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TMEFOILSAGRICULTURE HANDBOOK No. 223

Agricultural Research Service

U.S. DEPARTMENT OF AGRICULTURE
CONTENTS

Page

Origin and distribution 1

Description of trefoil species 1

Genetics and cytology of trefoil 3

Adaptation 4

Varieties 5

Birdsfoot trefoil 5

Narrowleaf trefoil 6

Big trefoil 6

Objectives of improvement 6

Establishment 7

Seed quality 7

Fertilization 7

Seedbed preparation 8

Inoculation of seed 8

Seeding 8

"^ eed control 8

Trefoil in mixtures 9

Composition and nutritive value 10

Utilization 11

Grazing management 11

Hay and silage 11

Seed production 11

Pollinators 12

Pure stands versus grass mixtures 12

Harvesting the seed crop 12

Diseases 13

Insects injurious to trefoil 15

Literature cited 15

Washington, D.C. Issued March 1962

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

Washington 25, D.C.—Price 15 cents
THE TREFOILS—ADAPTATION AND CULTURE

By PAUL R. HENSON, research leader, and H. A. SCHOTH, research agronomist. Crops Research Division,

Agricultural Research Service

' The perennial trefoils, Lotus species, are important

legumes on various soil areas of the United States for

permanent pasture and hay. For many years prior to

1935 many imported seed lots of trefoil, chiefly birdsfoot, were tested by the U.S. Department of Agriculture in cooperation with several State agricultural

experiment stations. The advantages of using trefoil

were not readily apparent in those early tests, because

most of the trials were made in comparison with

alfalfa and on alfalfa soils under hay management.

The discovery in the 1930's of productive, naturally

occurring stands of trefoil in permanent pastures in

various areas of the United States awakened agricultural workers to the realization of the potential forage

value of one or more of these species.

Since 1938 many continuing research programs

have been initiated to determine adaptation, culture,

management, and improvement of the trefoil species.

ORIGIN AND DISTRIBUTION

The cultivated forms of the trefoil species are native

to Europe in the region from the Mediterranean Sea

northward to the Scandinavian Peninsula. Robinson

{34)^ reports that the trefoils have been used to a

limited extent in the British Isles and in various parts

of France, Italy, Denmark, and elsewhere in Europe

for a great many years. These legumes have recognized forage value over much of Europe. They are

used for forage and seed production in the southern

countries, chiefly France and Italy. In more northern

areas, birdsfoot trefoil is used for pasturage and it is

an important species in many Alpine meadows.

Birdsfoot trefoil and big trefoil are weU adapted to

limited areas in Austrialia (11) and New Zealand.

In South America birdsfoot is adapted to various areas

of Argentina and Uruguay. In tropical environments

the species are reported by Hosaka (17) and Quiros

{33} to be well adapted at the higher elevations in

the Hawaiian Islands and Costa Rica.

When and how trefoils were introduced into the

United States is not known. It is quite probable that

the seed entered as impurities in ballast deposits and

in shipments of other seeds from Europe, and became

established on the east and west coasts.

The trefoils first became naturalized in eastern New

York; western Oregon, northwestern California, and

in the tidewater areas of Virginia. The success with

birdsfoot trefoil in these areas stimulated interest in

them in other areas. More detailed reports on the

origin and distribution of the trefoil species may be

found in reports by MacDonald (24) and McKee and

Schoth (27).

DESCRIPTION OF TREFOIL SPECIES

Three species of trefoil are presently grown in various areas of the United States: Birdsfoot trefoil {Lotus

corniculatus L.) (^rgr^ï) , narrowleaf trefoil [L. tenuis

Wald et Kit.) {-ê:gr2f, and big trefoil (L. uliginosus

Schkuhr) (figv^.^

Birdsfoot trefoil is a broad-leaved, long-lived herbaceous perennial with a well-developed, branching taproot and few to many ascending stems developing

^ Italic numbers in parentheses refer to Literature Cited,

p. 15.

from each crown. It is a tetraploid with a somatic

chromosome number of 24. It is similar to alfalfa

in growth habit. The plants, for the most part, are

erect or ascending and reach a height of 12 to 30

inches. The stems are comparatively slender, sparingly branched, and moderately leafy. The leaves are

borne alternately on opposite sides of the stem and

are composed of five leaflets, of which one is termmal,

two are apical, and two are at the base of each petiole.

The last two resemble stipules and are often mis-
FIGURE 1.—Flowering branches and plants of birdsfoot

trefoil.

taken for them. The flowers, generally numbering two

to six, are borne in umbels at the extremity of a long

peduncle arising from the leaf axil. The flowers, resembling the flowers of peas, are yellow with faint red

or orange stripes usually present in young flowers.

Pods form at right angles at the end of the peduncle

in the shape of a bird's foot; hence the common name

of the species, birdsfoot. The seeds are oval to spherical and number from about 324,000 to 5.50,000 seeds

FIGURE 2.—Flowering branches and plants of narrowleaf trefoil.

per pound. They vary from light to dark brown and

are usually speckled with dark spots.

Narrowleaf trefoil, as the name implies, has narrow,

linear-lanceolate leaflets on slender, weak stems with

comparatively long internodes. MacDonald (24)

found that this species has a more shallow root system

than the broad-leaved species. Flowers are slightly

smaller and fewer in number, and usually change from

yellow to orange red at maturity. Narrowleaf trefoil
is a diploid species with a somatic chromosome number of 12. Otherwise, narrowleaf is similar to the

birdsfoot species.

Big trefoil is similar to birdsfoot trefoil in appearance but differs in having; rhizomes and more flowers

per umbel than either birdsfoot or narrowleaf trefoil.

It is shallow rooted, lacks drought resistance, and

grows best in continuously moist soils. The seeds of

big trefoil are almost spherical and vary from yellowish to olive green, without any speckling. Like narrowleaf, big trefoil is a diploid species with a somatic

chromosome number of 12. Big trefoil seeds are much

smaller than the seeds of the other two species and

number from about 800.000 to 1.075.000 seeds per

pound.

FIGURE 3.—Flowering branches and plants of big trefoil.

GENETICS AND CYTOLOGY OF TREFOIL

Knowledge of the phylogeny of the tetraploid Lotus

species is basic to the development of any sound breeding program.

As indicated earlier, broad-leaved birdsfoot trefoil

IS a tetraploid having a somatic chromosome number

of 24. Cytological studies by Dawson (6), Tome and

Johnson (39), and Donovan [8] show quadrivalents

to be rare at meiosis. However, genetic studies of the

inheritance of cyanogenesis by Dawson ( 6 ). flower and

keel tip color by Bubar (5), keel tip color by Hart

and Wilsie (7.51, and leaf size by Donovan l<S'). show

that tetrasomic inheritance is involved. On the basis

of these studies, the species is believed to be autoploid

in origin. Dawson (6) and Guinochet (74) proposed

the narrow-leaved diploid species. Lotus tenais, as the

progenitor of L. corniculatiis. Tome and Johnson ( .'VJ I

were unable to successfully cross an artificiallv induced

tetraploid plant of L. tenais and L. cor/iiculalus; however. Erbe, Keim. Mears,- and Gershoy H'J) successfully made this cross. The diploid form of L. coniiculatus var. alpinas Ser., according to Larsen {'J2K

closely resembles and could have been the anccslur

of the tetraploid form. The existence of a great many

forms of the tetraploid L. corniculatiis lias i)epn nulcd

by taxonornists and geneticists alike. MacDnnaM

{24). McKee (1'6), and McKee and .Scholh CTl bave

'ERBE, L, W. A STI IIY OF THK FKIITU.ITV KKi.vrioN^inrs OK

MJTI N I (1HM< I L\TI ^, TKTUM'l.olll I,. ri;\l IN AMI TIIKIII I inlllllll

i'RO(,KNV. HJ.S.S. (Tli.-sis. M.S. Crad. Col.. Univ. Vermont. Burlin^loii. )

KKIM. W. F. INTKRSPECIFIC HVBRIDIZATinN STIIIIKS IN TRIFCIMI M \M) I.on ,s, I .MN(. KMDRVO (I 1.11 UK IKIillMl.H K. l'r)2.

