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LIBRARY OF THEUNIVERSITY OF ILLINOIS

AT URBANA-CHAMPAIGN

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SURVEY

TREE

AND

SHRUB

HOSTS

OF

V&ntlcllllatti atU-at/iairi

E.B.HIMELICK

BrOLOGICAL NOTES NO. 66

ILLINOIS NJTURAL HISTORV SURVEY

URBANA. ILLINOIS JULY. 1969

STATE or ILLTNOiS

DEPARIMETTT OF TTECTSTRATTON AND EDTJCATTON

NATURAL HISTORY SURVEY DIVISION

I r^

TREE AND SHRUB HOSTSOF VERTICILUUM ALBO-ATRUM

Verticillium wilt, caused by VerticiUium albo-

atntm Reinke and Berth., lias become increasingly

prevalent among plantings of ornamental trees and

shrubs in Illinois. Persons not familiar with Verti-

cillium wilt symptoms frequently attribute plant deaths

resulting from this disease to other causes, such as

transplanting shock and winter injury. Because this

fungus affects a wide range of woody ornamental

plants, it is difficult to estimate the economic loss it

causes to nursersmen and homeowners. Rankin ( 1914

)

first reported the disease on maple in the United States

and identified the fungus as a species of Acrostalagmus.

Zimm (1918) later proved pathogenicity and identi-

fied the fungus as a species of VerticiUium. A mono-graph on the disease by Rudolph ( 1931 ) lists the

known host range up to 1931. Engelhard (1957) pub-

lished a host index for V. alho-atnim that included

both herbaceous and woody plants.

NEWLY IDENTIFIED HOSTS

Routine isolations have been made at the Illinois

Natural History Survey from branch samples of dis-

eased trees and shrubs since 1926. During the last 42

years V. alho-atrum (including V. dahliae Kleb.) has

been obtained from se\eral hosts growing in widely

scattered areas of the state. Table 1 shows the woodyhosts reported for Illinois by 1956, including 30 tree

and shrub species and \arieties (Carter 193S, 1940,

1945; Engelhard & Carter 1956). Since the last of

these reports was published, 26 additional species andvarieties of woody ornamentals, also listed in Table 1,

have been identified as hosts in Illinois. Twenty-t\\'o

of the plant species or varieties, identified at the Illi-

nois Natural History Survey and listed in Table 1, are

belie\ed to be previously unrecorded hosts in the

United States, as no records of these hosts were found.

However, at least 3 of these 22 hosts have been re-

ported in other countries. A few of the new Verticil-

lium hosts reported here ha\e been mentioned in re-

ports which were primarily field survey reports. Wherethere is no indication that the fungus was isolated

from infected wood and positively identified, the field

report usually is not cited.

PATHOGENICITY TESTS

Since 1957 VertirilliuDi isolates from \-arious hosts

have been tested at the Illinois Natural History Sur\cy

for pathogenicity to the respective host plant. Most of

E. B. Himelick

the trees and shmbs were available in our research

arboretum. Occasionally certain species were not

available and had to be purchased as seedlings. Theseseedlings were established in pots in our greenhouse.

Pathogenicity was tested by inoculating 5-20 plants

of each species or variety, and an equal number of

uninoculated plants was used as a control for eachspecies. Each plant was inoculated by placing a dropof spore suspension in a diisel wound made in the

base of the trunk. An attempt was made to reisolate

the fungus within 7 days following the initial appear-ance of foliage symptoms. External symptoms wereproduced 2 weeks to 3 months after inoculation onall species except silver maple. Silver maple did not

produce typical foliage symptoms, but did havescattered faint green streaks in the twigs 4-5 feet

from the point of inoculation. The fungus was re-

covered from the discolored area 2 months after inoc-

ulation.

Pathogenicity was established for 18 of the 22 plant

species listed in Table 1 as new hosts in the UnitedStates. Pathogenicity was established for an addition-

al four plant species that were newly discovered hosts

in Illinois and for an additional eight species fromwhich V. alho-atrum had been isolated but for whichproof of pathogenicity had not been established.

HOSTS OUTSIDE OF ILLINOIS

Table 2 lists the VerticiUium tree and shrub hosts

identified in addition to the 1957 list of Engelhard andthose listed for Illinois in Table 1. Most of these hosts

ha\e been reported since 1957. Engelhard's list andTables 1 and 2 include most of the world's knownX'erticillium wilt hosts among trees and shrubs.

