a v‘

gamma/J i

Significant increases in forage and livestock productio
possible in the post oak-blackjack oak area of Texas by
grating brush control into a range management program. t
acreage occupied by post oak-blackj ack oak in the East and y,
Cross Timbers, the Central Basin and the East Texas post"
belt, a portion of the East Texas timberlands, is slightly gr
than ll million acres. k

   
  
  
    
  
   
 
 
  
   
  
 
 
     
  
 
  
    
   
 
   
  

Methods and costs of treatment by various mech -
chemical, burning and grazing practices are described for;
control of oak and associated species. Mechanical pra
suitable for small areas include girdling, cutting and mow' 5i
large areas, chaining is effective provided sprout growth c [
controlled. Bulldozing is effective in medium-textured so'
upland sites or in bottomlands preparatory to establishm I A
pastures.

Recommended individual plant treatments with h
cides include basal trunk spray, stump spray, frill spray, n
injection and soil injection. Oil solutions of 2,4,5-T ester‘
effective for all individual plant treatments. Water s <5:
sions of monuron or fenuron may be used in the soil-inj 1
method. Ammate as crystals or in solution may be -._
to freshly cut stumps, cups or notches and in frills.

Broadcast applications of herbicides for oak control
clude foliage or aerial spraying with 2,4,5-T or silvex '-
and soil surface application of fenuron pellets. The 2-
aerial spray program is recommended for large-scale p’
ment of areas lacking crops susceptible to hormone-type h
cides. Fenuron pellets are adapted for oak control on ' __
textured soil on areas with crop hazards which prohibit
use of hormone-type sprays. i

Goat grazing is an effective and economical method}
sprout and underbrush control on cleared areas with suit
fencing and other facilities. ‘

Under proper management, reduction in the woody p
cover in the post oak-blackjack oak area will result in m l
increases in forage production within 2 to 3 years follo 
control. Overstory removal on a range with good cover r f
in a five to sixfold increase in total herbage production '
years. Costs of treatment amounting to $27.23 per acre 
paid off in slightly more than 4 years on the basis of hay -'
duction. =

Broadcast chemical control treatments such as aerial s 
ing give the additional benefit of weed control and red f
competition with forage grasses. ~

Brush Control

   
 
   
   
    
  
   
    
  
  
  
  
  
   
   
  

 and
 Range Improvement

IN THE POST OAK-BLACKJACK‘

OAK AREA OF TEXAS

Robert A. Darrow
and
Wayne G. McCully*

 iT OAK-BLACKJACK OAK WOODLAND of the Cross
T, Central Basin and East Texas area has a
tential carrying capacity for grazing live-
A During the past several decades, the increase
A tinued spread of such brushy plants as post
ackjack oaks, haw, smilax and yaupon have
id the original open woodland or savannah in-
‘hy or dense woodland stands. With this in-
iin brush, the ground cover of desirable forage
<such as bluestems, beaked panicum, the pas-
, Indiangrass, switchgrass, the dropseeds and
ood grasses has been reduced materially. In-
i brush clearing and other control measures
 with suitable grazing management are nec-
to reduce this cover of undesirable brush and
in the continuing benefits of forage produc-

gdy vegetation of the region consistslargely
J arketable or poor quality trees having little
g commercial value for lumber. Post oaks are
ocally for fence posts and a limited amount
f1»: is cut for ‘fuel and charcoal. On the non-
ands of the region, livestock production is the
Q pal source of revenue. Throughout the East
 area and in parts of the Cross Timbers, large

tively, professor and associate professor, Department of
l; and Forestry.

areas were cleared initially for cultivation. Some
areas previously in cultivation have now reverted to
scrub oak or brushy areas and often are subject to
accelerated erosion.

This publication discusses methods of clearing or
controlling woody plants for the establishment of
crops and pastures and in the improvement of native
range in the post oak blackjack oak area.

Area of Distribution

The post oak-blackjack oak area of Texas occu-

pies fourregions: (l) West Cross Timbers and ad-
jacent fringe area; (2) East Cross Timbers; (3)
Central Basin; and (4) East Texas post oak belt of
the East Texas Timberlands (see map) . A consider-
able acreage of forest dominated by post and black-
jack oaks also occurs in the pine-hardwood type east
of the boundary shown on the map. The total acreage
occupied by the oak area in Texas is estimated at ll
million acres. ~

Annual precipitation in the oak area varies from
25 inches in the western portion to 45 inches along
the eastern limits. Rainfall is heaviest during April

and May with a secondary rainfall maximum in Sep-

tember and October. Summers are relatively hot and
dry. a

WEST ‘CROSS TIMBERS

The West Cross Timbers occupy unconsolidated
sandy materials with rolling and sloping topography
in Erath, Montague, Wise, Somerville, Comanche,
Eastland, Hood and Parker counties. A fringe area,
distinguished by Dyksterhuis (1948), includes out-
lying areas of oak brush in Clay, Archer, jack, Young,
Throckmorton, Palo Pinto and Stephens counties,
and it is associated with the sandstone soils of the
North Central Prairies.

Woody vegetation consists of post and blackjack
oaks with a limited amount of underbrush and such
associated species as greenbrier, live oak and mesquite.
A distinguishing feature of the fringe area is the
abundance of buffalograss.

Early settlers in the area report little bluestem

- as the principal species of grass in the original open

savannah; big bluestem, switchgrass and Indiangrass
were widely distributed and important on sandy or
sandy loam sites.

Sand lovegrass and purple lovegrass are common
south of the Brazos river but these secondary grasses
produce little palatable forage. Productive bottom-
land sites support stands of oaks, elm, pecan and bois
d’arc with a forage cover of bluestems, Indiangrass,
Canada wildrye and other climax species.

EAST CROSS TIMBERS

The oak belt characteristic of the East Cross Tim-
bers occurs on sandy loams and loamy sands in gently
rolling topography. Vegetational components closely
resemble those of the West Cross Timbers, but af-
finity with the East Texas Post Oak Belt is shown by
a greater number of such associated woody species
as winged elm, hickory and haw and by the presence
of panicums and paspalums in the forage cover.

CENTRAL BASIN

Post and blackjack oaks characterize the sandy,
noncalcareous soils of this heterogenous area derived
from granites, limestones, schists and sandstones.
Live oak, mesquite and juniper occupy the medium
and heavy-textured soils. In the adjacent Edwards
Plateau, particularly in Kerr and Gillespie counties,
post and blackjack oaks occur on soils derived from
flintrock.