('Iii(-ÍN. I'll. I). Cornell llni\., Illiaia. N.V)

\h.\li>, K. \. -II IIIKS I\ SI'K( IKK inilllimZMION IN THK I.KM S

l,oll^. IV.S.S. lTlirM>. M..S. Cra.l. Col.. I'niv. WrinniH- l!inlin"liiii. I

3
discussed the ínoipholegical differences of many of

these forms or vrnir lie^ There is evidence that some

of the different tetrapioid furns could have arisen by

ploidy from different dipioids.

Exploratory studies were made during the period

1956-60 at Beltsville, Md., on the content of tanninlike

substances in various Lotus species. The tannin content on individual plants was estimated in accordance

with the method used by Bates and Henson {3) for

Lespedeza cuneata (Dum.-Cours.) G. Don. When

green leaves of many Lotus species were pressed into

filter paper containing ferric ammonian citrate, the

color and intensity of the spot formed was reasonably

uniform within the species, but varied from a tan to

greenish brown in some species to a blue black in

others. Chemical analyses of tannin content showed

the latter group to be generally higher in total tannins.

It is suggested that at least some of the phenolic substances making up the tannin complex differ with different species, depending in part on their origin.

Differences in the tannin complex were first noted

between field-grown plants of tetrapioid forms of Lotus

corniculatus. Leaves of Empire, the variety or ecotype indigenous to New York State, produced tan to

brown spots on the treated paper. In contrast to this,

leaves from the erect-growing European form consistently produced darker, blue-black colored spots. Differences were less distinct within greenhouse-grown

plants, due possibly to lower light intensity.

Among the diploid species (2n = 12), the tannin

reaction of Lotus tenuis and L. filicaulis Dur. in Duch.

was similar to that of Empire. L. divaricatus Soland.

ex Buich, L. uliginosus, and L. parviflorus Desf. were

high in tannin content comparable to that of the erect

form of L. corniculatus from Europe. These observations indicate that the Empire ecotype may well have

arisen from L. tenuis through ploidy, since both are

relatively low in tannin and both contain cyanogenetic

plants. However, the low tannin content of L, tenuis

is not entirely compatible with the suggestion that this

species is the sole progenitor of the European type.

Plants of the two tetrapioid types. Empire and the

European form, cross readily, indicating a close

phylogenetic relationship.

d both -tJent, in Ac<i;cnt siuaies, successtully ci^" „

2n and 4n Lotus uliginosus with L. cornicul^^^^\ "^

was also successful in crossing L. uliginos^^ with L.

tenuis.

The present evidence suggests that although the

Empire ecotype appears to be an autoploid, the possibility that the erect European ecotype is of different

origin but closely related, should not be overlooked.

The self-fertility of a number of Lotus species has

been reported. Within the tetrapioid species, L.

corniculatus var. arvensis (Schkuhr) Ser. and var.

vulgaris W.D.J. Koch are relatively self-sterile.

Studies have shown that 70 to 80 percent of the plants

are self-sterile {26, 38).^'^ The most self-fertile

plants, however, produce 50 to 80 percent more seeds

when outcrossed, as compared to selfing. L. corniculatus var. hirsutus W.D.J. Koch is highly self-fertile.

The annual tetrapioid L. hispidus Desf. is apparently

autogamous.

Of the diploid species, Lotus tenuis is self-sterile.

L. uliginosus, as reported by Silow (38), Bent,^ and McKee {26), and L. corniculatus var. japonicus Regel, by

Bent,^ are moderately self-fertile. McKee {26) found

L. filicaulis to be highly self-fertile while L. divaricatus

and L. ornithopodoides L. were autogamous.

The inheritance of self-fertility in Lotus is complex.

Results of studies by Brandenburg ^ on L. corniculatus

and by Elliott ^ on L. tenuis did not support the

hypothesis that the inheritance of self-sterility is due

solely to oppositional factors. Additional studies are

needed to clarify the fertility relationships in the

genus.

^ BENT, F. C. INVESTIGATIONS IN INTERSPECIFIC HYBRIDIZATION AND FERTILITY OF CERTAIN LOTUS SPP. 1958. (Thesis,

Ph. D., Cornel] Univ., Ithaca, N.Y.)

* ERBE, L. W. See footnote 2, p. 3.

^ GILES, W. L. THE MORPHOLOGICAL ASPECTS OF SELFSTERILITY IN LOTUS CORNICULATUS L. 1949. (Thesis, Ph. D.

Univ. Missouri, Columbia.)

' BENT, F. C. See footnote 3.

^BRANDENBURG, N. G. SELF- AND CROSS-FERTILITY IN BIRDSFOOT TREFOIL, LOTUS CORNICULATUS L. 1959. (Thesis, Ph. D.

Univ. Maryland, College Park. )

** ELLIOTT, F. C. THE INHERITANCE OF SELF-INCOMPATIBILITY

IN LOTUS TENUIS WALD. ET PIT. 1945. (Thesis, M.S. Iowa

State College, Ames.)

ADAPTATION

The birdsfoot and narrowleaf trefoils are adapted

to the temperate climate of the northern part of the

United States. Within this region birdsfoot trefoil is

particularly well suited to the less fertile soils and is

productive on soils having relatively poor internal

drainage. On such soils it has become an important

long-lived perennial legume for pasture and hay {1, 7,

9, 31, 40),
I "^íoil also has a place on fertile soils in permanent

I pastures (37) that are left down for long periods of

time Or in pastures that are difficult to plow or cultivate. On well-drained fertile soils the present varieties

of trefoil are generally less productive for hay than is

alfalfa.

Birdsfoot trefoil is not well adapted in the regions

below an approximate line drawn from the eastern end

^ of the Nebraska-Kansas border to the east coast, except at higher elevations in the Appalachian Moun-

' tains. Farther south, stands of this species are short

lived due, in part, to its susceptibility to various crown-

^ and root-rotting diseases.

Narrowleaf trefoil is well suited to heavy, poorly

drained clay soils. This species is an important constituent in pastures in the Hudson River Valley of New

York State. In California, Peterson and others {30)

reported that narrowleaf trefoil is an important pasture plant, especially on the poorly drained, heavytextured clay soils. This species grows well in soils

containing large quantities of soluble salts and is the

most common legume on saline and alkali soils in

regions having relatively mild winters, as in the Rogue

River Valley of southern Oregon. In general, narrowleaf trefoil, particularly the strain from the West, is

not so hardy as birdsfoot.

Big trefoil, according to Howell {18), is well adapted

to the acid coastal soils of the Pacific Northwest. In

this region of mild winters, big trefoil grows well on

the low-lying soils that are frequently flooded during

the winter months. It also grows well in relatively

moist uplands. In contrast to birdsfoot trefoil, which

requires lime on very acid soils for maximum production, big trefoil grows well on soils of pH from 4.5 to

5.5. Lime application to such soils has not increased

the productivity of this species.

Big trefoil appears promising as a pasture legume

in the acid flatwood soils of the southeastern coastal

regions when adequately fertilized with phosphate and

potassium {41). The productivity of this species in

this southern climate may be reduced during periods

of warm, dry weather. Maximum and continued

growth of big trefoil occurs in regions of frequent

summer rains. During the long warm summers of

the Southeastern States, diseases such as Rhizoctonia,

anthracnose, and black patch may seriously reduce the

productivity of the species.

