>1

 

 

 

SUMMARY

Mesquite is an aggressive, deep-rooted, unde-
sirable woody, sprouting shrub that occurs on ap-
proximately 55 million acres of grazing lands in
Texas.

Economical control» of mesquite on grazing
lands depends largely on the selection of methods
that will provide the greatest sustained benefits for
the money expanded. Where mesquite thrives, no
single method or practice will give effective and
economical control under widely varying conditions.
Good range and livestock management are essen-
tial to obtain maximum benefits from the control of
mesquite. The chief value of controlling mesquite
is to increase the density, vigor and production of
palatable range forage species.

Some of the factors that influence the effective-
ness and cost of controlling individual plants, in
thin, open stands by hand or power grubbing, oil-
ing with kerosene and diesel fuel and basal appli-
cation of 2,4,5-T and soil application of monuron are
discussed in this bulletin.

Factors that influence the effectiveness and cost
of controlling moderate to dense stands by chain-
ing and cabling, use of heavy-duty brush cutters,
root plowing and aerial application of 2,4,5-T are
enumerated.

The benefits of mesquite control include in-
clude increased carrying capacity of the grazing
lands, reduced cost of handling livestock and more
efficient use of other range improvement practices.

Reinfestation of grazing lands by mesquite is
aided by the dissemination of large numbers of
viable seed by cattle, horses, sheep and rodents,
the apparent lack of palatibility of mesquite foliage
to most grazing animals and the failure to maintain
a heavy competitive cover of perennial grasses be-
cause of overgrazing, drouth and other factors.

The values of mesquite are limited largely to
utilization of the beans by grazing animals. Some
use also is made of the wood for fuel, fence posts
and a source of roughage for feeding livestock.
Additional uses include gum, preparation of char-
coal and other special products.

THE COVER PICTURE

Figure l. Dense stands of mesquite interfere seriously with the handling of livestock, production of grass and u 1

efficient grazing, and livestock-management practices.

CQNTENTS



Introduction . . . . . . . . . . . . . .   . . . . . . . . . . . 
Description and Distribution. . . . . . . . . . . . . . . ..
Good Range Management ls Essential. . . . 

Methods of Control........................
Thin to Open Stands....................§
Hand or Power Grubbing. . . . . . . . . . . . 
Kerosene, Diesel Fuel and Other Oils. . .1
Basal Application of Z,4,5-T. . . . . . . . . . .. A‘
Basal Application of Monuron and Fenur
Foliage Sprays with Ground Equipment.
Moderate to Dense Stands. . . . . . . . . . . . . ...
Chaining and Cabling. . . . . . . . . . . . . . . 
Heavy-duty Brush Cutters. . . . . . . . . . . . . . g
Root
Aerial Application of Chemicals . . . . . . . 
Effective Chemicals. . . . . . . . . . . . . . . 
Season of Treatment.................:
Moisture and Growing Conditions. . . . T
Rate and Volume of Application. . . . . . ._
Swath 
Type of Growth 
Range Site and Soil Type... .........;
Weed Control and Grazing Habits. . 
Spraying Equipment. . . . . . . . . . . . .
Effects of Repeated Aerial Applicatio ‘E

    
    
   
  
 
   

Benefits of Mesquite Control. . . . . . . . . . . . . . ..
GrazingResults...... 
Benefits of Chemical Control. . . . . . . . . . 
Benefits of Root Plowing and Seeding. . . 
Effects of Shade on Buffalograss. . . . . . . . . i

Reinfestation of Grassland. . . . . . . . . . . . . . . . . g
Seedling Emergence and Survival. . . . . . . .-
Influence of Livestock on Seed Germinati'_
Reinfestation Following Control Practices.

Value of Mesquite.........................'
Precautions on the Use of Z,4,5-T. . . . 
Acknowledgments...........................

LiteratureCited............................

  
    
 
  
   
  
   
 
  
  
  
  
   
    
   
  
  
 
   
  
   
 
  
  
    
    
   

HE INVASION OF MESQUITE, a thorny, sprouting,
woody tree or shrub, has been underway for
years on extensive areas of range and pasture-
' the Southwest. Under most conditions, mes-
' considered to be undesirable on grazing lands.
" tremely aggressive, forming dense jungles of
p. on productive grassland sites, which reduce
I ing capacity of the land. It also seriously
I the management of livestock and the use of
(le range-improvement practices (Figure 1).

,_ 1896, Smith (24) ‘, an agrostologist, stationed
ene, Texas, called attention to the hardy, ag-
e nature of mesquite and predicted the prob-
t» ranchmen face today. Similar observations
ade somewhat later in Texas by Bray 1904
p,“ 1908 (7), and by Griffiths 1904 (18) and
ber I910 (25) in Arizona. Within recent years,
, (2) estimated from surveys made by the Soil
’ ation Service that approximately 55 million
if rangeland in Texas were infested by mes-
f About l5 to 20 million acres of rangelands
ested in New Mexico and Arizona. More than
 the total infestation in Texas is moderate
‘e stands of brush that seriously affect the
,_ tion of forage and livestock. On the remain-
A esquite now occurs in sparse to thin stands

 develop into a serious problem in the
i. Mesquite also often is a noxious pest on
5v croplands, on perennial seeded pastures,
ts-of-ways, along fence rows and around wa-
"facilities.

CRIPTION AND DISTRIBUTION

esquite (Prosopis juliflora) belongs to the Mi-
family (M imosaceae) and is distributed in
i mostly dry, hot areas of United States, Central
A a, West Indies, Peru, Chile, Argentine, Iran, In-
waiian Islands and other countries of similar
, Dayton (9). Three varieties occur in the
l’ States, according to Benson and Darrow  :
mesquite (P. juliflora var. glandulosa) , velvet
"te (P. juliflora var. velutina) and western
(mesquite (P. juliflora var. torreyana) . Honey

p 'vely, formerly Superintendent of Substation N0. 7,
= exas, now superintendent of Substation No. 8, Lub-
q exas; technician, Substation No. 7, Spur, Texas; plant
"‘_ ‘st, Crops Research Division, Agricultural Research
, U. S. Department of Agriculture; assistant agronomist,
'on No. 7, Spur, Texas; associate animal husbandman
j- superintendent of Substation No. 7, Spur, Texas;
(arch agronomist, Crops Research Division, Agricul-
l‘ arch Service, U. S. Department of Agriculture. A

' : in parentheses refer to Literature Cited.

nfrzr/ 0/ Mesquite an wazing (Ta/ads

C. E. Fisher, C. H. Meadors, R. Behrens, E. D. Robinson, P. T. Marion and H. l. Morton*

mesquite occurs for the most part east and northeast
of the Rio Grande in New Mexico and throughout
South and West Texas and extends to the northern
portion of Oklahoma on the north and Louisiana on
the east. Velvet mesquite predominates in Arizona,
extreme western New Mexico, Lower California and
Mexico. Western mesquite is found in California,
southern Nevada, Utah, Western Arizona, southern
New Mexico and parts of Texas (Figure 2).

The three varieties of mesquite may be dis-
tinguished by the size, shape and hairiness of the
leaflets. The leaflets of honey mesquite are long,
linear, glabrous and widely spaced; those of velvet
mesquite are short, hairy and closely spaced; western
mesquite is intermediate between the two extremes.
From one to as many as four crops of flowers or
blooms may occur in succession from late April to
August. The “bean,” or seed pod, contains 5 to 20
seed. Production varies widely from season to sea-
son.

All three varieties vary in growth forms from
large single-trunk trees, 20 to 40 feet tall, to small,
few to many-stemmed shrubs, depending on environ-
mental factors of soil, water, temperature and dis-
turbance by grazing animals and man. Mesquite
grows up to elevations of 4,500 feet, where the av-
erage annual minimum temperature is above -5
degree F. and the frost-free growing season is 200
days or more. It thrives alongdrainage ways in the
desert, where the annual rainfall is less than 6 inches,
and persists on neutral and alkaline soils in areas
where the annual rainfall is more than 30 inches.

Mesquite typically has a tap root with an ex-
tensive lateral root system that enables it to with-
stand drouths, severe competition from perennial
grasses and adverse conditions due to prolonged over-
grazing of rangelands (26). The roots of well-estab-
lished plants may penetrate vertically to depth of 15
to 40 feet and often extend laterally as much as 50
feet from the base of the plant (Figure 3). Never-
theless, McGinnis and Arnold (20) found in southern
Arizona that mesquite is an inefficient user of soil
moisture. They determined that velvet mesquite dur-
ing the summer required four times as much water
as perennial grasses to produce 1 pound of dry matter.
Parker and Martin (22) found in field studies that
elimination of velvet mesquite doubled the yield of
perennial grasses and increased the yield of animal
grasses five fold. '_\

The spread of mesquite on native grassland
within the past 40 to 100 years has taken place so
rapidly that it has become common knowledge among

3

people of the Southwest. Introduction of plants
along the water courses is thought to have been
made first by roving herds of buffalo, later by the
Spanish horses and finally by the extensive move-
ment of cattle during the trail drives. Subsequent
invasion from these localized areas more than likely
was accelerated by fencing and watering, heavier
grazing, lack of repeated burning of grass, rapid
transportation of animals with large numbers of vi-
able seed in their digestive tracts, extended drouths,
and livestock-management. practices (l2) (Figure 4).

GOOD RANGE MANAGEMENT
IS ESSENTIAL

The chief value of controlling mesquite on
grazing lands depends largely on increasing the
density, vigor and production of palatable perennial
forage species. To obtain maximum benefits, treated
or cleared grassland preferably should be deferred
during the summer for 6 months or longer to permit
native or seeded grasses to become firmly established.
Parker and Martin, after careful study in southern
Arizona, stated that no practical management plan
that will completely eliminate the need for direct con-
trol measures is known. Nevertheless, any manage-
ment plan that includes seeding, summer deferment,
water spreading, conservative stocking or other prac-

     

tices that encourage and hasten the developmen
good competitive grass cover likely will help I
the survival of mesquite seedlings.

Following extended drouth when the grass i.
is greatly weakened and serously thinned, timel’
plication of 2,4,5-T (2,4,5-trichlorophenoxyy
acid) will help reduce the survival and establis t’.

of mesquite seedlings and unldiesirable range w
During the early stages of development, mes
seedlings and most range weeds are highly suscep
Failure to control these undes' s
plants when they are most vulnerable may i

to 2,4,5-T.

require the use of far more costly measures.

