More details of a
typical filling station
for aromatic solvent on
the Columbia Basin
Project is shown in
Figure 150. The elec-
trical centrifugal pump
provides for the deliv-
ery of 50 gallons per
minute to transport and
application tanks.

Accessories at the
filling station include
a totalizing meter, and
a batch dial which can
be reset to zero,
Filler valve has an
automatic shutoff,
similar to those in
use at gasoline serv-
ice pumps. Small pipe
Fig. 149 at hose connection to
pump permits draining
of hose into air vent pipe
at left.

Delivery of 1,000 gallons

of 2,4-D in bulk at the Win-
chester Watermaster storage
yard, Columbia Basin Proj-
ect, Washington, is shown
in Figure 151. The herbi-
cide contained 6 pounds of
active ingredients per gallon.
Previously a 4-pound-per-
gallon formulation had been
in use.

The 1, 000-gallon buried
tank filled with the 6-pound
2,4-D had the capacity of
30 nonreturnable steel
barrels; sufficient for one
full season's spraying.

A hand pump capable of
supplying 12 gallons per
minute, and a meter is shown
on the pedestal at the center
Fig. i50 of the illustration,

131


The intake line to the drum of chemical as illustrated in the dia-
gram, Figure 144, is fitted with a valve which controls the volume
of concentration entering the pump. This particular unit has been
used to apply chemical to ditches having a capacity ranging from

3 to 125 cubic feet per second. The rate of application recommended
for controlling submersed aquatic weeds is 6 to 10 gallons of chem-
ical for each cubic foot per second of water over a 30-minute

period.

On other projects, mixing units similar to the one described are
used which do not draw chemical from a barrel but the pumps are
connected directly to a gasoline meter on the reservoir tank. The
quantity of aromatic solvent is metered and by checking the volume
against time and waterflow, the chemical concentration built up in
the ditch can be determined.

Truck Mounted Supply Tank,
4" Discharge with Gate Valve,
Standard 55 gallon drm,
2 fte staff gage - graduated to 0.01.
‘Ap discharge with Quick Closing

Gate Valve,
Suction line to Lateral,

Self-prining pump.
1} Neoprene discharge to Lateral,

Fig. 144
125



In the application of nut-size crys-
tals of copper sulfate to an earth
section of East Low Canal, Colum-
bia Basin Project, Washington.
Copper sulfate is suspended in
open mesh bags, Figure 131, so
that the crystals will dissolve in
20 to 40 minutes for killing algae.
If dumped onto earth canal bot-
toms those crystals which become
embedded in silt may not dissolve
for several hours or days.

A nylon net bag designed by Mr.
Dean Schachterle, Agronomist,
Kansas River Projects, McCook,
Nebraska, is convenient to use
and has a long life.

Fig. 131

Copper sulfate dust should not be taken into the lungs or mouth, nor
should the skin be exposed to the chemical at high concentrations for
long periods of time. The copper sulfate bagging device shown in
Figures 132 and 133 was constructed in the Quincy Irrigation Branch,
Columbia Basin Project, Washington. With this device, copper sulfate
may be placed in open mesh bags with very little dust and contact with
the skin.

P222-D-29233

Fig. 132 Fig. 133


between dissimilar
metals in a medium
which will conduct

an electric current,

Reasonable precau-
tions should be taken
to install tanks where
the herbicide will not
escape into a ground-
water or surface-
water supply in the
event of tank leak-
age.

Typical of the stor-
age tanks in use for
the bulk storage of
xylene in Region 1
of the Bureau of
Fig. 146 Reclamation is one
having a size shown

in the sketch, Figure 147.

A 3,000-gallon bulk storage weed oil tank on the Delta-Mendota
Canal of the Central Valley Project, California, is shown in
Figure 148, Where oil is a large part of the spray mixture, the
supply should be near the point of use. This tank is on the canal
right-of-way, and is protected by a good quality woven-wire fence.

The use of aromatic solvents in large quantities on the Columbia
Basin Project, Washington, requires that several thousand gallons
be stored. Four 10,000-gallon tanks have been located at Branch
headquarters on the project to be near the expected locations at
which the chemicals will be used. Underground storage was required
in the urban area because of local fire regulations.

