Bulletin


STATE OF ILLINOIS

D WIGHT H. Green, Governor

DEPARTMENT OF REGISTRATION AND EDUCATION
Frank G. Thompson', Director

DIVISION OF THE
NAITRAL HISTORY SURVEY

Theodore H. Frison, Chief

BULLETIN Article 7

A Needle Blight of

Austrian Pine

ROBERT L. HULBARY

TRINTED BV AL'THORITV OF THE STATE OF ILLINOIS

L'RBANA, ILLINOIS

June 1941



Blighted needles of Finns nip-a var. auslriaca with areas of original infection apparent in

ious parts of the needles. In this, the fall, stage, there often is a droplet of resm near the

base of the lesion, and only the entostroma of the fungus is present,



ILLINOIS NATURAL HISTORY SURVEY BULLETIN
VOL. 21, ART. 7 JUNE 1941

A Needle Blight of Austrian Pine

ROBERT L. HULBARY*t

OV'ER a period of years, blighted

needles of ornamental pines ha\e

constituted an important part of

the diseased evergreen samples received by

our laboratory for diagnosis. Needle blight

is a well-known and widespread type of

pine injury. It has been attributed to such

environmental factors as frost, heat, in-

tense sunlight, wind burning and drought,

alone and in various combinations. Also,

it has been attributed to the attack of

certain fungi which have been classified

chiefly in the genus Septor'ui. In the case

of many of the samples submitted to us,

however, it has been impossible to attribute

the injury to any obvious cause or. when
a fungus was present, to assign this fun-

gus accurately to any described form.

Late in the fall of 1^)38, badly blighted

needles of Pinus nigra Arn. var. austriacti

Aschers. & Graebn. were obtained in

northern Illinois. Superficially these nee-

dles appeared to have been injured by in-

sects, for some uf them seemed to have

been punctured and there was oozing of

resin near the bases of the blighted re-

gions. Microscopic examination of trans-

verse sections of these needles revealed,

however, that the punctures were small

epidermal ruptures due to the develop-

I
ment of \ oung fungous stromata. Since

I

none of these stromata were mature, a

method of wintering the infected material

was devised, so that the needles could be

examined periodically and the development

lit the fungus studied in detail.

j

The Method

Twelve lots of infected needles, each

lilt consisting of 50 fascicles and including

at least 10 badly blighted fascicles, were

Technical assistant in tlie Section of .\pplied Botany
and Plant Pathology, Illinois Natural History Sur\'ey.

irom September, 1938. to June, 1939.

placed in as many test tubes. The open
ends of the test tubes were covered with
cheesecloth, and each tube was labeled

according to a predetermined order of ex-

amination. The test tubes were then laid

on the ground, in a well-drained grassy

spot, so as to be subject to out-of-door

winter weather. The\ were tilted slightly

to allow water to drain out of them rather

than collect in them.

Beginning with December 2i, 1^38, one
test tube of needles was examined everv

15 days. Beginning with March 10, 193'i,

the interval between examinations was
shortened to 10 days and, beginning with
April 5, to 5 days, in order to follow in

detail the rapid development of the fungus,

which accompanied warm spring weather.

Also, cultures of the fungus were made
on artificial media, but they failed to

produce spore-bearing structures.

For the purpose of hastening develop-

ment at certain times, diseased needles

which had been weathered in test tubes for

\arious periods were placed over moistened

filter paper in sterile Petri dishes and kept

at laboratory temperature. Conidiospores

were produced by well-developed stromata
in 4 to 5 days under these conditions.

Development of the Fungus

The first evidence of infection visible

on the needle is a small brown or tan re-

gion up to 10 mm. long, which in a few
days in\olves all sides of the needle, is

sharply delimited basally and fades dis-

tally into the normal green of the leaf

(frontispiece). Such a region may develop

anywhere on the needle ; usually, however,

it develops on the distal half. Often, if an

infected needle is held before a light, the

+The writer wishes to thank Dr. L. R. Tehon and
Dr. J. C. Carter lor helpl'ul suggestions during the
preparation of this paper.

