u

v^ULTURE OF SWEET SORGHUM

FOR SIRUP PRODUCTION

Agriculture Handbook No. 441

Agricultural Research Service

U.S. DEPARTMENT OF AGRICULTURE
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U.S. DEfAKTMENT OF AOKICUITUKE
CULTURE OF SWEET SORGHUM

FOR SIRUP PRODUCTION

Agriculture Handbook No. 441

Agricultural Research Service

U.S. DEPARTMENT OF AGRICULTURE

Washington, D.C. Issued May 1973

For sale bv the Superintendent of Documents

U.S. Government Printing Office, Washington, D.C. 20402

Price 60 cents domestic postpaid or 40 cents GPO Bookstore

Stock Number 0100-02720
PREFACE

This handbook summarizes information on sweet sorghum production in the United

States and is based on extensive research findings and grower experience. It is intended to

give essential information for growers, producers, processors, extension personnel, and others

interested in the production of this crop.

This handbook supersedes U.S. Department of Agriculture Farmers' Bulletin No. 2100,

"Culture of Sorgo for Sirup Production."
CONTENTS

Page

Introduction 1

Description of the plant 1

Characteristics of sweet sorghum varieties— 2

Varieties 3

Wiley 4

Sart 5

Tracy 6

Brandes 7

Dale 8

Sugar Drip 9

Honey 9

Georgia Blue Ribbon and Williams 9

Diseases 10

Downy mildew 10

Anthracnose and red rot- 11

Mosaic 12

Grey leaf spot or angular leaf spot 13

Bacterial stripe, 13

Leaf blight 14

Insecticide injury- 14

Rust- 14

Rough spot 15

Smut 15

Pokkah boeng 15

Zonate leaf spot 15

Root rot and seedling blight 16

Summary of disease-control measures 16

Page

Insects injurious to sweet sorghum 16

Lesser cornstalk borer 17

Sorghum midge 17

Sugarcane borer 17

Corn leaf aphid 17

Fall armyworm 17

Corn earworm 18

Wireworms 18

Other insects 18

Insects injurious to stored sweet sorghum

seed 18

Cultural practices 18

Soil requirements 18

Crop rotation 18

Fertilization practices 19

Seedbed preparation 20

Planting time 20

Planting methods _. 22

Row spacing- 22

Cultivation 23

Hoeing and thinning 24

Chemical weed control 24

Harvesting 24

Manufacture of sweet sorghum sirup 27

Literature cited 29

VI
CULTURE OF SWEET SORGHUM

FOR SIRUP PRODUCTION

By K. O. FREEMAN and D. M. BBOADHEAD, research agronomists, and NATALE ZUMMO, pathologist, Southern Region,

Agricultural Research Service, Meridian, Miss.

INTRODUCTION

Good sweet sorghum sirup is light colored and

mild and has a characteristic flavor. It is a wholesome food and is a favorite as a table sirup in sweet

sorghum areas.

Sweet sorghum is grown most extensively for

sirup in the Southeastern States. Eight States

(Alabama, Arkansas, Georgia, Iowa, Kentucky,

Mississippi, North Carolina, and Tennessee) in the

sweet sorghum sirup area produce about 90 percent

of the total sweet sorghum sirup in the United

States.

Sweet sorghum is adapted to diverse climatic

and soil conditions like those found in Alabama

and Minnesota. Consequently, some sweet sorghum

is grown for sirup in 19 of the 50 States. The

peak annual income from sweet sorghum sirup

was $21,670,000 in 1946 for 10,171,000 gaUons. During the 1960's, the annual income from sweet sorghum sirup averaged about $5 million for 2.5 million gallons. During this time, the price per gallon

and yield of sirup per acre have increased slightly

Some sweet sorghum sirup producers grow sweet

sorghum in large fields but the average producer

grows less than an acre for sirup. The manufacturing of sirup also is usually on a small scale.

Community projects, however, are becoming more

common. In these projects, the sirup for an entire

commimity is manufactured at one plant, which

is owned by an individual or a corporation. Even

though the average acreage is low, sweet sorghum

sirup constitutes a meaningful cash crop for most

of its producers.

The name "sweet sorghum" is used to identify

varieties of sorghum. Sorghum licolor (L.)

^ Italic numbers in parentheses refer to Literature Cited,

p. 29.

Moench, that are sweet and juicy. These sweetstalk varieties are also called "sugar sorghums."

Sweet sorghum is grown for sirup or forage,

whereas some other sorghums, such as kafirs and

milos, are grown for grain. Other types of sorghum include broomcorn, Sorghum dochna var.

Technicum (Koern.) Snowden, the head of which

is used in making brooms and brushes; and johnsongrass, Sorghum halepense (L.) Pers., and sudangrass, Sorghum sudanense (Piper) Stapf,

which are cultivated for forage.

Cultural practices for sweet sorghum used for

sirup or for forage are similar, but the harvesting

and processing methods are different.

The primary objective in growing sweet sorghum for sirup is to obtain the largest possible

yield of good-quality sirup atthe lowest cost. Yield

and quality of sirup are influenced by varieties,

diseases, insects, weeds, soil type, climatic conditions, cultural and harvesting practices, and manufacturing methods.

DESCRIPTION OF THE PLANT

Sweet sorghum, a member of the grass family,

is closely related to kafir, milo, broomcorn, johnsongrass, and sudangrass. Sugarcane, Saccharumi

ofßcinarum L., another member of the grass family

used to produce sirup, is more distantly related.

Sweet sorghum is a perennial in the Tropics but

it winterkills in areas where frosts occur. Young

sweet sorghum plants are small, and their growth

is slow. In the germinating process, the radical

(first root) bursts through the seedcoat. Shortly

thereafter, the plumules (first leaves) appear and

later develop into the shoot that grows upward.

The first node or joint is found just beneath the

soil surface where it develops permanent roots.

When the seed is planted deeply, the subcrown
AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

intemode may grow 2 inches or longer before the

first node is apparent. The crown roots develop

at this point, and the tiller buds are formed.

After the seedling stage, the early growth above

the surface consists mainly of leaves. The stalk,

however, is developing during this period, mainly

by the formation of nodes very close together. A

leaf is produced at each node; the base or sheath

of the leaf closely surrounds the stalk. The internodes from this time grow more rapidly and become much longer. The number of internodes varies

with the varieties and individual stalks. Stalks

of most varieties taper from the base toward the

top ; the diameter of the last intemode or the peduncle is the smallest. The exterior of the mature

internodes of most varieties is covered with a thin

film of waxy bloom. This outer region (rind) of

the intemode is hard and consists of numerous

fibers that strengthen the stalk. The interior of the

stalk is composed mainly of soft pith that contains

the sweet juice.

The feeding roots originate from the lower nodes

or joints of the stalks at a point slightly beneath or

at the surface of the soil. The feeding roots radiate

in all directions and are always most abundant in

the upper first few inches of soil. The plant obtains

most of its moisture and mineral nutrients from

the upper 1 foot of soil although some of the roots

extend 3 to 4 or more feet downward when soil

conditions are satisfactory. If the soil is moist for

long periods of time, tough brace roots may develop considerably above the surface of the soil.

Those from the lower nodes may help to anchor

the plants to the soil. When the plants are 3 to 6

inches tall, some of the buds at nodes below the soil

surface develop into shoots that later become secondary stalks or tillers. In early stages, these tillers

can be distinguished from the initial stalks by the

fact that they grow out obliquely from the base.

Later they grow upright and develop into independent stems. At the stage when these tillers are

stems, they cannot easily be distinguished from the

initial stalks. They may mature a few days later or,

in some special cases, even a few days earlier, but

their juice quality is normally equal to that of the

main stalk, and they also should be used for sirup

production.

Initial stalks and tillers may put out short side

branches from their upper nodes when the seed

heads (panicle) fail to develop normally or when

harvesting is delayed after the seed are ripe. These

side branches may grow 12 to 15 inches long and

produce small seed heads. Side branches should not

be used for sirup f)roduction, but their presence on

the plant does not decrease the yield or quality of

sirup.

CHARACTERISTICS OF SWEET

SORGHUM VARIETIES

The desirable characteristics of sweet sorghum

varieties for sirup production are: (1) Ability to

produce a high yield of medium to large stalks per

acre; (2) strong, erect habit of growth, not readily

lodging during storms; (3) a high percentage of

extractable juice; (4) juice having a high total

soluble solids (Brix) content, mostly sugars; (5)

resistance to diseases; (6) ability to produce a

high-quality sirup; (7) comparatively short

growth period; (8) tolerance to drought; (9)

tolerance to excessive water; and (10) resistance

to damage from insecticides. Varieties differ greatly in these qualities and in their adaptation to soil

and climatic conditions. The grower should carefully consider all these qualities in his choice of a

variety.

Varieties used for sirup production vary in stalk

characteristics and potential ability to produce a

high yield of stalks per acre. A good variety should

yield stalks that are large in diameter and vigorous

enough to reach a good but not excessive height

and to develop two to four tillers. Varieties that

do not tiller freely usually produce low yields of

stalks. Tillering is also influenced by the condition

of the soil and by cultural practices such as row

spacing and planting time. It is, therefore, subject

to some control by the grower.

Lodging of stalks increases the cost of harvesting, which is a major expense in producing sweet

sorghum sirup. A good variety should resist

lodging. Lodging may be due to: (1) Inherited

weakness of the stalks that causes them to bend to

a horizontal position before harvesting; (2) severe

disease infection that weakens the stalks by destroying their internal tissue; or (3) caving over

of the entire plant, which may be influenced by

varietal weakness of the root system, poor cultural

practices, insect damage, or high wind during

rainstorms.

The percentage of juice extracted depends primarily upon the juiciness of the stalks and the
CULTURE OF SWEET SORGHUM FOR SIRUP

milling equipment. Most of the available commercial varieties have adequate juiciness. In general,

the small mills used to crush sweet sorghum stalks

consist of three rollers propelled by motor power.

