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AGRICULTURAL RESEARCH SERVICE

UNITED STATES DEPARTMENT OF AGRICULTURE AGRICULTURE HANDBOOK NO. 238
CONTENTS

Page

Comparative yield and forage quality of species 2

Pruasic acid poisoning 7

Sudangrass 7

Pearl millet 10

Sudangrass hybrids , 12

Sorghum almum 13

Perennial sweet sorgrass 14

Foxtail miUet 15

Japanese millet 15

Browntop millet 15

Seed production 16

Issued February 1963

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington 26 ,D.C. - Price 10 cents
SUMMER ANNUAL FORAGE GRASSES

IN THE UNITED STATES

A. A. HANSON, research agronomist, Crops Research Division,

Açri€ultural Research Service

Summer annual grasses are used for supplementary pasture or

emergency forages in most of the United States. In general, they are

rehed on to provide dependable supplies of high-quality forage in

midsummer when perennial forage species are relatively low in yield

or quality, or m both. There has been an increasing trend to consider

these grasses an integral part of the total forage program rather than

mere supplementary crops, which may or may not be planted, or

emergency forage species to be seeded only when other crops have

xaiieci.

Summer annual grasses can be used as the sole source of pasture

for part of the grazing season or can be used to supplement the diet

ot animals on permanent pasture. Dairy cattle on permanent pastures

can be either fed green-chop or given access to annual pastures for 1

or 2 hours each day. In many Northern States, summer annuals

turnish grazing from early July through September; while in the

southern States the grazing period normally starts in early June and

continues to late August or, with late planting, good moisture supply,

and warm temperatures, often to mid-October.

For year-round grazing in the South, it is frequently practical to

rotate summer annual grasses with winter annuals, such as small

grains or mixtures of small grain and ryegrass. Summer annuals

are plowed under and winter annuals planted in September or early

October.

There has been some interest in planting sudangrass and other

summer annual grasses in permanent pastures in order to overcome

the midsummer drop in yield and quality of perennial grasses. However, plant development in "sod seedings" is poorer than that obtained

in well-prepared seedbeds because of excessive competition for moisture and nutrients. The relatively low yields of summer annual

grasses in "sod seedings" probably accounts for the failure of the

practice to become widespread.

Varieties of sudangrass, millets, johnsongrass hybrids, and sorghum

X sudangrass hybrids are used as pasture only or as some combination of pasture, green-chop, hay, and silage. Forage sorghum and

com are valuable silage crops ; tíiey are not included in this handbook

even though they are grown in certain areas for green-chop, dry

fodder, and supplementary grazing.

Sorghwm alrmum^ which is a sorghum X johnsongrass hybrid and

has some of the perennial characteristics of the johnsongrass parent,

and perennial sweet sorgrass are included with the summer annuals

because they are not strong perennials and in most areas have to be

replanted every year.
2 AGR. HANDBOOK 2 3 8, U.S. DEPARTMENT OF AGRICULTURE

COMPARATIVE YIELD AND FORAGE QUALITY

OF SPECIES

Dependability, high yield, and forage quality are of first importance

in choosing the best adapted species and variety for grazing, hay, or

silage. Although most of the annual grasses produce dependable

stands, they differ appreciably in forage yield and quality. The

region and the management practices affect the various species

differently.

Sudangrass is considered the standard summer annual for pastures,

because of its wide adaptation and the large acreage grazed. Although

sudangrass varieties differ in leafiness, coarseness, recovery after grazing, disease and insect resistance, and prussic acid levels, a number

of general comparisons with other grasses may be made. Thus, the

yield of sudangrass is inferior to that of improved varieties of pearl

millet over most of the southeastern United States—from Maryland

to east Texas and southward to and including Florida. The superiority of pearl millet is very marked in the southern part of this

region (table 1). The difference in production between pearl millet

and sudangrass is not so marked in the northern and western parts

of the region (table 2),

TABLE 1.—Average yield of sudangrass and pearl mulet varieties at

the CoastalPlain Experiment Station^ Tifton^ Ga.^ 195S-S6 ^

[Grown in rows 3 feet apart]

Variety

Dry-matter yield per acre at

harvest on *—

Total

July 1 Jnly29 Sept. 14

Sudangrass : Common

P0U7i4Î,S

443

732

498

542

369

606

2,725

2,198

2,802

Pounds

1, 149

1,447

1, 110

1,038

1,104

1, 145

3,029

4,017

4,990

Pounds

150

344

214

96

96

213

1, 155

1,837

2,946

Pounds

1,742

Piper 2,523

Greenleaf _ _ 1,822

Sweet 372. 1,676

Lahoma _ 1,569

Tift _ 1,964

Pearl millet:

Common _ _ _ __ 6,909

Starr 8,052

Gahi-1 10,738

1 Data fuinished by G. W. Burton, Georgia Coastal Plain Experiment Station. Tifton. Ga.

^ Average harvest date.