[231]



232 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 7

Fig. 1.—Cross sectional view in the mesophyll in the region of a lesion, showing how the

mycelium of the causal fungus grows within the mesophyll cells and brings partial disintegration

of these cells.

Fig 2 —Fragments of infected needles after overwintering. Stromata appear in various stages

f development. Not until the ectostroma is fully developed, as on the needle at the bottom of
„. „^.elop...-

, . • 1 J J
the illustration, do locules form and spores begin to be produced



IQ41 HULBARY; NEEDLE BLIGHT OF AUSTRIAN PINE 233

infected region will appear translucent.

The effect of the mycelium within a

needle is e\idently to cut off the flow of

nutrients, or at least to weaken it, for the

part of the needle distal to the infection

soon dies. In the blighted part of a needle,

hyphae can be found in abundance in and
between the mesophyll cells, tig. 1 ; but

they occur only rareh' in the transfusion

tissue and have not been found in the

laboratory from time to time during May
had mature, sporulating, ruptured stro-

mata.

Morphology of the Fungus

The stroma of this needle-blighting

fungus arises between the mesophyll and
the hypodermis, fig. 3, and is seated on

the mesophyll. The basal part of it is a

Fig. 3.—Section through two nuituro stronuita. Origin of the stroma at the periphery of the
mesophyll, dissolution ot the hypodermis, variable extent ot the cntostroma, palisadelike arrange-
ment of ectostromatic hyphae, poorly defined hut mature and sporiferous loculcs, and adherent
fragments ot epidermis are evident.

vascular bundles. Although a fruiting

body may appear at any point in the dead
portion of a needle, it usually develops

near the site of infection.

Under the out-of-door conditions de-

scribed above, rapid enlargement of stro-

mata began to take place on infected leaves

between February 15 and 28, Hg. 2. Be-

tween April 10 and 15, differentiated re-

gions appeared in the upper parts of these

stromata, in which the hyphae were lighter

amber than elsewhere in the stromata. A
month later these lighter regions had

been transformed into locules, contained

conidiophores and were producing conidia.

Overwintered needles brought into the

pseudoparench\ina, from \\hich hyphae
push up between the hypodermal cells,

usually dissolving them at the same time.

These hyphae spread out laterall)' below
the epidermis and form a compact, pseudo-

parenchymatic entostroma. Often the

entostroma becomes extensive and has at-

tachments to the myceliuin in the meso-
phyll at several points. This multiple an-

chorage is suggestive of the dothideaceous

family Polystomellaceae (Stevens 1Q25).
Growth of the stroma, produced by the

elongation of the stromatic h\phae, causes

the epidermis above the stroma to split

longitudinally, usually along a row of

stomates. As the stroma emerges, it ma>



234 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Art. 7

rip off sections of epidermis lying between

rows of stomates ; and these epidermal

fragments usually remain attached to the

top of the stroma.

The size and shape of the ectostroma are

correlated with the vigor and extent of the

hypostromatic mycelium, the thickness of

the host cuticle and epidermis, and the

ratio, as to volume of stromatic tissue, of

ectostroma to entostroma. There naturally

is, therefore, much variation.

The ectostroma ranges from 125 to

1,500
fj.

long, from 50 to 450 /n wide and

up to 600 /J. high. Usually it is elongated

and loaf shaped, and its height often ex-

ceeds its width. It is nearly always ori-

ented parallel to the longitudinal axis of

the needle, fig. 2. The tips of stromatic

hyphae, as they grow outward to form the

ectostroma, secrete a gelatinous fluid. On
the surface of the mature stroma this fluid

hardens into a crusty, dark brown coating

;

within the stroma it cements together the

walls of adjacent filaments.

The ectostroma consists of brown hyphae

with numerous cross-walls. These hyphae

are vertical, parallel and closely applied

to each other. In microscopic view, they

present the palisadelike appearance char-

acteristic of the Dothideaceae. Cells of

the stromatic hyphae are somewhat smaller

than the cells of the hyphae in the meso-

phyll and transfusion tissues and are also

darker.