VERTICILLIUM WILT SYMPTOMS

Some tree and shrub species tend first to showfoliage symptoms during a limited period of the grow-ing season; other species have s)'mptoms appearingat any time throughout the growing season. The times

when plant growth begins and ceases are \'ariable in

Illinois, since the state has three climatic zones(Rehder 1940:ii,xii). In Illinois, Verticillium wilt ap-

pears to be most prexalent in trees and shrubs in the

area that demarks the line between climatic zones IVand \ and appears progressi\('l\- less pre\alent oniM)th sides of this imaginary line. Both temperatureand moisture may be factors that contribute to the

Table 1.—Tree and shrub hosts of Veilicillium albo-atnim in Illinois.

iiUcilliuvi Isolations for

Illinois. 1926-1968Pathogenicity Tests Reported as a Host

Host Plant

NnmherFirst Year Number of Number NumberIsolated of Years Naturally of Plants of Plants

in Illinois Isolated Infected Inoculated Infected

Plants

United State Other Countries

Almond ( Pninus amygdalus Batsch.

)

Ash spp. ( Fraxiniis spp.

)

Black (F. nigra Marsh.)

Blue ( F. quiidrangulata Miclix.

)

European (F. excelsior L.)

Green ( F. pcunstiliituica Marshall

var. subiutegerrinui ( V'ahl ) Femald

)

White ( F. anwriciina L.

)

Azalea ( Rhododendron mollc G. Don

)

Barberry spp. ( Bcrberis spp.

)

Japanese ( B. thwihcrpii DG.)

Bcwvood, Korean ( Buxiis microphylla

korcana N'akai

)

Catalpa spp. ( Calalpa spp.

)

Western ( C. sfwciosa Warder

)

Coffee tree, Kentucky {Gymnocladusdioica (L.) K. Koch.)

Cork tree ( Vhellodendron amurenscRupr.)

Elm, American ( Vhnus umericana L.)

var. AuKiistine Ascending

Henry Field

Littleford

Moline

Chinese ( V. parvifolia Jacq.

)

English ( U. proccra Salisb.

)

Slippery ( V. rubra Muhl.

)

Goldenrain tree ( Koelreuteria paniculata

Laxm.)

Linden, American ( Tilia americana L.

)

Little leaf ( T. cordata Mill.

)

Locust, Black (Robinia pscudoacacia L.)

Magnolia spp. ( Magnolia spp.

)

Saucer (A/, soulangeana Soul.)

Star ( A/, stellata { Sieb. 6e Zucc.

)

Maxim.

)

Maple spp. ( Acer spp.

)

Amur (A. ginnala Maxim.)

Black (A. nigrum Michx. f.

)

1932

Table 1.—Continued

Verticillium Isolations for

Illinois, 1926-1968Pathogenicity Tests Reported as a Host

Host Plant

NumberFirst Year Number of Number NumberIsolated of Years Naturally of Plants of Plants

in Illinois Isolated Infected Inoculated Infected

Plants

United States Other Countries

19601937

variability in the prevalence of the disease, along \\ith

the presence of a large number of tree species gro\\'ing

in this area. Becanse of the loss of elms, a greater

variety of tree species is being planted than pre\iously.

Our plant disease clinic records indicate that 34

percent of the confirmed V. alho-atium isolations oc-

curred in the month of Jul>', 20 percent in June, 20

percent in August. 10 percent in September. 8 percent

in May, 6 percent in October, and only 2 perc(Mit in

March. April, and Xo\eniber.

For the past several \ears obser\ations have been

made of Verticillium wilt symptoms on various tree

species (Table 3). \'ariation in s\inptom expression

and in extent and speed of decline often occurs amongthe different species. For simplification, the table in-

cludes the more commonly observed symptoms for

each of the host species listed.

SUSCEPTIBILITY OF HOSTS

.\ summar\- of our laboratory records tor the past

42 \ears indicates that nine tree and three shriib

genera are most commonly affected by Verticillium

wilt. V. alho-atruni was recoxered most frequently

Table 2.—Tree and .slinib liosts of Verticillium albo-atniiii out>ide of Illinois

troni branch specimens of ash, barberry, catalpa, elm,

magnolia, maple, redbud. Russian oli\e, smoke tree,

sumac, tulip tree, and \iburnum.

