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UNIVERSITY OF ILLINOIS

Agricultural Experiment Station

BULLETIN No. 217

AN APPLE CANKER DUE TO
CYTOSPORA

By FRANK LINCOLN STEVENS

URBANA, ILLINOIS, MAY, 1919

CONTENTS OF BuuLerin No. 217

PAGE

DESCRIPTION OF THE CANKER...... eGiag tea ae OT ete SAO ecto 367
are FOMGUG 86s G ak awe ee TO ER a caGee 368
PROMALIONS occ © sic torets icles Sie, eid ese eee nee reyeencanete ete we ehstelacdisiishatelarCiate rahe etausveveia’ te 371
PIMILAR /HUNGI ON ROSACEOUB “Ll WIGS <6 cisix.cic ied orstah ciate os ane oar ewe eae 372
Valsas: On. Rose ceoun -FLORGS S15 s Giavarors sets eivie cpotasitan s Baloaiei ein abe ats aeerasaes 372
SSIBLIOGRAP HY sows cies ois oie.0'.s Bsc ajewisles's sip lp Qiowinlste 5 sis ease lee On celetes Wal@tas 377

AN APPLE CANKER DUE TO CYTOSPORA.

By FRANK LINCOLN STEVENS, Proressor oF PLANT PATHOLOGY,
UNIVERSITY OF ILLINOIS, IN COOPERATION WITH THE DEPART-
MENT OF HORTICULTURE

A canker on young apple trees which appears capable of doing
much damage was submitted to the author for identification in the
spring of 1918. Tho noted on only a few trees, its rapid and com-
plete possession of the tree, together with the fact that it does not
agree closely with other apple-tree cankers previously described,
makes it worth while to give rather a complete statement of the
present knowledge of it.

The apple cankers were sent by Mr. G. P. Callender, of Altona,
Illinois. He stated that he had received the trees from a certain nursery”
company in New York, on April 27, 1918. Requests were made of
the company that they send specimens of any cankers they might
find in their orchards, but no reply was received. |

DESCRIPTION OF THE CANKER

One specimen was found on the main trunk of a young tree
about 2 em. in diameter. The canker extended a total length of
22 cm., completely encircling the tree thruout most of that distance,
altho it extended 2 or 3 em. farther up and down on one side of the
tree than on the other side.

There was no abrasion or wound which seemed to mark the place
of the original infection. Altho several lateral branches had been
cut off from the portion found cankered, the wounds were in all
eases nicely healing over with callous. The canker for the most
part was of a tan color, similar to that which is frequently exhibited
in young ecankers of apple blotch. Portions of the canker, toward
one end, were of much darker bronzed or purplish color, altho at
the other end of the canker this color was absent.

The demarcation between the diseased and the healthy tissues
was very sharp with a slight breaking away of the diseased from
the healthy tissues. On removing the bark, a black transverse line
about 1 mm. wide was disclosed, apparently separating the healthy
from the diseased tissues. It is quite probable that the canker at
this point was in dormant condition, resting, not progressive. The
other end of the canker did not show sharp limitations between the
diseased and the healthy tissues, which gradually faded, one into
the other, and did not show externally the 2-em., dark, purplish band
mentioned above, adjacent to this end of the canker.

367

368 BULLETIN No. 217 [May,

The canker was studded thruout its area with black pustules
having the appearance of pycnidia or perithecia. These were slightly
raised conically above the surrounding surface, were black, about
1 to 2 mm. in diameter, and were so abundant that an unbroken
area of 5 square millimeters could scarcely be found. A color photo-
graph of this twig was made June 5.

THE FUNGUS

The fungus is apparent to the eye, externally, as small black
pustules under, or erumpent thru, the cuticle. On microscopic exam-
ination these prove to be relatively large compound pyenidia made
up of numerous irregularly arranged cavities in a mass of dense
stromatie structure. Views of the pyenidia from various sections
are shown in Figs. 1 to 11.

Fic, 1—Cross-SECTION OF A PYCNIDIUM

Fig. 1 shows a cross-section, i.e., a section in a plane parallel
to the base of a pyenidium, which represents the condition most
frequently found. There is a large number of locules, irregular in
size and shape, but arranged in a circular manner around a sterile
area, with their longer axes along the radii. Another pyenidium
is shown in similar view in Fig. 2, and a section in the same diree-
tion but farther from the base, in Fig. 3. Fig. 4 is drawn from a
section longitudinal to the twig and parallel to the plane of the
radius of the twig, therefore cutting from the top of the pyenidium
to its base. The irregular locules are here shown, and the large

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1919] AN APPLE CANKER DUE TO CYTOSPORA 369

Figs. 2-11.—Cross AND VERTICAL SECTIONS THRU PYCNIDIA

370 BULLETIN No, 217 [May,

covering mass of sterile mycelium, all below the cuticle but break-
ing thru it.