Results from these mills are satisfactory when the

rollers are properly adjusted. Simple extraction

tests to determine the set of the rollers can be made

by weighing 100 pounds of stalks, passing the

stalks through the mill, and weighing the juice

extracted. The weight of the juice is the percent

extraction. A good sirup variety and a good mill

will yield approximately 55-percent extraction in

such a test.

Sirup yield per ton of stalks is determined by

the extraction and the total soluble solids content

(Brix) of the juice. A good variety should have

a high content of total soluble solids in the juice.

Varieties differ widely in their potential ability

to produce such juice. The total soluble solids content may be influenced adversely by diseases and

by cultural practices and climatic conditions that

hinder the normal development of the plants.

All commercial varieties are susceptible to one

or more of the sweet sorghum diseases. A satisfactory variety should be resistant to the major diseases. Losses from diseases may range from a

slight reduction in yield and quality of sirup to a

total loss of the crop. In addition to type of variety grown, cultural practices and time of harvest

may influence the overall effects of a disease

epidemic.

A good variety should produce high-quality

sirup that has the following characteristics: (1)

Light-amber color that is almost free of opaqueness; (2) mild, sweet flavor, nearly free of a tang;

(3) little colloidal sedimentation or sediment confined to a trace of small particles near the top or

bottom of the container; (4) high viscosity, which

causes sirup to move slowly when poured from

a container but to be free of a jellylike consistency

usually associated with a high starch content; and

(5) no crystallization or crystallization limited to

a few small crystals. Sound cultural and manufacturing practices are also important in producing

high-quality sirup.

A good sirup variety should mature and be

ready for harvest well in advance of the first date

of killing frost. Sweet sorghum varieties are quite

divergent in their date of ripening. The grower

488-707 0—73 2

should select a variety that is adapted to the growing season in his area.

Sweet sorghum varieties are quite different in

their tolerance to drought or excessive water during growing season. A variety to be grown in the

hill area where drought stress is common should

be well adapted to growing under low available

moisture conditions. Varieties, however, that are

to be grown on bottom land where flooding is common should be able to withstand extended periods

of excessive water.

Kesistance to damage from insecticides, particularly those used on cotton, is important for sweet

sorghum varieties that are grown in areas where

cotton is the important crop and aerial dusting

or spraying is common. Care should be used to

choose varieties in these areas that are tolerant or

resistant to these insecticides.

VARIETIES

The selection of the variety that is grown is one

of the most important decisions in the production

of sweet sorghum sirup.

Explorations have brought to the United States

valuable breeding material for use in extensive

variety-improvement programs. Typical is the

breeding and improvement work conducted at the

united States Sugar Crops Field Station near

Meridian, Miss. Here, the sorghums of the world

are being assembled, crossed, and improved so that

better sirup varieties adapted to the specific requirements of each locality can be developed and

made available to farmers.

The results of selecting for red rot resistance in

an established sweet sorghum variety are shown

in figure 1.

Below are brief descriptions of some commercial varieties known to produce good-quality sirup

under some conditions and to be suited to a wide

range of soil and climatic conditions in the principal States where sweet sorghum is grown for sirup

production. Comparative yield and other data for

these varieties are included in tables 1 and 2.

Before the grower buys seed, he should ask the

nearest agricultural experiment station agronomist or county extension agent about the suitability of these varieties in his locality. He should

choose the variety carefully and should buy the

best pure seed available.
AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OP AGRICULTURE

FIGURE 1.—On the left, sweet sorghum selection susceptible to red rot ; on the right, selection resistant to red rot under

normal conditions.

Wiley

Wiley is a late-maturing variety that originated

from two crosses made by the U.S. Department

of Agriculture. The first cross, made in 1947, involved Collier and MN 822. A second cross was

made in 1948 between the first generation of the

first cross and MN 2046. A superior selection from

the second cross was tested; this was released in

1956 under the name of Wiley (9).

Seed heads of Wiley (fig. 2) are of medium

length and semiconipact to irregularly compact.

The small, mostly globuse, reddish-brown seed extend about one-half to three-fourths beyond the

length of the straw-color glumes. The brown subcoat is absent. Under optimum conditions, the

stalks grow 12 to 16 feet tall. The stalks tend to

lodge more than Sart, are quite juicy, and are

easily crushed in a small mill. Wiley is immune

to red rot and leaf anthracnose, moderately resistant to zonate leaf spot and rust, and highly resistant to injury by the common cotton

insecticides.

The quality of the sirup is excellent. Wiley is

about 1 foot taller than Sart but matures at about

the same time. It usually yields about 18 gallons of

sirup per ton of stalks. Acre yields of sirup average about 34 percent higher than those of Sart
CULTURE OF SWEET SORGHUM FOR SIRUP

because Sart fails to make commercial sirup some

years. Wiley is recommended for the area of Tennessee southward. It usually requires 130 to 140

days to mature.

Sart

Sart is also a late-maturing variety of sweet

sorghum for sirup production. It is an original

variety introduced by the U.S. Department of

Agriculture into the United States in 1945 from

the Kordofan Province of Sudan, Central Africa

Sart (fig. 3) has relatively large white seed

when grown in the greenhouse but the seed are

characterized by irregular purplish spots in the

field ; the brown nucellar layer is always present.

The seed protrude well beyond the blackish

glumes. Seed heads are erect, compact, and cylindrical. The plants grow 8 to 14 feet tall, depending on the fertility of the land, the available moisture supply, and the length of the growing season.

Sart has large-barreled stalks thattiller well when

the plants are properly spaced in the field. The

hard rind of the stalk enable^ Sart to resist lodging under ordinary field conditions. It may develop characteristic multiple buds atthe nodes late

TABLE 1.—Relative yields and days to maturity of sweet sorghum at

Meridian, Miss., Holly Springs, Miss., and Orossville, Ala.

Location and variety

Stripped Sirup Sirup Days to

stalks per ton per acre maturity

per acre of stalks

Meridian, Miss. : ^ Percent Percent Percent Number

Brandes 106 100 106 143

Dale 75 98 74 120

Honey 81 82 68 120

Sart 104 72 74 133

Tracy 80 68 57 115

Wiley (standard) 100 100 100 142

Holly Springs, Miss. : 2

Brandes 82 91 75 140

Dale 76 106 81 128

Honey 105 90 94 121

Sart 104 83 84 137

Tracy 81 87 72 113

Wiley (standard) 100 100 100 140

Crossville, Ala. : ^

Brandes 114 107 122 138

Dale 98 109 108 127

Honey 106 102 107 118

Sart 89 82 71 134

Tracy 83 87 74 110

Wiley (standard) 100 100 100 138

1 All yields are expressed in percentage of the yield of Wiley, which was—

Stripped stalks per acre 22.2 tons.

Sirup per ton of stalks 17.1 gallons.

Sirup per acre 374.0 gallons.

2 All yields are expressed in percentage of the yield of Wiley, which was—

Stripped stalks per acre 17.9 tons.

Sirup per ton of stalks 16.0 gallons.

Sirupperacre 284.0 gallons.

3 All yields are expressed in percentage of the yield of Wiley, which was—

Stripped stalks per acre 15.2 tons.

Sirup per ton of stalks 16.2 gallons.

Sirup per acre_ 240.0 gallons.
AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

TABLE 2.—Relative yields y days to maturity, and lodging oj sweet

sorghum at Blairsville, Ga., and Quicksand, Ky.

Stripped Sirup Sirup Days

Location and variety stalks per ton per to Lodgper of acre matu- ing

acre stalks rity

Blairsville, Ga.: i Percent

Brandes 104

Dale 89

Honey 108

Sart 76

Tracy 84

Williams 96

Wiley (standard) 100

Quicksand, Ky. : 2

Brandes 80

Dale 85

Sart 93

Sugar Drip 83

Tracy 89

Williams 76

Wiley (standard) 100

Percent Percent Number Percent

86 90 135 0

94 84 142 0

90 98 125 8

82 63 114 6

56 50 116 1

107 103 116 38

100 100 135 9

90 73 128 0

100 S5 132 1

42 37 136 7

56 47 129 12

39 34 129 4

68 49 132 76

100 100 128 38

1 All yields are expressed in percentage of the yield of Wiley, which was—

Stripped stalks per acre 20.7 tons.

Sirup per ton of stalks 15.5 gallons.

Sirup per acre 319.0 gallons.

2 All yields are expressed in percentage of the yield of Wiley, which was—

Stripped stalks per acre 17.7 tons.

Sirup per ton of stalks 16.1 gallons.

Sirup per acre 264.0 gallons.

in season. It is very resistant to leaf anthracnose

and stalk red rot, moderately resistant to damage

by cotton insecticides, but susceptible to zonate

leaf spot and rust and should not be grown where

the latter two diseases tend to be prevalent.

When free of disease, Sart has juice of high

sugar content and under ideal conditions makes an

excellent, mild sirup. Under some conditions the

juice of this variety cannot be boiled down to

commercial density because of the presence of too

much starch. It yields about 17 gallons of sirup

per ton of stalks when the juice can be boiled down

to commercial density. This variety usually requires about 134 daysto mature. Itis recomi^aended

for use in Alabama, southern Georgia, and Mississippi. Sart is sensitive to day length and temperature and may act as an early variety (mature

in 100 days) if planted in April in the South.

Sart may also act as an early variety if planted

later than April at high elevations.

Tracy

Tracy, a midseason variety, originated from a

cross between White African and Sumac made in

1923 by the U.S. Department of Agriculture. The

final selection was released in 1953 under the name

of Tracy (81),

Tracy has small, brown seed with no brown

nucellar layer. The seed extend well beyond the

small, dark, reddish-brown glumes. Seed heads of

this variety are small, erect, compact, and almost

cylindroid. Under optimum conditions the stalks

grow 9 to 12 feet tall. Amount of tillering is intermediate and somewhat less than that of Sart. The

erect, juicy stalks are easily crushed in a small
CULTURE OF SWEET SORGHUM FOR SIRUP

mill. Tracy is susceptible to leaf anthracnose, red

rot, zonate leaf spot, and rust, but moderately

resistant to damage by cotton insecticides.