The superiority of pearl millet in the southern United States has

been attributed to a combination of disease resistance, greater vigor,

and better growth on deep sandy soils. In spite of these valuable

characteristics, pearl millet has not attained much importance outside the Southeast. This situation may be explained in part by the

following observations : (1) Although neither pearl millet nor sudan-
SUMMER ANNUAL FORAGE GRASSES 3

TABLE 2,—Yield of Piper sudcmgrass and Gahi-l pearl mulet wnder

various management treatments at the Tewnessee Agricultural

Experimentstation, Knoxmlle, Tenn,, 1957 ^

[Grown in rpws 3 feet apart]

PIPER SUDANGRA88

Cutting management

Nitrogen, pounds per acre, applied at seeding—

0 60 120

Height or

maturity at

cutting

Stubble

height

after

cutting

Drymatter

yield

Cuttings

Drymatter

yield

Cuttings

Drymatter

yield

Cuttings

20 inches

30 inches

Do

Inches

6

6

10

4

Pounds

per acre

2,310

2,290

2,520

3,240

Number

6

4

5

3

Pounds

per acre

3,080

3,250

3,540

4,820

Number

6

5

6

3

Pounds

per acre

3,460

3,600

4,090

4,820

Number

6

6

6

Early 3bloom

GAHI-l PEARL MILLET

20 inches

30 inches

Do

6

6

10

4

3,670

3,790

5, 190

4,800

6

5

5

Early bloom 3

1 Adapted from K. R. Broyles and H. A. Fribourg, Agron. Jour. 51: 277-279. 1959.

grass thrive at low temperatures, sudangrass has a somewhat greater

tolerance to low temperatures. (2) Sudangrass recovers better than

pearl millet when subjected to very close grazing or clipping, and

this difference appears to be accentuated when moisture is limited.

(3) Sudangrass appears to be better adapted than pearl millet for

use in areas where moisture supplies are very limited. (4) Sudangrass is somewhat less susceptible to chinch bug damage.

Millet species, other than pearl millet, are decidedly inferior to

sudangrass for hay and pasture. However, limited acreages of several

millet species are planted either as catch crops or because environmental conditions are not well suited forsudangrass.

Adapted sudangrass varieties have a much higher tolerance to frequent grazing or clipping than Sorghwn almum ; consequently, under

intensive management they surpass 8orghmn almum in forage production (table 3). However, the yield of Sorghum almwrri may

equal or exceed that of sudangrass when compared either on the basis

of silage or silage plus aftermath.
j^

TABLE S.—Average yield and height of siidangrass varieties and hybrids and Sm^ghum almum at the Nebraska

Agriculimral Experiment Station^ Lvncoln^ Nebr.^ 1959^0 ^

[Grown in rows 1 foot apart ]

Variety or hybrid

Piper

Wheeler

Sweet 372

Perennial sweet sorgrass

Sorghum almum

Commercial sorghum X sudangraas hybrid

Dry-matter yield per acre

At harvest on ^ -

July

8

Pounds

1,413

1,621

1,232

530

878

1,629

July

25

Pounds

1,695

2, 132

1,330

943

1,432

1,371

Aug.

13

Pounds

1,297

1,634

922

698

854

1,262

Sept.

1

Pounds

1,077

1,265

712

745

1, 128

1,099

Oct.

15

Pounds

1,254

1,554

708

325

935

641

Total

Pounds

6,736

8,206

4,904

3,241

5,227

6,002

Average height at harvest on « -

July

8

Inches

31

31

23

20

23

29

July

25

Inches

31

34

26

24

26

28

» Data furnished by L. V. Peters, Nebraska Agricultural Experiment Station, Lincoln. Nebr 3 Average harvest date.

Aug.

13

Inches

28

29

22

19

18

28

Sept.

1

Inches

28

28

20

19

23

29

Oct.

15

Inches

28

30

22

16

17

24

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O

>
SUMMER ANNUAL FORAGE GRASSES 5

High yield potential is a characteristic feature of most commercially

available sorghum X sudangrass hybrids. Maximum yield is obtained

when these hybrids are harvested either at or near maturity or for

silage and aftermath. Although recovery is good, total production

under intensive grazing or frequent clipping is, in general, not superior

to that obtained from adapted sudangrass varieties (table 3 and 4).

These hybrids produce more silage than Sorghum almum; hence, the

selection of these for silage should be seriously considered in areas

where moisture supply restricts production to a single harvest.

Comparison of annual forage grasses on the basis of forage quality

is similar to that for forage yield. In general, with adapted species,

those that are tolerant to grazing or harvesting at frequent intervals

give higher quality forage as measured by animal performance and

chemical composition. This is true because the chemical composition

of the young grass is better suited to the needs of the animals. Thus,

the crude protein content of common sudangrass may exceed 20 percent when the first growth reaches the pasture stage, but it may fall

to 8 percent or less at full bloom. In addition, young grass is palatable

and succulent and is consumed in the large quantities needed for the

efficient production of milk and meat.