The first indication of the development

of sporiferous locules is a localized change

in the color of hyphae in the upper part

of the ectostroma. This change, which

may occur in one to several places in each

stroma, fig. 3, results in the formation of

an ovate to tubular chamber which lies

parallel to the longitudinal axis of the

ectostroma. The tissue surrounding the

locule is continuous with that of the

stroma, and no distinct locular wall is de-

veloped. The continuity of tissue from

stroma to locule wall also indicates rela-

tionship with the Dothideaceae. The locule

is sporiferous around its entire inner sur-

face.

Conidiophores arise directly as branches

from the palisadelike hyphae forming the

body of the stroma, and their bases form

the poorly defined boundary of the locule.

They are light amber to hyaline, un-

branched, very numerous, densely packed

and almost as long as the conidia but

slightly narrower. They cut off from their

tips h>aline, septate, scoleciform spores

which are blunt at the ends, straight or

slightly curved and, in ratio of length to

width, never greater than 10 to 1.

When the stroma is mature, a rift oc-

curs along the top of each locule, which
provides for the emission of spores. Spore
dissemination is evidently aided by wind
and by spattering raindrops.

Taxonomy

A careful study has been made of all

descriptions and, when possible, of exsic-

cati types or authentic specimens of the

species which might resemble the Austrian

pine fungus.

The majority of fungi associated with

needle blight in various parts of the coun-

try have been placed in the genus Septoria.

Spaulding (1909) reported Septoria spa-

dicea Patterson & Charles as the cause, in

the East, of a blight of white pine needles

similar to the brown-spot of longleaf pine.

Graves (1914) &iioc\SiX.tA Ascochyta pini-

perda Lind. {Septoria parasitica Hartig)

with a blight occurring on young shoots

of red and Norway spruce in North Caro-
lina. Dearness (1928) described Septoria

piiticola on blighted needles of the lower

limbs of Pinus virginiana Mill, in Vir-

ginia. Hedgecock (1929) and Siggers

(1932, 1934) studied Septoria acicola

(Thiim.) Sacc. in connection with brown-
spot on longleaf pine needles in the south-

eastern part of the United States and con-

sidered it a distinct threat to seedling

plantations in that region. Boyce (1938,

p. 98 ) has pointed out that brown-spot

ranges westward to Kansas and Texas and

occurs in Idaho on ponderosa pine and in

Oregon on knobcone pine.

The taxonomy of Septoria acicola, the

cause of brown-spot, has been given at-

tention by several men ; but it still is a

moot question.* At least two diseases, per-

haps more, have been included under the

term Septoria needle blight and attributed

*After the manuscript of this article was submitted for

publication, Paul V. Siggers defined the brown-spot dis-

ease, confirming the binomial Lecanosticla acicola (Thijrn.)

Syd. for the imperfect stage of the fungus associated with

the disease and proposing the binomial Scirrhia acicola

(Dearn.) Siggers for the perfect stage (Phytopath. 29(12):
1076-7. 1939.). Later still, Frederick A. Wolf and W. J.

Barbour also confirmed the binomial Lecanoslicta acicola

but considered the perfect state a Systremma and pro-

posed for it the binomial 5. acicola (Dearn.) Wolf &
Barbour (Phytopath. 3I(l);61-74. 1941.).



June 1941 HULBARY. NEEDLE BLIGHT OF AUSTRIAN PINE 235

to the brown-spot fungus. Sporiferous

chambers contained in the top of a highly

developed stroma such as that produced

by the Austrian pine fungus are, however,

conformable neither with the estromatic

pycnidium of a typical Septoria nor with

the non-septorioid structure of the brown-

spot fungus.

Of Sydow's genus Heniidothis there are

two species; both occur in V^enezuela on

the leaves of shrubby species of the me-

lastomaceous genus Miconia Ruiz & Pav.

From Sydows' (1916) original descrip-

tion and the exsiccati it is clear that the

Austrian pine needle fungus cannot be

assigned to Hernidothis, for in that genus

the locules are partially liberated at the

vertex, the stromata are arranged in con-

centric rings in the infected areas, and

the conidia are much longer and narrower

than in the pine fungus and are non-sep-

tate. Despite these points of dit+erence,

the dothideaceous structure of the stroma

in both forms suggests that they ma\- be

related.