In recent years strains of V. aJbo-utrum iia\e beenisolated that are quite \irulent to numerous tree andshrub species. One strain isolated from a naturally

infected pin oak tree {Qucrcus palustris Muenchh.

)

and inoculated into both pin oak and red oak (Q.rubra L. )

produced wilt symptoms and internal dis-

coloration similar to those of the oak wilt disease. Thepin oak strain appears to be more \ irulent than maplestrains in maple, ash. magnolia, and Russian olive.

Hou('\er. inoculation tests indicated that the pin oak

strain was not pathogenic on wliitc oak( Q. aiha L. ) or

bur oak {Q. macrocarpo Miclix. ). In addition, a strain

isolated from ash and inoculated into \'igorous. grow-

ing trees, such as maple, redbud. and tulip tree, did

not produce wilt symptoms. Ho\\e\er, when this

strain was placed in Russian oli\e. t\iiical wilt symp-toms were produced in 2-3 weeks.

Trees susceptible to \'erticillium wilt occasionally

sliow symptoms of this disease while they are still in

a weakened condition following transplanting. Since

there is cxidence that V. alho-atnnn isolates differ in

Host PLintReported as a Host

United States Other Countries

Apricot {Pruntis anhcniaca L.)

Az.ilea ( Rhododcmlron spp.

)

Boxwood ( Btixtis spp.

)

(B. scmpenircns L.

)

Chern- (Primus aiiiim L.

)

(P. cerasus L.)

Chestnut. Spanisli ( Castanca satita Mill.

)

Dogwood (Cornus florida L.)

Elm, Scotch (L'lmus ciimi>cstris L.)

HoH.v oli\e (Osmanthut ilicifolius (Hassk.) Mouillcf.)

Horse chestnut (Acsculus hippoctistanum L.

)

Judas-tree (Ccrcis siliqiiastriim L.)

Magnolia (Magnolia urandiflora L.)

Maple, Japanese (Acer palmatum Thunb.)Oregon (A. macrophyllum Pursh.)

Painted ( A. mono Ma.\iin.

)

Striped (A. pennsyhanicum L.

)

Sycamore (A. pscudoplatanus L.)

Oak spp. ( Quercus spp.

)

Turkey (Q. cerris L.)

Osage orange (Madura pomifera ( Raf .) Schneid.)

Peach (Prunus persica (L.) Batsch.)

Peony (Paconia spp.)

Plum (Prunus domestica L.)

Canada (P. nigra Ait.)

Rose ( Rosa spp.

)

Tree of heaven ( Ailanthus altissima (Mill.) Swingle)

\\'idesprcad (Parker 1959)

Mass. (Edson & Wood 1936)Eastern U.S. ( Hutchinson

1931 )>

Va. (Harrar 1937)

^\'idespread (Parker 1959)

Widespread (Parker 1959)Calif. (McCain 1963)

Mass. (Holmes 1957)

Va. ( Gruenhagen & Fordyce1963)

Pa. (Armstrong 1941)

Calif. (McCain 1963)

N.Y. (.Martin 1926)

NW states (Beducll & Cliikls

19.38), Calif, (Miclkc 1935)Tenn. (Felix 19.55)

N.Y. (Hiblxn 19.59)

Conn. (Waterman 1941)

\\'idespread (Parker 1959)Kans. (Martin 1926; Rogerson

19.57)

\\'idespread (Parker 1959)

Canada (Quebec 1961)

Canada (Quebec 1961)Canada (Quebec 1961)

Italv (Goidanich 1935), Hol-

land (van (Icr Mccr 1926)

Italy (Goidanich 19.35)

Canada (Quebec 1961), Italy

(Goidanich 1934)Ru.ssia (Krangauz 1958)Hungary ( Georgescu ct al.

19.59)

Italy (Goidanich 19.34)

Canada (Quebec 1961)

Canada ( Quebec 1961

)

Canada (Quebec 1961)Canada (Quebec 1961)Italy (Goidanich 1935)

VerticiUium sp. isolated.

virulence to various hosts, the transporting of infected

ornamental plants from one area to another mayaccount for the appearance of the disease in tree andshrub species not previously attacked by it. It seems

likely that the continued indiscriminate movement of

nursery stock from one region to another will eventual-

ly bring about a complete distribution of all virulent

strains to areas where they did not exist before.