The quality of the sirup is inferior to that of

Wiley but is excellent under ideal conditions.

Under other conditions the juice of this variety

cannot be boiled down to commercial sirup density

because of the presence of too much starch. Tracy

usually yields about 19 gallons of sirup per ton of

FIGURE 2.—Typical head of Wiley sweet sorglium.

FIGURE 3.—Typical head of Sart sweet sorghum.

stalks. It is an exceptionally heavy-tonnage variety for the midseason group. On an average, the

per acre yield of sirup is about 55 percent of that

of Wiley. Tracy matures in about 116 days. It is

well adapted to the area from Kentucky southward where rainfall is adequate.

Brandes

Brandes, a late-maturing variety, originated

from a cross between Collier 706-C and MN 1500

(6).
8 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

The name "Brandes" was selected in honor of

the late Dr. E. W. Brandes, Head Pathologist in

charge of Sugar Crops Investigations, U.S. Department of Agriculture.

Brandes (fig. 4) seed are small, with a white

chalky color seed but lack the brown nucellar layer.

The endosperm is mostly corneous. The mediumlength panicle is semicompact to irregularly compact. Brandes usually produces seed that have a

high germination, which is retained well during

storage. It has an excellent root system coupled

with stiff, pliable stalks that usually remain erect

aftersevere storms.

Brandes is resistant to leaf anthracnose, red rot,

and many other important diseases. It is, however,

very susceptible to cotton insecticides and is not

recommended for areas where these insecticides are

applied by plane.

The yield and quality of sirup of Brandes compare favorably with those of Wiley under average

conditions. Brandes is less drought resistant than

Wiley and should be planted on soils with good

moisture-holding capacity. Lodging resistance is

the major advantage of Brandes.

Dale

Dale, a midseason variety with superior disease

resistance, was developed at the U.S. Sugar Crops

Field Station, Meridian, Miss. It is a selection

from the progeny of the fourth back-cross between

Tracy and MN 960 (P.I. 152857),=' with Tracy as

the recurrent parent (3).

Dale is similar in appearance to Tracy and matures at about the same time as Tracy and about

3 weeks earlier than Brandes and Wiley. Dale

(fig. 5) has a medium-length, somewhat erect,

compact panicle, which approaches a cylindroid

in shape. The glumes cover about one-third of the

seed and are reddish brown to blackish, with tufts

of hyaline pubescence at the base, apex, and

margins.

The seed are small and thresh free, and they

" P.I. refers to the accession number assigned to foreign

introductions by the Plant Science Research Division,

Agricultural Research Service, U.S. Department of Agriculture.

FiouBE 4.—Brandes, a sweet sorghum with excellent

lodging resistance.

FiGUBE 5.—Dale, an anthracnose-resistant

sweet sorghum for sirup.

mid-season
CULTURE OF SWEET SORGHUM FOR SIRUP 9

vary from obovoid to globose. Seed color varies

from light to dark reddish brown and is often

somewhat lighter where the seed are exposed. The

endosperm is starchy, with a medium to thick

corneous layer surrounding a chalky-white center.

It does not have the brown nucellar layer. Dale

seed usually have high-percent germination and

retain this high germination when stored properly.

Dale is resistant to leaf anthracnose and stalk

red rot, whereas Tracy is susceptible. Dale is tolerant to cotton insecticides.

The medium-sized stalks of Dale grow upright

and straight and are covered with a waxy bloom.

The stalks are juicy and sweet, producing a high

yield of sirup per ton of stalks. Dale normally has

adequate starch in its juice to give desirable sirup

body, but not enough to interfere with sirup manufacturing.

The sirup made from Dale has a mild sorghum

flavor and good color and is of excellent quality.

Sugar Drip

The origin of this midseason variety is not

known. Sugar Drip (fig. 6) has medium-size,

brown seed. The seed have a brown subcoat and

extend well beyond the dark reddish-brown

glumes. The seed heads are erect, medium size,

relatively compact, and nearly cylindroid. The

stalks are somewhat shorter and smaller barreled

than those of Tracy. Under good growing conditions, Sugar Drip may lodge enough to handicap

harvesting operations. Sugar Drip is very susceptible to most sorghum diseases in the sweet sorghum sirup area.

Honey

This variety was grown as early as 1880 by the

U.S. Department of Agriculture and was formerly

known as Honey Cane. One of its common names

is Texas Seeded Ribbon.

Honey (fig. 7) has medium-size, brown seed that

have a brown nucellar layer and are usually shorter

than the brownish-red glumes. The large, erect

seed heads are open and are variable in shape.

Under optimum conditions, the large-barreled

stalks grow 7 to 10 feettall. This variety has a very

weak stalk in relation to its height and tends to

lodge badly under ideal growing conditions. It is

very susceptible to all the major sorghum diseases

in the sweet sorghum sirup-producing areas and is

FiGUEE 6.—^Typical head of Sugar Drip sweet sorghum.

particularly susceptible to damage by cotton

insecticides.

Under ideal conditions, it produces a good yield

of juicy stalks and an excellent quality of sirup.

, Honey usually matures about midway between the

maturity dates of Tracy and Sart.

Georgia Blue Ribbon and Williams

Two varieties, Georgia Blue Ribbon and Williams, have an uncertain ancestry and appear to
10 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

FiGTJKE 7.—Typical head of Honey sweet sorghum.

be closely related. They have medium-size, brown

seed with brown subcoat. The seed are about as

long as the dark reddish-brown glumes. Seedheads

are semicompact and erect. The juicy stalks are

somewhat shorter and smaller barreled than those

of Tracy. These two varieties lodge badly and are

very susceptible to the major sweet sorghum diseases in the sirup area. They mature at about the

same time as Tracy but yield somewhat less tonnage of stalks per acre. They produce an excellent

sirup.

DISEASES

Sweet sorghum, like all other agricultural crops,

is subject to a number of diseases. Damage to a

crop may vary from year to year, depending on

locality, environmental conditions, and resistance

of varieties, from little or no loss to complete destruction of the crop. Sorghum diseases are easier

to prevent than to control, therefore, the resistance

of different sweet sorghum varieties to the prevailing diseases in an area should be considered when

selecting a variety. Appropriate cultural practices

such as crop rotation, clean cultivation, and seed

treatment will also aid in the control of some diseases and minimize losses from others. In this report, the specific diseases are discussed in order of

economic importance.

Downy Mildew

Downy mildew incited by the fungus Sclerospora sorghi (Kulk) Weston and Uppal is one of

the newer diseases of sweet sorghum in the United

States. This disease was first reported from Texas

in 1964 (17). Since then, it has spread to Georgia,

Kansas, and Mississippi {12.13, 18). The disease

is presently limited in distribution but its potential for further spread is considerable.

The most conspicuous symptom of downy mildew (the systemic phase) is the appearance of

vivid green and white stripes on the leaves in the

late spring (fig. 8). These striped leaves later split

or shred along the white stripes. Plants systematically infected frequently fail to head. Close examination of the underside of the leaves during humid

weather will show the presence of a white downy

material. This down or fuzz is made up of the

asexual fruiting bodies (conidia and conidiophores) of the fungus. The conidia (asexual

spores) are spread by the wind and infect other

plants in the field. The infection produced from

conidia (foliar infection) somewhat resembles

mosaic symptoms in that the leaves are mottled

and yellow. Downy mildew, in many instances,

however, can be distinguished from mosaic by the

presence of the white downy material (conidiophores) during humid weather. Foliar infection

may repeat itself several times during a growing

season so that a high percentage of plants may

become infected. If foliar infection occurs early

in the growing season, infected plants may develop systemic symptoms later in the season. These

plants may not produce seed heads.

As the systemically infected leaves shred,

oospores (sexual spores) are released from the

white striped areas of the leaf into the soil. These

oospores may remain viable in the soil for several

years. When sorghum is planted in an infested
CULTURE OF SWEET SORGHUM FOR SIRUP 11

FiGUBE 8.—^Sweet sorghum plants systematically infected

with downy mildew.

field, these oospores can infect the young seedlings

before they emerge from the soil. Those infected

seedlings that emerge will show a chlorotic mottle.

Those that do not die at a young age generally

develop the systemic symptoms and the disease

cycle is repeated.

Com and johnsongrass are also attacked by the

downy mildew fungus. Some varieties of sudangrass and broomcorn are very susceptible to injury

by the fungus.

CONTROL.—Brandes (^5) is resistant to downy

mildew and should be grown in areas where the

disease is present.

Anthracnose and Red Rot

The fungus CoUetotrichum graminicolum (Ces.)

G. W. Wils incites two phases, anthracnose and

488-707 O—73 3

red rot, of one of the most destructive diseases of

sweet sorghum in the Southeast (14-) •

The anthracnose phase usually appears on the

leaves of susceptible varieties in midsummer as

small, circular to elliptical spots ranging from

one-sixteenth to one-quarter inch in diameter. The

spots are well defined and vary in color from tanorange-red to blackish-purple, depending on the

variety affected. Under conditions of high humidity the spots increase in number and enlarge to

cover a large part of the leaf area. Midrib infection commonly occurs as elliptical to elongate discolored lesions. These lesions frequently coalesce

so that the entire length of the midrib is covered.

Leaf anthracnose may occur at any stage of plant

development but normally shows up in midsummer when plants are from 3 to 5 feet tall. Anthracnose may defoliate the plants markedly, thus

reducing the sugar content of the juice. In severe

cases, plants of susceptible varieties such as Hodo,

Honey, C. P. Special, and Williams may be killed

before they reach maturity (fig. 9). Fortunately,

varieties such as Brandes, Dale, Sart, and Wiley

are resistant to the disease.

The red rot phase primarily affects the stalks of

the mature plant. Spores of the fungus from the

anthracnose phase produced on the leaves are

washed down behind the leaf sheath by rains.