For full realization of the benefits from a 
quite-control program, consideration needs to be V,
to selection of sites capable of sustaining a 
cover of palatable range grasses and the managl’
of grazing on these sites to obtain maximum pr
tion. Failure to manage grazing properly on tr?
or cleared areas may result in little or no imp‘-
ment. In fact, under poor grazing management
removal of mesquite may lead to the destructi
the few remaining grass plants that were notfl
cessible easily to grazing animals. The adageti
takes grass to make grass,” should be kept in 

at all times.

i p    cow tmn uue u,’
\ ' \ | -..'
NEV‘ " p\ "TA" coto. "w," KAN.

 

    

I

_ onsraueuruou- I954

o
n - w.» m - u . . - mm-aweui w aqua-i

Figure 2. Generalized map showing the distribution of mesquite in the Southwest. The northern limit of mesquite w .
pears to follow closely the average annual minimum temperature isotherm oi -5 degree F.

s.

   
   
   
   
  
  
   
   
 
  
   
  
 
   
   
   
  
  
  
   
    
    
   
   
  
  
   
 
   
 
  
    
  
  

METHODS OF CONTROL

; e chief problem facing ranchmen is the se-
 of brush-control measures that will provide
Qfeatest sustained benefits for the money ex-
l}?- No single method that will give effective
‘iionomical control of mesquite under all con-
’.- has been developed. In the early stages of
tion, hand or power grubbing may be used to
 te isolated plants and sparse stands at low
ZBut, after extensive areas become heavily in-
{with well-established stands and large num-
 seedlings with seed in the soil, repeated use
(‘=01 measures usually is necessary for the great-
itained benefits.

 ce mesquite is able to persist under an ex-
, Wide range of conditions, some of the more
l; ant factors that should be given consideration
 ting a method of control are: (1) density
tds; (2) stage and rate of infestation; 
b) forms, whether trees are many-stemmed or
 unked; (4) benefits that may be realized in
f the soils, moisture conditions and potential
tivity of land; (5) size of the area to be treated
the capital available; (6) the presence of other
fable woody plants; and (7) the likelihood of
f, of the control measures to livestock, grass
and nearby crops (Figure 5).

‘search has shown that mesquite trees and
 may be killed by mechanical or chemical
ifs which destroy the top and all the dormant
I  buds on the root crown and underground
l3). These buds are small, wart-like structures
§ithe bark that produce new growth if the top
 is killed (Figure 6). The bud zone of mes-
i it extend from less than 2 inches below the
, face- to depths of l2 inches or more on old,
s; ees. Usually the depth of these buds is great-
isbottomlands and on sites where soils tend to
 late around the base of the plants. Repeated
l of the topwood usually increases the diffi-
 killing mesquite since it greatly increases the
own area and the number of dormant buds
i al stems per plant, Fisher (ll) .

l) e methods of control reported in this bulle-
 based on experimental results obtained by
exas Agricultural Experiment Station at Spur
 1939-56 and at 39 off-station locations in co-
ion with ranchmen (Figure 7). Research
yuring 1948-56 was conducted in cooperation
e Crops Research Division, Agricultural Re-
Service, U. S. Department of Agriculture.

  Thin tojiQpen Stands

Qesquite trees, shrubs and seedlings in widely
ed stands may be controlled effectively and
gtically by the treatment of individual plants
A the early stages of infestation. Some of the

g used successfully to control stands of 50 to
ants per acre are described in this bulletin.

Figure 3. Root system of mesquite showing long lateral
roots extending 20 to 50 feet from the base of the plant.

Hand or Power Grubbing

Control of invading stands of mesquite seedlings
may be obtained at relatively low cost by hand grub-
bing. The sprout buds on seedlings are shallow and
plants can be destroyed by grubbing below the lowest
sprout buds, usually 3 to 4 inches below ground
level.

For the control of extensive areas of thin, open
stands of mesquite trees andshrubs, power-grubbing
equipment offers an effective and economical means

Figure 4. The large mesquite tree in the foreground
typifies the initial infestation of native grassland prior
to the advent of the grazing industry. The secondary
stage of infestation became noticeable soon after the
land was fenced and watered and utilization of grass
was intensified.

Figure 5. Six typical growth forms of mesquite. The growth forms vary with moisture conditions. soil type. low 
peratures in the northern areas and man's activities that influence the above-ground growth. (A) Trees in 
stands. (B) Shrub-type invading grassland. (C) Many-stemmed shrubs in dense stands. (D) Trees intermingle
with mixed brush. (E) Running mesquite growing on a deep, sandy soil. (F) Many-stemmed shrubs on a 

dune site.

  
   
   
   
   
   
  
   
  
  
  
  
   
 
  
   
   
  
  
  
  
  
 
 
   
 
   
  
   
    
   
  
  
 
   
   
 
  

root the plants well below the lowest dormant
 buds. A crawler-type tractor with a front-
ted “stinger” blade will do a satisfactory job
_ts of $3.00 to $7.50 per acre on stands up to 75
fper acre (Figure 8). The cost of power grub-
gmay be minimized by using the equipment for
g ing roads, tanks, spreader dams and clearing land
 ltivation. Other factors that will influence the
pf grubbing include the type of soil, such as
_ iclay, mixed land or sand, the moisture content
(Ye soil and the type of growth.

i, he chief advantages of grubbing are that the
t: are actually uprooted, leaving small soil ba-
and dead brush on the land to aid the estab-
_ gent of grass seedlings. For dense stands, grub-
costs usually are prohibitive, many small plants
(dissed and a high percentage of the grass cover
 troyed. The serious disturbance of the soil
encourages heavy growth of undesirable weeds
fQmay persist for several years until a good cover
Tss becomes reestablished.

(fine. Diesel Fuel and Other Oils

hin stands of single to few-stemmed trees grow-
n porous, gravelly and rocky soils may be killed
atively low cost throughout the year when the
e soil is dry by pouring 1 pint to 2 quarts of
ine or diesel fuel around the base of the tree
le 1). The killing action of the oils depends
 movement through the bark and making phys-
ontact with the sprout buds around the base
 tree (Figure 9) . Therefore, enough oil should
 to wet the bark and soil thoroughly to the
 sprout buds on the underground stem. Re-
it studies have shown that more oil is needed
jtain effective kills of mesquite growing on wet,
 ious clays, when the shrubs are many-stemmed,
yon lowlands or other sites where soil has ac-
lated around the base of the plants. For the
ol of moderate to dense stands, the cost of this
0d usually is prohibitive.

"The kill of brushy mesquite may be improved
fly with a considerable saving of oil if the top-
f; and lateral stems are cut back to the stump
i, to oiling. The percentage kill obtained by
i’; will range from 60 to 90, depending on the
ughness of application. Usually retreatment will
cessary within 3 to 5 years to control sprout
h of plants that were missed or not treated
irly.
kerosene and diesel fuel, whichever is cheapest
 ost readily availaibrle, may be used interchange-
i For control of-faxfew trees and shrubs along
 rows, use of a mixture containing 50 percent
fl fuel or kerosene and used crank case oil may
 the cost of treatment. The total cost of oiling
fee usually is 4 to 6 cents per tree. The chief
itages of oiling are the readily available supply

Figure 6. Sections of mesquite cut at ground level and
below the lowest dormant buds. These buds must be
destroyed to prevent sprout growth. The tree on the
right grew on upland and its lowest dormant buds were
6 inches below ground level. The tree on the left grew
on bottomland. where silting occurred, and the lowest
dormant buds were 12 inches below ground level.

of oils and the minimum amount of equipment re-
quired.

Basal Application of Z,4.5-T

Under conditions where oil alone is too expen-
sive and the use of other methods is not feasible, good
control of heavier stands, 50 to 125 trees and shrubs
per acre, may be obtained by basal applications of
2,4,5-T. (Figure 10). The addition of 2,4,5-T ester

Figure 7. Generalized map showing the distribution of
mesquite in Texas and the location oi cooperative ranch
tests tor the evaluation oi control practices.

Figure 8. Above-Thin open stands oi large mesquite
trees may be controlled on extensive areas by power
grubbing with a “stinger" attachment at moderate cost.
Below—Recovery oi grass in soil basins aiter the re-

moval oi mesquite. For dense stands, the cost is pro-
hibitive and the soil disturbance results in heavy rein-
iestation oi undesirable weeds.

to light oils, such as kerosene 0r diesel, improves the
percentage top kill of mesquite when limited amounts‘
of oils are used. The lower 8 to 12 inches of the
basal stems and root crown area should be sprayed
thoroughly until runoff is heavy with an oil solu-
tion containing 8 pounds acid of 2,4,5-T ester or 2
gallons of 2,4,5-T, ‘l-pound acid formulation, per 100
gallons of diesel fuel or kerosene. One gallon of
this solution will treat 10 to 15 moderate-size trees
at a cost of 2 to 3 cents per tree for material. Similar

Figure 9. The application oi kerosene or diesel Y
should be made around the base oi the plant in -
iicient amounts to wet the bark to the depth oi the i
est dormant buds. This method oi control has been 
eiiectively to treat open stands oi single-stemmed tr;
growing on porous. rocky or gravelly soils. ‘

    
   
 
 
 
 
    
   
   
   
   
 
 
 
   
  
   
 

treatment of stumps also has been effective.  
to 5-gallon knapsack sprayer fitted with a nozzle!“
delivers a coarse spray is suitable for basal applica

This treatment will give excellent kills of.
growth and root kills of 20 to 80 percent, depe 
on the size of trees, growth forms, nature of thef:
and thoroughness of application. Usually thef
centage of root kill obtained may be improve
using larger amounts of spray solution around;-
base of the plants. Increasing the amount of 2,4
acid above 8 pounds per 100 gallons seldom impi
kills. Applications are almost equally effective’
any season of the year; however, retreatment wil
needed at intervals of 3 to 5 years to control seedl;
and sprout growth. 

Basal Application oi Monuron and Fenuron U

Highly effective kills of mesquite also ma
obtained by spraying a narrow band of soil .g
the base of trees and shrubs with a suspension ‘
taining 1 pound of monuron, (3-(P-dichlorophon
1, 1 dimethylurea) , in l0 gallons of water. Ten t
trees of average size may be treated at a cost t
to 4 cents per tree with 1 gallon of the suspens
Since monuron will not dissolve in water, the?‘
pension must be agitated frequently to keep '
chemical from settling to the bottom of the s
can. Since the killing action of monuron is du

TABLE 1. EFFECT OF BASAL APPLICATIONS 01-" CHEMICALS AND OILS ON PERCENTAGE KILL or MESQUITE AND 
or MATERIALS t

 

  

Per 100 trees .