VARIETIES

Birdsfoot Trefoil

The present varieties of birdsfoot trefoil are derived

from either seed stocks from old established stands

in New York State or from imported lots from Europe,

chiefly Denmark, France, and Italy. Descriptions of

the named varieties of birdsfoot trefoil follow:

Empire.—An increase of an ecotype of naturalized

birdsfoot trefoil occurring on selected farms in the

vicinity of Preston Hollow, in Albany County, N.Y.

Empire is a semierect, hardy, late-maturing type with

leafy, much-branched stems. It flowers from 10 days

to 2 weeks later than the common European forms.

Flowering is indeterminate, occurring from late in

June to mid or late July in New York State. Young

seedlings of Empire generally lack seedling vigor

but once established, the variety is an exceptionally

long-lived, productive legume for pasture and hay.

Empire was developed and released by the Cornell

University Agricultural Experiment Station, Ithaca,

N.Y.

Cascade.—An erect-growing, productive, earlymaturing variety developed from an importation from

France, F.C. 20153.^ In the development of this

* Forage Crops accession number.

variety a large number of superior plants were selected

out of F.C. 20153 and aflowed to intercross. The

resulting seed was bulked, tested, and later released

as the Cascade variety. Cascade birdsfoot trefoil has

good seedling vigor and is relatively easy to establish.

It is not so hardy as Empire and is not grown in

regions having extremely cold weather. Cascade was

developed cooperatively by the Washington Agricultural Experiment Station at Pullman and the U.S. Soil

Conservation Service.

Granger.—Originated from seed lot F.C. 22557,^

imported from France. It is similar to Cascade in that

it is an erect, broad-leaved, early-maturing, productive

variety. Granger also has good seedling vigor and establishes with ease, but is not so hardy as Empire.

Granger was developed cooperatively by the Oregon

Agricultural Experiment Station at Corvallis, and the

U.S. Agricultural Research Service.

Viking.—Developed by selecting desirable plants

from a Danish importation and from two erect-growing, early-maturing New York State local strains. Selected plants were aUowed to cross and their progenies

tested. Superior plants on the basis of progeny tests

were combined for seed production. The bulked seed

was extensively tested and the resultant variety re-
leased as Viking. This is an erect, broad-leaved, rapidgrowing, productive type with good seedling vigor.

It is more winter hardy than imported stocks from

France and Italy and is superior to Granger and Cascade in this regard. Viking was developed and released by the Cornell University Agricultural Experiment Station, Ithaca, N.Y. (25).

Mansfield.—This variety is similar in many respects to Viking. In the development of Mansfield,

vigorous, erect-growing, productive plants were selected from the following seed sources: (1) An imported seed lot that had been grown at Shelburne, Vt.,

(2) a seed stock from Columbia County, and (3) a

seed stock of Danish origin. The selected plants were

isolated, allowed to intercross, and the resultant progeny tested. Several hundred superior plants were

combined to produce seed of the new variety. Results

of tests across the Northern States show that Mansfield is well adapted to the same general areas as Viking.

Mansfield was developed and released by the Vermont

Agricultural Experiment Station {12) at Burlington.

Tana.—A vigorous, erect-growing, broad-leaved

variety developed from a high-yielding lot from Europe.

Tana has good seedling vigor and is very similar to

Cascade and Granger. This variety was developed

and released by the Montana Agricultural Experiment

Station at Huntley.

Douglas.—Originated in Douglas County, Oregon.

Out of several European lots of birdsfoot trefoil under

test by the county agent, this one gave the best results.

It is an erect-growing, vigorous European type.

In addition to the above varieties, a number of

strains have been developed. Varieties of birdsfoot

are quite variable and when brought into a new area

and grown anu iiaivujtuu xui >^^^<^-^-,^.^ ^ p^.ierations, the resulting strain may be quite different from

the original variety.

Narrowleaf Trefoil

Los Banos.—A new variety, Los Banos, is the only

named variety of narrowleaf trefoil. It was developed

and released cooperatively by the California Agricultural Experiment Station at Pleasanton, and the U.S.

Soil Conservation Service. Other seed stocks of narrowleaf trefoil usually carry the State of origin, as

New York narrowleaf, or Oregon or California narrowleaf. All have fine stems, narrow leaves, and are decumbent to semierect in habit of growth. Tests at

various locations have shown that New York narrowleaf is somewhat more winter hardy than those of

west coast origin.

Big Trefoil

Seed of two varieties of big trefoil is available.

Both were developed by the Oregon Agricultural Experiment Station at Astoria, and the U.S. Agricultural

Research Service.

Beaver.—The variety Beaver is quite hairy, with

stems and leaves well covered with fine hairs, giving

the plant a gray-green appearance.

Columbia.—The variety Columbia, in contrast to

Beaver, is smooth with relatively few hairs. Its darkgreen foliage resembles that of birdsfoot in general

appearance. Both varieties are well suited to the wet

winters and cool summers of the Pacific coastal areas

of the Northwestern States.

OBJECTIVES OF IMPROVEMENT

The objective of any trefoil improvement program

may vary with the region and to some extent within

the region. General objectives are (1) greater longevity for pasture, hay and silage; (2) improved yields;

(3) increased seedling vigor; (4) improved seed habits; and (5) rapid recovery after cutting. Greater

winter hardiness is desirable in the more Northern

States, whereas resistance to crown and root rots is

extremely important in Southern States.

Widely adapted, more productive, longer-lived

varieties of birdsfoot trefoil must be developed if the

full potential value of this forage legume is to be realized. The present varieties are readily separated into

two groups, according to origin and plant type. In

one group are the spreading to semierect varieties

Empire and strains of Empire origin derived from old

naturalized stands. The second group is made up of

varieties derived largely from more recently introduced European seed stocks. These are Cascade,

Granger, Douglas, Mansfield, Tana, and Viking and

are essentially erect-growing with somewhat coarse

stems, and are similar in many respects to alfalfa.

Stands of the Empire type persist for many years

even under continuous, close grazing when once well

established in the more northern areas. Some seed is

produced each year and reseeding is a factor in maintaining stands. Seedling plants generally lack vigor.

Thin, unproductive stands frequently result from new
seedlings, due in part to the loss of seedlings through

severe competition with weeds and other species. Recovery is slow after cutting for seed or hay, with

resultant low aftermath production.

The erect-growing varieties are best suited for hay

or rotational pastures. Because of their growth habit,

plants may be completely defoliated by the grazing

animal. Repeated defoliation under continuous grazing weakens the plants, making them susceptible to

' prevailing crown and root rots, winter injury, and adverse environmental conditions. Good results have

been obtained under systems of rotational or deferred

i grazing. It is possible that as further studies are made,

I some of these erect varieties may prove to be more

persistent and productive than others under grazing.

The erect varieties are superior to the Empire types

in seedling vigor and can be established with greater

ease. However, even these varieties are lacking in

seedling vigor as compared with alfalfa, red clover, and

many other forage plants.

A high percentage of the trefoil seed produced may

be lost in the harvesting operation. At relatively low

I humidity, seed pods may dehisce as they mature, making it very difficult to harvest satisfactory quantities

of seed. All the seed does not mature at the same

time; flowers, green and purple pods, and dehisced

pods can usually be found on the same plant as the

pods begin to mature. These characteristics are largely

responsible for generally unprofitable seed yields and

usually high seed prices. Peacock and Wilsie (29)

reported a 17-percent reduction in pod dehiscence

through one cycle of selection. The possibility of developing varieties having relatively indéhiscent pods

appears promising. Also, the development of varieties

with essentially indéhiscent pods through interspecific

hybridization is a possibility since some other Lotus

species possess this character.