Figs. 5 to 10 give similar views showing considerable variation
as to the locules and their openings into the ostiole, but a general
agreement in that the sporiferous cavities are covered-in all cases
by a dense stromatie or clypeate structure. (Ectostroma, cf. Ruh-
land.3?) Fig. 11 shows a similar section, but nearly tangential to
the edge of a pycnidium. Fig. 12 shows the detail of the portion of
the pyenidium marked ‘‘a’’ in Fig. 1. The interlocular material is
seen to be a firm pseudoparenchyma, the walls of the outer cells
being somewhat thicker than the walls of the inner cells. The en-
tire inner surface of the locules is lined with a close palisade of
conidiophores, which are in the main simple and narrow, and about 17
to 20 » long by .5 to .7 » thick, tho in some instances they may
branch, as figured by Aderhold.1° This conidiophore layer is shown
still more clearly in Fig. 13. Fig. 14 shows the detail of the part
marked ‘‘a’’ in Fig. 10. It is seen that in certain parts the fungus
mycelium is loosely woven and with open interstices. Fig. 15 shows
the spores, which are produced in very great number. They are

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Fig. 12.—DETAIL OF PoRTION OF PYCNIDIUM MARKED ‘‘A’’ IN Fig. 1 |

1919] AN APPLE CANKER DUE TO CYTOSPORA 371

hyaline, 1-celled, obtuse, quite uniform in size (7x1.6 »), and either
straight or slightly curved,

The mycelium is thin and hyaline and by these two character-
istics is easily distinguished from the mycelium of the black-rot
fungus. Close search revealed no
ascigerous structures.

ISOLATIONS

The fungus was easily secured in
pure culture. Fragments from the
interior of a pyenidium were
placed in a drop of sterile water
and portions of this drop then
Fig. 13.—PorTION oF A CONIDIOPHORE transferred to tubes of melted

rade’ corn-meal agar and poured into
Petri dishes. Thousands of pure growths were thus secured. Corn-
meal agar was also poured into Petri dishes and allowed to solidify.
Then bits of diseased tissue from below the cortex were placed upon
its surface. Invariably those bits gave rise to the same fungus se-
eured by the dilution method. The fungus thus secured in pure
culture was maintained for several months on various media. Tho
the fungus vegetated luxuriantly on various agars it did not bear
pycnidia in them, or spores of any kind. The colonies on all media
were colorless and with a floccose, aerial mycelium.

Inoculations from these pure cultures were made on apple and
other twigs (pear, rose,
blackberry, plum, and
peach) in test tubes with
a few cubic centimeters of
water to keep the culture
moist. These resulted in
rapid growth and the de-
velopment in the bark, in
about three weeks, of very
numerous pyenidia of com-
pound, chambered struc-
ture, identical with that
found in the natural can-
kers as described above,
tho under these conditions
there was always an exten-

sive development of aerial

mycelium not found under “7

the less humid natural con- oo eS

ditions. On:all é f Fig. 14—DETAIL OF PORTION OF PYCNIDIUM
° n species 0 MarkKeEp ‘‘A’’ IN Fig. 10

A;
\EEAZ,
S07) 71

ut

372 BULLETIN No. 217 [ May,

twigs employed, except box-elder, cherry, and ‘maple, the fungus
grew well, penetrating under the cortex thruout the whole length of
the twig, some 8 to 10 em., and breaking out with its erumpent pyenidia
over all as of the twig. On certain twigs, e.g., those of black-
: berry, tho growth was abundant and rapid, the
pycnidia were much smaller than on apple
twigs, yet no difference was noticeable in the
spores. Careful search was made in all cultures
for an ascigerous stage, but none was found.
No attempts to produce the disease on trees
in the open were made because it was not thought
wise to run any danger of giving it wider in-
troduction in this state. From the laboratory
evidence as well as from the statements of Mr.
Callender it appears that this canker is one of
very rapid development and one that might
cause serious loss should it become widespread
and suitable conditions for its development ob-
tain.