. Amount used . Percent ,

Chemical per 100 gallons Dfluent kill Volume used. Co 

gallons mat,
Monuron l0 lb. Water 42 l0
Monuron Z0 lb. Water 64 l0
Fenuron 1U lb. Water l6 . l0
Fenuron 20 lb. Water 38 l0
Diesel iuel 73 27
1% 2,4,5-T 2 gal. Diesel iuel 4O l0

8

 

A l0. Above-Basal application of 2.4.5-T in diesel
 is effective when the lower 6 to 12 inches of the
 and all basal plant parts are saturated thoroughly.
—Basal application of 2.4.5-T or oils is not highly
 'cal for the control of brushy. many-stemmed mes-

y. tion of the herbicide by the roots of mesquite,
 soil texture and organic matter influence
Lesults obtained. It may take 2 0r more years
 e trees t0 die after treatment. This chemical
 not be used t0 treat mesquite if roots of orna-
 shrubs or other valuable plants are in the
Pelleted formulations of monuron containing
rcent active ingredient also have given good
fol when the material was applied around the
20f each plant at rates of 20 to 30 grams, or ap-
fately 2 to 3 tablespoons, per tree. Fenuron,
tituted urea closely similar to monuron, was
effective for the control of mesquite in these

y.

e Sprays with éijround Equipment

mall trees, sprout growth and seedlings often
be controlled effectively by application of
 ing sprays of herbicides to leaves, stems and
 plant parts with power sprayers. A suitable
solution consists of 1 pound of 2,4,5-T acid

     
 
   
  
    
    
  
    
  
    
  
  
 

equivalent or silvex (2-(2,4,5-trichlorophenoxy) pro-
pionic acid) of a low volatile ester in 50 gallons of
water. The spray solution should be applied in
coarse droplets at low pressure to wet the leaves and
stems of plants thoroughly. Some agitation usually
is needed to prevent the herbicide from settling out.
For most effective results the application should be
made 4O to 90 days after the first leaves appear in
the spring. The amount of spray solution required,
20 to 125 gallons per acre, depends largely on the
number and size of plants and the density of foliage.
Retreatment usually will be necessary within S to 5
years.

The use of boom-type sprayers to control mes-
quite generally has not been very effective. How-
ever, the application of 1 pound of 2,4,5-T acid

Figure ll. Above-Chaining offers a cheap means of
knocking down and thinning out heavy stands of mes-
quite. It is most effective for the control of large, single-
stemmed trees. Below—l year after the area was dou-
ble chained. Less than 5 percent of the plants were
destroyed. Within 3 to 5 years, more effective measures
will be required to control sprout growth.

 
 
  
  
 
 
  
 
 
 
  
  
 
  
  
 
 
 
 
  
 
 
 
 
  
  
 
 
  
 
 
 
 
  
 
 
  

equivalent in l0 to 15 gallons of water per. .1
the control of undesirable weeds also will s
mesquite seedlings and small sprout growth};
cautions should be taken to avoid spray n;
susceptible crops. 

Moderate to Dense Stands 

Experience has shown that extensive i‘
moderate to dense stands of ‘inesquite on ra 
pasture-land may be brought under control
ably by the use of large-scale treatments. Ch 
aerial application of chemicals, root plowi 
chopping with heavy-duty brush cutters are “
that have been developed to control brush 
prove the productivity of rangeland underia,
range of plant and soil conditions. Some of 
tors that influence the general effectiveness, 7
benefits and overall cost of these large-scale
ments are discussed in this bulletin. 

Chaining and Cabling  

This treatment consists of dragging a hea, 
anchor chain or cable 300 to 400 feet long in
behind two large crawler-type tractors (Figu
In most instances, a chain is preferred to 
because it is more flexible and hugs the grou J
ter owing to the rolling motion that tends to f’,
chain of uprooted trees and brush. 

The greatest value of chaining is the low
cost of knocking down and thinning out heavy i
of mesquite trees to increase grass production if
reduce the cost of working livestock. “Double p,
ing,” covering the area twice in opposite dirt”
will break off nearly all the above-ground gro 
brushy mesquite and may uproot l0 to 30 i
of the large trees when the moisture content

Figure 12. Above—Heavy-duty brush cutter weighing Soils is Hilativfily high- _
14,000 pounds used to crush and chop mixed brush. _ _ 
Below-Rotary shredder used to cut underbrush. Chemi- Chalnlflg generally offers Only IeIIIPOTHYY
cals are not effective for the control of mixed brush. fits for 3 to 5 years, the period depending ti;

Courtesy E. L. Caldwell Manufacturing Co., Corpus
Christi. Texas. '

TABLE 2. EFFECT OF ROOT PLOWING ON CONTROL OF MESQUITE AND NATIVE GRASS COVER AT SEVEN LOCK,

I.
a

thorou hness of the treatment, otential rodu‘
8 P P 

NEAR SPUR
£33229; Percent 
Location Treatment Grctxzslglgnd plants grass cover
v P91’ awe’ Buffalo Tobosa Others
1956

Spur [Plowed 1947 Tobosa-Buffalo 261 10 60 5

None . - Tobosa-Buffalo 500 25 60 5
Guthrie Plowed 1948 Tobosa-Buffalo 508 10 10 10

None Tobosa-Buffalo 1200 90 I 10 10
Kalgary Plowed 1948 Tobosa-Buffalo 857 30 5 T

None . Tobosa-Buffalo 1089 25 5 T 1
Clairemont Plowed 1948 Tobosa-Buffalo 290 15 5 T

None ~ Tobosa-Buffalo 500 _ 15 70 T
Gilpin Plowed 1950 Buffalo-Aristida 363 5 T 20

None Buifalo-Aristida 1000 15 T 20
Spur Plowed 1950 Tobosa-Buffalo 116 10 30 T

None Tobosa-Buffalo 1423 30 35 T
Crosbyton Plowed 1952 Buffalo-Aristida 131 15 O T 5

None Buffalo-Aristida 248 5 T 5
Average Plowed 361 14 16 6

None 851 21 26 6

l0

uflisite and moisture conditions. Follow-up treat-
“isuch as aerial applications of chemicals, root
g or power grubbing, will be necessary to con-
rout growth from plants that were broken off
 nd level and seedling mesquite. The contract
 chaining varies from‘3,£1.50 to $5.00 per acre,
ing on the type of growth and density of brush,
the area to be treated and the topography of
p? d. Properly used chaining, in combination
‘Zther methods, may provide maximum benefits
" money expended on large areas of land with
 moderate potential productivity.

-duty Brush Cutters

, ious types of equipment, including large cut-
eighing 2,000 to 14,000 pounds, have been
ped to chop and crush brush and trees of mod-
ize (Figure l2). Brush cutters have been used
ilfully to treat areas where mesquite is inter-
 with other brush species which cannot be
flled by chaining or chemicals, or where other
i" of control are not feasible. In much of the
-brush area of South Texas, on land with low
iterate potential productivity, heavy-duty cutters
ten used effectively for controlling brush. The
 cost of the treatment is $5 to $10 per acre.
‘tment usually will be necessary at intervals of
i0 years, depending on the productivity of the
nd the rainfall. For control of sprout growth
p, pastures, annual cutting with a light-weight
 cutter or shredder has considerable merit.
 owing

"he brush plow, or root cutter, was developed
 for clearing brush-infested land for crop

iaiml- M9“? recentlY it 3159 has be@n 11551 Figure 13. Above—Heavy-duty brush plow with fins on
'vely [Q Qgntrgl dgnge Stands 0f Inggquitg and the gutting blgdle thatGhelp Illiit roplts ofbundrerllarush cu;
z y - o t e soi. eow— iant eavy uty rus pow use

brush 9n ranggland’ Expermn“: has Shm/Yn on the King Ranch. These plows are equipped with
OOt PlOWIIIg has b€€n IIIOSt successful and prof1t- seeders that utilize the exhaust to plant grass seed at

the time of plowing. Courtesy of the Holt Manufactur-
ing Company, San Antonio, Texas, and the King Ranch,

 badly depleted range sites that have deep,

I soils with ample moisture to justify the cost Kingsvme, Texas.

re 14. An area of mixed brush la_nd in South Texas that has been root-plowed and seeded with a mixture of bui-
, and blue panic grasses. The grazing capacity of the brush land under favorable conditions has been increased
 4 iold. Courtesy of the Soil Conservation Service.

ll

   
  
  
  
   
   
     
  
   
  
   
   
  
    
   
    

of plowing and establishing highly productive native
and introduced grasses.

The cost of root plowing and seeding varies from
$8 to $25 per acre or higher, depending on the extent
of the operation, type and size of brush, nature of
the soil and the kind and amount of grass seed used
and the success in establishing stands. Generally,
this operation is too expensive to control brush on
extensive areas of rangeland of low to moderate po-
tential productivity. This is especially true where
the establishment of desirable range grasses by seed-
ing has not been successful.

The root plow commonly used is mounted on
a heavy-duty, crawler-type tractor which pulls an
8 to 10-foot V-shaped cutting blade 10 to 18 inches
below the soil surface. By cutting mesquite below
the bud zone and severing the roots of other woody
plants, sprouting is prevented, except where lateral

ling reinfestation.

12

Figure 15. Left—Aerial application of Z,4.5-T in 1950. This method has been used to control mesquite on approxi-
mately 2,500,000 acres of grazing land in Texas. Right-The same area in 1954. l

Figure 16. Working cattle in mesquite that had been sprayed by airplane with 2.4.5-T during the preceding year. ‘If
To be most beneficial. this method should be repeated at intervals of 5 to 7 years to control sprout growth and seed- “ ‘

roots of the smaller plants are not broken loose fr
the soil. The use of 3 to 5 fins, 20 to 30 inches l‘
mounted at a 28-degree angle on the cutting 

helps break up the surface soil and destroys many?
the plants that might otherwise survive. 