A complex of crown- and root-rotting organisms

attack, and under some conditions seriously reduce

trefoil stands. Plant losses from these diseases are

most noticeable at the more southern locations of the

trefoil region. A summary of plant losses within

many introductions and varieties at Beltsville, Md.,

from 1952 to 1958, reveals that two-thirds of the plants

are lost by the end of the second year after seeding.

Slight to serious plant losses partially caused by root

rots have been reported from various areas in the

Central and North Central States. Plant losses in the

Pacific Coast areas from diseases have been low.

To date foliar diseases have not been particularly

severe on birdsfoot trefoil. Graham (13) reported

that a species of Stemphylium on birdsfoot trefoil in

the INortheast has been causing significant leaf and

stem losses. Foliar diseases may become severe as

the acreage of the crop expands.

Winter hardiness is important in the northern tier

of States. In Minnesota, Schmidt and Thomas (35)

reported severe winterkilling of Cascade, Granger,

Oregon narrowleaf, and imported seed lots from

France and Italy. Stand losses due to winter injury

in Empire and Viking were not severe.

ESTABLISHMENT

The occurrence from time to time of unsatisfactory

stands of trefoil in seedings has been one of the

factors responsible for slow acceptance of the species.

Seedling plants of trefoil are less vigorous than those

of alfalfa or red clover. Competition with nurse

crops, grasses, and weeds often causes poor stands and

unproductive seedlings that later succumb to winterkilling or disease. Good stands depend upon seed

quality, fertilization, seedbed preparation, inoculation,

choosing the proper time, depth, and rate of seeding,

and weed control.

Seed Quality

Varying amounts of large to small and plump to

shriveled seed are found in most trefoil seed stocks.

Good quality seed should be plump, relatively free

from badly shriveled seed, and test high in germination, in the trefoil program at Beltsville, Md., many

seed stocks have been tested for seedling vigor. Results of these tests consistently show that, with few

exceptions, the large plump seeds produce the most

vigorous seedlings. Highly significant positive correlations exist between weight of seed and height and

weight of young seedling plants.

Fertilization

Birdsfoot is similar to red clover in its lime and

fertilizer requirements. Lime is needed on acid soils.

Phosphate is generally needed on less fertile soi s,

whereas potash is needed in many areas. ^J^^^'".^

is known of the fertilizer needs of a trefoil field, soil

samples should be taken and analyzed for hme, phosphate, and potassium needs. Apply Hme and fertilizer

as recommended from soils tests.

620137 O—62 2
Seedbed Preparation

Trefoil seedings generally fail when made on grass

sod without any seedbed preparation. A fine, firm

seedbed is necessary. Where land is plowed, it should

be done well in advance of seeding to permit rains or

irrigation to settle the seedbed. In the final preparation the field may be disked, harrowed, and rolled or

cultipacked before seeding. The preparation required

varies with the kind of soil, its moisture content, and

the season of the year. Delay seeding until a satisfactory seedbed can be prepared.

Inoculation of Seed

Since the trefoils are new to many areas, the seed

should be inoculated. Poor or no inoculation has

resulted in stand failures in some areas. The bacteria

that inoculate common legumes such as alfalfa and

red clover, will not inoculate the trefoil species.

Specific trefoil inoculum is required. Strains of bacteria that inoculate birdsfoot and narrowleaf trefoil

may not be effective for big trefoil {10), In seeding

any of the trefoil species, be sure to purchase the

proper inoculum. Follow the instructions printed on

the inoculum container.

Seeding

After a fine, firm seedbed has been prepared any of

several different methods may be used in seeding

trefoil. Band seeding or drilling has given satisfactory stands in many areas. In band seeding, fertilizer is drilled in bands IV2 to 2 inches deep and the

seed dropped above the fertilizer. The seed is covered

with a packer wheel attached to the drill or by rolling

the field with a corrugated roller. Seeding with a

cultipacker seeder also gives good stands. Another

method is to broadcast the seed with a cyclone seeder

and cover with a corrugated roller. More uniform

stands usually result from drilling.

Cover the seed to a depth of % to %^ inch only.

Do not cover too deeply.

Early spring seedings are generally most successful

in the central and northern parts of the United States.

The actual date of seeding varies from late March in

the southern part of this region to mid-June in the

North. Fall or February seedings are recommended

in California {30}. In Oregon {18), big trefoil is

seeded in March, whereas fall seedings are preferred

in Florida {41).

Four to six pounds of good quality birdsfoot and

narrowleaf trefoil seed per acre should give gooa results. Two or three pounds of big trefoil seed per

acre is enough for good stands. Seed stocks containing a high percentage of hard seed should be scarified

before seeding.

WeedControP«

New Seedings

Trefoil seedlings grow slowly and furnish little competition to rapidly growing weeds. Too often weeds

soon overtop the trefoil seedlings. Seeding oats as

a nurse crop to aid in controlling weeds is a questionable practice {4, 21, 36). A nurse crop, like weeds,

will compete with seedling plants for light, moisture,

and nutrients. Where there is a nurse crop or where

weedy grasses are allowed to grow unchecked, many

of the young trefoil plants may be killed or will be

weak going into the winter season. Winter injury

of weak plants is likely to be heavy, resulting in thin,

unproductive stands. If a nurse crop of oats is used,

it should be seeded at not more than 1% bushels per

acre and either grazed off" or cut early for hay.

Where upright, broad-leaved weeds, such as pigweed and ragweed, present a problem, they may be

partially controlled by mowing them close to the ground

after they have reached a height of 10 to 15 inches.

When mowing is delayed to this stage of growth, considerable effects of competition have already occurred,

but earlier mowing causes excessive lateral branching of the weeds and gives poor control. Repeated

mowings are necessary to prevent weeds from forming

a canopy over trefoil. Mowing sets back the trefoil

plants but the benefits of reduced competition partially

offset this injury. The second and subsequent mowings should be at a height of 3 or 4 inches to reduce

injury to the trefoil plants.

Grasses are more injurious to new seedings of birdsfoot trefoil than are the usual broad-leaved weeds.

Where weed grasses such as foxtail, crabgrass, and fall

panicum are present, they often provide severe competition to the young plants. Mowing is not effective

for control of most grasses.

Where practical, weeds can be partially controlled

by light grazing with cattle, which should be followed

by mowing to remove ungrazed weeds. New seedings

should not be grazed when soils are wet. Heavy grazing injures the stand on either wet or dry soils.

^^ Prepared by D. L. Klingman, Crops Research Division,

Agricultural Research Service.

8
Heroiciaes jor oroaa-ieavea Weed Control

Use the amine salt of 4-(2,4-dichlorophenoxy) butyric acid (4-(2,4-DB) )^^ at the rate of 1 to 2 pounds

per acre for selective control of such weeds as rao^-

weed, lambsquarters, pigweed, and mustard when they

are still small. There will be slight stunting and curvature of the birdsfoot trefoil seedlings but they recover.

Lespedeza, a serious competitor in new trefoil seedings

in some areas, is not well controlled with 4-(2,4-DB)

nor are the weed grasses. Other herbicides are required for their control. Ethyl A^, A^, di-n-propylthiolcarbamate (EPTC),'- applied at the rate of 2

pounds per acre to the seedbed just before planting and

incorporated in the surface 1 or 2 inches of soil by disking or harrowing, controls many of the broad-leaved

weeds and all the annual grasses without injury to birdsfoot trefoil.