These.spores germinate and the fungus enters the

stalks at any time after the jointing stage and

causes rotting of the interior of the stalk (fig.

10). Infected areas become discolored and the enFiGUBE 9.—Anthracnose on C.P. Special, resulting in total

destruction of plants.
12 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE 1

1

y

\

1

{ßJi). The disease normally appears on the upper

two to three leaves as an irregular mottling of

green and light-green areas often interspersed

with longitudinal white or light-yellow streaks

{11) (fig. 11). On some varieties, however, the

disease will appear as a brilliant-red, mottled

streaking of the upper leaves or as mottled necrotic

lesions on the upper leaves, depending on the variety afïected (fig. 12). The virus is transmitted

from diseased plants to healthy plants in the field

by several species of aphids (ß3).

Mosaic has been known on sorghum for many

years with little cause for concern. In the past,

mosaic has been confined to areas in the vicinity of

diseased sugarcane plantsthat have carried the disease over from year to year. However, since 1965, a

mosaic disease has been found on sorghum in

widely scattered areas of the Southeast where

sugarcane has never been grown. This form of the

J

9?f ;

•is,.

ps^'^

FIGURE 10.—Stalks of sweet sorghum on right Infected

with red rot.

tire stalk may become rotted in advance stages.

When diseased stalks are split lengthwise, discolored areas interspersed with white can be seen

throughout the affected parts of the stalk. Badly

rotted stalks yield less juice than healthy stalks

and produce poor-quality sirup with a reddish

color.

CONTROL.—To control anthracnose and red rot,

grow resistant varieties such as Brandes, Dale,

Sart, and Wiley. However, if a suspectible variety

is grown, crop rotation and clean cultivation will

help reduce the threat from this disease because

the fungus overwinters on the crop residues of

sweet sorghum. The fungus also attacks broomcorn, Johnsongrass, and sudangrass.

Mosaic

Mosaic on sorghum is caused by the sugarcane

mosaic virus (,?) or one very closely related to it

FIGURE 11.—Mosaic on sweet sorghum showing typical

mosaic pattern.
CXJLTURE OF SWEET SORGHUM FOB SIRUP 13

FiouRE 12.—Mosaic on sweet sorghum showing the red or

necrotic reaction.

virus also infects johnsongrass, corn (Zea mays

L.), perennial fescue {Festuca spp.), foxtail {Setaña spp.), and many other grasses. These grasses

may also harbor some vectors of the virus (corn

leaf aphid, rusty plum aphid) and if they become

infected, spread of the disease into nearby sweet

sorghum fields is likely.

Some varieties, such as Williams and Sugar

Drip, when infected at an early stage of growth,

may be severely stunted (^^). On the other hand,

varieties such as Dale, Sart, and Wiley may not be

severely affected by the disease. Brandes is moderately resistant to mosaic infection in the field.

Grey Leaf Spot or Angular Leaf Spot

Grey leaf spot or angular leaf spot of sorghum

incited by the fungus Cercospora sorghi Ell. and

Ev. is a conspicuous disease of rather minor importance. The spots are rather long and narrow

and limited somewhat by the leaf veins, giving

them an angular appearance (fig. 13). As the spots

enlarge, they become covered with copious greyish

mycelium of the fungus. This disease is also found

on johnsongrass and sudangrass.

Although all available sweet sorghum varieties

are susceptible to grey leaf spot, the disease generally occurs late in the growing season after the

crop is matured so that little loss results.

Bacterial Stripe

Bacterial-stripe disease of sweet sorghum, incited by PseudoTnomm androfogoni (E.F. Sm)

Stapp, is found throughoutthe sorghum sirup area.

The disease is characterized by tan-brick-red to

dark purplish-red stripes on the lower leaves. These

stripes are generally restricted to the interveinal

areas of the apical parts of the leaves (fig. 14).

WV.

;l.rflVTI' i I.I , , 1

FiGUKE 13.—Grey or angular leaf spot on Rio sweet

sorghum.
14 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

FIGURE 14.—Bacterial stripe on leaves of 3 sweet sorghum

varieties.

(The difference in color is due to varietal reaction to

the disease. )

They range in length from less than 1 inch to the

length of the leaf blades. Sometimes the stripes

fuse so that large areas of the leaf are affected. A

slime or bacterial exúdate may be found on the

affected part of the leaves and along the leaf

margins.

Bacterialstripe, although conspicuous in appearance and widely distributed throughout the sweet

sorghum belt, does not generally reduce yields

significantly.

Leaf Blight

Leaf blight incited by the fungus Helminthosporium turcicum Passerini and southern leaf

blight incited by the fungus H. Tnaydis Nisikado

and Miyake have been known on sweet sorghum

in the more humid areas of the South for many

years. Varieties that were injured by leaf blight

have not been grown extensively so that although

no direct effort has been made to obtain resistance

to leaf blight, sweet sorghum varieties now produced have some resistance. During the leaf blight

epiph3i;otic {H. maydis) of 1970, all sweet sorghum varieties showed some slight degree of

infection ; however, there was little or no damage

to infected plants.

Insecticide Injury

Some sweet sorghum varieties are susceptible to

injury from certain cotton insecticides such as o,odimethyl o-(/>-nitrophenyl) phosphorothioate

(methyl parathion), toxaphene, and some of the

other organic phosphates (fig. 15). Widespread

injury from airplane dusting of cotton may occur

when sweet sorghum is planted close to cottonfields. This injury appears as irregular, circular or

elliptical, watersoaked spots on any part of the

leaves within 24 hours of the time the chemical

is applied. These spots dry out and turn reddish to

blackish on the margin within 72 hours. When a

large quantity of insecticide is applied to a susceptible variety, large parts of the leaves may be

destroyed. Repeated applications of insecticides

may severely stunt or kill plants of susceptible

varieties.

CONTROL.—If sweet sorghum is to be grown near

cottonfields, plant varieties such as Dale, Sart, or

Wiley, which are only slightly affected by insecticides (7). If susceptible varieties such as Honey

or Brandes are to be grown, plantthem as far from

cottonfields as possible.

Rust

Sorghum rust incited by the fungus Puccinia

purpurea Cke. occurs generally in the more humid

regions of the sirup area every year. It is not as

prevalent in the less humid regions. Rust appears

on both surfaces of the leaves as small, raised,

brownish pustules, filled with powdery brown

spore masses (fig. 16). By rubbing the fingers

gently over these raised pustules one may easily

differentiate between rust and other leaf spots. In

severe infections, these pustules may be so nuFiQTiBE 15.—Insecticide injury on Honey sweet sorghum

72 hours after application of the chemical.
CULTURE OF SWEET SORGHUM FOR SIRUP 15

FiGXJEE 16.—Rust on Sart sweet sorghum.

merous that the entire leaf is destroyed. If severe

infection occurs when the plants are almost mature, as often happens in some areas, heavy losses

may be avoided by harvesting the crop in the late

milk or early dough stage. Growing resistant or

tolerant varieties is the only practical method of

rust control. All of the available sirup varieties of

sorghum, except Brandes, are somewhat susceptible to rust. However, all varieties can be grown in

most of the sirup areas with little or no damage

from rust. Brandes is completely rust resistant.

Rough Spot

Eough spot incited by the fungus Ascochyta

sorghina Socc. is prevalent throughout the sirup

area of the Southeast. This conspicuous leaf disease is easy to identify by the sandpaperlike roughness caused by the hard, black, raised fruiting

bodies of the fungus in the late stages. The disease

begins as small, circular to oblong, light-color

spots near the ends of the leaves. Small, hard,

black specks, the fruiting bodies of the fungus,

develop in the injured areas. As the spots enlarge,

they grow together so that the size of the diseased

areas may cover a large part of the leaf. Generally

the damage from rough spot is not severe.

Smut

Three smuts of sorghum occur in the United

States: covered kernel smut incited by the fungus

Sphacelotheca sorghi (LK) Clint; loose kernel

smut incited by the fungus Sphacelotheca cruenta

(Kuehn) Potter; and head smut incited by the

fungus Sphacelotheca reiliana (Kuehn) Clint.

These diseases are rarely destructive on sweet sorghum in the sirup area.

Covered kernel smut is readily controlled by

treating the seed before planting with any of the

good seed treatment fungicides on the market.

Loose kernel smut arising from seedbome fungus spores is also controlled by chemical seed

treatment. However, most of the loose kernel smut

found in sweet sorghum in Mississippi is not the

result of seedborne inoculum but is the result of

secondary infection resulting from inoculum originating on smutted johnsongrass growing in or

around the field {10). Chemical seed treatment is

of no value in controlling loose smut from this

source. Only certain varieties are susceptible to

this mode of infection : Sart is; Wiley and Tracy

are not.

Head smut cannot be controlled by chemical seed

treatment; however, the disease is not important

in the sirup-producing areas.

Pokkah Boeng

Pokkah boeng or twisted top incited by the fungus Gibherella moniliformis (Sheldon) Wineland

occurs during periods of high rainfall. This disease

is characterized by deformed or discolored leaves

near the top of the plant (fig. 17). In severe cases,

the leaves become so wrinkled and drawn thatthey

are unable to unfold properly. In very severe cases,

infection may pass from the leaves and sheath into

the stalks, causing death of the tops. Although the

disease may be very conspicuous on some varieties,

losses are usually minor.

Zonate Leaf Spot

Zonate leaf spot incited by the fungus Gloeocercospora sorghi Bain and Edgerton is common in
16 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

FIGURE 17.—Pokkah boeng or twisted top of sweet

sorghum.

the humid areas of the Southeast. The disease is

very conspicuous on sorghum leaves as circular

reddish-purple bands alternating with straw- or

tan-colored areas, forming a concentric or zonate

pattern (fig. 18). These spots vary in size from a

fraction of an inch in diameter in the early stages

to several inches in later stages. In these later

stages the entire width of the leaf may be covered

so that in effect the leaf may be considered cut

off from the stalk at this point. When a high incidence of the disease occurs on plants in the seedling stage, severe defoliation and death of infected

plants may follow. Abundant spotting on the

leaves of older plants may cause premature destruction of the foliage, reduction of sugar content

of the juice, and some reduction in yield of stalks.