On the Rolling Plains, experimental brush-c
trol studies conducted by the Spur station, in  .
operation with ranchmen, since 1947, on tobosa- '
falo type grassland have shown that root plow’
without fins on the cutting blades destroyed 
95 percent of moderate to dense stands of mesqu c
However, extremely heavy stands of sunflower (H
anthus annus) , Russian thistle (Salsola kali var. tel‘
folia) and other undesirable weeds developed on  
root-plowed areas soon after treatment and persist
on the land for several years. Results obtained
seven locations indicated that root plowing o;
without seeding had not materially improved 

  
  
  
   
   
 
  
   
   
   
  
    
  
  
  

pctivity of the rangeland because of heavy dam-
} existing grass cover and rapid reinfestation by
ilyite sprouts and seedlings (Table 2).

vurther studies were undertaken in 1953 t0 de-
_ e the value of root plowing and seeding prom-
lgnative and introduced range grasses on mod-
i productive tobosa-buffalo type grassland.
stan bluestem (Andropogon isclzacinzlni) , (Jau-
_ bluestem (Andropogon intermedius, variety
iius), several strains of sideoats grama (Boate-
iiurtipendula) , blue grama (B. gracilisq, buffalo-
T(Buchl0e dactyloidos) and weeping lovegrass
i’ ostic curvula) were seeded on root-plowed land
 as then disced to destroy a heavy turf of tobosa
Liria mutica). Good stands of all grasses were
led with both methods of seedbed preparation;
er, 3 years later stands of seeded grasses were
rious disadvantage where the tobosa grass was
estroyed after root-plowing. Results of grazing
ron both seeded and comparable unseeded pas-
are reported under “Benefits of Control” in
Vulletin.

in the Rio Grande Plain of South Texas, a
'nation of root plowing and seeding buffelgrass

(Pennisetum cilarie) and blue panic (Panicum anti-
dotale) holds excellent promise of greatly increasing
the productivity of badly depleted rangelands heavily
infested by mixed brush, (1,6) . The principal woody
species besides mesquite are blackbrush (Acacia
amciztacca), huisache (Acacia farnesiaiva), granjeno
(Ccltis pallida) , whitebrush (Lippia ligustriarza),
guaycarl (Porleria (mgtzstifolia), lote (Corzrlalia ob-
tmifrJia) , cactus (Ojnmtia spp.), cenizo (Leucoplzyl-
[um fruicsccfns) and paloverdes (Ccrcidium spp.).

Early work on the King Ranch and other ranches
in SouthTexas showed that root plowing alone usu-
ally was unsatisfactory because of relatively poor kills
of white brush, lote and other understory brush
plants; failure of native grasses to become reestab-
lished; and rapid reinfestation by brush seedlings.
M/ithin recent years, however, experience by ranch-
men and range technicians of the Soil Conserva-
tion Service in extensive trials indicates that most
of the undesirable features of root plowing may
be overcome. The use of fins on the cutting blade
of the root plow was effective in destroying a very
high percentage of undesirable, shallow-rooted woody

.,

TABLE 3. SUMMARY OF RANCH TESTS. 1949-56

    
   
   
  
   
   
 

- Date re-
Date Soil Type of Plant Moisture   Nature oi Weed treat-
treated type growth condition condition Top Rootl regrowth control ment
needed

5/29/49 Clay loam Small trees Good Good 98 45 Sparse Exc. 1956
5/24/50 Clay loam Small trees Good Fair 98 19 M. rapid Good 1954
6/2/51 Clay loam Small trees Good Fair 98 18 Moderate Good 1955
5/27/52 Clay loam Small trees Fair Fair 98 10 Moderate Fair 1956
5/ 27/ 53 Clay loam Small trees Good Dry 98 18 Moderate Fair 1957
5/ 29/ 54 Clay loam Small trees Good Fair 98 36 Sparse Good 1958
5/31/55 Clay loam Small trees Good Fair 98 69 Sparse Good 1962
5/24/56 Clay loam Small trees Fair Dry 98 17 Moderate Fair 1960
5/ 22/ 50 Sandy loam Small trees Good Fair 98 31 Sparse Good 1956
6/ 14/51 Sandy loam Small trees Good Fair 98 26 Sparse Good 1957
6/ 12/52 Sandy loam Small trees Fair Fair 98 20 Sparse Good 1953
6/ 12/53 Sandy loam Small trees Good Dry 95 27 Sparse Fair 1960
5/ 7/ 54 Sandy loam Small trees Good Fair 98 49 Sparse Fair 1962
6/7/55 Sandy loam Small trees Good Fair 98 23 Sparse Fair 1962
 6/ 1 6/ 56 Sandy loam Small trees Fair Dry 98 31 Sparse Fair 1963
i‘- v- an. 3/31/50 Sandy loam Med. trees Fair Dry 75 30 Moderate Good 1954
 a1 6/12/51 Sandy loam Small trees Good Fair 98 40 Sparse Fair 1956
an Angelo 5/ l 1/ 50 Clay loam Med. trees Good Fair 98 37 Sparse Fair 1954
 Odessa 5/ 13/50 Clay loam Small trees Good Good 98 45 Sparse Good 1953
1 Albany 5/ 15/50 Clay loam Large trees Good Fair 95 5 Moderate Good 1954
M. Gail 5/ 18/50 Clay loam Small trees Fair Fair 85 5 M. rapid Good 1954
 Paducah 5/29/50 Clay loam Med. trees Fair Fair 98 5 M. rapid Good 1954
v eg, Vemqn 5/ 31 / 50 Clay loam Med. trees Good Good 98 21 Moderate Good 1955
an. Dean 6/ 31/ 50 Sandy loam Small trees Good Good 98 65 Sparse Exc. 1956
'. Henrietta 6/ 5/ 50 Clay loam Large trees Good Good 98 ll Moderate Good 1955
l» 6/ 5/ 50 Clay loam Small trees Good Good 98 86 Sparse Good 1955
~ endon 6/ 8/ 50 Clay loam Med. trees Good Fair 98 17 Moderate Good 1954
~cino 5/ 7/ 51 Fine sand Med. trees Good Good 98 90 Sparse Exc. 1958
y " orias 5/ 8/ 51 Fine sand Large trees Good Good 98 45 Sparse Good 1956
I‘ orias 5/ 8/ 51 Fine sand Sprouts Good Good 98 95 Sparse Exc. 1960
I; '1'ilden 6/ 8/ 51 Clay loam Med. trees Good Good 98 40 Sparse Good 1958
Pi a Pryor 6/11/51 Clay loam Med. trees Good Fair 98 15 Moderate Fair 1956
 aria 6/‘22751 Clay loam Small trees Fair Fair 98 l0 Moderate Fair 1956
2' Sonora 7/‘1-0/51 Clay loam Med. trees Fair v.dry 98 5 M. rapid Fair 1954
1 uthrie 5/ 27/ 50 Clay loam Med. trees Good Good 98 23 Moderate Exc. 1954
- uthrie 5/ 27/ 51 Clay loam Small trees Good Fair 98 l0 Moderate Exc. 1954
_ thrie 5/ 27/ 53 Clay loam Med. trees Good Fair 98 20 Rapid Good 1958

- . Sparse
 - thrie 6/ 8/ 54 Clay loam Sprouts Fair Fair 90 l0 M. rapid Good 1958
. uthrie 6/ 7/ 56 Clay loam Med. trees Good Fair 98 31 Sparse Good 1962

 

f“ qe kill 1s

w

  

months after treatment.

l3

20-

PERCENT DRY WEIGHT OF
TOTAL AVAILABLE CARBOHYDRATES
5

3 , Spring growth Period folioqo
period s sprays effective

3n ans 4/1 4/l5 5/1 5/15 on 6/l5 1/: "ms an ans
SAMPLING DATE

Figure 17. Average total available carbohydrate content
oi mesquite root tissues at biweekly intervals during
1953-56. Aerial application oi 2.4.5-T has been most ei-
iective from May 20 to Iuly 15, when the carbohydrate
content of the roots is being replenished rapidly.

plants (Figure 13). By seeding 1 to 2 pounds
each of buffelgrass and blue panicum with special
equipment mounted on the root plow, a quick com-
petitive cover helped to prevent rapid reinfestation
by brush seedlings (Figure l4). It has been esti-
mated conservatively that the carrying capacity of
the badly depleted brushland was increased 2 to 4
fold or more during the first few years after the root
plowing and seeding operations were completed.

Some control of brush seedlings likely will be
necessary, depending on the early establishment of
a vigorous grass cover, management of the treated
area and seasonal rainfall. The chief advantage of
the root plowing and seeding operation is the rather
complete destruction of nearly all existing undesir-
able kinds of brush and the resultant greatly in-
creased carrying capacity of badly depleted range-
land. It is an excellent practice where the estab-

»- lishment of grass cover is successful and the potential

productivity of the land is sufficiently great to sus-
tain heavy production of grass forage.

The high initial cost of the operation, the lack
of knowledge of productivity and longevity of buffel-
grass and blue panic stands under a wide range of
conditions and the degree of success in obtaining
satisfactory stands are factors that should be consid-
ered in choosing this method of control. Failure to
obtain stands of grasses because of unfavorable rain-

TABLE 4. SUMMARY OF OBSERVATION ON THE EFFECT
OF SOIL MOISTURE AND FOLIAGE COVER ON PERCENT-
AGE KILL OF MESQUITE

Soil moisture Percent km

Foliage

Prior to Following cover

leafing out leaiing out Tops Roots
Deficient Deficient Sparse 50-90 Trace
Deficient Intermittent Variable 70-98 Tr. to l5
Deficient Adequate Normal 90-98 20 to 40
Adequate Normal Heavy 95-98 40 to 98
Adequate Below normal Normal 95-98 60 to 98

14

   
  
  
  
  
  
   
    
 
  
   
   
  
   
  
  
   
  
     
  
    
  
   
  
  
   
  
  
  
   
   
 
    
  

fall, poor soil conditions and other causes fol ~
the initial seeding often results in a serious
problem that may persist on the land for many l
This is not a serious consideration on land that ' 
able for crop production. On marginal crop
however, failure to obtain stands of perennial v
tion may bring about serious wind and water e]
and noxious weed infestation that have little i,
grazing value. Once established, weeds greatl
crease the difficulty of establishing a cover of 
on the land. In most instances, the control of v
infestations soon after emergence will increase
chances of obtaining satisfactory stands of g
grasses. 

Aerial Application of Chemicals

Extensive trials since 1949 have shown that _
control of moderate to dense stands of mesquite?
be obtained at low cost by aerial application of 2,
(16). This method lends itself to treatment:
tensive areas of grassland with low to moderate;
ductivity where it is desirable to obtain max'
amount of brush control for the money expe
(Figure l5, 16). Repeated applications at int
of 5 to 7 years will be needed under most condi
to control mesquite effectively (Table 
application of herbicides also provides an eff
and economical means of controlling sprout i?
seedlings and undesirable weeds following th-
of mechanical treatments. Herbicides have not Y=
effective for the control of mixed brush.