The good recovery and high percentage of leaves produced by properly managed sudangrass and pearl millet would seem to give these

species a decided advantage over sorghum X sudangrass hybrids and

Sorghum aZrrmm in the production of high-quality forage. Grazing

studies in which sudangrass proved superior to Sorghum almum in

both forage quality and carrying capacity confirm this observation.

Comparative grazing data are lacking for the newer sorghum X sudangrass hybrids, but clipping results suggest that many hybrids are inferior to the better sudangrasses in forage quality.

However, harvests made either at heading or full bloom favor pearl

millet, sorghum X sudangrass hybrids, and Sorghum almum where

these species are adapted. As a rule, these species are more resistant

than sudangrass to certain leaf diseases that reduce both forage quality

and yield. .

Improved sudangrass and pearl millet varieties are very similar m

forage quality, as measured by the performance of livestock grazing well-managed pastures. Thus, the selection of sudangrass or

pearl millet for pasture purposes can apparently be based on their

relative yield potential in a given area.
cyi

>

TABLE 4.—Average yield cmd height of Wheeler aiid Pipe)' siidangrass and a commercial sorghum X sudaiigrass

hybrid at the Fort Hays Branch Station^ Hays^ Kans.^ 1961 ^

[Grown in rows 1 foot apart on land summer-fallowed the previous year ^]

Dry-matter yield per acre

Height at harvest onVariety or hybrid At harvest on—

Total

July 10 July 31 Aug. 25 Oct. 4 July 10 July 31 Aug. 25 Oct. 4

Wheeler - - -

Pounds

1,740

1, 320

1,380

Pounds

2, 540

2, 500

2, 480

Pounds

3, 120

3,320

2,940

Pounds

2,220

1,940

1, 240

Pounds

9,620

9,080

8,040

Inches

37

34

34

Inches

39

35

33

Inches

47

45

47

Inches

27

Piper - -- -- -- -- 24

Commercial sorghum X sudangrass hybrid. __ 19

1 Data furnished by H. L. Hackerott, Fort Hays Branch Station, Hays, Kans.

3 Rainfall was above average in 1981.

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SUMMER ANNUAL FORAGE GRASSES 7

PRUSSIG ACID POISONING

Young plants and leaves of sorghum, sudangrass, and johnsongrass

contain the glucoside durrin, which breaks down to release a poison

known as prussic acid, or hydrocyanic acid (HCN). Caution must

be exercised in grazing plants that contain appreciable quantities of

this poisonous substance.

Sorghum is much higher than sudangrass in prussic acid, and, in

general, it is unsafe for pasturing except after plants reach maturity

and no new growth is present. Sorghum silage may contain toxic

quantities of prussic acid, but it escapes in gaseous form when the

silage is moved and fed. Under most circumstances, silage and wellcured fodder can be fed with safety. Prussic acid is released very

quickly from the glucoside form in frozen leaves, and hence frosted

sorghum is very dangerous until it begins to dry out.

Usually there is little danger of prussic acid poisoning in grazing

most varieties of sudangrass. However, the young growth that follows clipping, drought, frost, or grazing may contain appreciable

quantities of prussic acid. The following precautions are recommended: (1) Use pure seed that is not contaminated with sorghum;

(2) select varieties that are low in prussic acid; and (3) let animals

graze only when the plants have reached a height of 18 inches (sudangrass at this height contains a very small percentage of the rapidly

growing tissue that is normally high in prussic acid).

Prussic acid poisoning is more liable to be a problem in the Noithem

States than in the Southern States. The periods of low temperatures

common in the Northern States cause slow growth rates with a large

percentage of young tissue, which is high in prussic acid.

SUDANGRASS

Sudangrass {Sorghwn siidanense (Piper) Stapf) was brought to

the United States in 1909 from a seed collection made near Khartoum

in the Sudan. It was planted first at Chillicothe, Tex., and subsequently distributed to many experiment stations. Sudangrass soon

became the most important temporary pasture plant in the country—a

position that it has maintained.

Sudangrass is a freely tillering annual bunchgrass that grows to a

height of 4 to 5 feet in broadcast plantings and 6 to 8 feet in cultivated

rows. The stems are about ^/^Q to % inch in diameter; the blades are

approximately 1 inch wide. The typical loose panicle is about 18

inches in length. Seeds of most varieties remain enclosed in the

dûmes after threshing. Several leaf diseases attack sudangrass;

these reduce the yield and quality of plants grown for silage, hay, and

seed However, many of these diseases are of little consequence when

growth is rapid and the forage is grazed. Development of diseaseresistant varieties is the most effective method of control.