Typical of the Columbia Basin Project installations is that shown

in Figure 149. A 10,000-gallon tank for the storage of the aromatic
solvent is located adjacent to the corner of the building at upper
right. Storage of 1,000 gallons of 2,4-D is provided for in a tank

at left center, anda "high-volume" hydrant at lower left is used for
filling sprayer tanks during the irrigation season. Manholes were
installed for access to the tanks in case special cleaning procedures
were required. Each of the storage centers cost about $2,500 to
construct. This will be offset in less than 4 years from savings
possible by purchase of the weed control materials in large volumes,

129


developed by person-
nel of the Michaud
Flats Project, Idaho.
The equipment includes
the tank, trailer,
pump, and related
equipment essential
for transporting and
applying xylene for
pondweed control.

A typical arrangement
of pumping units and
accessories for han-
dling chemical weed
control materials is
shown on the diagram,
Figure 139. Estimated

Fig. 138 cost of the component

parts and their fabri-

cation into a satisfactory application unit is about $400.00. Incor-
porated in the unit are:

1 pump unit

20 feet of 2-inch-diameter suction hose Neoprene lined with
adapters

20 feet of 2-inch-diameter discharge hose Neoprene lined with
adapters

15 feet of 3/4-inch, 75-pounds-per-square-inch, plastic hose
with adapters and union

1 each gate valve, close nipple, and 2- x 2- x 4-inch tee

rr 15' - 3/4" plastic
|
iT \

i
H
id 3"

(7 25'2" plastic discharge
4

gate valve-y cHplus
SE = cS Cad
tf
H|
{i
ui
H
Ht h --- carrying handle
\ ---25'2" plastic =L B
50-gal. suction
drum for -"~~ screen
aromatic solvent
Fig. 139

121


two irrigation seasons. This is in sharp contrast to the scaling, peeling,
and deteriorating surface shown at right that has been in service for a
similar length of time, but exposed to the sunlight. An estimate of the
annual cost of maintenance with the shed roof is close to that for more
frequent painting.

It is estimated that the annual cost of painting is now $1.08 per linear
foot of flume. The cost of the shed-type structure to cover the flume
is estimated to cost $20.00 per linear foot. Some painting would have
to be done under the sheds at about 6- to 7-year intervals. Interest on
the investment would have to be added to the cost as well as the cost of
maintenance. A distinct advantage, however, and an important one, is
that the shed could be constructed during the winter and it would not be
necessary to clean and paint the flumes during the rush period just
before the start of the water season, when weather suitable for the paint-
ing operation permits. Preparations for repainting must include the
removal of adhering algae and cocoons as well as loose deteriorated
concrete and other foreign matter.

During the 1958 irrigation season, a considerable growth of algae formed
on a Parshall flume on the Meeker-Driftwood Canal system, Missouri
River Basin Project, Nebraska. The growth was so dense that it affected
the rating of the flume used to measure water deliveries to the canal.
Periodic applications of copper sulfate to the water in the canal helped
kill some of the algae, but enough remained on the flume to affect the
rating.

Prior to the
1959 irrigation
season, two
coats of copper-
base proprie-
tory antifouling
paint was applied
to the throat of
the 12-foot con-
crete Parshall
flume, Figure
135. The result
of this paint
application was
that the growth
of algae in the
throat of the
flume during
1959 was neg-
ligible.

°328-70)-7955

118


Antifouling Paints

Algae and naiad cocoons create a very troublesome problem on concrete
flumes, tunnels, and siphons of the Black Canyon Canal, Boise Project,
Idaho, The carrying capacity of the flumes particularly is seriously
reduced because of the attachment of the algae and cocoons to the sides
and bottom surfaces of the flumes. The infestation is usually heavier
on rough concrete surfaces and less severe at points of high turbulence
or high velocity flow of the water.

Several surface coatings have been applied to the concrete surfaces

over the years to reduce the attachment of the foreign adherents; among
these are CTP-3 paint, catalytically-blown asphalt, and antifouling
paints, In addition to the proprietary paints and asphalt coatings, chem-
icals which inhibit or retard the growth of algae were mixed with CTP-3
paint. More recently, a roof has been placed over a short reach of one
flume to determine the effect sunlight has on the algae.

Antifouling paints seems to inhibit the growth of the black-fly cocoons to
some extent and, applied to the bench flume, it has given generally good
results for periods up to 3 years. Whether this benefit can be attributed
entirely to the paint or to the smoothness of the concrete surfaces over
which the paint is applied has not been fully established.

Merely covering the flumes to reduce the light will not control black-fly
activity. Actually, the cocoons appear in tunnels and siphons where there
is virtually an absence of light. The heaviest infestation has been in

a tunnel 9 miles from the head of the canal.