The chemicals used to control mesquite are,
toxic to livestock and grass plants, but are haz A
to use near fields of cotton and other suscei
broadleaf crops. The effectiveness of the che;
treatment is governed largely by the environm
factors that influence the growth of mesquite 
Some of the factors that should be consideredi é
chemical treatment of mesquite are discussed fo;
ing. i
Effective Chemicals. Experimental studies *
ducted cooperatively with ranchmen at various,
tions throughout the mesquite area of Texas}
shown that low-volatile esters of 2,4,5-T are '_
effective for the control of mesquite under a"-
range of conditions and are much less hazard
use than 2,4-D (2,4-dichlorophenoxyacetic acid)’
combinations of 2,4-D and 2,4,5-T. Other che
tested were special formulations of 2,4,5-T, inc
water and oil soluble amines, (2 (2,4-dichlorof
oxy) propionic acid), MCPA (2 methyl-4-c
phenoxy acetic acid), MCPB (4-(2-methyl-4-c
phenoxy) butryic acid), amitrol (3 amino-1,2,
azole) , 2,3,6 TBA (2,3,6 trichloro benzoic acid).
many other closely related systemic chemicals. ‘a

Aerial application of monuron and fenur“
spray solutions and in pellet forms at rates up t
pounds of active ingredient per acre in 1955-56 y
to give effective control of mesquite. These ma '

 5. HERBICIDAL SOLUTIONS FOR THE CONTROL

RMAL GROWTH OF MESQUITE WITH 1/3 POUND

EQUIVALENT APPLIED AT A 3-GALLON RATE PER

ACRE
Gallons

5e Amount of

(4 lgelrgilgdzguiv. Diesel fuel Water Total

per gal.)

2/3 pt. .5 2.50 s

1-1/3 pt. 1.0 5.00 6
i" 1 qt. 1.5 7.25 9
 1 qt. 2/3 pt. 2.0 9.75 12
é! 1 qt. 1-1/3 pt 2.5 12.25 15

2 qt. 3.0 14.50 18

2 qt. 2/3 pt. 3.5 17.00 21

’2 qt. l-l/3 pt. 4.0 19.50 24
 3 qt. 4.5 21.75 27
 .3 qt. 2/3 pt. 5.0 24.25 30
. l gal. 2 qt. 1-1/3 pt. 10.0 48.50 60

2 gal. 2 qt. 15.0 72.50 90

3 gal. 1 qt. 2/3 pt. 20.0 96.75 120

4 gal. 1-1/3 pt. 25.0 121.00 150

5 gal. 30.0 145.00 180

fibeen effective for mesquite only when applied
 applications.

 he low-volatile ester formulations of 2,4,5-T
fbeen more satisfactory than amine salt or sus-
‘I acid formulations. The following esters ap-
f: to be approximately equal in effectiveness
‘d tests: butoxy ethanol ester, propylene glycol
‘ther ester, iso-octyl ester and butoxy ethoxy pro-
I ester. The use of high-volatile esters is con-

 unsafe because of the possibilities of herbi-

iidrift of vapors from the treated areas that might

I  sensitive crops.

 ason of Treatment. The stage of growth of
Mite is one of the most important factors in-
‘ing the effectiveness of growth regulators ap-
A to the foliage. Experimental applications at
‘ intervals from early spring to late fall, together
field trials, have shown that most effective kills

TABLE 6. CALIBRATION TABLE FOR THE CONTROL OF
NORMAL GROWTH OF MESQUITE USING SWATH WIDTH

OF 60 FEET
Gallons
of
232%?‘ of Lzsrgctttllilof iggtcxil: Acres in solution
miles I feet l swath swath per swath

(at 3 gal.

per acre)
.1 528 31.680 .727 2.18
.2 1.056 63.360 1.454 4.36
.3 1.584 95.040 2.181 6.54
.4 2.112 126.720 2.909 8.73
.5 2.640 158.400 ~ 3.636 10.91
.6 3.168 190.080 4.363 13.09
.7 3.696 221.760 5.090 15.27
.8 4.224 ' 253.440 5.818 17.45
.9 4.752 285.120 6.545 19.64
1.0 5.280 316.800 7.272 21.82
2.0 10.560 633.600 14.545 43.64
3.0 15.840 950.400 21.818 65.45

have been obtained 50 to 80 days after the first leaves
appeared in the spring. Good results may be ob-
tained during unusually early warm seasons by spray-
ing mesquite l0 to 15 days after the leaves are fully
formed and start turning from the characteristic light
green to dark green. The optimum date for treat-
ment of mequite at Spur has been approximately 65
days after the first leaves appear. Applications be-
fore the leaves have developed in the spring or during
summer and fall after mesquite has ceased active
growth usually give only partial kills of above-ground
stems and twigs.

Since it is known that lmaximum transport of
ZA-D and 2,4,5-T takes place when the plants are
actively growing and storing food (8), studies were
undertaken in 1950 to determine when the root re-
serves reached a low point and the approximate time
a rapid buildup of reserves might occur. Analyses
of root samples collected at monthly and later at
bi-weekly intervals during 1950-56 showed that the
low point of root reserves occurs when mesquite is

ure 18. Left—Bottom1and pastures at the Spur station that was heavily infested with mesquite prior to treatment

 1947. Right-The same area after mesquite had been brought under control. runoff water utilized by means of
 er spreaders and stocking rate adjusted to utilize 50 percent of the forage production. A combination of these
actices conservatively increased the grazing capacity two to four fold by 1954.

15

TABLE 7. CALIBRATION TABLE FOR THE CONTROL OF
DENSE REGROWTH OF MESQUITE AND HEAVY WEED IN-
FESTATION USING A SWATH WIDTH OF 42 FEET

Gallpns
Length oi Length of Square . ° .
swath, swath, feet in Acres“? soluumgh
miles feet swath SW“ I?“ swa
at 4 gal.
per acre)

.1 528 22.176 .509 2.04

.2 1,056 44,352 1.018 4.07

.3 1.584 66.528 1.527 6.11

.4 2.112 88.704 2.036 8.14

.5 2 .640 110.880 2.545 10.18

.6 3.168 133.056 3.055 12.22
.7 3 .696 155.232 3.564 14.26

.8 4,224 177,408 4.073 16.29

.9 4,752 199.584 4.582 18.33
1.0 5,280 221,760 5.091 20.36
2.0 10,560 443,520 10.182 40.73
3.0 15.840 665.280 15.273 61.09

leafing out and completing early-spring growth (Fig-
ure l7). Thereafter rapid replenishment of root
reserves follows, provided soil moisture and other
environmental factors are favorable. At this stage
of growth, aerial applications of 2,4,5-T have been
most effective.

Moisture and Growing Conditions. During the
spray season, the effectiveness of 2,4,5-T and other
growth regulator chemicals depends largely on factors
that influence the growth of mesquite. Experience
shows that good control of mesquite has been ob-
tained generally when moisture was adequate to sup-
port normal development of foliage in the spring
(Table 4).

The influence of soil moisture and plant con-
dition on percentage root kill of mesquite is indicated
strongly from results obtained in 33 ranch tests during
1949-56. In nine cases when soil moisture conditions
were considered to be good at the time of aerial

TABLE 8. HERBICIDAL SOLUTIONS FOR THE CONTROL

OF DENSE REGROWTH OF MESQUITE AND HEAVY WEED

INFESTATIONS USING l/z-POUND ACID EQUIVALENT AP-
PLIED AT A 4-GALLON RATE PER ACRE

Gallons

Acreage Amount of

to be herbicides D- H l W t T l
treated (4 1h acid equi“ iese ue a er ota

per gal.)

1 1 pt. 1 2.88 4
2 1 qt. 2 5.75 - 8
3 1 qt. 1 pt. 3 8.63 12
4 2 qt. 4 11.5 16
5 2 qt. 1 pt 5 14.38 20
6 3 qt. 6 18.25 24
7 3 qt. 1 pt 7 20.13 28
8 1 gal. 8 23.00 32
9 1 gal. 1 pt 9 25.88 36
10 1 gal. 1 qt. 10 28.75 40
20 2 gal. 2 qt. 20 57.50 80
30 3 gal. 3 qt. 30 86.25 120
40 5 gal. 40 115.00 160
50 6 gal. 1 qt. 50 143.75 200
60 7 gal. 2 qt. 60 172.50 240

  
 
  
  
  
 
  
  
  
 
 
 
 
 
 
 
  
  
 
  
 
  
   
 
 
 
  
  
  
 
   
  
 
  
 
 
  
  
 
 
 
 
  
  
  
  
 
  
   
 
  
 
  

application of 2,4,5-T, the root kill of mesquite v,‘
from 11 to 95 percent and averaged 60 percent. i.
der less favorable conditions in 18 cases when‘
moisture was considered to be fair, the perce t.
root kill varied from 5 to 69 percent for an av
of 24 percent. l-Vhen the soil was considered d-
the time of application in six cases, the root t;
varied from 5 to 31 percent for; an average of 21 *
cent. When plant condition fiyas considered t
good at the time of application, an average root ki
39 percent was obtained in 25 cases. When if
condition was considered to be fair, the average v
kill was only 15 percent in nine cases. i

If the growth and development of foliage}
affected seriously by drouth or leaf insects, of
intermittent showers stimulate new growth, spra
should be delayed until moisture conditions bee?
more favorable in later years. Unusually good '
trol of mesquite has been obtained at several
tions by spray treatments applied in wet years’-
lowing drouth years. .

Rate and Volume of Application. The am_
of chemical used in extensive aerial tests ranged n
l/6 to 2-2/ 3 pounds acid of a low-volatile este
2,4,5-T per acre on different growth forms of g‘
quite. These varying rates of chemical were ap
in 2, 4, 8 and in a few instances, 12 gallons oft
water emulsions and diesel fuel per acre. 
carriers tested included water alone, oil-water e,
sions containing in proportions of 1:8, 1:6, 1:4 5'
1:1 diesel oil, naptha, kerosene, low and high p11
toxic oils and many other materials.

Results of these studies show that the ori
or natural growth of mesquite was controlled i
effectively and economically by the applicatio 1
1 / 3 pound acid in 3 gallons of 1:6 diesel fuel- _
emulsion per acre (Tables 5, 6). Increasing
amount of chemical or the volume of the spray _,
terial did not improve the effectiveness of the
ment under a wide range of conditions.

Sprout growth of mesquite was controlled
fectively with chemicals when the above-gr
growth reached a height of 3 to 4 feet or more i
ure 18). In most instances, best results were 0b
ed by the use of l/2 pound acid of a low-vol,
ester of 2,4,5-T or silvex in 4 gallons of a 1:3 v.
fuel-water emulsion per acre (Tables 7, 8). T
ment of small sprout growth less than 3 feet
usually was much less effective because of an’
parent lack of balance between the above-gr
growth and that of a well-established root sys
Control of running mesquite, a decumbent gr, '
form, appeared unsatisfactory in limited trials.

Swath Width. Tests were conducted at six 
tions during 1954-56 to determine the influen ' g
swath width on the effectiveness of chemical n;
ment of mesquite. A Stearman biplane equi
with a 27-foot boom and 14 low-pressure nozzles;

s.