Desirable grasses include purpletop, sand love-
grass, plains lovegrass, cottontop and pinhole blue-
stem, in addition to the bluestem dominants.

EAST TEXAS POST OAK BELT

The western portion of the East Texas Timber~
lands was characterized originally by a savannah-type
vegetation consisting of an open woodland of oaks
with a dense forage stand of little bluestem, beaked
panicum, paspalums, dropseeds and such. Continued
grazing pressure and a reduction in the incidence of
fires have led to a marked increase in the density of

4

 
 
   
  
  
 
   
  
  
 
   
   
    
 
  
  
  
  
  
 
 
  
  
  
   
  
 
  

oak and underbrush. Associated woody sp
cluded hickory winged elm, eastern red cedar, y‘
French mulberry, parsley haw, chittamww
coralberry. A

In the pine-hardwood area east of the m'_
oak belt, savannahs of post and blackjack 0_
common on well-drained sites and are subj
similar brush control and niariagement prac

Woody Plant Control Meas 

Regulation of the woody plant cover to ;_
maximum forage production is the goal of ra f
management in the post oak-blackjack area.‘
satisfactory economic returns in most of the‘
dense woodlands or brushy stands should u;
verted to a tree-grass vegetation with scattere
making up not more than 25 percent of the co‘

The presence of varying amounts of unde
such as yaupon, greenbrier, haw, winged el"
other species may greatly influence the cho
methods used in control. Where underb 
present, it may increase rapidly in size whei
overstory is removed or deadened. Many ki 
underbrush cannot be controlled with existing’
ods. The methods chosen for brush control "J
be part of an overall management progruf
should provide for a continued treatment of f
regrowth and maintenance of optimum 
cover relationships. K

FACTORS IN THE SELECTION OF
SUITABLE CONTROL MEASURE i

Selection of a suitable control measure for i
cific area may take into account several factors:

1. Nature of the brush problem—lwoody*f
consisting of mature trees, brushy growth or I
with or without underbrush; woody plants in’
rows, scattered stands or continuous blocks; a;
and character of residual forage grasses.

2. Size and topography of the area to be

3. Availability of local or contract labor f’
mechanical or spray equipment and other fa“
adapted to specific control measures. ?~

4. Relationship of area to land use 
particularly with reference to the location of:
susceptible to hormone-type herbicides whic 
limit the use of aerial spray applications. A

5. Anticipated duration of clearing or 
programs, for example, whether work is to be o_
a single operation or in yearly or seasonal incri

6. Economics of expected cost-benefit ra
clearing operations. Investments as for goal
fencing. V 
7. Projected use of area to be cleared o
trolled. e

  
   
   
   
  
     
   
   
  
  
  
  
  
  
  
   
   
 
 
  
    
 

 Changes in existing management practices
{goats deferments and such.

i] Provision for maintenance of treated area if
five regrowth should develop.

 Entire pasture unit should be treated since
'  k prefer cleared or treated areas.

 MECHANICAL CONTROL
 "8

‘ling by hand ax or mechanically powered
f’ such as the Little Beaver Girdler will effec-
Tdeaden trees of post oak, blackjack oak and
p other kinds of hardwood (Figure  . Trees
ess of 8 to 10 inches in diameter are treated
effectively in this manner; smaller trees are
it to basal sprouting, particularly if the girdles
ced above ground-line height. Hickory, sweet
{water oak, elm and bitter pecan sprout basally
ding girdling and supplemental control mea-
A ay be needed to control sprouting.

p,

dling is efficient and economical for thinning
and stands of light or moderate densities. The
ymay be used by individual landowners for
j'ttent operation at all seasons on small-area
g with local or owner labor.

its of girdling vary from $1.50 to $10 or more
in depending on stand density, tree size and
"fcosts.

.8
 g

' tting by hand ax or with mechanized chain or
r saws is effective for-clearing small areas of
and with light or moderate amounts of under-

ees with diameters less than 8 to 1O inches are
t to sprouting when cut either at ground level
convenient stump heights for chopping. Ef-

 
    
    
 

g re 1. Girdles cut in early spring when the bark is
‘L; give relatively wide bands of exposed wood and mini-
atural grafting over the cut. Photo Courtesy of Soil
_, ation Service.

Figure 2. Motor-driven saws are effective in rapid clearing
of small woodland or brush areas.

fective management on cutover areas will provide
for control of sprouts by chemical treatment or fresh-
ly cut stumps, by grazing with goats, or by subse-
quent maintenance mowing.

Costs of cutting and sawing vary widely with
local conditions. Typical operations with power
saws may cost from $6 to $15 per acre for complete
woodland clearing. In recent years the use of trac-
tor-driven or self-propelled circular saws (Figure 2)
has declined in preference to the more adaptable
chain saw.

Mowing

Heavy-duty mowers or shredders can be used for
initial clearing and for cutting sprout growth with
‘stem diameters not exceeding 3 to 4 inches. Regular
mowing is necessary because oaks and most associated
species are aggressive stump sprouters.

Costs of initial mowing may range from $3 to $7
or more per acre; subsequent maintenance mowing
may be less expensive.

Bulldozing

Bulldozing to clear oak woodland in sandy or

sandy loam sites has been practiced extensively in.

clearing land preparatory to establishing temporary
crops such as watermelons and tomatoes, or for
temporary pastures. In general, bulldozing in sandy
sites for brush removal should be followed by an
immediate establishment of a cover or pasture crop
to minimize soil erosion.

Bottomland hardwoods in the post oak-blackjack
oak type often are cleared by bulldozing in the estab-
lishment of tame pastures on these highly productive
soils. On upland areas, clearing for improvement of
native forage stands without overplanting should be
limited to the medium-textured soils.

Costs of bulldozing vary with the density of tree
and brush cover and intensity of treatment from $10
to $75 or more per acre.

Chaining

In recent years chaining with heavy anchor chains
drawn by pairs of heavy-duty bulldozers has been
used extensively in brush clearing operations in the
oak type. Effective results have been obtained on
sandy or medium-textured upland sites in medium-
aged or mature stands relatively free of oak reproduc-
tion and underbrush.

In the West Cross Timbers and in parts of the
East Texas Post Oak Belt, goating pastures before
and after chaining has provided effective and profit-
able control of sprouts and underbrush (Figure 3) .
In areas in which goat grazing or sprout control by
chemical methods is not feasible, piling or wind-
rowing chained brush may allow for subsequent
sprout control by the use of rotary mowers.

Costs of chaining range from $5 to $10 per acre.