Dalapon Controls Grasses and Some Other

Plants

The sodium salt of 2,2-dichloropropionic acid (dalapon) applied at the rate of 2 to 5 pounds per acre

will kill the annual weed grasses and lespedeza and

severely injure volunteer red clover, alsike clover, and

Ladino clover, which are sometimes problems in trefoil seedings. A single treatment in the spring before

weed grasses are over 3 inches high may give seasonlong control in the Northern States. Where erabgrass

and other grasses continue to germinate during the

summer, two or more treatments are required. In

this case a spring treatment of dalapon followed with

another about a month later, if more grasses have germinated, will usually control grasses for the full growing

season.

At the recommended rates of treatment, dalapon will

not injure trefoil significantly at any stage of growth.

Trefoil is slightly stunted at the time of treatment but

quickly recovers and benefits from the weed control.

4-(2,4-DB) and dalapon cannot be recommended (as of

July 25, 1%0) for use on legume seedlings to be grazed by

livestock, since evidence has not been developed to prove that

they will leave no residue and/or tolerances have not been set

under Public Law 518. They can be used on seed production

fields.

Trefoil should not be grazed within 60 days after treatment.

WeÍ/tí'''' ^''^''^'^^'^^' ^^^ Usually More

Usually broad-leaved weeds and weed grasses occur

ogether as problems in new seedings of trefoil. Combmations of treatments are needed for their control

Applications of 4-(2,4-DB) at the rate of 1 to 2 pounds

per acre plus 2 to 5 pounds of dalapon per acre should

be made when the broad-leaved weeds still are small.

Later in the season if weeds again become a problem,

these herbicides can be applied singly or together, depending on the weed infestation. Dalapon combined

with mowing is also effective for control of grasses

and broad-leaved weeds when it is used as suggested

in the section entitled "Dalapon Controls Grasses and

Some Other Plants."

Weed Control for Seed Production

Weed grasses should be controlled in trefoil seedproduction fields. Dalapon is effective when 2 to 5

pounds per acre is applied before the trefoil exceeds

6 inches in height. Later treatments may reduce seed

production.

Where bedstraw is a problem in seed fields, spot

spraying with 2-(2,4,5-trichlorophenoxy) propionic

acid (silvex) in the early spring at the rate of 2 to 3

pounds per acre is effective, but the trefoil seed production will be greatly reduced for a season in the

sprayed spots.

Other legumes in trefoil may be controlled with applications of one-half pound of silvex per acre.

Treatments in the spring cause little injury to the

trefoil.

Where broad-leaved weeds such as ragweed, pigweed, and lambsquarters are a problem in seed fields,

apply sprays containing 1 pound per acre of an amine

salt formulation of 4-(2,4-DB) early in the spring

while weeds are small.

On old established stands in the humid Pacific Coast

region, the application of 1^2 to 21/2 pounds of

3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron) per

acre in the fall gives excellent winter-annual weed control and often controls those germinating in the following spring.

TREFOIL IN MIXTURES

More uniform all-season production may be expected from mixtures of trefoil and a single grass

specie. Including a grass results in the formation of

a sod that permits grazing during wet conditions with

little injury from trampling. In pure stands trefod

tends to lodge, reducing hay and seed yields. The

presence of a grass reduces lodging. Simple mixtures

of a grass with 4 to 6 pounds of trefoil seed per acre
are generally successful. Attempts to establish trefoil

in mixtures with other legumes and with more than

one kind of grass usually results in poor stands of

trefoil.

Timothy is less competitive to trefoil in establishment than most of the other grasses. Seeding a mixture of 3 to 4 pounds of timothy and 4 to 6 pounds of

trefoil per acre is a common practice in the Northeastern and North Central States for hay and pasture.

In the more northern part of the Bluegrass region, a

mixture of Kentucky bluegrass and trefoil is successfully used for permanent pasture. In establishing

pastures on land which has been in row crops, 4 to 5

pounds of Kentucky bluegrass seed and 4 to 6 pounds

of birdsfoot trefoil seed is sufficient for good stands.

In areas where orchardgrass, bromegrass, and tall

fescue are well adapted they provide severe competition to seedling piaius ui Licron. x luauLiivt pastures

of mixtures of trefoil with these grasses have been

secured. Seeding rates of the grasses are reduced to

4 to 5 pounds per acre in a mixture with 6 pounds of

Viking, Granger, Mansfield, and other varieties of

birdsfoot trefoil having good seedling vigor.

In the Pacific Northwest good results have been

obtained by seeding trefoil in alternate rows with a

grass.

Meadow foxtail in association with narrowleaf or

big trefoil has been successfully used in the Northwest.

Trefoil is frequently seeded on old pasture sods

which have been renovated either by shallow plowing

or by disking several times. It is usually not necessary to reseed the grass. This is particularly true with

Kentucky bluegrass and on sods where timothy predominates.

COMPOSITION AND NUTRITIVE VALUE

Many analyses have been made on birdsfoot trefoil

hay. Its composition is similar to that of alfalfa. At

Beltsville, Md., protein analyses were made on a large

number of plots of birdsfoot trefoil and of alfalfa cut

at comparable stages of growth. The average protein

content for two cuttings of all plots was 16.7 percent

for birdsfoot and 17.4 percent for alfalfa hay. MacDonald {24) reported a decreasing protein content

with maturity, ranging from 28 percent for young immature growth to 9 percent in plants having mature

seed pods. He reported a somewhat higher percentage

of lignin in an erect-growing European type than in

New York common (Empire type).

Loosli and others {23) found that milk from cows

fed birdsfoot trefoil hay had excellent keeping qualities and contained more carotene, vitamin A, and tocopherol than milk from cows receiving Ladino clover

and timothy hay.

In studies at the Indiana Agricultural Experiment

Station at Lafayette ^^ on the carotene content of a

number of legume-grass associations, the carotene content of birdsfoot trefoil was higher than that of alfalfa

^^ BURGER, 0. J. INFLUENCE OF SPECIES AND VARIETY INTERACTION UPON THE CAROTENE CONTENT OF THE COMPONENTS OF

CRASS-LEGUME MIXTURES. 1947. (Thesis, M.S., Purdue Univ.,

Lafayette, Ind.)

BURGER, 0. J., HAUCE, S. M., and MOTT, G. 0. EFFECT OF

GRASS-LEGUME ASSOCIATIONS UPON THE CAROTENE CONTENT OF

VARIOUS LEGUME-GRASS COMPONENTS. 1947. (Paper presented

at Agronomy Society Meeting, Cincinnati, Ohio, Nov. 1947.)

and Ladino clover whether grown alone or in mixture

with grass, and remained so throughout the season.

Plummer (32) found that carotene losses in rapid drying of green forage of comparable cuttings of birdsfoot

trefoil, alfalfa, and Ladino clover were 11, 22, and 48

percent, respectively. Studies by the Animal Husbandry Division, at Beltsville, Md.,^^ indicate that the

average percentage loss of carotene in drying at 60°

F. was only 1.3 percent for birdsfoot trefoil. Under

the same conditions, two samples of Ladino clover and

one sample of alfalfa hay lost 38.2 and 19.1 percent

of carotene, respectively.

Various reports indicate that the trefoils are somewhat less palatable than other .commonly used legumes.

In general, when animals become accustomed to trefoil forage they consume it readily. Sericea lespedeza

is a legume of low palatability, partly because of the

high tannin content of the leaves. In preliminary

tannin analyses of leaves of various trefoil species,

varying but relatively small amounts of tannin were

found. The highest—5.5 percent—was found in big

trefoil and European broadleaf. The leaves of Empire

and the narrowleaf species contained less tannin.

Indications are that the composition of trefoil is different from that of many other legumes. Much work is

needed on the composition of the trefoil species as related to nutritional values. Trefoil herbage seems to

be nonbloating, and this also needs more study.