Sudangrass will grow on a wide range of soil types, but it does not

make satisfactory growth on cold, wet soils. Yields are low on sandy

658064 O—63 2
8 AGR. HANDBOOK 2 38, U.S. DEPARTMENT OF AGRICULTURE

soils unless moisture conditions are favorable and the crop is supplied

with, adequate fertilizer. Sudangrass does best on good loam soils.

In general, a complete fertilizer should be applied at planting. It is

advisable to supply a total of 50 to 100 pounds of nitrogen per acre;

the amount needed depends on the initial level of soil fertility. Half

the nitrogen should be added in midsummer to encourage regrowth.

Sudangrass requires warm-to-hot weather for good growth. It

should not be planted until the soil becomes warm, which may be 1 to

?) weeks after corn-planting time. In humid regions, good-quality

sudangrass seed is drilled or broadcast at 20 to 25 pounds per acre; in

dry areas, 12 to 15 pounds per acre is usual. Forage plantings are

sometimes made in rows 24 to 36 inches apart if moisture is limited

or cultivation is required to reduce weed competition. Seed-production fields are planted in rows 36 to 42 inches apart at 5 pounds of seed

per acre or less.

Although sudangrass is palatable and readily eaten at the earlyheading stage, recovery is improved if plants are grazed at an earlier

stage of growth. However, pasturing should be delayed until the

stand reaches a height of 18 to 24 inches. Sudangrass pastures should

be divided into fields of such size that they can be grazed down quickly.

Under rotational grazing, the carrying capacity for short periods may

exceed six animals per acre. Grazing when the regrowth reaches a

height of 24 inches helps to maintain the supply of young, succulent,

and highly nutritious forage.

The feeding value of good-quality sudangrass hay, harvested at

early heading, is about equal to that of timothy and johnsongrass.

In humid areas, hay quality may be reduced by leaf diseases and curing problems; thus, it may be desirable to make excess forage into

silage. Sweet varieties are easier to preserve and make better silage

than nonsweet strains. In some areas, 30 to 60 pounds of soybeans

per acre are drilled with sudangrass to improve silage quality.

Varieties

Sudangrass varieties differ in several imi>ortant respects, including

prussic acid potential, sweetness of stem, and amount of regrowth

after gi-azing or clipping (fig. 1). Eecovery differences among sudangrass varieties are shown in tables 3 and 4, but these data are not representative of varietal performance in all environments. Most other

commercially available varieties are two to three times higher than

Piper in prussic acid content. However, there is very little likelihood

of poisoning, provided reasonable precautions are taken, in grazing

these varieties. Sweet varieties, such as Sweet 372 and Lahoma, have

sweet, juicy stems and can be distinguished by the cloudy appearance

of the leaf midrib. Sweet varieties are very palatable and, for this

reason, are preferred by some farmers to the dry, pithy-stemmed nonsweet types. Improved varieties of common sudangrass are higher

yielding than sweet sudangrass; in many trials they have produced

substantially more forage and more livestock products per acre.

Named sudangrass varieties were developed in different parts of

the country, and for the most part they were selected for specific

traits. A knowledge of their important characters is essential to

understanding the conditions under which they perform best. Certi-
SUMMER ANNUAL FORAGE GRASSES 9

fied seed of the varieties described in this handbook can be purchased

in those regions where the varieties are adapted.

FIGURE 1.—^Plots of sudangrass varieties about 3 weeks after the grass had been

clipped, at Lincoln, Nebr. Clipped on July 27 ; photographed on August 15.

(Courtesy of the Nebraska Agricultural Experiment Station. )

California 23.—Ca,lifomia 23 was selected from common sudangrass at the California Agricultural Experiment Station. It is vigorous and productive under California conditions but not outstanding

at other locations. This variety is very susceptible to leaf diseases

when gi'own in humid regions.

Greenleaf.—Greenleaf was selected at the Kansas Agricultural Experiment Station from a cross between common sudangrass and Leoti

Red sorghum made at Chill icothe, Tex. Greenleaf is a vigorous

variety that is variable for the sweet character. It has some resistance

to foliage diseases and is adapted over much of the southern Great

Plains and the eastern United States.

Lahoma.—Lahoma is a sweet variety selected at the Oklahoma

Agricultural Experiment Station. It is late maturing and possesses

distinctive broad, yellow-green leaves. Leaf diseases may be troublesome when moisture is excessive. Lahoma has not been outstanding

in most comparative yield trials.

Piper.—Piper was developed at the Wisconsin Agricultural Experiment Station, from the Tift variety and lines received from the

Texas and Kansas Agricultural Experiment Stations. Piper was

selected for its low prussic acid content. It has some resistance to

leaf diseases at northern locations. It is the only sudangrass variety

recommended for use in several Northern States. Piper is widely

used throughout the United States because of its low prussic acid

content and its excellent recovery after grazing or mowing.