Clements & Shear (1931, p. 367) list

Septocyta Petrak as a synonym of Henii-

dothis Sydow. Petrak's (1927) descrip-

tion of Sep/rjcy/ii indicates distinct simi-

larities with the Austrian pine fungus; but

the spores of Septocyta are long, threadlike

and continuous. In Septocyta a dothid-

eaceous relationship is suggested by the

structure of the stroma and conidiferous

chambers.

Sydow & Petrak (1922) described a

fungus associated with brown spots on pine

needles in Arkansas and Oregon, which

they later (1924) called Lecaiiosticta aci-

cola (Thiim.) Sydow. According to Sy-

dow's description, this fungus has a rim

of hairlike appendages on its stroma, dark

spores and branched conidiophores—char-

acters markedly difierent from those of the

Austrian pine fungus.

Hansborough (1936), in his paper on

the T>mpanis canker of red pine, has illus-

trations of the imperfect stage of Tym-
panis, which in arrangement of locules and

in internal structure somewhat resemble

the stromata of the Austrian pine fungus.

He reports, however, that in Tympanis

the conidiophores are branched and that

the spores measure 2—1- X 1-2 ;u and are

borne at the tips and on lateral branches

of the conidiophores. The fact that the

needle blight fungus on Austrian pine,

which is distinct genetically as well as

speciticall\ from all previously described

needle-blighting fungi, cannot he placed

in any recognized genus warrants the pro-

posal of a suitable genus. This genus is

placed in the scolecosporous division of the

Phomaceae and is closely associated therein

with genera such as Heniidothis Sydow
and Septocyta Petrak, which exhibit

dothideaceous characteristics.

Dothistroma gen. nov.

Stroma dark, elongated, endogenous, be-

coming prominently erumpent and swollen,

dothideoid, with a stalk extending into

the substratum ; composed internally of

densely arranged, vertical, parallel, sep-

tate hyphae. Locules separate, one to sev-

eral in the upper part of the stroma, ovate

to tubular, not distinguished from the

surrounding stroma, the entire inner face

sporiferous. Conidiophores simple, arising

directly from stromatic hyphae. Conidia

hyaline, scoleciform, sexeral-septate.

Stroma atratuni, elongatum, endogenum, mox
multo exsertum et bullatum, dothideoideum, cum
pede in substrate extante, intus hypharum com-
pactarum, vertlcalium, parallelarum compositum.
Loculi sejuncti, unus vel plures in parte superiore

stromatis, ovati usque tubulosi, non stromate
circumdante distinct!, in facie interna oninino

sporiferi. Conidiophora simplicia, ex hyphis

stromatum directe orienta. Conidia hyalina,

scolecif'orma, nonnulla-septata.

Dothistroma Fitii sp. nov.

Stromata seated on the mesophyll, form-

ing more or less extensive hypostromata

between mesophyll and hypodermis,

erumpent through rents in the epidermis,

oriented parallel to the longitudinal axis

of the needle, dull dark brown, 125-1500

/x long, 50-450 IX \\ide, up to 600 /i high.

Locules oriented parallel to the longitu-

dinal axis of the stroma, without a distinct

wall. Conidia hyaline, scoleciform, 1- to

5- but usually 3-septate, blunt at the ends,

straight or slightly curved, 16.5-29 X 3.5

fi. Conidiophores numerous, approximate-

ly the same size as the conidia, hyaline or

amber, dense, unbranched, producing co-

nidia at their tips.

Stromatibus in mesophyllo stantibus, inter

mesophyllum et hypodcrmidem hypostromatem
plus minus magnum formantibus, per scissos in

epidermide erumpentibus, cum axe longitudinali



236 ILLINOIS NATURAL HISTORY SURVEY BULLETIN ^'ol. 21, Art. 7

foliorum parallelis, atrotuscis, 125-1500 m longis,

usque 600 n altis; locuiis cum axe longitudinali

stromatum parallelis; conidiis hyalinis, scolcci-

formibus, 1- usque 5- frequentissime 3-septatis,

apicibus rotundatis, rectis vel curvulis, 16.5-29 x

3.5 m; conidiophoris nunierosis, conidiis sub-
aequantibus, hyalinis vel succineis, compactis,

simplicibus, conidios in apicibus generantibus.