   
 
   
   
  
    
   
  
   
    
  
   
  
   
 
  
   
  
  
  
   
   
  
  
  
    
  
  
  
   
   

l/3, l/2 and l pound acid of 2,4,5-T
.2, 54, 67 and 84-foot swaths. The results ob-
‘Show that, for natural or original growth of
e, swath widths of 60 to 84 feet gave just as
ntrol as the 30 to 42-foot swaths (Table 9).

“U
“E.
~<

a treatment of dense sprout growth 3 to 4
l, the 42-foot swath width appeared to be
pat more effective than the 60 and 80-foot
but further study is needed.’ ln these tests,
jtions were made with cross winds of 3 to 7
3- hour. Under downwind or no wind con-
, experience has shown that a swath width
et usually tends to give more uniform control.

 of Growth. Extensive trials have been
ed on various growth forms of mesquite.
ilants and seedlings have been destroyed ef-
 by chemical treatment. Good to excellent
fof mesquite brush with stems up to 4 inches
eter also l1as been obtained when moisture
:nt conditions were reasonably favorable. For
p‘ of large trees with trunks 6 to 18 inches in
‘If, good top kills with some root kills have
btained only under the most favorable con-
 Under average soil and plant conditions,
y when the trees lacked vigor and had con-
e dead top wood, chemical treatments usu-
F- fair top kills but little or no root kill. A
Option of mechanical methods that will destroy
Jhpercentage of the old trees followed several
ter by chemical treatment of sprout growth
j instances have given good control at low cost.

f‘ ge Site and Soil Type. Throughout nearly
the test areas, noticeably more effective con-
; mesquite has been obtained on light sandy
i“ upland sites. In cooperative ranch tests in
, the average percentage root kill of mesquite
; on clay and clay loam soils was 24 percent.
j l3 cases where mesquite occurred on fine
jams and fine sands, an average root kill of
jnt was obtained. In most instances on bot-
ti} sites with moderate to heavy clays, top kills
‘iftisfactory; however, heavy regrowth usually
J- at the base of the plant, indicating little
movement of chemical below the soil line.
ply, it is thought that mesquite is more diffi-
kill on bottomlands because the trees tend
Erger and the dormant buds are buried deeper
,he soil line. A swath width of less than 42
heavier rates of chemical did not improve the
ness of the treatment.

i‘ ed Control and Grazing Habits. Under fa-
F growing ccmditions, seedlings and young
0f annual broomweed (Gutierrezia dracun cu-
 cockleburs (Xanthium spp.) , sunflowers
‘thus annus) , Russian thistle (Salsola kali var.
la), lambs quarters (Chenopodiom alba) , an-
joton (Croton spp.) and many other annual
af plants are controlled satisfactorily by aerial

treatment of mesquite with l/3 to 1/2 pound acid
of 2,4,5-T per acre. The chemical treatment becomes
less effective as weeds approach maturity.

The grasses on land that has been sprayed with
2,4,5-T to control mesquite, almost without exception,
are heavily utilized by livestock even though there
may be large areas of untreated land available to
the grazing animals. It is thought that the greater
amount of sunlight and moisture made available to
the grasses following treatment of mesquite is pri-
marily responsible for this grazing preference. Some
chemical changes probably occur in the composition
of the grass plants, but no definite information has
been obtained on‘ this subject.

To obtain greatest benefit from the use of chem-
icals for the control of mesquite and undesirable
weeds, careful consideration should be given to the
selection of seasons and sites. Following extended
drouths, the grass cover usually becomes thin and,
therefore, mesquite seedlings and other undesirable
plants can gain a foothold. Timing the chemical
treatments when rainfall becomes favorable to help
eliminate these invading plants will greatly speed
up the recovery of native grasses on the range.

Spraying Equipment. Research work on the
effect of droplet size of the spray solution delivered by
aerial equipment has been conducted under field and
laboratory conditions. These tests showed that equip-
ment which delivered a major portion of the droplets
within a range of 100 to 400 microns is most satis-

factory for the control of mesquite. The use of drop-

lets of less than 100 microns increased the danger of

TABLE 9. EFFECT OF AERIAL SWATH WIDTH AND VARI-
OUS RATES OF 2.4.5-T ON PERCENTAGE KILL OF MES-
QUITE AT SIX LOCATIONS, 1954-57

Swath Volume. gal. Percent
width, Pourfds Oi 2'4'5'T 1:3 emulsion root
feet acld per acre per acre kill‘
30 i 1/4 5.59 31
30 1/2 5.59 34
30 3/4 5.59 30
30 l 5.59 34
42 1/4 4.00 33
42 1/2 4.00 31
42 3/4 \ 4.00 34
42 1 4.00 32
54 1/4 3.10 31
54 1/2 3.10 35
54 3/4 3.10 33
54 1 3.10 29
67 1/4 2.54 31
B7 1/2 2.54 31
67 3/4 2.54 31
67 1 2.54 33
84 1/4 2.00 33
84 1/2 2.00 40
84 3/4 2.00 31
84 1 2.00 33

‘Percentage root kill 15 months or longer after treatment.

17

spray drift, whereas droplets above 400 microns
tended to give inadequate coverage of the foliage.

For best results, only experienced operators with
approved equipment should be employed to apply
these chemicals. The height of flight, nearness of
susceptible crops, wind direction and velocity, con-
dition of the plants to be treated and many other
related factors must be taken into consideration by

the operator for the greatest benefit and safety to 1

the landowner.

The cost of aerial ‘chemical treatment of mes-
quite varies from 32 to $3 per acre depending on
such factors as the amount of chemical applied, swath
width used, the size of the area to be treated and the
distance to the landing field.

Effects of Repeated Aerial Applications. Early
experimental tests with 2,4,5-T under a wide range
of climatic and environmental conditions showed
that in nearly all instances excellent top kills were
obtained, but that root kills varied from 5 to 95
percent. Even though root kills, in many cases, were
low because of unfavorable plant conditions and other
factors, in every instance there was insufficient sprout
growth to permit retreatment within a period of less
than 3 years after the initial treatment. In cases
where root kills of 30 to 50 percent were obtained,
sprout growth rarely was large enough to permit
retreatment within 4 to 7 years. Where kills above
50 percent were obtained, retreatment at intervals
of 8 to 10 years couldbe expected to give good to
excellent control of mesquite.

Results of aerial retreatment tests conducted at
Spur and Guthrie are shown in Table l0. The av-
erage kill obtained from one application varied from
l0 to 29 percent under a wide range of conditions;
however, retreatment 3 to 5 years later increased the
average kill from 19 percent for the initial treatment

TABLE 10. EFFECT OF REPEATED AERIAL APPLICATIONS
OF 2.4.5-T ON THE ROOT KILL OF MESQUITE

Retreatment

Initial treatment
Height of
D-t- 212st‘ fszrzzi:   Ffiffifil
I SPUR
1949 Small trees 21 1952 24-26 34
1949 Small trees 29 1954 36-48 58
1950 Small trees l0 1953 24-36 24
1950 Small trees 10 1954 36-48 39
1951 Small trees 16 1953 24-36 49
1951 Small trees 16 1954 36-48 57
GUTHRIE
1950 Small trees l0 1953 36-48 42
1950 Medium trees 17 1953 36-48 32
1950 Small trees 27 1954 36-48 38
1950 Small trees 31 1955 36-60 54
1950 Small trees 26 1955 36-60 32
1951 Small trees 20 1956 36-60 47
1953 Medium trees l0 1957 36-60 30
Average percent kill 19 41

18

  
  
 
 
  
 
  
  
  
 
 
 
 
 
 
  
  
 
  
 
 
  
  
 
  
 
 
 
 
  
 
  
  
 
 
  
 
 
  
 
 
  
  
 
  
  
  

to 4-1 percent for two treatments. These results t
cate that, under favorable conditions, repeat i
cations of 2,4,5-T will gradually bring mesquite u
control at relatively low cost. ‘

BENEFITS OF MESQUITE CONTRO i

The chief benefits realized from the contro
mesquite on rangeland include a marked reducg
in cost of handling and caririg for livestock, ani
crease in the ‘carrying capacity of the land, red ‘
hazards of death losses from mesquite bean poiso”
and the use of other sound range and livestock n;
agement practices that often are not feasible i
tures heavily infested with brush (Figure 18). ~
extent of the benefits derived from the control:
mesquite will depend largely on the degree and t
of infestation, the potential productivity of the 
and the condition of desirable range vegetation 
management. ‘

Grazing Results

Benefits oi Chemical Control

Grazing trials with yearling steers were conducf
at the Spur station in the summers during 1945-54
eight 20-acre native pastures that originally had m
erate stand of brushy mesquite. In 1945, two upl
and two bottomland sites were cleared of mesq
by removing the top wood and treating the stu t‘
Later, the sprout growth and seedling mesquite w
controlled at intervals of 5 years by aerial appl
tion of 2,4,5-T. On four closely adjoining pastu“
two on upland and two on bottomland, compara
stands of brush received no treatment. The past 
were stocked on the average from May 1 to Octo
3 at a moderate rate of 6.50 acres per head for
annual grazing period of 156 days. s‘

Grazing trials for the 10-year period show
average steer gain of 204 pounds for the cleared r»
tures and 173 pounds for the brush pastures (Fi i
19), a difference of 31 pounds per head in favor?
the cleared pastures (Table ll). During the f‘
sons of 1948, 1952 and 1953, acre-gains on cle .
pastures were 42, 53 and 35 percent higher, res,
tively, than on the pastures infested with mesqu‘
The average gain of yearling steers was lowest, l-
pounds per head, on upland sites infested with t,
quite, and highest, 224 pounds per head, on bott
land sites where mesquite was controlled (Figure _
For the overall period of study, the annual acre-I
was increased an average of 18 percent by the c,
trol of mesquite. This increase was worth $1 t;
acre where yearling steers were valued at 20 ce
per pound. Reynolds and Tschirley (23) estima;
that, under normal conditions in Arizona, the c‘
trol of mesquite would give a three-fold increase -r
grazing capacity. g

In addition to the increased returns obtai ’
by the control of mesquite, it was estimated that I

 19. Cleared and mesquite-infested pastures used in the grazing trials. Control of mesquite increased steer
 an average of 31 pounds per head annually during 1945-54.

‘fequired for working and handling livestock
cleared pastures was less than one-fourth that
111 to work cattle on the brush pastures. The
Yon the cleared pastures tended to be more
‘Land those on the brush pastures usually be-
ore difficult to handle as the season progressed.
1'01 Root Plowing and Seeding

 area of upland native grassland of moderate
151 productivity, with. a fair cover of tobosa,
i, sideoats grama grasses, vine mesquite and a
‘Rte stand of mesquite, was divided into two
fipastures in 1953. One pasture was root-plowed

A lied during March. Good stands of Causasian

11 King ranch bluestem, several strains of side-
 a, buffalo, blue grama and mixtures of these
éwere obtained on the seeded pasture. This
g was not grazed during 1953-54; however, a
 crop was harvested during the fall of 1954.
g er 10-acre pasture, which previously had been
 with power equipment, was treated with

Y!»