Sweet 372 (Texas SA 372) .—Sweet 372 is the original sweet variety

developed at Chillicothe, Tex., by crossing common sudangrass and

Leoti Eed sorghum. It is similar to common sudangrass except for

itssienna-colored glumes and sweet, juicy stems. Sweet 372 is resistant

to bacterial blights, but susceptible to several other leaf diseases and
10 AGR. HANDBOOK 2 38, U.S. DEPARTMENT OF AGRICULTURE

is lower yielding than improved nonsweet types. Sweet (S-1), a

selection made within Sweet 372, is fairly similar in performance

to the original variety.

Tift.—Tift was developed cooperatively by the Agricultural Eesearch Service, U.S. Department of Agriculture, and the Georgia

Agricultural Experiment Station. TiÄ is a late-maturing, leafy,

fine-stemmed variety that is resistant to many of the leaf diseases

found in the Southeastern States. Tift is very productive, but it has

failed to attract very much attention—probably because improved

pearl millet varieties are more productive in the region for which

Tift was developed originally.

Wheeler,—^Wheeler is an early-maturing variety selected out of

common sudangrass by Carl Wheeler of Bridgeport, Kans. Wheeler

is vigorous and tillers freely, but it is very susceptible to disease.

Wheeler is the first named variety of sudangrass developed in the

United States. Its continuing popularity in parts of the central

Great Plains can be attributed to its excellent resrrowth after ffrazinff

(tables). ^ ^ ^

PEARL MILLET

Pearl millet {Pennhetym typhoïdes (Burm.) Stapf & C. E. Hubb.)^

is used almost exclusively for forage in the United States. Pearl

millet became established as a minor pasture crop in the Southeastern

and Gulf Coast States following its introduction during the mid1800's. It has increased in popularity with the release of the improved

variety, Starr, in 1951, and there is every indication that this trend will

continue in the Southeastern States. Pearl millet has been called Penicillaria, Pencilaria, Mandas Forage Plant, and cattail millet.

Pearl millet is an annual that grows to a height of 10 feet or

more and produces many tillers. Stems range from % inch in diameter at the base with high planting rate to 1 inch with low planting

rate. The heads are about 1 inch thick and 8 to 24 inches or more

m length : the "pearllike'' seed, which thresh free from the hulls, are

larger than those of other millets. Pearl millet maintained in the

vegetative condition remains relatively free from disease. Leaf diseases cause some damage on mature plants, and young millet plantings

may be seriously damaged by armyworms and the lesser cornstalk

borer. Pearl millet is free of the prussic acid glucoside that is found

m sudangrass and other sorghums.

Pearl millet is used primarily for pasture, but it is also a valuable

silage crop. In the humid Southeastern States, pearl millet produces

higher silage yields than either sorghum X sudangrass hybrids or

Sorghum almnm. It can be made into hay, but curing is difficult

throughout most of the humid area because of the hiffh moisture content of the fodder.

Pearl millet will grow on sandy soils. However, a complete fertilizer at planting and topdressing with nitrogen during the growing

season improve yields on most soils. Where rainfall is adequate, 100

to 150 pounds of nitrogen give a profitable return on a wide range of

soil types.

'This species has been incorrectly known as Pennisetum glaucum (L.) R. Br.
SUMMER ANNUAL FORAGE GRASSES 11

Good-quality pearl millet seed is seeded at 10 pounds per acre in

rows 24 to 36 inches apart and at 25 pounds per acre in close-drilled

rows. Much of the seed produced in the Southeastern States is low

in quality; hence, heavier planting rates should be used for locally

grown seed. Highest forage yields have been obtained from drilled

plantings that have been supplied with adequate nitrogen. Since

row plantings permit cultivation, they are preferred on weedy soils.

Proper management of pearl millet pastures varies with number

of livestock, acreage available, and growth rate of the millet. However, under all circumstances, the millet acreage should be divided

into individual pastures, each planted on a different date, and rotational grazing should be practiced. Tliese practices extend the grazing

season and provide good-quality forage. Pastures that cannot be

grazed at the correct stage of growth should be harvested for silage.

When the millet provides only part of the forage requirements of

the livestock, the available forage is best utilized by stocking at a sufficiently heavy rate so that most of the herbage in an individual pasture

is grazed within a few days. Additional control of stocking rate

can be obtained by the use of an electric fence to divide pastures into

smaller units. Individual pastures should be grazed when the millet

is 24 to 30 inches high and the ungrazed plants and stubble clipped

to a height of 8 to 10 inches when the animals are moved to another

pasture. Mowing encourages the development of leafy, high-quality

aftermath. Livestock should be given access to the high-quality

pearl millet for a short period each day, with the rest of their forage

requirements met from permanent pastures.

When pearl millet provides all or nearly all the pasture needs for

most of the growing season, there may be considerable difficulty in

maintaining the larger acreage of pearl millet pasture at the proper

grazing height. Grazing should start as soon as the plants reach a

height of 15 inches and continue until most of the leaves are grazed

off. The cattle may have to be moved before the first pasture is graced

completely for, insofar as possible, the second pasture should be

grazed before the millet reaches a height of 24 inches. Pastures

should be mowed to an 8- to 10-inch height when the accumulated stubble is about 30 inches high. Animals should never be forced to graze

the stemmy material that accumulates on these pastures. Regrowth

after mowing is ready to graze when it is 18 to 24 inches tall.