The fungus also attacks corn, johnsongrass, sudangrass, sugarcane, and other grasses.

CONTROL.—Fully developed measures for the

control of this disease are not presently known.

Crop rotation and clean cultivation to destroy

residues of susceptible host crops should reduce the

likelihood of severe losses in sweet sorghum.

Highly resistant varieties are not presently

available.

Root Rot and Seedling Blight

Several soilbome and seedbome fungi reduce

stands by rotting the seed after they are planted

or by killing young plants soons after the seed

germinate. These fungi may be particularly

FIGURE 18.—Zonate leaf spot of sweet sorghum.

damaging if a period of cool weather occurs soon

after planting. Seed treatment with the same

chemicals used to control the smut diseases may

help to reduce thistype of damage.

Summary of Disease-Control Measures

Three primary control measures should always

be considered in growing sweet sorghum: (1)

Planting resistant varieties when they are available; (2) crop rotation and clean cultivation; and

(3) chemical seed treatment.

INSECTS INJURIOUS TO SWEET

SORGHUM '

Sweet sorghums are infested by several species

of insects. Usually insect damage is slight but occasionally it is severe.

'Reviewed by C. A. Henderson, research entomolglst,

Southern Grain Insects Investigation, Southern Region,

Agricultural Research Service, U.S. Department of Agriculture, State College, Miss. For information on Insecticide

control of Insects attacking sweet sorghum, consult your

State agricultural experiment station.
CULTURE OF SWEET SORGHUM FOR SIRUP 17

Lesser Cornstalk Borer

The lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), may severely damage young sweet

sorghum plants during dry periods. These insects

bore into the plant near but below the soil surface

and reduce the stand.

This larva is slender and greenish and has darkbrown, longitudinal bands. It is about 1 inch long

when full grown. It makes a rapid jerking motion

when disturbed.

The lesser cornstalk borer can be controlled by

the proper use of insecticides.

Sorghum Midge

The sorghum midge, Gontarinia sorghicola

(Coquillet), occurs over most of the Gulf Coast

and ¡South Atlantic States. It is a small orangecolored fly that deposits white eggs in the glumes

at blossoming time. The larvae feed on the developing glumes and destroy the sorghum seed. As they

grow, the larvae darken from pink to orange. A

generation is produced in about 15 days.

The sorghum midge feeds on the heads of sweet

sorghum, grain sorghum, broomcorn, johnsongrass,

and sudangrass, but does not have a detrimental

effect on sweet sorghum used for sirup. It winters

as a cocooned larva in the spikelets of the host

plant. The flies appear early in the spring at about

the time johnsongrass begins to bloom; they lay

their first eggs in the heads of this grass.

It is difficult to control the midge with insecticides. Losses can be reduced by locating sweet

sorghum fields where johnsongrass is not common

or b}^ cutting or destroying nearby johnsongrass

before it blooms. Plant all the sweet sorghum at

the same time and properly space and cultivate

it to produce uniform heading. Destroy heads that

bloom much before the main crop. Before the

flies emerge in the spring, plow under or destroy

all material in which the midge may hibernate.

Satisfactory crops of sweet sorghum for seed

can be obtained if paper bags are tied over the

heads of selected plants during the blooming season to protect them from midge infestation. Eemove the bags shortly after the blooming period

because they provide conditions favorable for the

corn earworm and corn leaf aphid that attack the

seed heads.

Sugarcane Borer

The Sugarcane borer, Diatraea saccharalis (Fabricius), occurs in southern parts of Florida, Louisiana, and Texas, but rarely in Mississippi. It attacks sugarcane, corn, rice, broomcorn, sorghum,

sweet sorghum, and several wild grasses. The adult

is a moth that deposits eggs in clusters on the

leaves of the host plant. The eggs hatch into small

white larvae that bore into the stalk and make

tunnels in it. These tunnels reduce the growth of

the injured plants, weaken them so that they break

over, and furnish entrance places for various organisms that may lower the sugar content. A generation of the sugarcane borer is produced in about

40 days. The pest overwinters as a larva in the

stalks or stubbles left in the field.

Borer injury to sweet sorghum usually is not

heavy until the latter half of August or September. Consequently, early-maturing varieties or

early plantings are valuable in decreasing injury.

In infested areas, plant sweet sorghum as far as

possible from fields of sugarcane, corn, and rice.

Before moth emergence in March or April, plow

under or destroy stubble and pieces of sweet sorghum in which the larvae hibernate.

Corn Leaf Aphid

The corn leaf aphid, RTiopalosiphwn rnaidis

(Fitch), is sometimes very common on sweet sorghum throughout the sirup-producing area. It is

usually found in the central whorl of the plant or

on the panicle after it has emerged. This aphid has

been seen in such heavy numbers that it prevented

the formation of grain. It transmits the sugarcane mosaic disease, which attacks sweet sorghum.

Plant sweet sorghum as far as possible from mosaic-infected sugarcane or wild grasses.

Fall Armyworm

The fall armyworm Spodoptera frugiperda

(J. E. Smith), is found in the United States

wherever sweet sorghum is grown for sirup. The

larva is grayish and has three whitish longitudinal

bands and a blackish head. It is about 1% inches

long when full grown. It eats the leaves of corn,

sugarcane, sweet sorghum, and a number of wild

grasses, and may strip the plant of leaves.
18 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

Com Earworm

The corn earworm, Heliothis zea (Boddie), is

found throughout the United States. It attacks

many food plants. The moth varies from a light

olive green to a dark reddish brown. Eggs are laid

singly on sweet sorghum leaves and hatch in about

4 days. The caterpillars, feeding mostly in the leaf

whorl, become full grown in about 3 weeks and

are then about Xy^ inches long. They are pink,

green, cream, or yellow, and often striped. The

pupae pass the winter in the soil. In the Gulf Coast

States, there are four full generations each year.

Wireworms

Wireworms are the larvae of click beetles, Elateridde. They are yellow or brown and about i/^ to

1 inch long. They are hard, shiny, and slender.

Wireworms injure sweet sorghum by boring into

the plant seed, drilling into the young shoots, and

feeding on the roots. Sometimes replanting is

necessary. Wireworms can be controlled by

insecticides.

Other Insects

The whorls of the sorghum plant often are infested by a sharp-nose grain leafhopper, Draeculacephala portóla Ball. Stink bugs, Pentatomidae,

have been observed in considerable numbers sucking the glumes. Flea beetles, Chrysomelidae, sometimes feed on the under surface of the leaves. The

white-fringed beetle, Graphognathus spp., damages stand under some conditions.

INSECTS INJURIOUS TO STORED

SWEET SORGHUM SEED

Sweet sorghum seed is attacked by many kinds

of insects that commonly infest stored grains. The

more important ones are the Angoumois grain

moth, Sitotroga cerealella (Olivier), and the rice

weevil, Sitofhilus oryzae (L.). These insects begin

their attack on the seed in the field before harvest

and continue their infestation and damage during

storage. Other species attack the seed only during

storage. Malathion, pyrethrins plus piperonyl butoxide, or diatomaceous earth applied to stored

seed will control these pests. Follow the directions

on the label for application as grain protectants.

Additional general information on bulk grain protectants and application methods can be found in

U.S. Department of Agriculture Marketing Bulletin No. 20.

CULTURAL PRACTICES

Yield and quality of sweet sorghum sirup and

the economy of handling the crops are affected

by the soil type, crop rotation, fertilization practices, growth and diameter of the stalks, erectness

of the stalks, uniformity of plant maturity, and

ability of plants to withstand deterioration after

reaching approximate maturity. Cultural practices that influence some of these factors are discussed in the following pages.

Sail Requirements

Many different types of soil are used for the

production of sweet sorghum, but a soil of good

physical character and high fertility produces the

best yield. Poor soils usually produce slow-growing plants with small stalks. In general, loam

and sandy loam soils are best for the growth of

sweet sorghum for sirup production.

Soils high in organic matter are thought to have

a detrimental effect on the quality of sirup. However, if other cultural practices are satisfactory,

good-quality sirup is frequently made from sweet

sorghum grown on soils that are high in organic

matter supplied by green manure crops.

The field should have good natural drainage,

especially in localities that may have periods of

heavy rainfall. Ample moisture during the growing period is also important for good yields of

stalks and sirup. Organic matter improves the

waterholding capacity of the soil.

If the planting is to be done early in the season,

a soil that becomes warm early should be used.

Heavy clay soils that warm slowly in the

spring often remain cloddy after the seedbed has

been prepared and have a tendency to form crusts

through which the sweet sorghum seedlings cannot push to the surface. These soils usually produce poor stands, poor yields, and poor sirup.

Crap Ratatian

Sweet sorghum usually fits into most common

crop rotation systems. Cotton and com are the
CULTURE OF SWEET SORGHUM FOB SIRUP 19

principal crops in most of the sweet sorghum

sirup area. They can be used with sweet sorghum

in a rotation system. Because cotton is a cleancultivated crop, it usually leaves the land in good

condition for sweet sorghum the next year; few

weeds will be present in the soil to interfere with

the young sweet sorghum plants. The cotton stalks

should be thoroughly chopped into the soil several

weeks before sweet sorghum is planted so that

the deterioration of the stalks will not interfere

with the germination of the seed.

A winter cover crop may be grown in the cotton rows. However, during many seasons a cover

crop cannot be planted early enough in the fall to

produce a satisfactory growth before cold

weather. Because the cover crop must be turned

under early in the spring to avoid damage to sweet

sorghum seed, the cover crop usually does not have

time to produce a satisfactory yield of green

manure.

Sweet sorghum may be grown successfully following a corn crop. The cornstalks should be

thoroughly chopped into the soil several weeks

before sweet sorghum is planted. However, an

abundance of weed seed is usually present in the

soil following the corn crop ; therefore, weed control in sweet sorghum following corn may be

difScult.