Table 3.—Symptoms of Verticillium wilt observed on trees and shrubs.

Host Plant Type of Decline Leaf SymptomsVascular Symptoms

in Xvlcm

Ash

Azalea

Bo.wvood

Catalpa

Coffee tree

Cork tree

Elm

Goldenrain tree

Linden

Locust, black

Magnolia

Maple

Oak

Pasoda tree

Redbud

Rose daphneRussian olive

Smoke tree

Sour gum

Sumac

Tulip tree

Viburnum

Vellowwood

Twig or branch dieback. Abscission when still green; Faint tan streaks (when theyYoung trees usually appear to yellow ing and scorching of occur); seldom found inrecover. other leaves twigs.

Usually rapid decline, 2-4 weeks. Yellowing and browning \cllowish-bro\\n to brownish-Shrubs usually die. black streaks

Twig dieback. Some plants may Browning and defoliation Brown discolorationrecover.

Twig or branch dieback; occa- Yellowing and scorching Purplish-pink to bluish-brownsionally branches or whole upon dr>ingtree wilts. Trees appear to re-

cover.

Twig dieback. Young seedlings bellowing, scorching, and de- Liglit brown streaks

recover. foliation

Branch wilt. Young trees appear 'lellowing and defoliation Faint brown streaks

to recover.

Twig dieback. Sometimes whole Flaccidit>-, yellowing, and de- Brown streaks

tree dies. foliation

Usually rapid decline, 2-4 weeks. Scorching and brow niug Brown streaks

Young trees may recover.

Usually branch dieback. Some ^ellowing and browning Brown streakstrees may reco\er.

Twig dieback. Yellowing, browning, and de- Light to dark reddish-brownfoliation streaks

Usually rapid decline; sometimes Yellowing, browning, and de- 'Greenish-brown streaksonly branches are affected. foliation

Varies with species from rapid Scorching, browning, and de- Light to dark green streaks;to no decline. Symptoms may foliation often difficult to find.disappear and reappear years

later.

Twig dieback, slow decline Flaccidity, discoloring, brown- Brown streaks and sometimesing, and some defoliation; bands; similar to conditionsimilar to oak wilt. caused by oak wilt.

Slow decline, 1-2 years. Yellowing and browning No discoloration obser\cd.Usually rapid decline, 2-4 weeks. Flaccidity, yellowing, brown- Brown streaks

Trees usually die. ing, and some defoliation

Slow decline over 2-3 years. Yellowing and defoliation Brown streaksTwig dieback; may occur each Yellowing and browning Brown streaks

year or skip a year or two andreappear. Some trees may die.

Rapid decline. Trees usually die. Margins reddish-purple; later Yellowish-brown to browni.sh-

yellowing, browning, and black streaks

defoliation.

Usually rapid decline, 2-4 weeks. Scorching and browningTrees usually die.

Rapid decline, 2-4 weeks. Yellowing and browningShrubs usually die.

Rapid decline, 2-4 weeks.Trees usually die.

Chocolate brown streaks

Liglit green streaks

Rapid decline, 2-4 weeks.

Shrubs usually die.

Rapid decline, 2-4 weeks.Trees usually live.

Yellowing and defoliation

Browning and defoliation

Browning and defoliation

Greenish-brown streaks. Bark

m;iy be killed in strips ontrunk.

Light to dark reddish-brown

streaks

Brown streaks

LITERATURE CITED

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Baines, R. C. 1945. Verticillium wilt and die-back of Vi-burnum. Phytopathology 3.5:145-147.

Baker, K. F., W. C. Snyder, and H. N. Hansen. 1940. Somehosts of Verticillium in California. Plant Di.sease Reporter24:424-425.

Beuwell,J. L., and T. W. Ciin.DS. 1938. Verticillium wilt

of maple and elm in the Pacific Northwest. Plant Di.sease

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8

Bo\-D, O. C. 1930. Some diseases of shrubs and ornamont.ils

in Massachusetts. Plant Disease Reporter 14:201.C.\KOSELLi. Nestor E. 1961. N'erticilliiim wilt of smoke bush,

Plant Disease Reporter 45:24-25.