Root Plowing

Root plowing has been given limited trial for
brush clearing in the post oak-blackjack oak area.
Recommendations are not currently available for
the practice nor for the reseeding practices essential
for forage stand improvement following root plow-
ing. The practice appears to be adaptable to young
to medium-aged stands of brush in medium-textured
soils.

GOAT GRAZING

Goats have been used extensively in the Cross
Timbers area and more recently in the East Texas
Post Oak Belt for the control of underbrush and
sprouts of post oak and blackjack oak following me-
chanical or chemical treatment (Figure 4) . The use
of goats for this purpose requires that suitable fencing
facilities are available for management and protection
of the goat herd. Spanish-type goats are preferred
in the East Texas area but Angora goats are used
widely in the Cross Timbers and other western areas.
In Leon and Freestone counties 30,000 to 40,000

6

Figure 3. Girdling, bulldozing or chaining followed by goating in the WVest Cross Timbers has given effective control?
brush and excellent stands of forage under suitable management. . i‘.

 
  
 
 
 
 
 
 
 
 
 
 
 
  

     
   
  
  
   
  
     
 
   
  
    
    
   
    
   
  
  
   

Figure 4. Grazing with goats is an effective and i.
able method of brush control in oak areas. Photo Cour a»;
Soil Conservation Service. ‘

goats are currently used for brush clearing and i
trol of regrowth in post oak areas (Polk, 1958)

Mohair-producing goats have an economic ,
vantage over other control measures in providi g
source of income during the control operations. ‘Y
some instances, goats may yield a higher net I3
than a cow operation and serve to improve the r i’
conditions at the same time. Combination stoc  :
with goats and cattle probably is the most 
nomical. i‘

Stocking rates commonly used are one goat to .
S acres on areas subjected to chaining or girdling 
cutting. By using large numbers of goats for sh
periods in a rotation system on fenced units, ani;
will consume large amounts of brush with 1i.
damage to grasses. With continued stocking at h  
rates, goats may overutilize grasses and cause det
oration of the forage stand. Goating should pre k
or follow immediately after mechanical clearing,

deadening operations in order to control sprouts 

   
 

  

_ e 5. Excellent grass recovery may be secured on areas
 intensive grazing by goats is used for control of under-
‘d oak seedlings. Indiangrass production 2 years after
i‘ of large trees and summer deferment of cattle. Photo
i‘ of Soil Conservation Service.

y. For the first 2 or 3 years following brush
 optimum conditions are provided for growth
;_,:|PI‘0V€II1€I1[ of native grasses provided suitable
ent or light stocking is practiced (Figure 5) .
,present prices of mohair, gross annual sales of
{l0 per goat may be realized. According to eco-
' studies by Magee (1957) in the Grand Prairie
L, the returns from Angora goat operations re-
_ ithin a 5-year period the cost of stock, fencing
rush control costing an average of $7.23 per
f Careful handling and livestock management is
fry in an economical operation.

BURNING

a ntrolled or prescribed burning has been given
_trial for the control of woody plants in the
p oodland type. Small-diameter oaks and some
brush apparently can be rootkilled by properly
 d ground fires in situations with an adequate
 of grass stubble for fuel.

juestem grasses and some associated species are
vely tolerant of fall or early spring burning.
. such as railroad rights-of-way which have been
 periodically show a predominance of fire
nt grasses, notably little bluestem (Figure 6).
upon and other kinds of underbrush common
 East Texas area show marked reduction in stand
5y with systematic burning (Goddard, 1954).

CHEMICAL CONTROL

ormone-type chemicals or other herbicides may
lpplied in individual plant or broadcast treat-
l) for control of woody plants.

l Trunk Spfay

‘asal spray applications of oil solutions contain-
2,4,5-T ester or water suspensions of monuron
er are recommended for control of post and
jack oaks with diameters of less than 5 to 6
(es. Oil sprays containing 16 pounds acid equiva-

   
 
 
 
   
 
  
 
  
  
 
  
  
  
 
 
 
 
 
  
 
  
 
  
 
 
 
 
  
  
  
 
  
 
  
  
  
  
  
 
 
 

Figure 6. Periodic burning followed by a year’s defer-
ment has resulted in a pure stand of little bluestem on this
oak area. Proper burning and management are essential for
this control measure. Photo Courtesy of Soil Conservation
Service.

lent of 2,4,5-T ester in 100 gallons of diesel fuel or
kerosene give effective control of oak in dormant
season or early summer applications (Figure 7).
Basal spray applications of 2,4,5-T ester have proved
more effective than treatments of silvex and the re-
lated Z-(ZA-DP) ester or 2,3,6-TBA (Table l).
Monuron in suspensions containing 8 to l0 pounds
of wettable powder per 100 gallons of water is ef-
fective in applications made at any season. The mix-
ture in the spray tank should be kept well agitated
to insure uniform delivery.

Care should be taken in basal trunk spraying to
thoroughly wet the lower 8 to- l2 inches of stem to
the point of runoff. Applications can be made most
effectively with a knapsack sprayer. Species associ-
ated with post and blackjack oak such as gum elastic,
honey locust, red haw, bitter pecan and bois d’arc can
be controlled with basal sprays of 2,4,5-T ester at
8 pounds in 100 gallons of diesel fuel.

Cost of treatment with oil sprays of 2,4,5-T
ranges from 3 to 5 cents per tree. One gallon of spray
will treat from 25 to 40 trees of S-to 6-inch diameter.
A minimum of one fluid ounce of spray solution
per inch diameter of tree should be applied.

HERBICIDES TESTED IN THE CONTROL OF OAKS ANDC

OTHER WOODY SPECIES
Phenoxy-type herbicides
(Available as low-volatile esters or amines)
2.4-D ZA-dichlorophenoxyacetic acid
Z.4.5-T 2,4,5-trichlorophenoxyacetic acid
Combinations of 2.4-D and 2.4.5-T are commonly known
as brushkillers ,
Silvex or 2-(2.4.5-TP) 2-(2.4.5-trichlorophenoxy)propionic acid

2-(2.4-DP) 2-(ZA-dichlorophenoxy)propionic acid
4-(2.4-DB) 4-(Z,4-dichlorophenoxy)butyric acid
4-(MCPB) 4-(2-methyl-4whlorophenoxy)butyric
acid
MCPA 2-methyl-4-chlorophenoxyacetic acid
Other herbicides