_. .1
*5‘
e

‘cl-l. SUMMARY OF GRAZING TRIALS WITH YEAR-
RS DURING THE SUMMER ON CLEARED AND
JNFESTED PASTURES, FOR THE IO-YEAR PE-

RIOD. 1945-54

Aver- Number
_ age Acres oi days Average gain. pounds
 number per grazed
Qf head P91’ Steer Daily Acre
steers p season

0.0 0.0 154 104 1.19 22.75
 0.0 0.0 154 140 .90 11.92
5.0-;  150 224 1.41 44.24
y» and 1.0 5.0 150 190 1.25 00.40
11 0.5 0.5 150 204 1.00 00.50

'10 0.5 0.5 15s 170 1.10 20.10

2,4,5-T to control mesquite sprout growth and seed-
lings. This pasture was grazed during the period
the grasses were becoming established on the seeded
pasture. ‘

Grazing trials with yearling steers were begun
on both pastures in the spring of 1955. Results of
these trials with yearling steers during the summers
of 1953-58 are shown in Table l2. For the 11-year
period, 1955-58, when the reseeded pasture was ready
to be grazed, gains of yearling steers averaged 196
pounds per head, compared with 157 pounds per
head for steers on native grass cleared of mesquite.
The acre-gains also were higher on the root-plowed
and reseeded pasture. For the 6 years, 1953-57, how-
ever, there was no advantage for the pasture that was
root-plowed and seeded over the native grass pasture
cleared of mesquite.

If the seeded grasses continue to maintain satis-
factory stands and vigor under moderate grazing, a
distinct advantage should develop in favor of re-
seeded pastures over a period of years. It would be
expected that on land with high potential produc-
tivity, greater benefits likely would be realized from

    

   
  

      

           

225 - 224 - 6°
E Steer gain ' E-
‘é 200 .. E Acre qoin I98 * _ 5O 8
j i z
:1 z =-

o 104 .._ = _ g
a. = i i ‘a 0 1  a.
9 = i .0 _ 9
< = uni w ..... .7 4
Q i i j .:.:.:. (9
K —- -_ i»: " i 1111111 m
w I50 _ I48 z  -—  _ 3° n:
m .1 "- '''''''  O
1;, = —' I;I~I-f .3 <
125 __ -; :§:§:§; .... §:§:§:j _ 20
100 ' = "it! 15:1: =  I0

   

UPLD um. 0 0011014041110 001101414100
0110511 01.2mm anusn 01.541250

Figure 20. Influence of mesquite control on steer and
acre gain during 1945-56 at Spur on upland and bot-
tomland pastures. Bottomland pastures have produced
approximately twice as much beef gain per acre as
closely adioining upland pastures.

19

root plowing and reseeding to adapted, palatable
range grasses. Experience has shown that on land
with low potential productivity, forage production
is too low and unstable to justify the use of this prac-
tice.

The cost of root plowing, seeding and spraying
annually with 2,4,5-T to control undesirable weeds
and seedling mesquite was $20 per acre, whereas the
cost of controlling mesquite with a treedozer followed
by one basal application of 2,4,5-T to control sprouts
and seedlings was $10 per acre. The cost of these
treatments must be considered to be relative since
the cost will vary with the size of the area to be
treated, type and density of brush, cost of estab-
lishing a good stand of grass, nature of the land and
need for subsequent weed and brush-control measures.

Effect oi Shade on Buifalograss

Experimental studies were undertaken in 1938
to determine the influence of different amounts of
shade on buffalograss. Special lath cages were con-
structed to simulate no shade, light shade, moderate
shade, heavy shade and dense shade by mesquite
(Figure 21) . The plots were clipped during the late
spring, summer and fall to determine the yield and
nutritive content of the forage. Basal density of the
buffalograss was estimated each spring soon after
it began growth.

The yield of Buffalograss when grown in full
sunlight and different amounts of shade for the 6-year
period of study, 1939-44, is shown in Table 13. The
data indicate that the yield of buffalograss grown in
light to moderate amounts of shade was not ma-
terially affected, but that it was seriously reduced
by heavy and dense shade. Increasing the shade
tended to increase the protein content of the forage.

" This increase, however, appeared to be associated

with an increase in crude-fiber content and a decrease
in nitrogen-free extract (Table 14). Determinations
also showed that the moisture content of the forage
increased and grass leaves tended to become elongated

 
   
 
   
    
  
 
    
    
  
  
    
   
   
   
   
    
   
  
 

with increasing amounts of shade. » Observati
dicated that the elongated leaves were much t‘,
to break during certain seasons of the year tha i
grown in light shade or full sunlight. The.
cover of buffalograss for all plots averaged 6“
cent in 1939, when the studies were begun. Six‘
later, the basal cover declined to 52, 40, 29, l
0 percent, respectively, for buffalograss grown i
sunlight, light, moderate, heavy/"land dense sha

These results indicate that small amour
artificial shade did not materially affect the i
nutritive content and basal cover of buffal‘
Under conditions of natural shade, the addedj
petition for soil moisture and plant food by m i
undoubtedly reduces the productivity of the ,
especially where moderate to dense stands of i’
prevail, as shown by Parker and Martin worki=l
Arizona. i

REINFESTATION OF GRASSLA ;

It is common knowledge among ranchmeni
farmers that effective control of well-established .~ ’
of mesquite on grazing lands depends on 
ing a high percentage of the existing plants 1
prevention of rapid reinfestation from se_
the soil and those brought in by grazing an'
rodents, wind, water and by sprout growth of 
that were not destroyed. - '

Seedling Emergence and Surviv,

Research conducted at Spur during l!
showed that heavy emergence of mesquite see
might occur within 1 to 3 years following cont
well-established stands of mesquite, especially If
soil and grass cover were seriously disturbed. '
an area of tobosa-buffalo type grassland pro ‘
from grazing animals for 15 years, 871 seedli ,'
a total of 2,952 per acre that emerged withi
months after 237 trees and small mesquite had,
removed by hand grubbing, became well establ

TABLE 12. SUMMARY OF GRAZING TRIALS ON ROOT-PLOWED AND RESEEDED PASTURE AND ON A NATIVE A
PASTURE CLEARED OP‘ MESQUITE. 1954-58 '

  

Average gain. pounds

 
 
 

Average annu -_

pounds '3
Treatment ' Item g g f
1959 1954 1955 195s 1957 195s  .-
Root plowed, Steer gain 0‘ 01 275 142 263 139 195
seeded Acre gain 0 0 68 43 53 42 51
Daily gain 0 0 1.56 1.45 1.43 .84 1.29
Native grass. Steer gain 123’ 117’ 253 94 196 115 157
control of Acre gain 16 17 62 28 39 34 41
mesquite Daily gain 1.41 .94 1.43 .96 1.06 .69 1.03
Date grazed 4/28-8/31 4/28-9/1 5/10-11/4 4/24-9/4 5/1-11/1 4/29-10/10
Number o1 days 87 125 177 132 184 165 152
Rate of grazing, acres per head 7.68 10.00 4.07 3.33 5.00 3.33 3.82

‘Not grazed in 1953-54.

‘Data from comparable native grass pasture.

20

   
  
  
   
 
    
 
  
  
   
  
 
 
   
  
   
  
  
   
  
    
   
   
   
   
 
 

 s 22, 23). The heaviest mortality of the
 p gs occurred soon after emergence. A gradual
lillOfl of only l6 percent in seedling numbers
glace during the next 12 years. The growth of
gngs, however, was greatly restricted by severe
tition of a heavy cover of grasses consisting pri-
 of tobosa, buffalo, vine mesquite and traces
piers. Timely application of 2,4,5-T, together
A 1e competition of grasses, might have prevented
rvival of a majority of the seedlings. The sur-
f seedlings that emerged in later years averaged

 2O plants per acre annually. The heavy

~19
.1

énce of mesquite seedlings in 1941 undoubtedly
pifluenced by the prolonged drouth from 1933
i0, which greatly reduced the basal cover of
 ial grasses. Attempts to destroy well-estab-
tmesquite seedlings by burning a heavy cover
gsa and buffalo grasses during the early spring
 mmer failed to destroy an appreciable number
3Y1 seedlings during a 2-year period of study.

ince oi Livestock on Seed Germination

ceding trials were undertaken in 1940 to deter-
fthe influence of mastication and digestion by
‘m classes of animals on the germination of
 ite seed. It was found that 97, 79 and l6
t of a total of 745 sound beans fed in pods‘
f} through the digestive tracts of horses, yearlings,
land ewes, respectively, during a period of 158
 The greatest number of seed was expelled
‘f animals 42 to 60 hours after feeding. Germi-
 of seed that had passed through the animals
 82 percent for the horses, 69 percent for
' fyearlings and 25 percent for ewes. For seed
  pods and not fed to the animals, germination
 ply 26 percent, whereas germination of seed re-
i mechanically from the woody capsules that
 the seed was 86 percent. The longevity of
‘Finder range conditions is not known; however,
 certain conditions bean weevils (Mimosestes
 and (Bruchus prosopis) often destroy a high
tage of the embryos of many mature seed.
 insects that commonly attack mesquite include
thead wood borer (Buprestidae spp.) , the twig
t (Oncideres trinodatus) and the measuring
1,19 member of the Geomatridae family. A fun-
Ganoderma zonatum) also attacks the basal
ivparts under some conditions.

Figure 21. Bufialograss grown under heavy shade was
taller, higher in moisture and protein and crude fiber
contents. but lower in carbohydrates during the first 3
years of study. For the 6-year period of study, however.
the average yield dropped from 1,235 pounds for grass
produced in full sunlight to only 191 pounds for grass
grown under heavy artificial shade.