Planting soybeans in May or June on land to

be used for sweet sorghum the following year is

usually a very good practice. The plants may be

disked down and permitted to remain on top of

the soil during the winter months. In the spring

they are turned under and allowed to deteriorate

in the soil. Sometimes the beans are harvested and

the stalk refuse spread on the land. After any of

these treatments, the land usually has enough

organic matter to place it in good condition for

the sweet sorghum seed the following year.

Other types of leguminous plants, particularly

blue lupine {Lupinus angustífoliiis L.) or field

peas (Pisum sativum subsp. arvense (L) Poir)

(wheie these crops grow well), have been used in

rotation with sweet sorghum with equal success.

Fertilization Practices

Fertilizer requirements for land used for growing sweet sorghum depend largely on soil types,

rainfall, crop history, and previous additions of

manure and fertilizer.

The heavy types of soil may produce a good

sweet sorghum crop with a moderate amount of

fertilizer. Sandy soils are generally less fertile

than heavy soils and usually require more fertilizer for a good growth of sweet sorghum. Some

upland soils of intermediate types such as silt

loams produce a poor sweet sorghum crop without

fertilizers. Lime should be applied to acid soils

to correct soil acidity, supply calcium, improve

availability of other plant nutrients, and increase

eiSciency of added fertilizer and manures.

When legume cover crops are used for green

manure, the need for fertilizer, especially nitrogen, is reduced. This need for fertilizer is also

reduced on land that has been well manured in the

past or on land just plowed out of improved pasture.

Many growers add fertilizer or manure before

planting sweet sorghum. This treatment furnishes

the young plants with an abundant supply of

plant food to give them a quick start. It also helps

them to overcome such hazards as weeds, soil

crusts, insects, and diseases.

In a fairly fertile soil a small application of

fertilizer to help this early growth may be all that

is necessary for the entire season. On many soils,

however, the quantity of fertilizer applied at

planting time should be greater than that needed

for a starting effect only. Moreover, fertilizer may

be added later.

Each grower should study his soils and fertilization practices and get current fertilizer and liming

recommendations from the nearest experiment

station or the county extension agent.

Most of the fertilizer used for sweet sorghum is

a mixture of nitrogen, phosphorus, and potassium.

The ratio varies in different localities, depending

on local requirements or customs. Nitrogen particularly is needed in most soils and is usually

given first consideration.

It is not possible to recomimend a single fertilizer practice to fit all farm conditions. In the

absence of specific information about the needs

on a particular farm, the grower should use the

standard fertilizer formula for his area such as

4-12-12 (N, P2O5, K2O), 6-8-8, 12-8-8, or

13-13-13. These mixtures should be applied in

amounts that will supply approximately 40 pounds

of nitrogen (N) and phosphate (P2O5) [18 pounds

of phosphorus (P) ] and 30 to 40 pounds of potash
20 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

(K2O) [25 to 33 pounds of potassium (K)] per

acre. On sandy soils, it may be advisable to apply

part of the nitrogen at planting time and the remainder as side dressing before the crop is 30

inches tall. Typical yield data from fertilizer tests

in Mississippi with the Wiley variety of sweet

sorghum (table 3) indicate that 40 pounds of nitrogen per acre produced maximum economically

profitable yields (^).

It was formerly believed that nitrogen added in

an organic fertilizer such as cottonseed meal or

tankage produced a superior sirup. Present (1972)

information indicates that a sirup of good quality

can be produced also by the use of inorganic nitrogen in ammonium sulfate, sodium nitrate, ammonium nitrate, and anhydrous ammonia {15).

Nitrogen should be applied during early growth

in amounts not exceeding the requirements of the

crop.

A late application of manure or high-nitrogen

fertilizer ordinarily should be avoided. When a

side dressing is used, the fertilizer should be applied before the crop is 30 inches tall. If fresh

manure is used, it should be applied to the previous crop instead of directly to the sweet sorTABIíE 3.—Efeçts ojfertilizer on the yield oj Wiley

sweet sorghum at State College, Miss.

FçrtiUzer per acre Stripped Sirup per Sirup

stalks per ton of per

N P2O5 K2O acre stalks acre

Pounds Tons Gallons Gallons

0 0 20___ 17.0 18.7 312

0 40 20___ 17.2 19.0 324

0 80 20_._ 17.3 18.7 324

40 0 20___ 21. 1 20. 1 418

40 40 20___ 20.5 19.4 390

40 80 20_-_ 20. 1 19.3 380

80 0 20___ 21. 1 19.4 401

80 40 20___ 21.6 19.5 412

80 80 20___ 22.2 19.2 416

Mean 19.8 19.2 375

L.S.D. at

5-percent

level 1.3 NS 40

L.S.D. at

1-percent

level 1.7 54

ghum crop. If heavy additions of manure are made

directly before the sweet sorghum is planted, a

poor-quality sirup may be produced.

When the fertilizer is applied in the row, either

beside or below the seed, smaller applications are

required than when it is broadcast. Both methods

appear to be satisfactory. The need should never

be allowed to come in contact with the fertilizer.

This contact may kill some emerging seedlings

and result in a poor stand.

Seedbed Preparation

Thorough preparation of the seedbed by breaking to a depth of 4 to 6 inches is important in the

production of sweet sorghum. The land should be

plowed early so that there will be ample time

for all plant material to decay before the average

planting date for sweet sorghum.

Disking the land thoroughly after plowing

destroys clods and facilitates decomposition of the

organic matter. Usually the organic matter is left

on top of the soil through the winter months,

where it protects the soil against erosion and remains in the best form until spring. This material

is later disked into the soil during seedbed preparation. After the land is disked, the rows are set

up in ridges with a middle buster.

Rows should be set up in time for settling by

rainfall before planting. Firm beds preserve essential moisture until optimum planting time. A

firm, moist seedbed is essential for obtaining a

stand of sweet sorghum.

At planting, the tops of beds are scraped off

down to the moist soil with a planter with running

wings (fig. 19). The planter destroys early weeds

and leaves the land in ridges about 4 inches high.

This operation makes possible a uniform depth of

planting, fertilizer application, and preemergence

application of chemicals for weed control in a

firm moist seedbed.

Planting Time

The optimum time to plant sweet sorghum can

best be determined from actual practices in the

community. Planting when the soil is thoroughly

warm produces good germination, early growth,

and uniform stands. An adequate supply of moisture is also essential for satisfactory germination
CULTURE OF SWEET SOEGHUM FOR SIRUP 21

-Firm, moist seedbed developed by scraping off tops of ridges and placing seed, fertilizer, and weed-control

chemical with planter with runner wings.

and early growth. Therefore, delay m planting

until rainfall is scant and the warming of the soil

has resulted in nauch loss of moisture is not

advisable.

Typical yield data from date-of-planting tests

in Meridian, Miss., with sweet sorghum (fig. 20)

show that under normal conditions the best planting time may extend over a period of several days.

In the early plantings the early growth was slow ;

as a result, weed control was difficult. In the late

plantings, total production was low. The best

planting period is usually from the middle of

April to the middle of May.

Eesults from tests made at Meridian, Miss., to

show the influence of planting date on time required to reach the dough stage of maturity were

as follows :

Time to

maturity

Date of planting : ( Days)

April 1 , 126

May 1 117

June 1 106

Late plantings grow more rapidly than early

plantings. However, sweet sorghum must be

planted early enough to mature before the first

killing frost.

The late-maturing varieties usually produce the

highest yields of sirup per acre. However, even

under the best planting conditions the latematuring varieties take longer to develop than

early varieties. The late-maturing varieties can be

grown only in localities where the plants reach

maturity by harvesttime.
22 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

<

(O

I-'

w

D

a.

'C+.*

V)

April 1 May 1

Planting Date

June 1

FiGUEE 20.—Yields from date-of-planting tests of sweet

sorghum at Meridian, Miss., 1968-70.

In the major sirup-producing areas the planting period may extend from the middle of April

to about the middle of May. The planting period

may be limited in the northern part of the sweet

sorghum belt to a 10- to 15-day period near the

middle of May. Otherwise, the plants may not mature before the first killing frost.

Planting Methods

Planting is one of the most important cultural

operations in sweet sorghum production. A uniform, adequate stand influences the yield obtained

and the amount of work required to control weeds.

The seed should be covered with about IV2 inches

of sandy soils and about 1 inch of the heavier soils.

The soil should be firmly packed around the seed.

Many dependable planters are available that drop

the seed regularly either in hills or in drills. These

planters are also equipped with a split, concave

wheel for covering and packing the soil around the

seed. Hill plantings of two stalks every 16 inches

and four stalks every 24 inches have produced

yields equal to those of drill plantings where one

stalk is left every 6 to 8 inches in the row. Tables

4 and 5 show results from hill plantings in Mississippi. Hill plantings require less seed for planting

and less labor for thinning, cultivating, and harTABLE 4.—Effects of spacing on the yield of Tracy

sweet sorghum at Meridian, Miss.

Method of Stripped

planting Spacing stalks Lodging

per acre

Plants/hill Inches Tons Percent

DriU:

1 8 12.4 3.4

Hill:

2 16 1L9 2.4

3 24 11.2 1.9

4 24 1L9 1.8

L.S.D. at 5-

percent level .4

L.S.D. at 1-

percent level .5

vesting than drill plantings require. Seed planted

in hills emerge better in crusted or compacted soUs

(fig. 21) than seed planted in drills. Sweet sorghum

seed germinate within 3 to 5 days under optimum

moisture and temperature conditions.

Row Spacing

Most sweet sorghum is planted in rows that are

spaced about 42 inches apart on low ridges or on

FIGURE 21—Hill-planted sweet sorghum plants emerging

in crusted soil.
CULTURE OF SWEET SORGHUM FOR SIRUP 23

TABLE 5.—Efects of spacing on the yield of Wiley sweet sorghum at

Meridian, State College, and Holly Springs, Miss.