Ammate Ammonium sulfamate

Monuron 3-(P-chlorophenyl)-l.l-dimethylurea
Fenuron S-phenyl-Lldimethylurea

2.3.6-TBA 2.3.6-trichlorobenzoic acid

PBA Polychlorobenzoic acid

TABLE 1. PERCENT ROOTKILL OF POST AND BLACKIACK

OAKS OBTAINED FROM WINTER AND SUMMER BASAL

SPRAY APPLICATIONS OF OIL SOLUTIONS OF 2.4.5-T AND
OTHER HERBICIDES, 1952-57

Percent rootkill

Number . Relative
Treatment of tests ($6122; 38:13? rating‘
ber-March) August)
2.4.5-T ester p
8 pounds ahgf 17-17 57.7 44.7 100
16 17-17 65.3 61.3
24 17-17 _ 71.6 67.3
2-(2.4.5-TP) ester
8 pounds ahg 5-3 30.8 22.7 58
16 5-3 56.2 29.3
24 5-3 54.6 20.3
2-(2.4-DP) ester
8 pounds ahg 3-2 34.3 44.0 81
16 3-2 56.3 25.5
24 3-2 60.0 79.5
' 2.3.6-TBA acid
8 pounds ahg 4-3 28.7 26.7 52
16 4-3 31.0 29.7
24 4-3 37.7 36.0

‘Based on 2.4.5-T as standard at all rates.
“ahg means acid equivalent per hundred gallons.

Soil Injection

Rootkills averaging 75 percent or more have been
obtained 0n post oak, blackjack oak, winged elm,
honey locust, and gum elastic by injecting an herbi-
cide solution into the soil at the root collar zone.
Soil fumigant equipment such as a Mack’s Anti Weed
Gun (Model 44AX) may be modified for this pur-
pose (Figure 8). The chemical solution should be
released at a depth of approximately 4 inches below
the soil surface at opposing sides of the root collar.

Oil solutions of 2,4,5-T ester containing 8 pounds
acid equivalent in 100 gallons of diesel fuel or water
solutions containing 6 to 8 pounds active ingredient

“of either monuron or fenuron powder per 100 gal-

Figure 7. Average calendar dates and stages of plant development in East Central Texas for effective control of post
blackjack oak. 

8

lons of water are recommended. Two fluid 
of herbicide solution should be injected for eac,
of trunk diameter on trees up to 8 inches. ‘a

cations of 2,4,5-T ester should be made in s

or early summer when the soil is moist and j
are growing actively (McCully, 1956). Mo,
and fenuron powder probably can be applied a
season.  g

The method is adapted foilftrleatment of ind"
al plants in fence rows and small areas in stands
tively free of underbrush. Costwise, the meth
cheaper than the basal trunk spray method 
duced amounts of herbicide are required. La,
quirements for the two methods are nearly iden;

Stump Spray a

Freshly cut stumps of post oak, blackjack
hickory, winged elm, yaupon and most associated.
cies may be sprayed with oil solutions containin"
pounds acid equivalent of 2,4,5-T ester for eff
control of sprouts (Figure 9). Stump spray r
ment is effective at any season. 

In the East Texas area, post and blackjack
on upland sites may be controlled by application
ammate crystals or water solutions containing 2 
pounds of ammate per gallon to freshly cut stud

This method is most effective when used during

and winter.

When applying solutions of ammate or 2,4,5-Tl

exposed wood and bark of stumps should be

oughly wet to the point of runoff. Ammate c.  4
should be concentrated where bark and wood 
Oil solutions of 2,4,5-T should be applied wi
a few hours after cutting or sawing. For effe
control, ammate crystals or solutions should be;

plied immediately to cut surfaces.

Cost of treatment including labor and chej
ranges from 3 to  cents per stump, depending on,

 

   

“:-
.

Spray
nding trees with diameters exceeding 3 inches
 deadened by applications of an oil spray of
. esters 0r by a water solution of ammate in
 ax frills which completely encircle the trunk
lie l0). Frill treatments should be used in
Qence to basal trunk sprays for trees larger than
6 inches in diameters.

 control of post oak, blackjack oak, hackberry,
lk, ash, elm and many bottomland hardwood
oil solutions should contain l6 pounds of acid
ialent of 2,4,5-T ester in 100 gallons. Effective
i1 may be obtained with dormant season or mid-
d, er frill spray treatment.

  
  
  
  
  
  
   
   
  
   
   
 
  
   
  
  
   
  
  
  
  
   
   
   
   
  
  
  
  
   
  
  
  
   
  
   
   
  
   
  

p} mate solutions containing 1 to 3 pounds of
te per gallon of water may be applied in frill
ip treatment of upland oaks in the East Texas
ZOak Belt. Fall and winter treatments are most

i ve.
j» 0f frill treatment with ammate or 2,4,5-T
l» average 10-inch tree ranges from 3 to 7 cents

I ee.

1k Injection

ldividual trees may be deadened by means of a
 injector such as the Cornell Tree Tool or Little
 Injector. These implements consist of a 11/2-3
ecylinder for herbicidal solution fitted with an
'0n blade and a valve mechanism for release of
lution into the incision.

for control of oaks and most hardwood species,
_s ions containing 1.5 pound acid equivalent of
'15 ester in 41/2 gallons of diesel fuel or kerosene
‘been effective from February to August. During
remainder of the year, a brushkiller mixture of
 and 2,4,5-T esters at 2 pounds acid equivalent
2*“ be used in place of 2,4,5-T ester.

ncisions should be made at intervals of 2 to 4
es apart completely around the trunk base. Ash,
Tory elm, hackberry and other resistant species re-
9e close spacing of incisions. The amount of
ical solution released should be sufficient to soak
incision thoroughly without excess runoff.

iiosts of the tree injection method are compar-
 to those of the frill spray method in terms of
lunt of herbicide and labor required.

‘g8 Spray

oliage spray applications with ground equipment
l be used for the control of young oaks and sprouts
 or more years in age. The volume of spray
tion required for complete coverage generally
ts this practioe sin rangeland brush control to
tered stands of brush not exceeding 6 to 8 feet in
eht.

Livestock sprayers equipped with hand-gun noz-
i or tractor-mounted tank sprayers with boomless
ter-jet nozzles may be used for spraying open
ds of brush. For boomless, swath-type spraying,

Figure 8. Soil injections of oil solutions of 2,4,5-T or
water suspensions of monuron powder placed next to the root
collar will effectively control trees up to 8 inches in diameter.

a minimum volume of 2O gallons per acre is required.
For right-of-way maintenance and clearing in dense
brush, power spray applications at volumes of 6O to
150 or more gallons per acre are used. Dense brush
stands should be wet to the point of runoff and spe-
cial care taken to insure complete coverage.