C.\RTER,J. C. 1938. W'rticillium wilt of woody plants in

Illinois. Plant Di.sease Reporter 22:253-254.1940. Some isolations of Verticillium in Illinois

durinj; 1938 and 1939. Plant Disease Reporter 24:133-134.1945. Isolations of Wrtiiillium from trees and sluiihs

in Illinois, 1940-1944. Plant Disease Reporter 29:95-96.Edson. H. .\,. and Jessie I. Wood. 1936. Disea.ses of plants

in tlie United States in 1935. Plant Disease ReporterSupplement 96:115-289.

Ellett, C. W. 1957. Diseases not previously reported in

Ohio. Plant Disea.sc Reporter 41:369-371.Engelhard, .Vhthvr W. 1957. Host index of \'ertieillium

allK>-atnim Reinlce & Berth. ( including \"erticilliimi dahliaeKleb. ). Plant Disease Reporter Supplement 244:21-50.

andJ. C. C.^HTEH. 1956. I.solations of Verticillium

albo-atnim from woody hosts in Illinois, 1945-1955. PlantDisease Reporter 40:459-462.

Felk, E. L. 1955. Some tree diseases in Tennessee. PlantDisca.se Reporter 39:882.

Ceorcescu, C. C, S. Orenschi, and M. Pethescu. 1959. In-

vestigations of a \crticilliosis of Q. Cfrri.s [in Romanian w itli

Russian and French summaries]. Omaeiu lui T. Savulcscu39:247-257. (English abstract in Review of Applied My-colog>- 39:743-744.)

CoiDANiCH, C. 1934. Vcrticilliosis of Acer pliilaiioidcs L.,

AciT itscudophitaiiiis L., and Madura auraiitiaca L. [in

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Gruenhacen, R. H., and C. Foruyce. 1963. Osmanthusilicifolius, a new host of Verticillium alho-atruin. PlantDi.sea.se Reporter 47:688.

Hahhar,J. G. 1937. Some unusual diseases of ornamentals in

Viririnia. Plant Di.sease Reporter 21:217.

Hefting, George H., and E. Richard Toole. 1950. Somesoutheastern tree diseases— 1948 and 1949. Plant DiseaseReiwrter 34:135-137.

HibBEN. Craig R. 1959. A new host for Xx-rticillinm albo-atrum Reinke & Berth. Plant Disease Reporter 43:1137.

HoL>it>, F. W. 1957. Verticillium wilt of dog\vood. Phyto-pathology 47:17. (Abstract)

Hutchinson, \V. G. 1931. Study of a disease of boxwood in

the eastern United States. Proceedings of the PennsylvaniaAcademy of Science 5:13-14.

Kelsheimer, E. G., and G. May. 1940. Verticillium wilt ofelm. Plant Disoa.se Reporter 24:282-284.

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Martin, G. Hamilton. 1926. Diseases of forest and shadetrees, ornament;il and miscellaneous plants in tlic UnitedStates in 1925. Plant Disease Reporter Supplement 50:413^78.

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McCain, Arthur H. 1963. New or unusual hosts of Verticil-

lium albo-atrum. Plant Disea.sc Reporter 47:233.Mielke,

J. L. 1935. VerticiUium wilt of maple in California.Plant Disease Reporter 19:303.

Parker, K. G. 1959. Verticillium hadromycosis of deciduoustree fruits. Plant Disease Reporter Supplement 255:37-61.

Quebec, Ministere de l'Aghiculture de la Province de.1961. Noms Francais des maladies des plantes au Canada.Puhlic:ition 263. 169 p.

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ScHREiBER, Lawrence R., Claude Fordyce, Jr., and R. J.Green, Jr. 1961. Verticillium wilt of saucer magnolia,magnolia soulangeana. Plant Disease Reporter 45:108.

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This paper is published by authority of the State of Illinois,

IRS Ch. 127, Par. 58.12, and is a contribution fromthe Section of Botany and Plant Pathology of

the Illinois Natural History Survey.Dr. E. B. Himelick is a Plant

Pathologist at the Survey.

(4-91091-.5M-7-69)