Fig. 15.—SPoRES

SIMILAR FUNGI ON ROSACEOUS TWIGS

This fungus evidently belongs to the form genus Cytospora Ehrenb.
(Cytispora Fries.) Several Cytosporas have been referred, on more
or less conclusive evidence, to the ascigerous genus Valsa Fries. It
is therefore of interest in connection with this canker to note other
eankers that have been reported upon related hosts, due either to
Valsa or to Cytospora.

VALSAS ON Rosaceous Hosts

There are more than 225 species of the genus Valsa proper noted
by Saceardo.8 Lindau,® with a broader conception of the genus, says
there are about 400 species. The following list, tho not entirely com-
plete, at least contains the names of the most important of these, from
the viewpoint of pathology, that occur on Rosaceous hosts. The
synonomy and conidial relations, when stated, are as given in the arti-
ele cited.?

1. Valsa ambiens Fries (1:565) (2:120) conidia—Cytispora carphosperma Fries
(2:120) (5)=—Cytispora leucosperma Fries (25:826)—C. ambiens Fr.
(7:2,729). On apples in Europe (8:1,131) (11:278). On most deciduous
trees (5)

2. Valsa acclinis Fr. on Pyrus (8:1,130)

3. Valsa amphibola Sace. on Pyrus (8:22,354)

4. Valsa ceuthosporae Cke. on Prunus (8:1,143)

1The first number given in parentheses refers to the Bibliography, as does also any
number standing alone in parentheses. Numbers following indicate volume and page.

1919] An APPLE CANKER DUE TO CYTOSPORA 373

20.
21.
22.
23.

24.
25.

26.
27.
28.
29.

30.
31.
32.

33.
34,
35.
36.

Valsa ceratophora Tul. (5) (8:1,108) on broad-leaved twigs in Europe
and North America

Valsa cerasi Feltg. on Prunus (8:17,563)

Valsa cincta Fries (10) (8:1,143) (5) on Prunus in Sweden, London, Ger-
many, and France—Cytospora rubescens Fr. (33)

Valsa coenobitica (de Not) Ces. and de Not (5) on broad-leaved trees in
Germany and Italy

Valsa clypeata Fuck. on Rubus (5) (8)

Valsa coronata (Hoffm.) Fr. on Crataegus (8)—Cytospora

Valsa crataegi Allesch. on Crataegus in Europe (5)

Valsa cydoniae on Cydonia vulgaris in Portugal (5)

Valsa excipienda (5) Karst. on Sorbus (8:1,139) Finland and Lapland

Valsa excorians C. and E. on Pyrus (8)

Valsa flavovirescens (Hoffm.) Nitz. (5) on various broad-leaved trees in
Europe :
Valsa hoffmanni Nitz. on Crataegus (8:1,118)—Cytospora. On peach, plum,

and almond (29:485). On apricot

Valsa lauro-cerasi Tul.—Cytospora lauro-cerasi on Prunus (8)

Valsa lata (Pers.) Nitz. (5) on various broad-leaved trees in Europe

Valsa leucostoma (Pers.) Fries (8:1,139) (10) (22) (2:120) (5) (28)
(27:515) (4)=V. personii Nitz. (5)—Cytospora rubescens Fr. (5) (14)
(33) (11:278)=C. leucostoma (10) (6:180). On Prunus in Europe
(34) and North America (8) (4:264). On pome and stone fruits in
Europe, Australia, and America (11:278). On peach, plum, and almond
(29). On peach, plum, apricot, and cherry (14). On cherry in Amer-
ica (9:184). On peach (4:264) (15). On cherry (10)

Valsa leucostoma Fr. var. cincta Rolfs, common on stone and pome fruits
everywhere (9:180). On peach (9:300)

Valsa leucostoma Fr, var. rubescens Rolfs. On apricot and almond
(9:157). On plum: (9:360) :

Valsa massariana de Not on Sorbus (8:1,138)—Cytospora

Valsa macrostoma Rehm. on Prunus (8:1,145)

Valsa maheleb C, and E. (8:1,137) on Prunus

Valsa maura (Fr.) Nitz. (5) on wood of Prunus spinosa in Sweden and
Germany

Valsa microspora (Crouan) Sace, on Crataegus (8)

Valsa microstoma (P.) Fr.=(Cytospora microstoma) on Prunus (3) (7)
(8:8,111)