' Agricultural Research Service, 1953-54. (Unpublished.)

10
UTILIZATION

Where birdsfoot trefoil is well adapted it is a very

desirable long-lived perennial legume for permanent

pastures. It can also be harvested for hay and silage

and is valuable as a seed crop. Because of the nonbloating character of this crop, there is no need for

growing a grass with it solely for bloat control.

Grazing Management

The varieties of birdsfoot trefoil vary in their ability to persist under different systems of grazing.

The erect-growing varieties. Cascade, Granger, Viking, Mansfield, Douglas, and imported stock from

Europe, can be completely defoliated by the grazing

animal. These varieties are similar to alfalfa in their

response to grazing. Continued close grazing or overgrazing greatly reduces the vigor of the plants and if

carried on too long the weakened plants die, leaving

thin, unproductive stands. Continuously grazed pastures should be so managed as to leave a minimum of

4 inches of growth on the plants at all times.

Rotational grazing or a system of supplemental

grazing is preferable for these erect-growing varieties.

Fields may be divided into three or more pastures and

grazed in rotation. In grazing each of the pastures, 2

to 4 inches of growth should be left on the plants at

the end of each grazing period. During periods when

birdsfoot is growing rapidly one or more pastures may

be cut for hay.

Empire and locally adapted strains originating from

Empire are less affected by close grazing due to their

low or more prostrate type of growth. Cattle rarely

graze off all top growth from these varieties; the leafy

stems close to the ground remain ungrazed. These

stems provide nutrients for continued plant growth.

In addition, they produce seed, which is important in

maintaining stands through natural reseeding.

Many stands of Empire birdsfoot trefoil are continuously grazed, particularly by beef animals. However, rotational grazing may be desirable, depending

upon the kind and class of livestock utilizing the pastures. Sheep are more selective in their grazing habits and may overgraze birdsfoot trefoil under continuous grazing. Grazing three or more fields in

rotation or using some form of deferred grazing when

other pasturage is available seems to be the most desirable program for sheep. High-producing dairy cows

benefit from the more nutritive forage provided by

rotational grazing.

Both narrowleaf and big trefoil are spreading, lowgrowing plants. In the West the grazing management

for these species is very similar to that for Empire and

strains derived from Empire.

Hay and Silage

Birdsfoot, narrowleaf, and big trefoil are not usually

grown for hay alone. However, in the utilization of

the trefoils for pasture it is frequently desirable to

take a cutting for hay or silage. Where rotational

grazing is practiced, the first growth on the last pasture grazed in the first grazing round may become

quite heavy and tall. In grazing, a large part of this

tall growth is lost by trampling and fouling with

manure. Cutting a part of the acreage for hay or

silage gives more profitable utilization of the crop.

The trefoils make good quality hay. In general,

they can be cut as they come into bloom. Cutting

should be done after the dew dries from the plants.

High-quality hay is leafy hay. All raking, stacking,

or bahng operations should be so handled as to preserve maximum percentages of leaves. Under good

drying conditions, the crop should be windrowed or

raked 4 to 6 hours after cutting. The leaves will become brittle and a high percentage of them will be

lost if raking is delayed. Windrow-cured hay may be

baled from the windrow or stacked, if the proper equipment is available.

Preliminary tests have shown that the trefoils make

good silage. For specific information on making trefoil silage consult your county agent or write to your

State agricultural experiment station.

SEED PRODUCTION

Seed yields of birdsfoot trefoil are usually low compared with other legumes. Satisfactory yields of trefoil seed are difficult to secure. Various reports show

yields of 40 to 100 pounds per acre as common in the

North Central and Northern States. Top yields of

300 pounds per acre have been reported. Peterson

and others (30) report California seed yields as ranging from less than 100 to 425 pounds per acre. The

low seed yields make seeding costs high and have hmited the use of this legume. Low yields are due primarily to the tendency of pods to dehisce as they

mature. Seed harvesting is further complicated by

11
the fact that mature and green pods are found on most

plants throughout the seed-production cycle since the

plants flower over a long period of time. Considerable

experience is required to determine when to harvest

the seed crop.

Statistics on total seed production of trefoil in the

United States are not available. Important seed-producing areas are indicated in the report by Hill (16)

on amounts of certified seed produced in 1958. A

total of slightly less than 1 million pounds of seed of

all classes—foundation, registered, and certified—was

produced in 1958. New York and Vermont produced

63 percent, Minnesota and North Dakota 16 percent,

and California and Oregon 21 percent of the total certified seed crop in 1958. Many of the adjoining

States produce some seed. Wiggans and others {42)

reported a production of 40,000 pounds in Iowa in

1955.

Considerable birdsfoot trefoil seed is imported from

Europe, primarily from France and Italy. According

to Agricultural Statistics of the U.S. Department of

Agriculture, 893,000 pounds of trefoil seed was imported annually during the 10-year period 1948-57.

Pollinators

Practically all trefoil seed is produced from cross

fertilization of the flowers by various insect pollinators.

Good seed yields are produced only when adequate

numbers of pollinating insects are present. Honey

bees and various species of wild bees, including bumblebees, are effective pollinators of trefoil flowers.

Honey bees are generally relied upon, since the numbers necessary for effective pollination can be supplied.

Studies by Morse (28) in New York showed that an

average of one bee per square yard is adequate to

pollinate all flowers. On this basis one average-sized

colony of bees could be relied upon to pollinate the

flowers of an acre of trefoil.

Pure Stands versus Grass Mixtures

Studies have been conducted in various areas showing the effect on seed production of seeding various

grasses in mixture with trefoil. MacDonald (24) concluded that severe lodging greatly reduced seed yields

and among the grasses tested, trefoil, in association

with timothy, appeared to have some value in increasing seed yields. In central Iowa, Anderson and Metcalfe (2) reported significantly greater seed yields of

trefoil when grown in association with Kentucky bluegrass, orchardgrass, or timothy, than when grown in

pure stands. In their tests the highest yields were

obtained fro^ ^ ^ _ scture.

Birdsfoot trefoil in pure stands was rated as 69 percent lodged for the 2 years of the test. The average

lodging of trefoil when grown with Kentucky bluegrass, orchardgrass, and timothy was 6.5, 21.0, and

17.8 percent, respectively.

After a 2-year study, Schoth and Rampton ^^ found

that grasses were oí little value in increasing trefoil

seed yields. In California, Peterson and others (30)

recommended only pure stands of birdsfoot trefoil for

seed production under irrigation. Additional studies

on this point are needed, but present evidence indicates that severe lodging in birdsfoot trefoil reduces

seed yields in the North Central and Eastern States.

When lodging is a problem it may be reduced by planting birdsfoot trefoil in mixture with Kentucky bluegrass or timothy, thereby increasing seed yields. Where

no lodging occurs there is no advantage in mixtures.

For information on weed control for seed production,

see page 9.

Harvesting the Seed Crop

The first crop of trefoil is usually harvested for seed.

Two seed crops may be possible under irrigation in

some areas of the West. Much lower seed yields were

secured from the second crop in Iowa (2) and New

York (23) when the first crop was taken for hay.

Time of Harvest

Seed fields should be observed frequently to determine when to harvest the crop. From flowering to

pod maturity requires approximately 30 days. Warm,

dry weather during this period hastens maturity from

2 to 4 days, whereas cool, moist weather delays maturity of the seed. The crop should be harvested when

a high percentage of the pods are light brown to brown

and before appreciable shattering occurs. The crop

should be mowed before the dew is off to reduce shattering as much as possible. The use of a mower with

swather attachment to the cutter bar is a widely accepted practice. The crop should be combined as soon

as it is dry enough to thresh. If it is dry and warm

with correspondingly low humidity, 8 hours in the

swath may be all that can be allowed before combining. Under more humid conditions a drying time of

24 to 48 hours may be necessary before combining

the crop.