Covering the flumes definitely has some advantages. The antifouling
paint in the shade of the roof was in much better condition than that
exposed to direct sunlight. The condition of the paint with and without
protection of the shed are illustrated in Figure 134. The smooth,
adhering paint under the shed in the left illustration, had been in service

Fig. 134

117


>
am
‘© 800 Gallons Capacity
KR
' — a _
|
®
‘s
Y

BULK STORAGE TANK FOR XYLENE

Fig. 147

Fig. 148

130


Labor and transportation of labor
2-1/2 gallons of paint at $9. 62
Muriatic acid (surface preparation of.

BOMEMETSD! cans sowncwn wrenens eomrese © oxen 9 sien in sbiems @: ries eaene 3,00
BYOORE ee saree acres ware wecare © nee & eye © eee @ HHO He 1.00

Total

The paint used contained 14.7 percent active ingredients expressed
as metallic copper, and 85.3 percent inert ingredients. A source
of the paint may be obtained by writing the Office of Assistant
Commissioner and Chief Engineer, U.S. Bureau of Reclamation,
Building 53, Denver Federal Center, Denver 25, Colorado, Atten-
tion: D-400.

Aromatic Solvents

The use of aromatic solvents in the control of aquatic-type weeds
has received widespread acceptance and in the following few pages
of this section of the bulletin equipment for the handling, mixing,
and storage of these solvents is discussed.

The essential components of a piece of equipment for the trans-
porting and field application of aromatic solvents are embodied
in the trailer-mounted equipment shown in Figures 137 and 138,



CONTROL OF AQUATIC WEEDS
The Problem

Unretarded growth of aquatic weeds in lined canals can materially affect
their carrying capacities. This is especially true during the hot sum-
mer months when the demand for water is the greatest and any interrup-
tion in service may mean costly crop losses.

Aquatic weed may consist of so-called mosses, algae, pondweed, and
similar types of growths that occur primarily within the water prism of
our waterways. Typical plants of this type are shown in Figure 130.

Moss Algae Sago Pondweed
Fig. 130

True moss may grow in water, but it is often found on shady banks at
the waterline or above, Water channels in the United States are seldom
infested to a degree necessary for control. In Australia and New Zea-
land, moss is a problem. Control methods have been developed there
which are superior to mechanical scraping. Waters low in salts are
most likely to contain moss. True moss has parts which strongly
resemble stems and leaves.

Algae is often called moss, frog moss or green slime. The filamen-
Tous kinds, as shown, offer the most problems in irrigation systems.
Prevention and control may be obtained by the use of copper sulfate,
aromatic solvent, andotherchemicals. Waters high in salts may
require more chemicals than less salty water. Of the weedy algae in


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NOILVOIYY! NI LNSAIOS SILVWOYNV ONIAIddVY YOS
SNLVYVddY GS3LNNOW WONNL 4O ATISWASSV YOS WVYSVIC

adh] asoy easly ‘ajZZ0N~~. Pesinbey SD anjon
Pose eel 4004 PUD JOUIDILS-~-r¥t BP
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b¢

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Fig. 141

123



Fig. 140

The arrangement of a somewhat larger truck-mounted tank and
accessory equipment used on the Columbia Basin Project, Washing-
ton, is shown in Figure 140.

The assembly of apparatus for the illustrated unit is as shown in
the sketch, Figure 141.

Truck-mounted aromatic solvent application equipment devised by
the Kennewick Irrigation District, Kennewick, Washington, is
shown in Figure 142. The tank and metering device were obtained
from an oil delivery tank truck. The pump intake and outlet lines
are black semiflexible polyethylene tubing. The cost of the tubing
is much less than the more flexible hoses, is resistant to the
aromatic solvent, light in weight and may be used for suction as
well as discharge lines. The tubing becomes less flexible during
cold weather, but this is not a problem since aromatic solvent is
seldom applied when the air temperature is less than 70° F.

In applying aromatic solvent to control submersed water weeds,

it is recommended the concentrated solvent be introduced at a drop
structure so that the turbulence of the water will effect good mix-
ing. Naturally, ideal conditions for mixing chemical with the water
do not exist at every point where introductions are to be made, so

122


Fig. 136

Figure 135 is a view of the flume looking upstream showing the
left side of the flume and the copper-base coating applied. Growth
of algae on the side of the flume downstream from the painted
throat is apparent.

Toward the end of the irrigation season there was evidence that
some of the protective paint was wearing off. This was especially
true of the bottom of the flume and the lower sides. In order for
the algae protection to be maintained, the Project Manager
believed the flume should be painted again before the next irriga-
tion season.