Valsa monadelpha Fr. on Prunus (8:1,128)

Valsa opulifolia Pk. on Spirea (8:9,449)

Valsa prunicola Pk. on Prunus (8:9,452)

Valsa prunastri (Pers.) Fr. on Prunus in Europe and North America (5)
(2:111). On plum, apricot, and pear (4:264) (13:218) (6) pyenidia=
Cytospora rubescens (2:111) (12:196). Lindau (4:264) says the con-
nection is doubtful. On apple, plum, ete. in England (11:278). On
apricot, peach, and plum (26:77)

Valsa rhodophila B. and Br. on Rosa (8:1,136)

Valsa rubi Fuck. on Rubus (8:1,109)

Valsa sorbi (All. and Schw.) Fries (5) on Sorbus in Europe=Cytospora
rubescens (12:196)

Valsa siberica Thiim. on Cotoneaster (8)

Valsa sorbicola Nitz. on Sorbus (8:1,124)

Valsa sepincola Fuck. on Rosa and Rubus (8:1,134)

Valsa tumidula Cke. and Pk. (5) on Crataegus and Platanus

374 BULLETIN No. 217 [May,

In the accompanying tabulation are given the Cytosporas recorded
as such on Rosaceous hosts; also the Cytospora-like conidial forms of
various Valsas on Rosaceae.

CYTOSPORAS AND CYTOSPORA-LIKE FORMS ON ROSACEAE
Arranged in order of minimum spore length (1)

Saccardo Spore
No. Name Vol. Page|LengthxBreadth| Shape | Locules
1)C. cerasicola Sace. ........ 3 255 3X1 Curved Many
2|C. dendritica Berl. and Vogl.| 10 244) 3-4X.5 Allantoid | Many
3|C.asterophora Sace. ...... 3 254 3.5-4X1 Allantoid | 4-5
AV. japonica . ...c..ceees bs] “oe: oe al Oeeebaet sae, Obe sc, pa Spe ese e
5|C. rubescens Fr. ......... 3 253 7 Allantoid |........
6|V.ceratophora Tul. ....... 1 108 4X1 - | Allantoid |Many
7 |C. candida Speg. .......... 22 956 '46X1 Curved |...csee 4
8|C. microstoma var. amelan-
chéeris Cke. 2.53 eases 10 244 ay Aa CSE einirnner ys .
9|C. leucostoma (Pers.) Fr...| 3 254 a ke TN EPS a sepilsc eae
10|C. capitata Sace. and Schl...| 3 254 5-6 Oblong-
botuliform|Sinuous
11|V. hoffmanni Nitz. ........ 1 118 5-6X1 Allantoid |,.......
12|V.microstoma (P.) Fr.....| 1 111 5-6X1.4 | Allantoid |Many
13 |C. rosarum Grev. ......... 8 253 5-6X1.5 | Allantoid |Many
14|C. carphosperma Fr. ...... 3 274 5-6.5 Allantoid |,.......
15|V.rhodophila Berk. and Br.| 1 136 5-7X1 Allantoid |Many
16|V.excipienda Karst. ...... 1 189 as ee PETE . | Many
17 |C. niphostoma Sace. ....... 11 509 5-8X1-1.5|Allantoid |Many
18|C. farinosa Feltg, ........ 18 297 §.5-7X1.5-2) 0. oes Few
19|C. cydoniae Schl. ......... “22. 955 Ci} She Pits Many
20|V.coronata (Hoffm.) Fr...| 1 110]. 6X1 Allantoid |........
21'C. clypeata Sace. ......... 3 252 6x1 Allantoid |Many
22 |C. ambiens Sace. .......... 3 268 6X1 Botuliform |........
23... sepincola: Fol: occ ci. 4.0070% 1 134 6X1.5 |Curved Many
24|V. massarriana de Not. ....| 1 138 6-7 X1 Allantoid |........
25|C. microspora (Cda.) Rabh.| 3 253 6-7 X1-1.3).......... Many
26|C. microstoma var. cotoneas-
WG cA whan as anen meeak 10 244 G-2 X25. View View enw sb beeen
27 |C. lauro-cerast Fuck. var.
ramulorum Sace. ..... 3 276 6-8 X1 Botuliform |........
28 |C. cincta Sace. ........... 3 254 6-9 X1.5-2|Curved Few-
many
29|C. cydoniae B. and K. ..... 18 297 6-9 x2 Allantoid |Many
30 | C. anceps’ Saces: 005 esc 8 255 6-10X1 Allantoid |1-—few
31|C. folticola Lib. .......... 3 275 7X1 Botuliform |........
32 |C. mespilt Sace. .......... 11 509 7X2 Allantoid |Many
33 |C. prunorum 8. and 8. ..... 18 297 7-8X1.5-2|Allantoid |Many
34|C. crataegicola P. Brun. ...| 14 915 7-8X3 Straight |........
35 |C. leucosticta Ell, and Bart.| 14 916 7-10X1.5 (Curved /|Many
36/|C. cincta Sace. var. amyg-
dalina Karst, ........ 10 245 7-102 Curved Many
37 |C. macularis Sace. and Schl.| 3 256 8x3 Allantoid !\......-