Pearl millet should be harvested for green-chop when it reaches

a 30-inch height and for silage when the first heads appear. A stubble

height of 6 to 10 inches is suggested when fields are cut for green-chop

or silage. Silage should be chopped fine, mixed thoroughly with

a preservative (such as ground corn at 100 to 150 pounds per ton), and

packed in an airtight silo. Plastic covers keep air out and help to

reduce spoilage.

Varieties

Starr and Gahi-1 are the two most important pearl millet varieties

in the United States and the only ones ^or which adequate seed supplies are available. They were both developed at the Georgia Coastal

Plain Experiment Station, Tifton, Ga., by the Agricultural Eesearch

Service of the U.S. Department of Agriculture and the Georgia Agricultural Experiment Station. The excellent performance of Gahi-1
12 AGR. HANDBOOK 238, U.S. DEPARTMENT OF AGRICULTURE

and Starr in southern Greorgia is shown in table 1. Gahi-1 is higher

yielding than common pearl millet over its entire range of adaptation ;

while, at many locations in the Southeastern States, Starr and common

do not differ appreciably in total dry-matter production.

Starr,—Starr has broader leaves and shorter intemodes and stems

than common pearl millet. Although these two types are often comparable in total dry-matter production, Starr is much leafier. Starr

is easier to manage, lasts longer, and produces more beef and niilk

under grazing than common pearl millet ; as a result, dairymen have

a high regard forthis variety.

Gahi-l,—Gahi-1 is a hybrid variety, produced by harvesting openpollinated seed from isolated plantings of four inbred lines. Seed

should not be harvested from Gtihi-l plantings, as vi^or declines

sharply in the second generation. This variety is very vigorous and

produces good forage yields in some marginal areas where Starr and

common pearl millet are very poorly adapted. It is leafier, later

maturing, and recovers faster after grazing than the common type.

Gahi-1 appears to be comparable with Starr in forage quality, and it

can be recommended for maximum forage yields. Because of its rapid

growth and recovery, Gahi-1 is more difficult to manage properly than

the lower yielding Starr.

SUDANGRASS HYBRIDS

Farm experience indicates that sudangrass hybrids can be used very

effectively forsilage and, by taking proper precautions to avoid prussic

acid poisoning, for grazing. Little information is available on the

management of hybrid varieties.

Sorghum X sudangrass.—Commercial seed companies have marketed seed of closed-pedigree sorghum X sudangrass hybrids since

about 1959. These Fi hybrids were developed by crossing cytoplasmic

male-sterile sorghum lines with improved varieties of sudangrass.

These hybrids are leafier and tiller more than typical forage sorghums;

they vary in yield, prussic acid potential, and growth habit with the

particular male-sterile sorghum and sudangrass pollinator selected

for crossing.

In general, these hybrids have equaled or surpassed some openpollinated forage sorghums when harvested for silage, but, as previously mentioned, they are not superior to adapted sudangrass varieties in yield when clipped frequently to simulate rotational grazing

(tables 3 and 4). It is possible that the forage quality of some, if not

all, sorghum X sudangrass hybrids will prove to be below that of

improved sudangrass and pearl millet varieties. The hybrids are

resistant to many leaf diseases, but those that have been tested have

had three to seven times more prussic acid than Piper sudangrass.

5iiAî-/.—-Suhi-1 was developed at the Georgia Agricultural Experiment Station, Experiment, Ga., by pollinating male-sterile Rhodesian

sudangrass {Sorghwm arundmaceum Stapf) with Tift sudangrass.

Suhi-1 is above average in leafiness and has a high yield potential in

some environments. It has surpassed standard sudangrass varieties

m total yield and recovery in the Southeastern States, but its recovery

has been inferior to that of adapted sudangrass varieties in some

Midwestern and Great Plains States. Suhi-1 is comparable with
SUMMER ANNUAL FORAGE GRASSES 13

Sorghum almv/ni in prussic acid content; it has 6 to 11 times more

prussic acid than Piper sudangrass. Extreme caution should be

exercised in grazing this variety, especially in northern latitudes.

SORGHUM ALMUM

Sorghum almum has a fascinating history. Seed was collected first

in 1936 by an agronomist in the Province of Sante Fe in Argentina.

This collection was studied in 1943 by the botanist Lorenzo Parodi,

who named the grass Sorghum almmn Parodi. He concluded that

it must have originated under cultivation as a hybrid betAveen sorghum

and Johnsongrass {Sorghwnhalepense (L.) Pers.).