Figure 136, taken at the end of the irrigation season, shows the
downstream section of the treated Parshall flume and the untreated
section below the flume throat. In the untreated area, long strings
of algae growth are visible while there is practically no algae in
the treated section. The treated bottom has a very thin layer of
algae and much of the paint had started to wear. Also evident are
areas of loss of protective paint at the bottom of the sides of the
flume.

The cost in 1959 of applying a total of 2-1/2 gallons of the copper-
base antifouling paint in two coats was approximately $63.00. The
cost as estimated by maintenance personnel is broken down as
follows:

119


action in the stilling basin assures satisfactory diffusion throughout the

entire cross section. The material is dumped at as uniform a rate as

possible over a 15-minute period. Allowing an additional 5 minutes for

total dissolution, the entire treatment covers a 20-minute period. Using

2 pounds per second-foot, a concentration of 26.6 parts per million for

20 minutes is achieved. This concentration usually results in restoring
practically the full capacity of the canal within 24 hours. A treatment -
usually clears the entire lined section. However, in some systems it

might be necessary to add additional material at 4- to 6-mile intervals

to secure the best results.

The chemical is purchased in 20 and100 pound bags to facilitate closer
measurement of the material. The fine crystals dissolve faster than
the "nut" or coarse grade, and are less irritating to skin and eyes of
the operator than the powdered grade. Inall, the fine crystals proved
most satisfactory from all angles.

Only one man and a pickup truck are required for the operation. Each
of the material bags is opened before the actual application begins,
assuring no lost time or irregularity in the rate of application. This
method has proven entirely satisfactory and the most economical of all
methods tried.

A schedule of the optimum time between treatments has been worked

out, based upon curves expressing the relationship between the discharge
through the needle valves, discharging into the canal, anda gaging sta-
tion located about a mile downstream from the dam, These curves are
kept on a daily basis. When the recorder at the gaging station shows

a 4- to 6-percent rise in the apparent canal flow, and the valve discharge
has not been increased, a treatment is scheduled. Likewise a daily
climb of 2 percent at the recorder (no increase having been made at

the valves) usually indicates an application of copper sulphate is needed.

Treatments have been required most frequently during the warmer
summer months. Over the past 3 years, four or five applications have
sufficed for the months of June, July, and August, with two or three
others spread over the spring and fall months.

Concentrations up to 35 parts per million have not killed fish in the
canal. However, higher concentrations have been known to do so on
certain species. This is a secondary consideration because no effort
is being made to propagate or protect the fish. Fishing and hunting
are not allowed along the canal right-of-way.

115



24" pulley--~_
N
. . \ 7
3 hp motor~._ ~1 9!
\ 1750 rpm

EMULSIFIER AGITATION TANK
275 GALLONS
Fig. 145
An emulsifier agitation tank, shown diagrammatically in Figure
145, isusedby the Big Wood Canal Company, Shoshone, Idaho, in

the application of solvents to canals and laterals.

Metering Aromatic Solvents

Aromatic solvent can be measured as it is applied to delivery and
disposal channels by adding the chemical to the suction side of a 1-1/2-
or 2-inch (input) centrifugal pump. The pump circulates water from
and to the waterway. This method in common use on projects in

the northwestern part of the United States is facilitated by instal-
lation of a rate of flowmeter which gives a direct reading in gallons
per minute.

For example, if the rate of application of aromatic solvent is 10
gallons per cubic feet per second over a 30-minute period and the
measured flow in the lateral is 14 cubic feet per second, 140 gallons
of aromatic solvent should be applied. A uniform flow of 4-2/3
gallons per minute of the solvent is desired.

On the Columbia Basin Project, a deflection-type meter is installed
in the aromatic solvent delivery pipe. The flow of aromatic solvent
is regulated by a valve until the meter reads the desired rate of
flow. A meter of this type is shown in Figure 140.

126



Storage Criteria

Good housekeeping, plus a definite consideration of the storage and
handling requirements of chemicals used in the control of aquatic
weeds, willpreventaccidents. A herbicide storage structure and
its equipment should:

1. Accommodate the quantity of herbicide which can be deliv-
ered, and safely retain it until it can be used over a practical
length of time.

2. Provide means for taking the herbicide from storage in a
clean and rapid manner.

3. Provide means for measuring the material into and out of
storage.

4, Not present a hazard to the community in the event of fire,
collision, or other extraordinary circumstances. Such a hazard
might be air pollution, water pollution, or a long-term odor
nuisance.