1919] AN APPLE CANKER DUE TO CYTOSPORA 375
Saccardo Spore

No Name Vol. Page| Lengthx Breadth Shape | Locules
38 |C. oxycanthaevar.monogynae| 14 915 8-9 X2-2.5 Botuliform | 10-12
39 |C. cotoneastri Thm. ....... 3 256 O- TOMES hos oc Speavtidtigannas
40|C. phyllogena P. and S.....| 3 275 10-12 X2.5-3).......... Many
41|C. eutypelloides Sace. ...... 22 956 11-14X1.5-2)Allantoid {20-30
42|C. prum Ell. and Dear. ....| 11 509 12-16 X2.5-3|Fusoid 1-2
43 |C. selenospora Oud. ....... 16 . 903 ES Bic Oy tains lees sia che ia eeovs am
44|C.acharti Sace. .......... Pa OG. ia) Inca gwicisve's ooeee (Curved 1
45 |C. radophila Sace, ........ Reem tll eee chase cow vine ooliolalt ca vies wraliaelsieeaes
46 |C. rhodocarpa Sace. ....... A PRE Ue ot nO cen chai ale\Sieibon ines - kere ; Many
47 |C.rubé Schw. .......0c00. Ea TRUS ET Tec shape CLs aia’e widcnllic bis cera eh wce: aor sremscerete
48 |C. piricola West. .......... Date eR OLad atic ad thalee asl etecaecaifaiand'c's:s malsleie Seiaie wie
49 |C. oxycanthae Rab. ....... : ae. ee ee Sierpisiolieiere acne tere Many
50 |C. persicae Sch. .......... Bair aM pate wis cin, ois 010160 | sieves Cass Falun teeee
51|C. personata Fr. ........-- Bx DR Fr eviaeesaadses Curved Many
53 1C. lewcpapermag. (Pork.) Brit = SB ye a coi e's cine oto 0]'s 50 se cveeee seeseae
53 |C. flavo-virens Sacec. ....... Dae BOOM We Ne es cua aiaeuesess Carved. hoa
54|C. floccosa Wallr. ......... Big COBIAN occ! f alate's aieleine litera 8'0;s-0) sielefi ace oteseioee
55|C. globifera Fr, ........¢. Died ASMP ne Bake otis ic, oie etelereiftetara’s aid ore eral Lote) tpitlers
56|C. henderson Berk. and

LON. oo oic Fa eaalre'ste HS fey 457 ta FI ee ert Carved eSscivees
57|C.leucophthalma B. & C. ..| 3 255 Small Carved “rls ws este

The questions of the identity of the various species of fungi
similar to this, and of their parasitism, are interesting and are worthy
of consideration. Obviously final classification must rest on rather
complete knowledge of both the ascigerous and the conidial stage
and of the biologic or host relationships. As to all of these much
uncertainty at present exists. The genus Valsa as treated by Lindau‘
contains the subgenera Eutypa, Endoxyla, Cryptosphaeria, Crypto-
valsa, Cryptosphaerella, Endoxylina, Leucostoma, Eutypella, Euvalsa,
and Valsella, chiefly distinguished from each other in stromatiec char-
acters. Saccardo treats of these subgenera as genera. Many sugges-
tions as to the ascigerous connection of conidial forms have been made,
often based merely on the association of the two forms on the same
twig. Many of these claims are conflicting, assigning several conidial
species to the same Valsa, e. g., at least three Cytosporas are given as
the conidial form of V. ambiens ; or several Valsas to the same conidial
form, e. g., C. rubescens is by various writers connected with at least
four separate Valsas. As to the parasitism of these forms there has
also been much discussion and divergence of opinion. Many species,
probably a large majority of them, are purely saprophytic, growing
only on dead twigs; some follow closely on frost injury or injury
from other causes, or may be classed as wound parasites. Con-
cerning the particular question of parasitism of Valsa on drupes:
Goethe,°° Labonte,*® Sorauer,*® 49 Raschen,47 and Zapfe,37 held the