By the time Parodi described Sorghum almum in 1943, it was being

grown on a limited commercial scale in Argentina. In the mid1940's seed was distributed from Argentina to research workers in the

United States, Australia, South Africa, and England. The only

sizable increase in the United States directly attributable to these early

introductions was made by the Soil Conservation Service in California ; but this increase work was discontinued because of concern over

the possibility that the species might become a serious weed.

Another introduction of Sorghmn almu/m was brought to the United

States from South Africa in about 1952. This accession, known by

the South African name "columbusgrass," is thought by some workers to be superior to other strains of Sorghum almum. Sorghum

alm/wm seed has also been marketed under the name "sorghum grass."

At present, the major source of Sorghumn almum in the United

States traces to a small seed lot received in the early 1950's by a rancher

in western Texas. This seed lot was sent to him by a friend in New

Zealand ; hence, the name "New Zealand" Sorghum almum.

Sorghum almum is a weak perennial that persists reasonably well

where winters are mild, but it is subject to severe winterkilling in most

Northern States. It has failed to survive under intensive grazing

in parts of northern Texas, and it has not overwintered satisfactorily

in Oklahoma. Sorghum almum has very short, thick rhizomes that

turn up close to the crown. But where Sorghmn almum. is adapted no

difficulty has been experienced in killing the plants by plowing.

The seed shatters readily, and shattering may cause a serious weed

problem in irrigated areas where seed could be distributed through

irrigation water. In general, volunteer seedlings are very thick in

seed fields. Productivity of these fields can be maintained, in part,

by applying fertilizer and by cultivating to destroy seedlings growing between the original rows.

No one has been too concerned about the control of typical Sorghum

almwn on cropland ; however, research workers have been concerned,

and rightly so, with the danger of introducing johnsongrass or hybrids

between johnsongrass and Sorghum almum. Sorghum almum, seed

is somewhat larger than johnsongrass seed, but otherwise they are

indistinguishable. Seed size in these two species overlap, and it is

virtually impossible to certify that no johnsongrass seed is in any

particular seed lot. Johnsongrass is widespread in the seed-producing areas of New Mexico and Texas; and it is very difficult to insure

against occasional outcrossing with johnsongrass. The lack of dis-
14 AGR. HANDBOOK 2 38, U.S. DEPARTMENT OF AGRICULTURE

tinguisliing seed characteristics has been one of the principal reasons

why Sorghum. alvwMti has been classed as a noxious weed in several

States.

SorghiMTb alniwrn. is a robust species that looks very much like a

large version of johnsongrass. First-year stands make a very fine

appearance, especially when grown to maturity. Sorghum almum

is relatively late in maturing and remains green and continues to grow

longer than either common or Piper sudangrass. Thus, mature stands

of Sorghum, almum may look more impressive than early-maturing

sudangrass varieties.

Yield data collected at several locations indicate that Sorghum

almum is not so outstanding as appearances might lead one to expect.

Sorghum almum has not outyielded adapted sudangrass varieties; in

fact, it has actually produced as much as one-quarter to one-half ton

less dry matter per acre when seeded in rows 1 foot apart and clipped

to simulate grazing.

The highest yields of Sorghiim, almnMn. have been obtained from

rows spaced 3 feet apart and seeded at 3 to 5 pounds per acre. Yields

of 2 to 4 tons of dry matter per acre have been reported from this

type of seeding in Texas. It seems fair to conclude that Sorghum

alm/ijim has a reasonably good yield potential ; but, when it is managed

to obtain high yields, forage quality is inferior to that of improved

sudangrasses.

Sorghwm, (Hrruwrrv is somewhat better adapted than the sudangrasses

for living through protracted dry periods and recovering with fall

rains. The sudangrasses, however, appear to be better adapted for

taking advantage of limited rainfall received at the beginning of the

growing season or for capitalizing on moisture reserves in the soil.

This explanation might account for those dryland tests in which the

sudangrasses have produced more forage than Sorghum almum. As

mentioned previously, Sorghum almum, is high in prussic acid and

must be grazed with caution.

PERENNIAL SWEET SORGRASS

Perennial sweet sorgrass was released by the Texas Agricultural

Experiment Station in 1957. Tt was developed from a cross between

common sudangrass and johnsongrass {Sorghum halepense {JJ.)'PQTS-)

made at Cornell ITniversity. The hybrid seed was crossed with sweet

sudangrass in Texas and selected for its sweet juicy stalks, good fertility, and a perennial root growth habit intermediate between jolinsongrass and sudangrass. Tlie seed, which is not subject to shattering,

is similar to that of sweet sudangrass in size, shape, and color.