5. Conform with the safety requirements of the local govern-
ment.

Bulk Storage

Bulk storage of fluids and flowable herbicides is feasible where a
large quantity is used, where the storage can be near the point of
use, where the disposition of many small containers is a problem,
and where the herbicide may be obtained’ at a lower price in bulk
than in smnall containers. By the use of bulk storage and pool pur-
chasing, the cost of aromatic solvents or xylene have been cut 50
percent.

Storage tanks for aromatic solvents, weed oils, and 2,4-D are
best constructed above ground for delivery by gravity, so that no
pump or electrical installation is required, so that inspection of
the tank for leaks is a simple procedure, and so that the tank may
be cleaned readily. Such a tank used by the Big Wood Company,
Shoshone, Idaho, is shown in Figure 146.

If underground installations are required to satisfy local regula-
tions, to prevent a hazard or nuisance to the community or to save
space, precautions should be taken against rust and electrolytic
corrosion. A means of checking and cleaning the inside of the tank
should be provided.

Pumps, meters, piping, hose, and other equipment used at storage
sites in the filling of transporting equipment should be made of
materials resistant to corrosion by the herbicide. The tank con-
struction should be such that galvanic activity will not take place

128



The sediment from Angostura Reservoir caused greater light reduction
at lower concentrations than did the commercial bentonite.

When plants were exposed to reservoir sediment concentrations of

50 parts per million, the percent reduction of dry weight of plant mate-
rial was approximately 33 percent less than the dry weight of plant mate-
rial in the control drum. Reservoir sediment concentrations greater
than 1, 250 parts per million were not effective in producing additional
significant growth reductions than that attained at the 1, 250-parts-per-
million level. The commercial bentonite sediment caused growth reduc-
tions of a similar trend but required greater concentrations than field
sediment to produce similar effects.

Chemical Methods for Control of Aquatic Weeds

Copper Sulphate. Treatment

The problem of algae growth in the Madera Canal on the Central Valley
Project in California, is, no doubt, typical of conditions in many other
canal systems. This canal is 36 miles long and has an initial capacity
of 1,000 cubic feet per second. Only the first 7.7 miles is lined, and
it is this lined section which is appreciably affected by algae growth,
In past years (this part of the canal was placed in operation in 1945),
before an effective schedule of treatment had been worked out, the
capacity between treatments was occasionally reduced by as much as
29 percent. It has been determined that the most prevalent algae form
present was "Ulothrix."

Early methods of treatment consisted of suspending "nut" size copper
sulphate in burlap bags, in the canal as near the outlet valves of Friant
Dam as possible. These treatments, at 7- to 10-day intervals, were
frequently insufficient to restore the full capacity of the canal; and
another treatment was required within 2 or 3 days. When the algae
growth was far advanced, and the required dosage was in doubt, as many
as 13 or 14 treatments were made each water season (usually 6 to 8
months long). Later experience, together with aid from the Bureau of
Reclamation's Laboratory in Denver, Colorado, established that

2 pounds of copper sulphate to each second-foot of flow provided an
optimum rate of application, Lesser amounts frequently proved insuf-
ficient, and the treatment had to be repeated. Heavier applications
appeared unnecessary.

Other methods tried included: placing copper sulphate in solution before
applying, the use of chlorinated lime, and the application of Rosin Amine
D. acetate with a weed spray rig. Satisfactory control was achieved
with these various chemicals but all required considerable time and
labor to get these materials in solution.

The present method of application is to "slug" the canal with fine crys-

tals of copper sulphate, dumped directly into the stilling basin at the
head of the canal. The fine crystals dissolve rapidly and the turbulent

114



fresh water only a few forms resemble land plants with stems and
branches. Chara, a pondweed-like algae may often be found in irriga-
tion channels. The plant has a gritty texture.

Pondweed, also called moss, water weed, ditch grass, and horsetail
moss, is a rooted flowering plant. Sago pondweed is one of several
flowering plants which are obligated to live in water, and which reduce
the capacities of irrigation channels. These weeds must be prevented,
controlled, or removed if the capacities of channels are to be main-
tained.

The control of aquatic weeds on irrigation projects is most effectively
accomplished by the use of chemicals and equipment for dispensing them,
or by the use of mechanical control methods. However, sediment in the
canal water may beadeterrentto the growth of some types of aquatic
weeds under some conditions.