Stripped Sirup Sirup

Method of Spacing stalks Stalk Lodging per ton per

planting per weight of acre

acre stalks

Plants/hill Inches Tons Pounds Percent Gallons Gallons

Drill:

Hii:

1

3

6

9

12

24

16.3

16.6

15.8

15.0

14.6

15.4

0.5

LO

L4

L7

1.9

L8

11

9

4

4

3

17.9

18.4

18.9

18.6

18.4

19. 1

300

310

301

282

271

295

L.S.D. at 5- LO NS 25

percent level.

L.S.D. at 1- L3 NS

percent level.

practically level land. Planting sweet sorghum in

rows 4 to 6 feet apart results in decreased yields.

The data in table 6 show typical yields from

different row spacings (19). Most of the equipment on farms in the sweet sorghum sirup area is

not designed for cultivating rows spaced 2 feet

apart. The relatively small advantage of using

such narrow rows usually does not justify the

extra total expenditure that is involved in redesigning the equipment. Eows spaced about 42

inches apart are satisfactory for sweet sorghum

production in the sirup area.

Cultivation

Cultivation should start when the plants are 3

to 4 inches high. Early cultivation can be performed successfully with horse-drawn or tractor

cultivators equipped with spring teeth, small

plows, or small disks. These critical, early, shallow

cultivations control the young weed growth and

furnish a mulch around the plants. Depth of cultivation depends largely on the root spread; it

should destroy weeds but not prune the root system

excessively. Early cultivations may be somewhat

deeper than later ones because root development in

the early stages is not extensive. The early cultivations may be deeper in the middles than next to

the plants ; moderately deep cultivation may often

be continued there without causing injury until

the crop is ready to lay by.

The cultivation may be level or the rows may be

ridged (fig. 22). Eidges reduce soil erosion, facilitate drainage, and anchor the stalks against

lodging.

Time of planting, variety of sweet sorghum,

type of weed infestation, and climatic conditions

inñuence the number of cultivations. Because late

plantings grow rapidly, fewer cultivations are

needed for them than for early plantings. EarlyTABLE 6.—Results from a typical row-spacing test

at Meridian, Miss.

Row spacing

(feet)i

Weight of stalks

Per Per

acre stalk

Sirup

per

ton of

stalks

Sirup

per

acre

Tons Pounds Gallons Gallons

2 _ 19.6 1.2 18.3 359

3 _ 18.2 1.5 19.0 436

4 . 12.2 1.4 19.5 238

5 _ 11.9 1.4 19.1 227

^ The plants were spaced 8 inches apart in the drill.
24 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

FIGURE 22.—Bidged sweet sorghum during lay-bycultivation.

maturing varieties grow faster early in the season

than late-maturing ones, shade the soil sooner, and

usually require fewer cultivations. Perennial weeds

such as Johnsongrass and bermudagrass, Gynodon

dactylon (L.) Pers., and fast-growing, vigorous

annual weeds may necessitate more cultivations.

Hoeing and Thinning

Planting six to eight good seed in hills 24 inches

apart and early cultivation will usually eliminate

the need for hoeing and thinning (spacing). However, if hoeing is required to remove weeds and

space plants properly in drills, the ground may

be hoed when the plants are about 3 inches tall.

Whether the ground is hoed immediately before or

imfnediately after the first cultivation depends

largely on the weed infestation. When the weed

infestation is heavy, hoeing is usually easier and

cheaper after the first cultivation. Plants should

always be thinned before tillers are put forth;

the earlier the plants are thinned, the better.

The plants in single drills should be spaced 6

to 8 inches apart at the time of first hoeing {6).

Four plants can be left in hills spaced 24 inches

apart when the plants are about 3 inches tall (fig.

23).

Close spacing of the plants results in small,

weak stalks that lodge readily, have small heads

and irregular maturity, or fail to mature under

adverse growing conditions (figs. 24 and 25). The

amount of leafy material on close-spaced plants

( 1 inch) is much greater than on plants spaced 6

to 8 inches apart.

Varieties differ in their ability to compensate

for wide spacing or gaps in a drill. With most

varieties the yield of sirup per acre decreases when

single plants are spaced more than 9 inches apart.

This reduction in yield is due to a decrease in the

population of stalks per acre even though the size

of individual stalks is usually larger.

Chemical Weed Control

A preemergence treatment with 2-chloro-4,6-

bis(isopropylamino)-s-triazine (propazine) at the

broadcast rate of 2.0 to 3.2 pounds per acre (active

ingredient) will control many species of smallseed annual weeds in sweet sorghum without injury to the crop in most situations. On light soils,

rates of 2 to 2.5 pounds per acre control these

weeds adequately, whereas higher rates would be

likely to injure the crop severely. Residues from

such treatments with propazine may injure susceptible crops unless their planting is delayed for

at least 18 months after applying the propazine

{16). The county agent or nearest agricultural

experiment station can usually provide current information on weed control.

Harvesting

Changes in the composition of the juice and

soundness of the stalks as the crop matures influence the quantity and quality of the sirup. It is

FIGURE 23.—Stand of sweet sorghum in which 4 plants

were left in hills 24 inches apart.
CULTURE OF SWEET SORGHUM FOB SIRUP 25

FiGTJBE 24.—stripped stalks of sweet sorghum spaced:

Left to right, 3 plants in hills 24 inches apart; plants 6

inches apart in drills ; plants 1 inch apart in drills.

essential that the grower be skilled in judging the

right time for harvesting.

After the stalks reach their full size, maturity

of the entire plant advances at about the same rate

as maturity of the seed head. The plants are generally considered mature when the seed are hard

(ripe). However, this is only an approximate

method of determining maturity of the plant. Difference in maturity of the stalks as shown by the

seed heads depend on varieties and on climatic

conditions from one year to another.

Descriptions of the stages of maturity of the

seed are as follows:

Early-flowering Flowers open 2 inches down

from the top of the seed

head (panicle).

Flowering ..^_ Flowers open three-fourths

of the distance down from

the top of the seed head.

Late-flowering All flowers on the seed head

open.

Bariy-mllk Contents of the seed a thin,

milky liquid.

Late-milk Contents of the seed a thick,

milky semisolld. This

stage is often described as

late-milk to early-dough.

Dough _— Contents of the seed of the

consistency of soft doug^

Hard-dough — Contents of the seed firm,

pliable, and easily cut with

thumbnail.

Ripe Seed firm and hard and cannot be cut with thumbnail.

When suitable facilities are available, the most

accurate way to determine the time for harvesting

is to run adequate mill and laboratory tests to evaluate the yield and quality of sirup. The best product is usually obtained if the sweet sorghum is

harvested sometime before the ripe stage.

The effect of time of harvesting sweet sorghimi

at different stages of maturity on yield of sirup is

shown in table 7. The data indicate a progressive

increase in the sugar content of the juice and the

yield of sirup per ton of stalks from the earlyflowering through the ripe stage. Harvesting

should therefore be delayed until the seed reach

the dough stage, provided other factors permit the

manufacturing of a good-quality sirup. Delaying

the harvesting operations after the seed have

reached the dough stage is not usually profitable

in the southern part of the sweet sorghum area.

Some varieties such as Sart and Tracy that produce a good-quality sirup when harvested in the

dough stage often produce a poor-quality sirup

when harvested at a later stage. Varieties that are

particularly susceptible to diseases may produce a

good-quality sirup, though in a smaller quantity,

in the late-milk stage ; if harvesting were delayed,

the stalks might be almost worthless.

Harvesting methods vary considerably throughout the sweet sorghuni sirup area, depending

largely on the acreage involved and on local customs. If leaves are customarily stripped from the

stalks, they should be stripped while the stalks are

standing. Leaves can be stripped with a paddle, a

FiouBE 25.—Effect of spacing of sweet sorghum plants on

lodging. Plants at right spaced 1 inch apart in drills ;

plants at left placed 3 plants in hills 24 inches apart.
26 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

TABLE 7.—Results from 4 time-of-harvesting tests of sweet sorghum at Meridian,

Miss.^

Stages of maturity

Weight

per

stalk

Juice analyses

Extraction

Brix Sucrose Purity

Sirup

per

ton of

stacks

Pounds Percent Degrees Percent Percent

Early-flowering

Flowering

Late-flowering

Early-mUk

Late-milk

Dough

Hard-dough

Ripe

Post-ripe 1 week-.

Post-ripe 2 weeks.

Post-ripe 3 weeks.

L45

L43

L39

L45

L40

L39

L30

1.41

1.34

L26

L24

57.3

57.8

58.0

58.5

57.5

57.9

56.8

56.2

55.7

56. 1

54.4

11.23

12.07

13. 14

14.73

15.20

15.76

16.34

16.54

15.79

15. 18

14.65

4.70

5.64

6.92

8.86

9.57

10.28

10.94

11.29

10.64

10. 11

9.32

41.9

46.7

52.7

60. 1

63.0

65.2

67^0

68.3

67.4

66.6

63.6

Gallons

12.7

13.8

15.0

17.0

17.3

17.8

18.3

18.4

17.4

16.8

15.8

Each flgure is the average of 100 observations.

cane stripper, or the knife used to cut the stalks, or

they may be pulled off by hand. I^af sheaths

usually are left on the stalks. All side branches

should be removed from the stalks. The top internode, or peduncle, contains less sugar than the rest

of the stalk and should be removed with the seed

head.

Sweet sorghum for sirup production can be harvested by hand or machinery (fig. 26). A cane

knife, corn knife, or hoe can be used for hand

cutting. Corn binders are adequate for harvesting

even though hand labor is needed to load the bundles of stalks onto trailers or trucks. The stalks

can be topped by hand or machine before milling.

Some growers have modified silage harvesters to

cut stalks into 4- to 8-inch-long sections (2). Stalk

sections and leaves are separated by air while the

cut sections are being conveyed to a trailer body.

Leaf removal or stripping is very effective by this

harvesting method (fig. 27).