Perennial sweet sorgrass has short, thick rootstalks, but it has not

persisted so well as Sorghum, almum. The Texas station recommends

reseeding it every year in most areas. It is considered to be superior

to Sorghum, almum in quality, but in many areas it has been less productive than Sorghum almum, and adapted varieties of sudangrass

(table 3). Recommended seeding rates are 4 to 5 pounds per acre in

wide-spaced rows or 15 to 20 pounds in close-drilled or broadcast

plantings.
SUMMER ANNUAL FORAGE GRASSES 15

FOXTAIL MILLET

Foxtail millet {Setaria itálica (L.) Beauv.) has been used almost

exclusiA^ely in the United States for emergency hay production. It is

used to a lesser extent for grain, birdseed, silage, and pasture. Foxtail millet grows best under warm conditions, and it is well adapted

for use as a late-planted hay crop.

The foxtail millets have erect, mostly simple but sometimes branching stems that grow to a height of 21^ to 5 feet under cultivation.

The seeds are borne on a rather dense, cylindrical spike. Lobed heads

distinguish the German variety from other varieties of foxtail millet.

Several varieties are recognized ; the better known are common, German, Hungarian, Siberian, and Kursk. German and common are the

ones most generally grown.

Foxtail millet seed is planted with a grain drill at about 10 to 15

pounds per acre in dry areas, and at 25 to 30 pounds per acre where

moisture conditions are favorable. The normal growing period for

common foxtail is 70 days, and that for the German variety is 85 days.

Under favorable conditions early varieties can be harvested for hay

within 50 days after planting. Foxtail millet produces good yields

of hay on fertile soils, but it is not suited for pasture because the shallow-rooted plants are easily destroyed by grazing and recovery is

poor.

Foxtail millet has declined in importance since the introduction of

sudangrass and the development of early-maturing varieties of sorghum and corn. The reduction in acreage and value can be attributed

also to increasing mechanization, which greatly speeds up replanting

operations. Under most conditions, sudangrass and early-maturing

forage sorghums are more suitable than foxtail millet even when used

as late-seeded catch crops.

JAPANESE MILLET

Japanese, or barnyard, millet {Echinochloa crusgalli var. frumentacea (Koxb.) W. F. Wight) is coarser than foxtail millet. It makes

much better growth under cool growing conditions than either foxtail

millet or sudangrass. Itis used to a limited extent in the Northeastern

States as a source of cut green feed for dairy herds. Japanese millet

seed is ordinarily drilled or broadcast at 25 to 30 pounds per acre.

BROWNTOP MILLET

Browntop millet {Panicum ramosum L.) is a minor forage plant in

parts of north-central Georgia and adjacent areas. It is a finestemmed plant that grows 2 to 4 feet tall and produces good-quality

hav and pasture. However, it has a relatively short season of growth

and produces much lower forage yields than sudangrass or pearl millet.

Tlie seed shatters readily, and volunteer stands following crimson

clover are sometimes used for forage. It is planted at 8 pounds per

acre in rows 2 feet apart or at 10 to 12 pounds in broadcast seedmgs.

Browntop millet; because of its high seed yields and natural reseeding characteristic, is included in wildlife plantings made to encourage

ffame birds.
16 AGR. HANDBOOK 238, XJ.S. DEPARTMENT OF AGRICULTURE

SEED PRODUCTION

Summer amiual grasses are grown for seed in the central and

southern Great Plains and under irrigation in the Southwestern

States. California, Texas, and Colorado are the leading sudangrassproducing States—^both in acreage and in total production of clean

seed. Average yield per acre in these States range from about 1,600

pounds in California to 300 pounds in Colorado ; the average yield

per acre for the entire country was 614 pounds in 1960. Seed production of some other summer annuals is concentrated in the following

States: Pearl millet in Texas, Arizona, and New Mexico; German

millet in Texas and New Mexico ; Sorghmn almv/rrb in Texas and New

Mexico ; and perennial sweet sorgrass in Texas. Pearl millet produces

1,500 pounds of seed per acre, or more, under irrigation but only

around 500 pounds per acre in nonirrigated fields. Sorghum almvm

seed yields range from 300 to 1,500 pounds per acre. Under favorable

conditions 1,000 pounds of foxtail millet seed per acre is not unusual.

All the summer annuals may be combined directly, but with sudangrass this practice leads to heavy seed losses because of uneven ripening and excessive shattering. Windrowing sudangrass-seed crops and

combining from the windrow is a widespread practice in the major

seed-producing States. However, considerable acreages of sudangrass are harvested by cutting with a binder when most of the seed

is in the hard-dough stage, placing the bundles in shocks, and threshing from the shock with a combine. Pearl millet and German niillet

are combined either directly or from the windrow. The best yields

of Sorghwm ahnwrb have been obtained by cutting with a binder when

the first seeds are ready to shatter, shocking the bundles, and threshing from the shock.

Seed of the summer annuals is usually harvested from the first crop,

although it is possible to harvest seed from a second crop of sudangrass and pearl millet under the long-season irrigated conditions of

the Southwest. Under these circumstances, the first crop is grazed

or cut early for silage and the regrowth saved for seed.

U.S. GOVERNMENT PRINTING OFFICE: 1963 O—658064