Effects of Suspended Sediment on Pondweeds

In the past, field observations have frequently been made regarding a
possible correlation between the amount of suspended sediment contained
in canal water and the amount of aquatic plant growth in canals. Field
observations have often indicated that as suspended sediment increases,
the amount of aquatic weed growth decreases. Reports of observations
reviewed have in no case given details of various factors contributing

to suppression of aquatic plant growth. These statements have been of

a general nature.

To obtain more information under controlled conditions on this subject,
a joint study by the Weed Control Investigations Unit of the Physical
Investigations Laboratory Section, Chemical Engineering Laboratory
Branch, and the Sediment Investigations Unit of the Hydraulic Labora-
tory Branch, Bureau of Reclamation, Denver, Colorado, was initiated
to determine shading effects of suspended sediment on aquatic weeds.
The scope of the program consisted of determining the growth response
of various species of submersed pondweeds exposed to environment

of various concentrations of two types of suspended sediments.

Species of submersed pondweeds, commonly found in irrigation canals,
were planted in pots and grown in drums containing a range of suspended
sediment concentrations. Ungerminated plant propagules and estab-
lished cultures of pondweeds were used in the study.

Two different sediments were used, one a commercial sodium-base
montmorillonite-type bentonite, and the other a natural occurring
bentonite-type sediment obtained from Angostura Reservoir.

Light quantity and spectral quality, penetrating the sediment-laden
water, were measured by use of a limnophotometer which has a spe-
cially constructed photoelectric cell system. Light measurements
indicated the intensity and spectral quality of sunlight were consider-
ably changed upon penetration into water containing suspended sediment.

113



other means such as
compressed air, stir-
ring the water with
paddles, and mixing of
the chemical in a pump-
ing unit have been
investigated. A practi-
cal preintroduction
technique of assuring
dispersal of aromatic
solvent has been devel-
oped and used by per-
sonnel of the Sunnyside
Valley Irrigation Dis-
Fig. 142 trict, Sunnyside,

Washington, as illus-
trated in Figure 143. The method of mixing is referred to in that
area as the ''Sunvalid Solvent System."

The mixing of solvent with water before it is introduced into the
canal eliminates the necessity for nozzles. It also assures thor-
ough dispersion of chemical in the first few hundred feet down-
stream from the introduction point which so often is difficult to
obtain when nozzles are used,

The unit consists of a 4-inch centrifugal pump with intake lines to
both the reservoir of chemical and to the lateral. Violent mixing
of chemical and water is accomplished in the bell casing of the
pump before fluid is discharged back into the lateral.

Fig, 143

124


This particular meter is calibrated for xylene at rates of 3 to 15
gallons per minute. The same meter will measure larger flows if
placed in bypass position with dial scales made to correspond with
the calibration of the hookup.

The meter scale should be reealibrated for each type of liquid
metered if there is a wide difference in velocity or a specific gravity
difference of 0.15 or more. Rates of flow smaller than 3 gallons
per minute can be measured by a smaller meter.

Deflection type of meters are inexpensive (cost, less than $60),
may be mounted in any position, have one moving part, and can be
obtained in aluminum, bronze, or other noncorrosive materials.

Storage of Herbicides

Storage of weed control materials offer few problems other than
those encountered with other materials required for operation and
maintenance of the irrigation system. Costs may be reduced as

the quantities required become large enough for bulk storage,
especially the storage of liquids, but aromatic solvents, acrolein,
oils, sodium chlorate and other inflammable materials have specific

storage requirements.

A few herbicides, such as dinitro, are highly toxic to humans and
animals, when taken internally. Most herbicides are low in flam-
mability and have a very low toxicity to animal life. They may have
an extremely high toxicity to plantlife. Many hérbicides are toxic
to fish and to fishfood organisms. Several herbicides especially
those containing chlorinated phenol components provide a long
lasting odor and taste to water used for domestic purposes.

The aromatic solvents, xylene, acrolein and solvents employed as
liquid carriers in some herbicides may be highly toxic in closed
rooms under conditions which would expose humans to fairly high
concentrations in the air, or, in the case of some of these mate-
rials, to low concentration for a long period of time.

Few weed chemicals are highly acid or alkaline, or strongly irri-
tating to the skin on short contact, unless in concentrated form.
Diluted forms may be a source of irritation if left in contact with
the skin for several hours. Susceptible individuals may show
allergic reactions on one or more herbicides. The diagnosis and
treatment of these conditions are medical problems.

Copper sulfate in solution in water is highly corrosive on metal
containers and parts and the aromatic solvents accelerate the dis-
integration of natural rubber and paints.

127