376 BuLLETIN No. 217— [May,

fungus to be secondary, while Frank,*®: 44 Aderhold,!® Stewart e¢ al.,1§
Rolfs,14 15.16 and later several others,*: 2° 52 have held that it was
the cause of the disease, a view that is now definitely established.

The most comprehensive articles bearing on Cytospora and Valsa
on drupes are by Aderhold 1° and Rolfs.1® Aderhold referred the
form on drupes to Valsa leucostoma, and by extensive cultural and in-
oculation studies demonstrated. its parasitism.

Rolfs studied Valsa on peach, plum, apricot, and cherry, and
showed that the forms are interinoculable; but on the basis chiefly of
slight variations in spore measurements, tho to some extent on vari-
ations in growth on media, he distinguished two varieties, V. leu-
costoma var. cincta on cherry and peach, and V. leucostoma var.
rubescens on apricot and plum, a varietal distinction that has been
recognized in at least one textbook. That such a varietal segregation
should exist is somewhat surprising, especially when the biologic re-
lations claimed are considered, and the question naturally arises as
to the validity, for taxonomic purposes, of the characters selected.

While the literature regarding Valsa and Cytospora on drupes is
extensive there are but few references to either as causes of disease
on cultivated pomes.

Aderhold’® made inoculations upon apple, but makes no reference
in later publications to its natural occurrence upon that host, tho
in 190045 he recorded it as the cause of cankers on pear in Proskau.

Von der Byl,®? also Evans,5* noted Cytospora leucostoma as the
cause of die-back of apple trees in South Africa; Darnell-Smith and
MacKinnon?’ report Valsa and Cytospora on apple in New South
Wales; Nicholls®+ reports death of apple trees in Tasmania associated
with Valsa prunastri and Valsa ambiens; and Ideta?* in his textbook
gives Valsa mali as the cause of canker on apple twigs. The illustra-
tions given by Darnell-Smith agree closely with the canker under
discussion.

Cockayne*> mentions what is probably a Valsa on apples, pears,
and other trees in New Zealand, but with inconclusive evidence as to
parasitism and as to the species of fungus involved.

To place clearly before the reader the difficulties of classification
and the necessity of taxonomic revision of these fungi the preceding
tables and lists are presented. Truly Aderhold was justified in con-
eluding that from the conidial forms alone it is impossible to make a
specific determination.

Tho the fungus here discussed agrees well with the Cytospora of
Valsa leucostoma, it is best to defer final judgment as to its specific
name. It is to be noted that many similar fungi described on other
hosts may in fact also grow on Rosaceae; also that Cytosporoid fungi
belonging to genera of the Valsaceae other than Valsa may cause
cankers on these hosts.

1919] AN APPLE CANKER DUE TO CYTOSPORA 377

10.

MM.
12.
13.

14.
15.

16.

af
18.
19.
20.
21.

22.

23.

BIBLIOGRAPHY

MASSEE, GEORGE. Diseases of Cultivated Plants and Trees. 1910.
CooxE, M. C. Fungoid Pests of Cultivated Plants. 1906.

ALLESCHER in Rabenhorst, L. Kryptogamen Flora von Deutschland 1. Pt.
6. 1901.

Linpav in Sorauer, P. Handbuch der Pflanzenkrankheiten, 2. 1908.
Linpav in Engler and Prantl. Die Natiirlichen Pflanzenfamilien, 1. Abt. 1.

Rant, A. Die gummosis der Amygdalaceae. Diss. Amsterdam, 1906. In
Ztschr. Pflanzenkrank., 17, 179. 1907.

Winter, G. Die Pilze in Rabenhorst’s Kryptogamen Flora von Deutsch-
land, ete.

Saccarpo, P. A. Sylloge Fungorum Omnium Hucusque Cognitorum.

HEsueER, L. R., AND WHETZEL, H. H. Manual of Fruit Diseases. 1917.