'"Schoth, H. A., and Rampton, H. H., Crops Research Division, Agricultural Research Service, in cooperation with the

Oregon Agricultural Experiment Station, Corvallis. 1949-50.

(Unpublished data.)

12
« /crc<f f/C'rcfii

Direct combining of birdsfoot trefoil without defoliants is practicable to a limited extent in some areas.

Where the crop is not lodged, most of the seed pods

will be in the upper parts of the plants and fair to

good seed yields can be obtained. Under these conditions the speed of the combine must necessarily be

slow, thus limiting the acreage that can be harvested

per combine. Under most conditions the rank, leafy

growth of the crop makes direct combining a slow

and difficult process.

Direct Combining With Defoliants

Chemical defoliants can be successfully used {20,

29, 41) to defoliate or partially defoliate the green

trefoil plants. When sprayed on the green plants, the

defoliant will cause some of the leaves to drop and

others to wilt, thereby reducing the moisture content

of the plant to the point where it may be combined

before seed shattering becomes severe. The time between defoliation and combining will depend on the

kind and concentration of defoliant used and on the

weather. Growers interested in defoliants should consult their State agricultural experiment stations for

specific information.

Freshly combined seed contains various amounts of

green stems, pods, leaves, and other foreign matter,

all relatively high in moisture. The seed also may

contain green and partially dried seed. The combined

seed should be screened immediately to remove wet

trash and then spread out to dry.

After harvesting, trefoil seed should be watched

carefully to prevent heating, molding, and loss of germination, as the moisture content may be high in the

seed itself and, under some circumstances, in the inert

material mixed with it. It is usually advisable to scalp

off most of the inert material before storing. Store

the seed in small lots until it is dry enough to prevent

heating.

The separation of trefoil seed from those of other

small seeded legumes such as white and alsike clover

is rather difficuh. On the Pacific Coast the removal

of hop clover seed is very difficult.

Hard Seed

Seed of birdsfoot trefoil normally contains a high

percentage of hard seed. The seed coat of hard seed

is impermeable to water and the germination of such

seed is greatly retarded. Hard seeds may eventually

germinate but they are of little value in securing good

stands. Seed lots containing over 15 percent of hard

seed should be scarified before seeding. The amount

of scarification necessary to reduce the hard seed content should be carefully determined. Hughes and MacDonald {19), reporting on studies in Iowa, showed that

excessive scarification injures the seed, causing lower

germination and seedling emergence. Seed viability is

generally reduced w^hen it is mechanically scarified

and then stored. Wood (43) suggested the use of infrared heat treatment for scarification to reduce the

number of hard seeds without loss of viability in

storage.

DISEASES'*

The most destructive disease of big and birdsfoot

trefoil is caused by the soil-inhabiting fungus Rhizoctonia solani Kuehn, which incites not only foliar

blight but crown and root rots as w^ell. It is most destructive in dense stands during hot, humid weather

from May to September. The disease is less prevalent

at higher elevations, possibly because of cooler nights.

Damage occurs in patches and the fungus sometimes

kills up to 90 percent of the plants in an affected area.

Rhizoctonia solani usually attacks the lower leaves

first and mycelium of the fungus rapidly overruns

foliage and stems. The fungus sometimes attacks so

rapidly that plants are killed within a few days. Affected leaves wilt, turn gray, and become matted to

"Prepared by K. W. Kreitlow, Crops Research Division,

Agricultural Research Service.

stems and petioles. New shoots are killed and large

gray- to straw-colored lesions with irregular reddishbrown margins are formed on stems. The lesions

often girdle the stems, causing death of the foliage.

All varieties of big and birdsfoot trefoils are susceptible. The disease can be controlled to some extent by

harvesting the crop at the earliest sign of infection.

Next to the blight caused by Rhizoctonia sokni,

the crown- and root-rot fungi are most destructive.

Fungi associated with root rots include Fusarium spp.,

Verticillium spp., Leptodiscus terrestris Gerdemann,

and Sclerotinia trifoliomm Eriks. Limited observations indicate that birdsfoot trefoil is more heavily

damaged by root-rot fungi than is big trefoil. Ihese

fungi frequently occur in localized areas and may be

serious in some fields. They are most prevalent m

heavier, wetter soils but sometimes occur m any soi

13
in a wet season. Root-rot fungi attack plants at any

stage of growth, but they appear to be most destructive on plants one or more years old. With the exception of S. trifoliorum, the above fungi are mostly

associated with summer dying.

Sclerotinia trifoliorum attacks plants mainly during

late winter and early spring. The fungus causes a watery soft rot of the crown and upper taproot. The

entire plant is usually killed and tufts of white, cottony

mycelium can sometimes be seen at or near the crown.

Later the fungus forms gray to black round, or oblong,

sclerotia from i/^ß- to Vi-inch in size. These are usually found attached to the outside of the crown or

taproot or embedded in diseased tissue.

Leptodiscus terrestris is sometimes associated with

root rot of birdsfoot trefoil. It is characterized by

decay of the crown and taproot. The advancing margin

of decay is black or sometimes reddish brown and

many tiny sclerotia are present in decayed tissue. Root

tissues affected by L. terrestris are usually dry and

shredded. The disease is sometimes difficult to distinguish from root and crown rot caused by Rhizoctonia solani. Also, the disease is frequently associated with other root-rotting organisms.

There are no specific symptoms associated with infections by species of Fusarium and Verticillium. In

most cases these fungi are found in association with

R. solani and L. terrestris. Undoubtedly, the several

organisms acting in association attack crowns and roots

under different environmental conditions and possibly

do more damage collectively than they do individually.

The southern blight fungus, Sclerotium rolfsii Sacc,

sometimes attacks plants of big and birdsfoot trefoil

during warm, wet w^eather. This fungus infects plants

singly or in groups at or near the soil line, producing

grayish-tan lesions that enlarge and girdle the stems.

Infected plants usually wilt in 3 or 4 days. Leaves

of diseased plants often turn grayish green and then

cinnamon brown and resemble foliage of plants that

are mechanically girdled. The fohar blight and stem

girdling from S. rolfsii sometimes resembles symptoms

resulting from infection by Rhizoctonia solani. Generally no reddish-brown margin borders the lesions incited by 5. rolfsii. Creamy-white to reddish-brown,

round sclerotia 1 to 2 mm. in diameter form on dead

stems and further characterize the disease. Since the

disease occurs sporadically, no effort has been made

to develop resistant varieties.

In the Southeast big and birdsfoot trefoil are susceptible to attack by four species of root-knot nematodes. Nematode infection induces formation of

swellings or galls on the roots. These sometimes resemble the swe^ icted

plants become stunted and yield poorly. No varieties

presently grown are resistant.

Aside from foliar blight caused by Rhizoctonia solani, the most prevalent foliar disease of birdsfoot

trefoil (leaf spot and stem canker) is caused by Stemphylium loti Graham. This disease generally occurs

throughout the growing season wherever birdsfoot trefoil is cultivated. Principal damage is from defoliation. Formation of one lesion may cause a leaflet to

drop prematurely. S. loti produces reddish-brown

circular spots on leaflets and copper-colored cankers

on stems of birdsfoot trefoil. Spots range from pinpoint to 5 mm. in diameter and often are concentrically

zoned. The centers of mature lesions are usually

lighter than the surrounding borders. The fungus

survives on host tissue and in association with seed.

When seedborne, the fungus kills young seedlings. No

resistant varieties are known at present.