Ester formulations of 2,4,5-T, 2- (2,4,5-TP) or
silvex, and mixtures of 2,4-D and 2,4,5-T esters, as
well as ammate are generally used in foliage spraying
of oak and other deciduous brush. Silvex is most ef-
fective in post oak stands. 2,4,5-T or brushkiller
mixtures of 2,4-D and 2,4,5-T esters are useful in
mixed brush stands. Ammate at 1 to 2 pounds per gal-

Figure 9. Sawn or cut stumps should be sprayed with oil
solutions of 2,4,5-T ester immediately after cutting to prevent
sprouting.

 

Figure l0. Single ax-frilling and application of oil solu-
tion containing 2,4,5-T ester give effective control of oaks and
other hardwoods. Photo Courtesy of Soil Conservation Service.

lon in water sprays is effective for right-of-way clear-
ing in areas with susceptible crop hazards.

Silvex 2,4,5-T and brushkiller mixtures should
be used at rates of 2 to 4 pounds acid equivalent per
100 gallons of water or in 1O gallons of diesel oil
and 90 gallons of water. June applications of these
three herbicides at College Station during 1953-56
on 4-to 6-foot sprouts ‘have given 4O to 5O percent
rootkill of post oak and 25 to 60 percent rootkill of
blackjack oak (Table 2) .

Effective control can be obtained from applica-
tions made from early May to early July. Spraying
in late summer or during periods of drouth has given
poor results.

Preliminary tests of invert emulsions of 2,4,5-T
ester have given initial defoliation and topkill equiv-
alent to that of standard emulsion sprays. Invert
emulsions are water-in-oil emulsions with ratios of
one part of oil to four or five parts of water. Their
mayonnaise-like consistency requires the use of modi-
fied or special centrifugal disc equipment for appli-
cation.

TABLE 2. PERCENT ROOTKILL FROM FOLIAGE SPRAY
APPLICATIONS MADE IN IUNE WITH 10 PERCENT OIL
EMULSION SPRAYS 'AT 50 TO 100 GALLCNS PER ACRE.

1953-56
Percent rootkill"

Treatment Post oak Blackjack oak
2 pounds ahg‘ 49 44

2.4.5-T ester 49 44

2-(2.4.5-TP) ester 44 28
3 pounds ahg

2.4.5-T ester 39 39

2-(2.4.5-TP) ester 44 25

2.4-D/2.4.5-T esters 46 61
4 pounds ahg

2.4.5-T ester 5O 28

2-(2.4,5-TP) ester 43 27

2.4-D/2.4.5-T esters 46 28

‘ahg means acid equivalent per hundred gallons.

l0

   
   
  
   
  
    
  
  
    
   
   
   
   
 
    
    
   
   

Figure 11. Aerial spraying with 2,4,5-T or silvex l‘
probably the most effective and economical method
control for large acreages.

Herbicides which have proved ineffective o.
economical for foliage spray application on oak r
Texas conditions include: amitrol, 2,3,6-TBA, .-
QA-D ester, ZA-D amine, 2,4,5-T amine, 4- (2,4- p
4- (MCPB) . 2- (ZA-DP) or ZA-D propionic, close‘
lated to silvex, has given excellent control of pos‘
blackjack oaks.

Precautions in the Use of Chemicals

for Brush Control l

Special care should be taken in foliage spr
and aerial applications of 2,4,5-T and silvex t0 i
damage to nearby crops. Injury due to drift;
occur if spraying is done during periods of ap.
able wind movement. Cotton, alfalfa, t0m'
clovers, peanuts, watermelons and other-bran
crops are extremely sensitive to small amounf
these herbicides. Y
Spray equipment for herbicides may be 
used for livestock sprays but should not be use‘
applications of insecticides or fungicides on
vated or ornamental plants. ‘

a:

Applications of hormone-type herbicides
control of oaks and other brush and weeds s
be made in conformity with the Herbicide R‘
tions of the State Department of Agriculturefj
formation on the use of these chemicals may v
tained from your county agricultural agent 0r
the Texas State Department of Agriculture, 
Texas. i j-

Aerial Spraying 

Aerial spray application of herbicides for theff
trol of post and blackjack oaks is adapted to:
treatment of large acreages of upland sites with f“
ing topographic situations (Figure ll). Aeri
plication of herbicides is limited principally by
proximity of broadleaf crops such as cotton;
matoes, peanuts, and other desirable vegetation e

   
   
  
  
  
   
   
 
  
 
  
  
  
  
  
    
  
  
  
  
  
  
  
  
   
  

'  PERCENT ROOTKILL OF POST AND BLACKIACK
PROM SINGLE AERIAL SPRAY APPLICATIONS OF
 2.4.5-T AND SILVEX ESTERS. 1951-57

I m Post oak Blackjack oak

 ~ Number Percent Number Percent
;. of tests kill of tests kill
.5191’
= 8 43.1 6 14.3
13 49.7 6 25.3
20 52.4 15 23.1
18 48.6 12 32.1
20 , 37.4 14 30.9
22 53.9 13 31.6
7 70.1 5 32.6

le to drift from hormone sprays during appli-
(Cw-volatile esters of 2,4,5-T and 2- (2,4,5-TP)
 ex are recommended in a 2-year spray program
ft at a high degree of rootkill and improvement
rage production (Figure 12) . Increasing ef-
eness is obtained with rates up to 4 pounds per
1 Consistently better controls have been obtained
v t oak than on blackjack oak (Table 3).

or relatively pure stands of post and blackjack
‘ as in the Cross Timbers, Central Basin and
_ portion of the East Texas Post Oak Belt,
 applications of 1.25 pounds per acre of silvex
 pounds per acre of 2,4,5-T should be followed
 repeat application 1 or 2 years later con-
jg of 0.75 pound per acre of silvex or 1.0 pound
v acre of 2,4,5-T (Table 4). Rootkills of 65 to 75
 on post oak and 35 to 6O percent of blackjack
" iare obtained with this 2-year program at a total
a $10 to $12 per acre. In relatively pure stands
2st and blackjack oak, silvex may be used to ad-
ge (Figure l3) .
p the main East Texas area, brushy or woodland
,s of post and blackjack oaks with appreciable
illres of winged elm, hickory, red oak, yaupon
j other underbrush should be treated initially

   
 

_ Figure 12. Aerial applications of silvex or 2,4,5-T ester can convert dense stands of oak brush to desirable forage cover
"%-:.-~ to range livestock. Photo Courtesy of Soil Conservation Service.