Reiniestation Following Control Practices

To obtain information on the influence of re-
infestation by seed in the soil and those brought in
by rodents, birds and coyotes, a 160-acre experimen-
tal pasture was cleared of mesquite by hand grubbing.
The pasture was grazed during the summers of 1940-
56 by cattle which did not have access to mesquite
beans for at least 10 days prior to the beginning of
the grazing season. In 1940, when the land was
grubbed, there was an average of 213 trees per acre.
Five years later, 109 seedlings per acre had reached
grub-hoe size, 18 to 24 inches tall, and were removed.
In 1952, 185 additional seedlings per acre were re-
moved from the land. Thus, since the initial clear-
ing, 294 seedling mesquite per acre were removed
during an ll-year period in addition to the original
213 trees. Observations in 1957 showed that 50 to
75 additional seedlings had become established and
will need to be removed to prevent seed production.
It is not known how long seedlings will continue to

 19. INFLUENCE 0F DIFFERENT AMOUNTS 0F SHADE ON THE YIELD. POUNDS PER ACRE, 0F AIR-DRY BUFFALO-
  GRASS, 1999-44

 spl-afgg  " 1999 1940 1941 1942 1949 1944 Average
None 109 574 2599 1909 1910 590 1295
4-inch 259 714 299s 1924 1920 702 1952
949911 a 904 ~ 919 2929 1909 1999 570 1270
2-inch 994 990 1952 295 994 74 s50
149911 299 994 499 0 0 0 191

21

TABLE 14. INFLUENOE OF DIFFERENT AMOUNTS OF
SHADE ON THE PERCENTAGE NUTRITIVE COMPOSITION
OF BUFFALOGRASS. OVEN-DRY BASIS. 1939-41

Nutrient Full sun Light M31121“ Heavy Dense
Protein 8.85 9.50 9.47 10.53 12.62
Crude fat 2.13 2.11 2.19 2.37 1.97
Crude fiber 26.42 26.46 28.16 28.05 27.04
N.F.E. 49.54 49.52 47.76 46.21 41.14
Ash 13.06 12.52 12.41 12.84 20.44
Ca° .64 .67 .57 .64 .72
P205 .44 .54 , .53 .55 .67

emerge on the land, but likely the land will never
reach the point of being completely free of mesquite
under grazing conditions.

Additional studies, in cooperation with ranch-
men, have shown that land that was hand-grubbed
to remove a moderate stand of mesquite had an av-
erage of 668 mesquite seedlings 3 to 4 feet tall per
acre 14 years later. Eight years after moderate to
dense stands of mesquite, averaging 851 plants per
acre, were controlled by root plowing at seven loca-
tions, an average of 361 seedlings, 3 to 5 feet tall, per

Figure 22. Above-Reinfestation of ungrazed native
grassland by seedling mesquite 2 Years after the area
was cleared of all mesquite plants. Fifteen years later,
871 of these seedlings survived even though the area
had not been grazed since 1940. Below—Heavy emer-
gence of mesquite seedlings on badly deteriorated
grassland following a severe drouth.

22

 
  
   
   
   
  
  
   
 
  
   
  
   
  
   
  
   
   
  
  
   
   
 
  
  
   
  
  
   
  

acrfr had become well established on the land ( '
2) . These results indicate strongly that no one l,
ment will completely eliminate mesquite on ; 
lands. Repeated treatments, together with 
range management practices that will favor de 
ment of a good cover of grass to reduce the n 
of seedlings that may become established, will
needed at intervals of 5 to  years. A

VALUE OF MESQUITE

The value of mesquite as a forage plant is u;
largely to the utilization of the seed pods, com)
called beans. Nearly all classes of livestock, wily
and rodents relish the mature, sugary beans d y)
the summer and fall. Chemical analyses show 
the seed pods with seed contain approximatel
percent protein, 48 percent carbohydrates, 27 per
crude fiber and 2 percent fat. The seed alone ‘
tain approximately 38 percent protein, but t;
of them are not digested by range animals (17). _
leaves are seldom browsed to any noticeable ex‘)
during the growing season, but occasionally live 
make good use of dry leaves following an early,
ing frost in the fall. A

The utilization of beans by grazing anima.
riously hinders the success of any mesquite-co
program. Even though the production of bea
highly variable from season to season, the app“
longevity of seed, 44 years in a herbarium repi
by Martin (21), results in a build up of a h”
seed source in the soil. Recent work by Doll]
and Anthony (10) showed that during prolo 
drouths when other forage is scant, cattle may.)
velop mesquite bean poisoning, which results in
vere losses in weight and in some cases in 
During seasons when heavy bean crops are prod J
many horses and mature cattle are often lost bec
of compaction of the beans in the digestive trac

Formerly mesquite wood was used for fuel y,
fence posts; only limited use of mesquite for 
purposes is now made. Within recent years, M'
et. al. (19) and others have shown that mesq;
stems 1 to 3 inches in diameter have value as r01,
age when ground and fed to cattle. The che 
contents of such ground mesquite stems collecte
monthly intervals from March to November are sh
in Table 15. f A

Mesquite wood samples have been submitt
various commercial paper interests and other inf
tries that make use of wood cellulose in large q)
tities. In all instances, other sources of wood 
found to be more economical to process or they;
duced a higher quality product. The collectio
mesquite gum that is exuded during certain  i
of the year, manufacture of charcoal and other
cial products offer limited uses for mesquite w

Other values of mesquite include protection
a source of food for quail, dove and other wild

  
 
  
 
 
   
  
  
   
  
    
    
  
 
 
   
  
 

‘lite honey is highly prized by beemen. The
of. mesquite for shade to grazing animals is
 able.

 AUTIONS ON THE use 01-" 2.4.511"

ilnchmen in the Southwest have sprayed more
 million acres of mesquite without affecting
wth of susceptible plants such as cotton, grapes,
1= elons, tomatoes and many other broad-leaved
 The following suggestions are offered to
,1 injury and possible damage to broad-leaved

st; only low-volatile formulations of 2,4,5-T that
‘en tested and approved for the control of
rite. Fumes from volatile ester formulations
fffect susceptible plants several days after ap-
E1 Drift resulting from the application of
vvolatile or low-volatile formulations will affect
owth of susceptible crops.

1o not use 2,4-D or mixtures of ZA-D and 2,4,5-T
* control of mesquite. Sprays of ZA-D and the
1 es are not as effective as 2,4,5-T and are much
"hazardous to use where susceptible crops are

a

» ccessful and experienced aerial applicators
ound the following distances give a safe mar-
g operation for the application of low-volatile
‘lations of 2,4,5-T for the control of mesquite
froper equipment:

Proximity to susceptible crops, miles

   

'j v locity,
 hour

    
  
  
   
  
  
  
    
 
  
 
 
 
 
  

Upwind Downwind
iwind 2 2
. - 3 1/2 2
 6 1A3 3
f- 10 1A; 4

p - l0 Not recommended

* irplane spraying equipment should be designed
justed to apply the spray solutions in coarse
ts at low pressure on the boom. Positive cut-
iould be used on each nozzle and between the
:1 tank and the boom. The equipment should
a constant type agitator.

here should be no leaks or drip of any kind
the nozzles, boom or spraying equipment.

leaded planes should not be ferried over sus-
le plants. The use of municipal airports

f be avoided. 5 

(v

_or ground application, 2,4,5-T should not be
iflnearer than 1 mile downwind to susceptible
7when these crops are making rapid growth.
olatile esters may be used upwind within 300
 susceptible crops. In the fall, most summer

300° Legend
..._.. No treatment
-‘\ .._.- Gross burned in spring of I942-44

2590 j \ _._Grass burned I944

'-. 

E \
2000 ‘-

I500

      
 

I000

\---
______ — — — - — ——

NUMBER OF MESQUITE SEEDLINGS PER ACRE

I_|-unnI-"—'_'_I-|-
_ I -

50o
:94: 42 43 ~44 4s 41 4e 49 5| s2 s: s4 s5 5s,

YEAR
Figure 23. Survival of mesquite seedlings on ungrazed
tobosa-buffalo type grasslands, during 1941-56. following

the removal of 213 small trees and seedlings per acre
in 1940.

crops are fairly tolerant to 2,4,5-T. Low pressures
with coarse sprays are safest.

Equipment used for. the application of 2,4,5-T
should not be used to spray susceptible crops in other
control programs unless adequate steps have been
taken to clean the equipment thoroughly by special-
ized procedures.

2,4,5-T is not poisonous and grazing animals
may remain in the area being treated with this chem-
ical. Where poisonous weeds are present in treated
pastures, “there is some likelihood of the animals
taking the sprayed plants when palatable forage is
scant.

For greatest effectiveness and safety, employ only
experienced and qualified operators who recognize
the value of 2,4,5-T as well as its hazards to other
crops. '

Ranchmen and farmers should be informed of
the value of 2,4,5-T and its limitations for the con-
trol of mesquite.

For further information on the use of 2,4,5-T
for the control of mesquite, see your county agri-
cultural agent or write to the Texas Agricultural
Experiment Station, Spur, Texas.

TABLE 15. AVERAGE PERCENTAGE NUTRITIVE CONTENT
OF GROUND 1 TO 3-INCH MESQUITE STEMS COLLECTED
AT ‘MONTHLY INTERVALS, MARCH TO NOVEMBER, 1957

Analysis Average Range
Water 7.96 6-10
Protein 7.09 4-10

Fat 1.36 .9-l.75
Fiber 41.16 33-46
Ash 6.37 3-14
N.F.E. 35.82 32-38
Ca° 2.00 1.75-3.55
P205 .07 .03-.11
Carotene‘ 18.13 - 6-55

‘Parts per million.

23

ACKNOWLEDGMENTS

The authors are especially indebted to  E.
Swenson of Emery Farm Lands, Spur, Texas; D.
Burns of the Pitchfork Ranch, Guthrie, Texas; and
George Humphries, 6666 Ranch, Guthrie, Texas, for
furnishing land, facilities and other valuable assis-
tance; to the Dodge Jones Foundation, Abilene, Tex-
as, for grant-in-aid funds that made much of the
research possible; to J. E. Hooper of Aerial Sprayers
of Stamford and to Clint Fry of the American Dust-
ing and Spraying Company of Chickasha, Oklahoma,
for furnishing aerial spraying equipment and other
valuable assistance; to the Flying Farmers Founda-
tion; the Dow Chemical Company, Midland, Michi-
gan; the American Chemical Company, Ambler,
Pennsylvania; the Ethyl Corporation, New York City;
Hevden Chemical Company, New York; Chemagro,
Pittsburgh, Pennsylvania; and E. I. Dupont DeNe-
mours and Company, I/Vilmington, Delaware, for
grants-in-aid and materials; to ranchmen in South
and West Texas for providing land and facilities, in-
cluding the cost of chemicals and applications to
conduct ranch tests; to commercial organizations for
furnishing experimental materials including chem-
icals, oils and other items for evaluation; to members
of the Texas Agricultural Extension Service and the
Agricultural Stabilization and Conservation Commit-
tee for assistance in locating the ranch tests; and to
Alvis C. Bilbery, who assisted with the research work
during 1938-56 as foreman.

These investigations were conducted cooperative-
ly by the Texas Agricultural Experiment Station and
the Crops Research Division, Agricultural Research
Service, U. S. Department of Agriculture.

LITERATURE CITED

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24

 
   
 
  

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