Because most sweet sorghum sirup is manufactured on small-scale equipment, stalks must sometimes remain in the field or at the mill for several

days before they are milled. This practice does not

cause a loss of sirup if the stalks are in good condition at the time of harvest, if they are stored not

longer than 7 to 10 days, and if they are not subjected to freezing temperatures.

Some farmers shock the sweet sorghum stalks in

the field or at the mill during the storage period,

either with or without the leaves. If the leaves are

not removed before milling, the quality of sirup

may be decreased during rainy periods (8).

Many farmers save seed for planting the next

crop or for sale to other farmers. This is a good

practice if (1) the seed have reached the harddough stage of maturity at the time of harvest,

(2) the field is sufficiently isolated to prevent mixFIGUEB26.—Machine harvesting (cutting) sweet sorghum.
CULTURE OF SWEET SORGHUM FOR SIRUP 27

' • "^ ^f-i?» ill»*

ITiQUBE 27.—heft, top to iottom, Effect of stalk chopping

on stripping 4-, 8-, and 16-incti sections; right, wliole

stalks of sweet sorghum.

ing with other varieties, (3) the seed have not been

damaged by insects or freezing temperatures, and

(4) suitable facilities are available for drying the

seed.

The seed may be dried by (1) spreading the seed

heads thinly on a floor where there is good aeration or on an almost flat roof during dry weather,

(2) tying the seed heads in bunches or placing

them loosely in burlap sacks and hanging them in

a sunny or airy place, or (3) subjecting the seed

heads to artificial heat in a drier. The last method

is usually the surest and quickest way of adequately drying the seed. A good procedure dries not

only the seed but also the peduncles and branches

of the seed heads in a relatively short time.

When the seed heads are dry, the seed should

be threshed immediately either by hand or with a

suitable thresher. After threshing, the seed should

be thoroughly cleaned and cured by proper aeration or in a drier. They should be placed in tight

containers and treated chemically to prevent insect

damage during the winter months. (See "Insects

Injurious to Stored Seed," p. 18.)

MANUFACTURE OF SWEET

SORGHUM SIRUP

The yield and quality of sorghimi sirup are influenced by the equipment and process used in

manufacture and by the skill of the sirup maker.

Examples of methods successfully used by many

farmers for small-scale manufacture of sorghum

sirup are briefly described here. Large conunercial

sirup manufacturers, however, usually employ

other types of continuous-processing operations,

including enzymatic treatments, to assure highquality products.

Several types of mills have been used in the

past, but since 1950 the small upright three-roller

mill propelled by animal power usually has been

replaced by the larger mill consisting of three horizontal rollers propelled by motor power- (fig. 28).

The extraction of juice should be between 50 and

60 percent; that is, 100 pounds of stalks should

furnish 50 to 60 pounds of juice. Extracting less

juice results in less sirup. More juice may be extracted in a good mill if such a procedure does

not lower the quality of the sirup.

Most farmers make sirup on continuous-type,

galvanized-iron, or copper evaporators (fig. 29).

These evaporators are shallow and have crosswise

baffles. One big advantage of the continuous-type

evaporators is that a steady stream of cold or preheated juice enters the cooler end of the pan and

then flows slowly to the opposite end, where it is

drawn off as finished sirup.

The Stubbs pan is another continuous type of

evaporator. It is not used so widely as evaporators

with baffles, but it requires somewhat less skill for

efficient operation. The model shown in figure 30 is

12 feet long, 3 feet 6 inches wide, and 10 inches

deep. The juice side is 1 foot 3 inches wide; the

other side is 2 feet 3 inches wide. Juice enters the

cool end and travels lengthwise along the high,

longitudinal partition, around the end of this parFiGTJEE 28.—Grinding sweet sorghum at sirup mill at

Booneville, Miss.
28 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

FIGURE 29.—Continuous-flow type evaporator at Boaz, Ala.

FIGURE 30.—Stubb-type evaporator.
CULTURE OF SWEET SORGHUM FOR SIRUP 29

tition, and back up to the finishing-off

compartment.

Fuels used for heating the evaporators include

wood, oil (kerosene or fuel oil), liquid petroleum

gas, and coal. In small-scale operations, the fire

heats the bottom of the evaporator. In some largescale operations, steam coils placed in the evaporator heat the juice.

The juice is heat clarified in the evaporator.

When the cold juice is heated, certain proteins and

nonsugar substances are coagulated. This coagulated material, called skimmings, rises to the

surface and is removed.

After clarification, the juice is evaporated to

sirup density as rapidly as possible. The desired

sirup density can be determined by a sirup hydrometer or a thermometer. A suitable thermometer is preferred because it provides an accurate

and continuous indication of the sirup density.

When sirup is tested near the boiling temperature,

the reading for sirup of good density should be 35°

to 36° Baume with the sirup hydrometer. The boiling temperature should be 226° to 230° F. or 108°

to 110° C. with a good thermometer.

The finished sirup should be filtered as efficiently

as possible, cooled to the proper temperature, and

stored in containers. The temperature of the sirup

should be 190° F. for filling one-half-gallon and

smaller containers, 180° F. for 1-gallon containers, and 120° F. for barrels.

LITERATURE CITED

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

BRANDES^ E. W.

1920. ARTIFICIAL AND INSECT TRANSMISSION OF

SUGARCANE MOSAIC. J. Agr. Res. 19: 131-

138.

BROADHEAD, D. M.

1972. EFFECTS OF STALK CHOPPING ON LEAF REMOVAL AND JUICE QUALITY OF RIO SWEET

SORGHUM. Agron. J. 64: 306-308.

• CoLEMAN, O. H., and FREEMAN, K. C.

1970. DALE, A NEW VARIETY OF SWEET SORGHUM FOR

SIRUP PRODUCTION. Miss. State Expt. Sta.

Inform. Sheet 1099, 2 pp., illus.

and FREEMAN, K. C.

1964. EFFECTS OF FERTILIZER ON YIELD AND QUALITY

OF SORGO FOR SIRUP. Miss. State Expt. Sta.

Inform. Sheet 849,1 p.

STOKES, I. E., and FREEMAN, K. C.

1963. SORGO SPACING EXPERIMENTS IN MISSISSIPPI.

Agron.J. 55:164-166.

- and CoLEMAN, O. H.

CoLEMAN, O. H., and BROADHEAD, D. M.

1968. BRANDES, A NEW VARIETY OF SWEET SORGHUM

FOR SIRUP PRODUCTION. MÍSS. State Expt.

sta. Inform. Sheet 1013, 2 pp., illus.

and DEAN, J. L.

1964. INHERITANCE OF RESISTANCE TO METHYL

PARATHION IN SORGO. Crop. Scl. 4: 371-372.

and STOKES, I. E.

1964. STORAGE STUDIES OF SORGO. U.S. Dept. Agr.

Tech. Bui. 1307, 54 pp.

STOKES, I E. FREEMAN, and OTHERS.

1956. NEW VARIETY OF SORGO SIRUP DEVELOPED,

WILEY. Miss. Farm Res. 19(8) : 1, 7.

DEAN, J. L.

1966. LOCAL INFECTION OF SORGHUM BY THE JOHNSON GRASS LOOSE KERNEL SMUT FUNGUS.

Phytopathology 56: 1342-1344.

(11) -

1959. NECROTIC AND RESISTANT REACTIONS TO THE

SUGARCANE MOSAIC VIRUS IN SORGHUM. U.S.

Dept. Agr. Plant Dis. Rptr. 43(5) : 522-527.

(12) FREDERIKSEN, R. A., and CASPER, J W.

1968. NEW FUNGUS DISEASE ATTACKS CORN AND

SORGHUM. Crops and Soils 29(9) : 25.

(13) FuTRELL, M. C. and RAIN, D. C.

1967. DOWNY MILDEW OF SORGHUM IN MISSI8SIPPL

(Abstract). Phytopathology 57 : 459.

(14) LEBEAU, F. J.. STOKES, I. E., and COLEMAN, O. H.

1951. ANTHRACNOSE AND B.ED ROT OF SORGHUM.

U.S. Dept. Agr. Tech. Bui. 1035, 21 pp.

(15) LYONS, E. S., STOKES, I. E. O'KELLY, J. F., and

CROCKETT, S. P.

1951. RESULTS OF FERTILIZER EXPERIMENTS WITH

SORGO GROWN FOR SIRUP IN MISSISSIPPI 1942-

49. Miss. Agr. Expt. Sta. Cir. 167, 10 pp.

(16) PALMER, R. D., and BROADHEAD, D. M.

1965. WEED CONTROL IN TRACY SORGO. MlSS.

state Expt. Sta. Inform. Sheet 864, 2 pp.

(17) REYES, L., ROSENOW, D. T., BERRY, R. W., and FuTRELL, M. C.

1964. DOWNY MILDEW AND HEAD SMUT DISEASES OF

SORGHUM IN TEXAS. U.S. Dept. Agr. Plant

Dis. Rptr. 48(4) : 249-253

(18) SowELL, GROVER, JR., and HARRIS, H. B.

1969. DOWNY MILDEW IN GEORGIA. U.S. Dept. Agr.

Plant Dis. Rptr. 53(1) : 4.

(19) STOKES, I. E., COLEMAN, O. H., and DEAN, J. L.

1957. CULTURE OF SORGO FOR SIRUP PRODUCTION.

U.S. Dept. Agr. Farmers' Bui. 2100, 32 pp.

(20) COLEMAN, O. H., O'KELLY, J. F., and OTHERS.

1951. sART, A NEW VARIETY OF SORGO FOR SIRUP

PRODUCTION IN MISSISSIPPI. Miss. State.

Expt. sta. Inform. Sheet 458, 2 pp. illus.
30 AGRICULTURE HANDBOOK NO. 441, U.S. DEPT. OF AGRICULTURE

(21) STOKES, I. E., COLEMAN, O. H., O'KELLY, J. F., and

OTHERS.

1953. TRACY, A NEW MID-SEASON VARIETY OF SORGO

FOR SIRUP PRODUCTION IN MISSISSIPPI. MiSS.

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