TABLE 4. PERCENT ROOTKILL OF POST AND BLACKIACK
OAKS FROM REPEATED AERIAL SPRAY APPLICATIONS OF

2,4.5-T AND SILVEX ESTERS. 1952-57

Treatment

pounds 2:112:95 Post oak Blackjack oak
per acre
2,4.5-T ester
1.0 + 1.0 3 51.0 0
1.5 + 0.75 6 64.5 32.7
2.0 + 0.75-1 12 77.5 51.3
Sflvex
1.0 + 0.75 7 60.2 41.0
1.25 + 0.75 8 75.1 37.7

1.5 + 0.75‘ 13 82.4 71.6

with 2,4,5-T ester at 2 pounds per acre and re-treated
the following year with l or more pounds per acre
(Figure 14) .

Volumes of 4 or 5 gallons of spray solution per
acre appear to be adequate for control of post and
blackjack oaks. Emulsions containing one part of
oil to three or four parts of water are generally more
effective than oil solutions. Care should be taken
in the use of emulsions to insure thorough mixing
and emulsification at the time of application.

Applications of 2,4,5-T and silvex esters give best
control when made from early May to early July.
Plants in full leaf in an active growing condition
show the best response to aerial spray application.

The size and character of oak brush may influence
the degree of control obtained. Relatively mature
trees and pole size stands, less than 6 inches in di-
ameter in vigorous growth, show the best response.
Sprout regrowth less than 6 feet in height is readily
controlled with 1.0 to 1.5 pounds per acre of either
silvex or 2,4,5-T. Plants in deep-soil, valley sites
respond better to 2,4,5-T applications than trees or
brush on shallow rocky slopes or ridge crests.

Broadcast Granular Application

Soil surface applications of a pelletized herbicide,
fenuron, are recommended for broadcast or indi-

ll

TABLE 5. PERCENT ‘COMPOSITION OF FORAGE IN 1951
AND 1954 IN WOODLAND AREA PRIOR TO AND 3 YEARS
AFTER OVERSTORY REMOVAL (from Koshi, 1957)

Percent composition

Medium
thinning

Complete
removal

1951 1954 1951 1954 1951 1954

Forage species Undisturbed

Little bluestem 70 66 82 61 81 51
Paspalum and

panicum 10 2O 7 2O 6 3U
Other perennial '

grasses 18 9 10 16 6 l0
Forbs and annual

grasses 2 5 1 3 7 9

vidual tree treatment of post and blackjack oaks.
The method may be used in areas in which proximity
of susceptible crops prohibits the use of hormone-type
spray herbicides. Chemically, fenuron is a substi-
tuted urea herbicide and is available commercially
in pellets containing 25 percent active ingredient
(Figure 15). For broadcast applications, 4 pounds
of active fenuron or a total of 16 pounds of pellets
per acre should be distributed uniformly over the
area to be treated (Darrow and McCully, 1958).

Small areas can be treated effectively by hand
using a common method of broadcasting seed, Cy-
clone seeders or similar devices for scattering seed or
granular materials may be used to secure uniform
distribution in stands relatively free of underbrush.
Scattered trees in fence rows and small areas may
be treated individually by applying 1 to 2 tablespoons
of pellets around the base of each plant.

Agricultural aircraft, equipped with seed or dust
distributors may be used for broadcasting pellets on
large areas (Figure 16). Equipment should be cali-

brated carefully to insure uniform delivery of l6

pounds of pellets per acre over a uniform swath.

Figure l3. Pure stands of post and blackjack oaks (in
the Cross Timbers) show rapid recovery of forage grasses with
control of oak by aerial spray applications of silvex or 2,4,5-T
low-volatile ester.

12

 
 
  
  
   
   
  
   
    
    
   
   
   
  
  
  
  
   
   
   
  
    

Fenuron pellets should be applied between
February and mid-May to insure adequate soil r
ture for maximum uptake by the plant roots. 
effective results are obtained on sandy 0r 
loam soils. Applications should not be mad
places where the herbicide will be absorbed by 
of desirable plants or washed from the area of at
cation by hard flooding rains. fjApplication of?
lets on soil saturated from previous rains shoul,
avoided to minimize leaching and possible sud;
washing. ’

Post oak, blackjack oak and winged elm are ‘
readily by fenuron (Figure 17). Aerial applica,
in April 1956 of 16 pounds per acre of fenuron’
lets gave 80 to 95 percent rootkill of post and j
jack oaks at four out of five locations, as evalu,
in July 1958. Although some variations in effect
ness have been noted with the amount of spg,
moisture received, rate studies conducted in 195
support the recommended rate of 16 pounds of
lets per acre on sandy or medium-textured soils.

Yaupon is intermediate in susceptibility, but
greenbrier and French mulberry usually are
damaged by the recommended treatment.

Deep-rooted desirable perennial grasses such, ~
bluestems, paspalums and gramas are more tole 
of fenuron than short-lived, less desirable fo 
grasses. Marked increases in volume of little bl
stem take place after fenuron treatment in oak si
but the increase in growth is slower than that foll
ing spray application of 2,4,5-T ester. Applicatii
from December to April at rates up to l2 pou
of active fenuron per acre showed little or no red?
tion in forage yield on sites with little bluestem, si
oats grama and brownseed paspalum. Partial con,
of annual grasses and forbs has been obtained if
fenuron treatment (Darrow, McCully, Hughes, 195

 
     
 

Figure 14. Woodland with mixture of post and blackjil
oaks, hickory, winged elm and dense underbrush may be V,
trolled with a 2-year aerial spray program with 2,4,5-T 9-.
at 3 pounds per acre. 

..
I‘

  
   
   
   
  
   
    
  
   
  
   
    
   
   
   
    
 
   
   
  
  
  
   
  
  
 
   
   
    
  

1 ts of Control Measures on
‘itation and Soil Conditions

fVEGETATIONAL COMPOSITION

oval of competing brush vegetation by meth-
ich minimize soil and site disturbance will
rapid improvement in composition and dens-
the forage cover under suitable management.
l infested brush areas in the oak savannah
A en support only scattered stands of the de-
 forage grasses such as little bluestem, pas-
 panicums, and gramas. Overstory removal
lj: soil moisture, light and nutrients to this
cover and results in increased vigor and estab-
‘t of the long-lived perennial grasses. Defer-
iduring the growing season following control
"lent is essential on most areas to permit ade-
l-recovery.

