S. 1964. Comparative toxicity of
tetramethylthiuram monosulfide and tetramethyl­
thiuram disulfide. Kauchuk i Rezina 23:34-35.
(No. 7586f in Chem Abstr 61, 1956).
----. 1965. Study of the comparative toxicity
of Thiuram compounds in relation to the number
of sulfide groups. Gig Tr Prof Zabol 9:53-56.
(No. 97438 in Bioi Abstr 47, 1966).
WAIBEL, P. E., ELTON E. JoHNSON, B.S. PoMEROY,
and L. B. HowARD. 1957. Toxicity of tetramethyl­
thiuram disulfide for chicks, poults, and goslings.
PoultrySci 36:697-703.
WALTERs, J., and J. Soos. 1961. The relative
efficiency of three hare-repellents in protecting
Douglas-fir seedlings. Forest Chron 37:22-28.
WELCH, J. F. 1954. A review of chemical repellents
for rodents. J Agr Food Chem 2:142-149.
WILDE, S. A., and D. J. PERSIDSKY. 1956. Effect
of biocides on the development of ectotrophic
mycorrhizae in Monterey pine seedlings. Soil
SciSoc Amer Proc 20:107-110.
volume 15, number 4, 1969 / 445