ADERHOLD, R. Ueber das Kirschbaumsterben am Rhein, seine Ursachen und
seine Behandlung. Arb.a.d. Biol. Abt. fiir Land und Forstw. Kais.
Gsndhtsamt., 3, 309, 563. 1903. An extensive discussion of the morph-
ology, taxonomy, and pathogenicity of the fungus, with studies of pure
cultures. See also review in Zeit. Pfk., 15, 339.

Stevens, F. L. The Fungi Which Cause Plant Disease. 1913.

FucKkeL, L. Symbolae Mycologicae, 196. 1869.

DUKE OF BEDFORD AND PICKERING, 8S. U. Observations on a Disease of Plum
Trees. Report on the working and results of the Woburn Experimental
Fruit Farm, Report II, 218, London, 1900; also review in Zeit. Pfk.,
12, 177. Reports Eutypella prunastri Sace. on plum and almond.

Routrs, F. M. Die Back of Peach Trees. Science, 26, 87, July, 1907. Cyto-
spora rubescens followed by its ascigerous stage Valsa leucostoma is
given as the cause of the disease on peach and plum.

A Disease of Neglected Peach Trees. Mo. St. Bd. Hort., Rpt. 2,
278-83. 1908. Due to Cytospora (Valsa leucostoma), which he thinks the
same as that reported by Stewart et al.’

Winter Killing of Twigs; Cankers and Sunscald of Peach Trees.
Mo. St. Fruit Exp. Sta. Bul. 17, 1-101. 1910. An extensive account
of the morphology, pure cultures, and inoculations. Two varieties of
Valsa leucostoma are erected, var. cincta on cherry sa peach, var.
rubescens on apricot and plum.

Waters, R. Jour. Agr. N. Zealand, 14, 190-96. 1917. Netéa presence of
Valsa ambiens (?) and Valsa auerswaldia as saprophytes or facultative
parasites on apple and other fruit trees.

Srewart, F. C., Routrs, F. M., anp Hatt, F. H. A Fruit Disease Survey
of Western New York. N. Y. (Geneva) Agr. Exp. Sta. Bul. 191, 304, 318,
323. 1900. Cytospora sp. on apricot, peach, and plum.

McALPINE, D. Fungus Diseases of Stone Fruit Trees in Australia and
their Treatment. Melbourne, 1902.

WorMALD, H. The Cytospora Disease of the Cherry. Jour. Southeast Agr.
Col., Wye, Kent., No. 12, 367-80, pl. VII-XXII. 1912. Description
of canker with plates; studies of morphology, pure cultures, and inocu-
lations. Attributed to Cytospora leucostoma—Valsa leucostoma.

LtstHer, Gustav. Untersuchungen iiber die Ursache des Rheinischen Kirsch-
baumsterbens. Ber. d. Konig]. Lehranst. fiir Wein Obst u. Gartenbau,
Geisenheim a. Rh. (1907) 307. 1908.

Ewert. Ist das Rheinische Kirschensterben auf eine Pilzekrankheit zuriick-
zufiihren, Proskau. Obstbau Ztg., 13, 2-8. 1908.

Ipeta, A. Handbook of Plant Diseases of Japan, 295. 1909. Gives Valsa
mali Miz. and Yam. on apple.

378

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BULLETIN No. 217 [May,

LAPINE, FRANK N. Zum Krebs der Apfelbaiume Landw. Jahrb. 21, 937-49.

CooxE, M. C. Handbook of British Fungi. 1871.

Hartig, R. Lehrbuch der Pflanzenkrankheiten. 1900.

KIRCHNER, O, Die Krankheiten und Beschaidigungen unserer Landwirt-
schaftlichen Kulturpflanzen. 1906.

Frigs, E. Systema Mycologicum, 2, 387, 1823,

Eu.is, J. B., AND EVERHARDT, B. M. North American Pyrenomycetes. 1892.

GOETHE, R. Das Absterben der Kirschenbaéume in den Kreisen St. Goar,
St. Goarshausen und Unterlahn. Deut. Landw. Presse, 26,999, 1111-12.
1899. The Cytospora is regarded as secondary following frost injury.

ScHROETER, in F, Cohn’s Kryptogamen-Flora von Schlesien, 3,I1,405. 1908.

RUHLAND, W. Untersuchungen zu einer Morphologie der Stromabildenden
Sphaeriales auf entwicklungsgeschichtlicher Grundlage. Hedwigia, 39,1.
1900.