“luations of forage plant response to overstory
l has been made in a mature oak woodland
lrtson county during 1951-54 (Koshi, 1957).
 condition prior to treatment of woody plants
Qted as good. Little bluestem comprised 70 to
ent of the total herbaceous vegetation. Other
lincluded panicums, paspalums, dropseed and
‘stop.

 thinning treatments made by basal spray and
i; treatments reduced the woody overstory from
ltial cover of 65 percent to 39 percent canopy
fie medium-thinned treatment and l8 percent
 on the complete removal. Overstory remov-
iulted in a decrease in the relative amount of
itbluestem as compared to an increase in basal
 nsity of panicums and paspalums equally de-
‘ ' as forage (Table 5).

Vlially sprayed areas show comparable increases
__sity and proportion of desirable grasses follow-
ieatment, provided suitable management prac-
are used. Residual plants of little bluestem,
 grass, dropseed, panicums and paspalums make
itgrowth with removal of brush competition.
p treated by broadcast application of fenuron
i: have shown definite increases in the percent-
» “desirable forage grasses but annual grasses and
j may be killed in the season of treatment. The
'ng effect of fenuron on the short-lived plants
ars by the end of the first growing season
"treatment. In contrast, the 2-year aerial spray
fm with 2,4,5-T or silvex provides weed control
iyears.

GE AND LIVESTOCK PRODUCTION

Fntrol of post and blackjack oaks is important
f uring improved forage and livestock produc-
p the Cross Timbers and East Texas forest areas.
 ample, in Brazos county, clearing a dense stand
pond-growth oak 8 to 30 feet in height resulted
fourfold increase in total density and a thirteen-

TABLE 6. FORAGE YIELDS (POUNDS PER ACRE OF OVEN-

DRY FORAGE) FROM WOODLAND AREAS SUBIECTED TO

PARTIAL AND COMPLETE OVERSTORY REMOVAL (FROM
KOSHI, 1957)

Forage yield

Date Undisturbed Medium thinning Complete removal
1951 (prior to 453 385 545
treatment)
1952 212 419 1168
1953 247 610 1597
1954 209 484 1106

fold increase in total herbage production over a 2-
year period (Young, 1952). In a mature oak wood-
land with a forage cover in good condition, complete
overstory removal resulted in a fivefold to sixfold
increase in total herbage production after 2 years
(Koshi, Darrow and McCully, 1953). Data from
this study (Table 6) show that the fivefold increase
was maintained for a 3-year period (Koshi, 1957).

Complete removal by individual basal and frill
treatments cost $27.23 per acre in this test. By con-
verting 50 percent of the total herbage produced
over the 3-year period to hay valued at $25 per ton,
the increase in forage production from complete re-
moval of woody overstory could be valued at $6.67
per acre. Thus the initial cost of treatment could
be amortized in slightly more than 4 years. Areas
with less initial forage will require careful manage-
ment for a longer period.

Marked gains in livestock production have re-
sulted from the forage improvement from removal
and control operations in the oak savannah type.
Spectacular livestock gains have been obtained on
aerially sprayed areas, for example on the Crownover
Ranch in Montague county. Aerial spray applica-

Figure 15. Fenuron pellets are an easily applied herbicide
for oak control. Pellets may be scattered broadcast at the
rate of 16 pounds per acre or used on individual trees in fence
rows or open stands.

13

Figure 16. Fenuron pellets may be applied aerially in post
and blackjack oak areas aerially during the spring growing
season. Seeding and fertilizing equipment may be modified to
release l6 pounds of pellets per acre.

tion of 2,4,5-T and silvex in research tests conducted
in 1954-55 on 320 acres of this 663-acre tract resulted
in an increase in calf weight of 100 pounds at wean-
ing time and an increase from 34 to 50 mother cows
by 1958. Total feed bills for cottonseed cake supple-
ment were cut in half following the brush clearing
operation.

SOIL jCONDlTlONS

Control methods vary in their effects on soil and
site conditions with the general nature and intensity
of treatment. Chaining, bulldozing and other me-
chanical measures result in soil disturbance and may
cause temporary tillage effects on soil-moisture pene-
tration. Burning in oak woodland may modify mois-
ture infiltration and plant-soil-water relationships by
the temporary removal of litter and ground cover.

“Individual or broadcast applications of herbicides re-

sult in minor disturbance and changes in the physical
characteristics of the soil.

Figure 17. Post and blackjack oak brush to the right of
the stake in the foreground was treated with 16 pounds per
acre of fenuron pellets. "

l4

 

 

Removal or deadening of competing woody i
will release soil moisture and nutrients for the ‘
and herbaceous cover. Woodland areas ‘in w
county subjected to complete removal and me
thinning by Koshi (1959) showed marked differ
in moisture availability to forage plants be ‘
thinned and undisturbed areas. During a 16- y
period, complete overstory rernoiaal reduced the i
od in which moisture was unavailable to plan
the surface 6 inches by 42 days, at the 6 to 121
depth by 24 days, and at the l2 to 24-inch dep 
99 days. Thus, removal of woody overstory incr
the amount of water available for growth by}
herbaceous cover by reduced losses through tra ‘j
ation, particularly in the subsoil layer. i

Soil moisture contents were consistently 
on cleared areas, intermediate in thinned areas
lowest in undisturbed stands (Koshi, 1959).
ferences in physical properties of the soil 2 l
after clearing, such as lower percent of aggreg
and lower capillary pore space in the subsoil 
higher bulk density of the surface soil, could 
been caused by increased trampling of livestock,
tracted to the improved forage and possibly to‘;
duced organic matter incorporated in the soil.

   
 
  
   
  
  
   
  
   
   
  
  
   
  
  
  
   
   
 
  
  
   
   
    
    
    
  

Management of Improved l a
Stands   

GRAZING DEFERMENT

Grazing should be deferred for at least one 
preferably two growing seasons following brush i
trol by either chemical or mechanical metho
order to secure maximum recovery and growth?
residual grasses. Winter utilization by lives
should be moderate to insure adequate recovery.