A foliar blight of stems and leaves of birdsfoot trefoil caused by Fusarium roseum Lk. has been reported

from New York. Infection induces bleaching and

wilting of the shoot tips which often involves the entire

plant. Symptoms often start as apical yeHowing followed by bleaching of blighted shoots. In some plants

the blight progresses from the tips of the shoots to

the crown of the plant. In others it becomes arrested and only stem tips wither and die. Affected

plants have been observed in seedling stands and in

those 2 to 5 years old. Blighted plants are conspicuous among the normal dark green, vigorously growing

plants. The disease occurs sporadically and seldom

involves many plants. When first seen, the symptoms

somewhat resemble those of blight caused by Rhizoctonia solani. No resistant varieties are known.

In the Southeast big trefoil is sometimes attacked by

the blackpatch fungus Rhizoctonia leguminicola Gough

& Elliott. The fungus is most prevalent during warm

weather, causing the leaflets to blight and the stems

to turn dusty green, darkening to brown. The coarse,

black fungus mycelium can nearly alw^ays be seen on

leaves and stems without the aid of a hand lens.

A leaf spot caused by the fungus Cercospora loti

Hollos has been found defoliating plants of big trefoil

in Maryland, Georgia, and Florida. The disease occurs mostly in the spring but can be found on older

plants throughout the growing season. Lesions produced on leaves are usually circular, 3 to 5 mm. in

diameter, and olive gray to reddish brown when mature. Diseased leaflets shrivel and drop on at the

slightest touch. No resistant varieties are available.

14
This icai-spui luu^us. nas iiui Dcen louiid on birdsfoot the oreenhn^^^^ 1.0 u 1 1 . .

..foil in the field. However, artific.al infecúon in .Sdi; sutpTble ^ i: " ''" ''''''''' ' ^^°" ^^

INSECTS INJURIOUS TO TREFOIL >'

Several species of insects attack and injure birdsfoot trefoil. The meadow spittlebug iPhilaenus

spumarius \L.) ) is probably the most important pest

in the Midwest and East. x\ymphs of this species,

protected by a mass of spittle, suck the sap from

stems and leaves, causing a rosetting of the foliage and

stunting of the plants. Nymphs and adults of the potato leafhopper iEmpoasca fahae (Harris)) also suck

the plant juices and cause the foliage to turn red or

'' Contributed IDV the Entomology Research Division, Agricultural Research Service.

yellow, beginning at the tips of the leaflets. The

alfalfa plant bug {Adelphocoris lineolatus (Goeze))

and the rapid plant bug {A. rapidus (Say)) also suck

plant sap. Lygus bugs [Ly^us spp.) may cause a

blasting of buds, floret blight, and loss of seed. Stink

bugs, grasshoppers, cutworms, and seed chalcids are

pests at times.

For information regarding control of insects on trefoil, consult your county agent. State agricultural experiment station, or write to the U.S. Department of

Agriculture, Washington 25, D.C.

LITERATURE CITED

Q) AiiLCREN, G. H., BRIGGS, R. A., SPRAGUE, M. A., and

WAKEFIELD, R. C.

1955. BIRDSFOOT TREFOIL. N.J. Agr. Expt. Sta. Bui. 779,

15 pp.. illus.

12) ANDERSON. S. R., and METCALFE, D. S.

1957. SEED YIELDS OF BIRDSF(J(JT TREFOIL (LOTUS CORNICULATLS L. I AS AFFECTED BY 1>RE-HAR\EST

CLII'PING AND BY GROWING IN ASSOCIATION WITH

THREE ADAPTED GRASSES. Agron. Jour. 49: 52-55.

<3) BATES, R. P., and HENSON, P. R.

1955. STUDIES ON INHERITANCE IN LESPEDEZA CUNEATA

D(JN. Agron. Jour. 47: 503-507.

(4) BAYLOR, J. E.

1958. ESTABLISHMENT AND EARLY PLANT DE\EL(JPMENT

OF BIRDSFíJOT TREFOIL (LOTLS CORNICULATUS L.)

AS AFFECTED BY SE\ERAL FACTORS OF C(JMPETITI(JN.

Diss. Abs. 19 (1): 10-11. (Thesis, Ph. D. Pa.

State Univ. 119 pp.)

Í5) BLB^R, J. S.

1957. FLOWER C(JLOL'R INHERITANCE STUDIES IN BROADLEAF BIRDSFOOT TREFOIL (LOTUS CORNICULATUS

L.). (Abstract 278) Plant Breeding Abs. 27 (1):

40.

Í6) DAWSON, C. D. R.

1941. TETRASOMIC INHERITANCE IN LOTUS CORNICULATUS

L. Jour. Genetics 42 (1-2) : 48-72. illus.

(7) DODD, D. R.

1948. BIRDSFOOT TREFOIL—NEW LEGUME YOK OHIO.

Ohio Farm and Home Res. 33: 156-161, illus.

Í8) DONOVAN, L. S.

1959. THE INHERITANCE OF LEAF SIZE IN BROADLEAF

BIRDSF(JOT TREF(HL, LOTUS CORNICULATUS L.

Ganad. Jour. Plant Sei. 39 Í2) : 141-157, illus.

<9) EAKIN, J. H., Jr.

1954. BIRDSFOOT TREFOIL. Pa. Agr. Ext. Serv. Cir. 411,

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( 10) ERDMAN, L. W., and MEANS, U. M.

1949. STRAINS OF RHIZOBIUM EFFECTIVE ON THE TREFOILS,

LOTUS CORNICULATUS AND LOTUS ULIGINOSUS.

Soil Sei. Soc. Amer. Proc. 14: 170-175, illus.

(11) GARDNER, C. A., and ELLIOTT, H. G.

1945. GREATER BIRDSFOOT TREFOIL (LOTUS ULIGINOSUS

scHKUHR. ). West Austral. Dept. Agr. Jour. 22:

358-360, illus.

(12) GERSHOY, ALEXANDER.

1956. MANSFIELD, A NEW TREFOIL FOR VERMONT. Vt.

Farm and Home Sei. 1 (4): [3]-4, 15, illus.

(13) GRAHAM, J. H.

1953. A DISEASE OF BIRDSFOOT TREFOIL CAUSED BY A

NEW SPECIES OF STEMPHYLIUM. Phytopathology

43: 577-579, illus.

(14) GUINOCHET, M.

1952. EXPERIMENTAL TAXONOMIC STUDIES ON THE FLORA

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HI. CARYOSYSTEMATIC NOTES ON L. CORNICULATUS L.

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( 15 ) HART, R. H., and WILSIE, C. P.

1959. INHERITANCE OF A FLOWER CHARACTER, BROWN

KEEL TIP, IN LOTUS CORNICULATUS L. AgrOH.

Jour. 51: 379-380.

(16) HILL, S. E.

[1959.] REPORT OF SEED CERTIFIED IN 19 5 7 BY STATE

CERTIFYING AGENCIES. U.S. Dept. Agr. CropS

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(17) HosAKA, E. Y.

1957. TREFOILS IN iiAWAH. Hawaii Univ. Ext. Ur. óo/,

[12] pp., illus.

(18) HowELL, H. B.

1948. A LEGUME FOR ACID SOILS, LOTUS ULIGINOSUS (L.

MAJOR,. Oreg. Agr. Expt. Sta. Bub 456, 25 pp.,

illus.

15
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HUGHES, H. D., and MACDONALD, H. A.

1951. BiRDSFOOT TREFOIL. In Foiages, pp. 215-233,

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JONES, L. G.

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LoosLi, J. K., KRUKOVSKY, V. N., LOFGREEN, G. P., and

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16

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