Type specimen : Collected by J. C.

Carter, De Kalb County, Illinois, No-
vember 2Q, 1Q38, on Piniis nigra Arn.
var. austriaca Aschers. & Graebn., 111.

Nat. Hist. Surv. Ace. No. 27,093.

Through the courtesy of Dr. Paul V.

Siggers, the following specimens have been

examined and found conspecific with the

above: ( 1 ) on Pin us flexilis James, Wa-
terloo State Forest, Ohio, February 26,

1936, C. C. Green col.; (2) on P. nigra

Arn. var. austriaca Aschers. & Graebn.,

Springfield, Ohio, May 8, 1932, R. L.

Beard col.; (3) Miami, Oklahoma, Au-
gust, 1934, Moore col.; (4) Sherman
Nursery, Charles City, Iowa, January,

1934, B. C. Helmick col.; (5) on P.

nigra var. calahrica Schneid., Waterloo
State Forest, Ohio, January 11, 1936, C.

C. Green col.; (6) on P. resinosa Ait.,

Old Man's Grove, Hocking County, Ohio,
February 26, 1936, C. C. Green' col.

Summary

In blighted needles of Austrian pine col-

lected in northern Illinois in the fall of

1938, immature stromata indicated the

cause of the blight. Infected needles were
wintered out-of-doors and examined peri-

odically. The stromata remained quiescent

through the winter but very early in the

spring began to develop and by March 1

had emerged as strongly erumpent, loaf-

shaped structures. A month and a half

later, pycnidial locules were becoming dif-

ferentiated, and by May 15 conidia were
being produced.

The distinctive dothideaceous structure

of the stroma distinguished the fungus

from every described group. For it the

new genus Dothisiroma is proposed.

The well-marked dothideaceous struc-

ture of the stroma and the spore char-

acters place the new fungus in the scoleco-

sporous group of the Phomaceae close to

Hemidothis Sydow and Septocyta Petrak.

LITERATURE CITED

Boyce, J. S.

1938. Forest pathology. McGraw-Hill
Book Company, Inc., New York and
London.

Clements, F. E., and C. L. Shear

1931. The genera of fungi. The H \V

Wilson Company, New York.

Dearness, J.

1928. New and noteworthy fungi V. Mvcol.
20:235-47.

Graves, A. H.

1914. Notes on diseases of trees in the

southern Appalachians III. Phvto-
path. 4:63-73.

Hansborough, J. R.

1936. The Tympanis canker of red pine.

Yale Univ. School Forestry Bui. 43.

Hedgecock, G. G.

1929. Septoria acicola and the brown-spot
needle blight of longleaf pine seed-

lings. Phytopath. 19:993-9.

Petrak, F.

1927. Mycologische Notizen IX. .^nn.

Mycol. 25:193-344.

Siggers, P. V.

1932. The brown-spot needle blight ol

longleaf pine seedlings. Jour. For-

estry 30:579-93.

1934. Observations on the influence of fire

on the brown-spot needle blight of

longleaf pine seedlings. Jour. For-
estry 32:556-62.

Spaulding, P.

1909. The present status of white pine

blight. U. S. Dept. .'\g. Bur. PI. Ind.

Circ. 35:1-12.

Stevens, F. L.

1925. Hawaiian fungi. Bernice P. Bishop
Museum Bui. 19.

Sydow, H., and F. Petrak

1922. F.in Beitrag zur Kenntnis der Pilz-

flora Nordamerikas, insbesondere
der nordwestlichen Staaten. Ann.
Mycol. 20:178-219.

1924. Zweiter Beitrag zur Kenntnis der '

Pilzflora Nordamerikas, insbesondere
der nordwestlichen Staaten. Ann.
Mycol. 22:387-419.

Sydow, P., and H. Sydow
1916. Fungi Amazonici a cl. E. lecti. .Ann.

Mycol. 14:65-98.