Livestock tend to congregate on areas cleare
defoliated by various methods. Cattle are attra
to aerially sprayed units shortly after applicatioli
herbicide and tend to utilize forage heavily. 
control operations are carried out on only a p01‘,
of a single pasture, it is advisable to fence off
treated portion temporarily, reduce the rate of st
ing, or remove stock from the entire unit to prep
excessive use by livestock. Wherever possible, _
plete pasture units should be treated at one time
facilitate grazing deferment. i’

1*

z

REMOVAL OF DEAD STANDING TIMB

Oak trees or brush deadened by girdling or ch
cal control measures disintegrate readily and ma
left standing for rapid decay.‘ Broken branches
litter from standing trees furnish a continuing i
ment of organic matter as well as partial protec
of rejuvenated grasses. Deadened brush may;
knocked down easily by bulldozers or by chai“
if cleared pastures are desired. Dead brush she
be left standing for at least 2 years following
application of heribicides to insure the effective:

tion of the chemical. -~

   
   
  
   
  
  
   
   
   
  
  
   
  
  
 
   
   
   
 
  
    
  
   
  
  
   
   
 
  
   
   
   
 
   
  
   
 
  

k SPROU-T CONTROL
tregrowth and underbrush on cleared areas

introlled or maintained by periodic mowing
V‘ mowers, by heavy utilization with goats,
lng, by bulldozing with a light tractor or by
"tting. Goating underbrush areas is prob-
p, .most efficient and economical method of
ntrol in pasture units with suitable fencing
ities for handling.

_ Literature Czted
i R. A. 1956. Aerial applications of herbicides
brush and weed control. In Handbook on
ial Application in Agriculture, Short Course
ice, Texas A8cM College, College Station, Tex-
pp. 97-102.
R. A. 1957. Grass profits from oak removal.
__ . Agric. Prog. 3 (3) : 6-7.
i, R. A. and W. G. McCully. 1958. Pellet ap-
 ations of fenuron for the control of post and
jikjack oaks. Tex. Agric. Expt. Sta. Prog. Re-
h t 2041. 4 pp
‘,'R. A., W. G. McCully and E. E. Hughes.
Q 9. Woody plant and grass response to granu-
i applications of fenuron and chlorinated
zoic acid. Proc. 12th So. Weed Conf. pp.
e-l47.
lhuis, E.  1948. The vegetation of the
estern Cross Timbers. Ecol. Monographs 18:
s76. "
"d, R. E. 1954. Use of hand-applied chemi-
‘j, , sprays alone and in conjunction with pre-
ifbed fire in the control of yaupon and other
ociated hardwood brush species in Southeast
jexas. Texas Forest Service Res. Note no. 9.

. PP-

? P. T. 1957. An evaluation of forage produc-
(n, vegetational composition, tree growth and
vysical characteristics of soils under varying
nsities of oak woodland overstory. Unpubl.
osertation, Texas A. 8c M. College. 116 pp.
P. T. 1959. Soil-moisture trends under vary-
g densities of oak overstory. Southern Forest
 pt. Sta. Occas. Paper 167. 12 pp.

, P. T., R. A. Darrow and W. G. McCully.
954. Forage production in oak woodland as
y luenced by removal of tree cover. Tex. Agric.
pt. Sta. Prog. Rpt. 1661. 4 pp.

i, A. C. 1957. Goats pay for clearing Grand
1 irie rangelands. Tex. Agri. Expt. Sta. Misc.
. bl. 206. 8 pp.

lly, W. G. 1956. Soil injection of herbicides
1 controlling individual brush plants. Tex.
l“, gr. Expt. Sta. Prog. Rpt. 1869. 5 pp

F 1y,W.G. and w. E. McCullough. 195s. Oak
ontrol studies "at the West Cross Timbers Ex-
riment Station. Tex. Agr. Expt. Sta. Prog.
f pt. 1612. 4 pp.

.~D. B. 1958. Use of Angora goats in East Tex-
 for brush control. Sheep and Goat Raisers
i agazine 38 (4): 10-12. Jan. I

Walker, A. H. 1955. More grass from controlling

trees and brush with chemicals. Tex. Agric. Ex-
» tension Serv. Bull. B-800. 6 pp. Revised.

Young, V. A. 'l952. Desirable grasses increase after
post oak control. Tex. Agr. Expt. Sta. Prog. Rpt.
1448. .7 pp.

Acknowledgments

Acknowledgment is given to the large number of‘

ranchmen, county agricultural agents, personnel of
the Production Marketing Administration, Agricul-
tural Stabilization and Conservation Committee and
the Soil Conservation Service, U. S. Department of
Agriculture; custom aerial operators; and students
in the Department of Range and Forestry, Texas
A8cM College assisting in the research tests in chemi-
cal methods of control reported.

Extensive tests of individual plant treatment were
conducted for several years in collaboration with B.
C. Langley, superintendent, and W. E. McCullough,
formerly of the WestCross Timbers Substation.

Aerial spray application tests were made in Bas-
trop, Erath, Jack, Wise, and Young counties in 1952-

1954 and in Clay, Freestone, Jack and Montague

counties in 1954-55 and in Brazos, Burleson and Mad-
ison counties during 1951-57. Aerial applications of
fenuron pellets were made during 1956-58 in Gon-
zales, Bastrop, Brazos, Hopkins, Leon, Limestone,
Palo Pinto, and Wise counties. The financial as-
sistance of cooperating ranchmen in these counties
who made these tests possible is gratefully acknow-
ledged. .

The following chemical companies generously
donated herbicides and other materials for the test-
ing program on individual plant treatment and broad-
cast applications: General Chemical Division, Allied
Chemical 8c Dye Corp.; Amchem Products, Inc.;

Armour 8c Co., Research Division; California Spray-i

Chemical Corp.; Chemagro Corp.; Chipman Chemi-
cal Co.; Diamond Alkali, Organic-Chemicals Division,
Inc.; Dow Chemical Co.; E. I. DuPont de Nemours
8c Co., Grasselli Chemicals Division; Ethyl Corpora-
tion; Geigy Agricultural Chemicals; B. F. Goodrich

Chemical Co.; Heyden-Newport Chemical Co.; Hook--

er Electro Chemical Co.; Hercules Powder Co., Atlas
Division; S. C. Johnson 8c Son, Inc.; Lion Oil Corp.;
Minerals 8c Chemicals Corp. of America; Monsanto
Chemical Co.; National Aluminate Corp.; Nauga-
tuck Chemical Co.; Olin Mathieson Chemical Corp.;
Rohm and Haas Co.; Standard Agricultural Chemi-
cals; Standard Oil Development Co.; Stull Chemical
Co.; Thompson-Hayward Chemical Co.; Union Car-
bide Chemical Corp.; U. S. Borax 8c Chemical Corp.;
and Visco Products, Inc.

The loan of equipment by the Reuel Little Tree
Injector Corp.; McCullough Corporation and [Home-
lite Division of Textron, Inc. and the financial assist-
ance of the Dow Chemical Corporation and E. I
duPont de Nemours 8c Co. are acknowledged.

15

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ment of‘ Agriculture cooperating. Distributed in furtherance of the _Acts of Congress of May 8, 1914, as amended, and June 
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