NITSCHKE, TH. Pyrenomycetes germanici, 223,228. Breslau, 1867.

Ltstrer, G. Beabachtungen iiber das Rheinische Kirschbaumsterben, 1906.
Ber. d. Kénigl: Lehranst. fiir Wein Obst u. Gartenbau, Geisenheim a.
Rh., 1905. Review in Zeit. Pfk., 16, 324.

CockaYyNnE, A. H. Jour. Agr. N, Zealand, 11,504. 1915. A die-back of
apples, pears, and other fruit trees is noted. A Valsa may be the cause,
but the evidence is incomplete.

WEHMER. Zum Kirschbaumsterben am Rhein. Deut. Landw. Presse, 26,96,
1080. 1899. Cites presence of Valsa leucostoma.

ZAPFE. Kirschenzucht und Kirschbaumkrankheit in Camp a. Rh. Prakt.
Rathgeber Obst u. Gartenbau, 14,473.. 1899.

DaRNELL-SMiTH, G. P., AND MACKINNON, E. Fungus and Other Diseases of
the Apple and Pear. Dept. Agr. New South Wales, Farmers’ Bul. 99, 18.
1915. Reports Cytospora and Valsa on apple.

WALTON, R. C., AND Bascock, D.C. Abst. Phytopath, 6,112. 1916.

FRANK. Das Kirschbaumsterben am Rhein. Deut. Landw. Presse, 26,249.
1899. ;

Gelungene. Infektionsversuche mit dem Pilze des Rheinischen
Kirschbaumsterbens. Deut. Landw. Presse, 27,1024. 1900. True para-
sitism of the fungus was proved by inoculations.

Rours, F. M. Fruit Tree Diseases and Fungicides. Mo. St. Fruit Exp. Sta.
Bul. 16, 15-16. 1907. Attributes die-back to Valsa leucostoma=
Cytospora rubescens,

PERSOON, C. H. Synopsis Methodica Fungorum, 39. 1801.

ADERHOLD, R. Unserer Obstbaume Hausarzt, Proskau. Obstbau Ztg., 37.
*1899. :

Arbeiten der botanischen Abteilung der Versuchstation des
Kgl. Pomologischen Instituts zu Proskau. Centbl. Bact., II, 6,620.
1900. Cytospora rubescens noted on pear.

LaBontE. Die Krankheit der Kirschbiume am Rhein und ihre verschiedenen
Ursachen. Mitt. iiber Obst u. Gartenbau, 102. 1900.

RASCHEN. Kirschbaumsterben und Kalkdiingung. Deut. Landw. Presse,
27,1,7. 1900. No mention is made of parasitic fungi.

SorAvER, P. Das Kirschbaumsterben am Rhein. Deut. Landw. Presse, 27,18,
201. 1900. Holds the fungi to be secondary.

Das massenhafte Absterben der Siisskirschen am Rhein. Naturw.
Wehnsehr., 15,133. 1900.

TASCHENBERG, O. Schutz der Obstbaiume gegen feindliche Tiere, III, 108.

HEALD, F. D. Report on Fungous Diseases. Tex. Dept. Agr. Bul. 22,158.
1911.

1919] AN APPLE CANKER DUE TO CYTOSPORA 379

52.

53.

54.

55.

56.

57.

Hemi, T. On a New Canker Disease of Prunus yeodoensis, P. mume ana
Other Species Caused by Valsa japonica n, sp. Jour. Col. Agr. Tohoku
Imp. Univ., 7,257. 1916. These fungi cause disease and gummosis.

Von vDER ByL, P. A. Die Back of Apple Trees Caused by Cytospora
Leucostoma, So. African Jour. Sci., 12,545, 1916. Reported as serious
on apples in many localities; also on drupes.

NicHoutis, H. M. Agr. and Stock Dept. Tasmania, Rpt. 1916-18. Valsa
prunastri and Valsa ambiens are reported on dying apple trees.

StérMeEeR, K. Obstbaumsterben und Kartoffelblattrollkrankheit. Jahresb.
Ang. Bot., 7,119: 1909. Discusses Valsa leucostoma as the cause
of death of cherry trees, and Cytospora piricola of death of apple trees.

Evans, I. B. P. Union So. Africa, Dept. Agr. Rpt. 1912-13, 169. Cytospora
leucostoma is reported as causing death of apple trees.

SPRENGER. Influences Affecting Cherry Culture. Cultura, 27,325. 1915.

fit uy