AN ABSTRkCT OF TEE
THESIS
OF
- fOr the- h-.---1n
____
(Maj*r)
(Degree)
ÇNaDIe)
Date Thesis presented--..43.,-3Ç4].----T
i-tie
--e- r-
xt
_________________________________________________
Abstract Approved:
(Major Professor)
X.
Irt
the
W
ti1Eøtte
b13HOn an t*riç
id
sud it
bi4t
blight
r of
During the
This
of Orern the **oh hae 1on been
duo
tere
fcnmd that
tm
01Lu584
by
th
brown
sxazition
rot f uztu.,
b1iht
19WJ ai wtsua1 typc of twig
to * moro critloal
tG
to infotion
of the twt
aubjeat to
w
observed.
b11ht dtustion
dit&net types of bremi rot twig
re t
4ttt.r.nt speoies of the brown rot fungus,
Salerotiiiia.
1.
hf
er]y b1o*m
funua
ird1ing it,
blight type reaulta when b1ossn.s
reflda f rc*n
3
ud
thus
th
ousin
b1iht.d
inteubed
blossoet into the twig,
the datth of the twig beyond the
point of girdling.
2.
The l*te
frwt infection type
rotted b
s1t
Uil trown rot fti;ue and
rotten fruit into the twig.
ttie
wei
t.urìng fruits ere
funus eprcdc from the
If girdling results, the twig. beyond
the point of a.ttohmezit of the rotten fruit is dIled.
h.spp.ns in
n
1to
swnzner the blighted twig with its
Thon this
uerous
dead, exhibits a very conspicuous type of twig blight.
leaves,
&batrot (eonttnd)
nl'erabl
II.
eri&1 w.s oo11cted and cultured and from thia lt
t
wan detertnod that the t*, typen of
1arely though not antire1
bltht aro caised qu.te
by twG diffrent npeois of t.e brown
rot f unus.
of the
!ost
1.
ca4y bloior type
'clerotinit laxa,
wore due to thin
-
,.
2.
-
In the
f erial
peoen and only
of blight
tuc1tcd 96
i
rtre
caused by
of the
mn
due to another speoin,
fruotloals.
the
otbr
type were
ty4eøtioxi
hand raost cacen, 71%, of the lato fruit infection
*uaed by
by.
laxa
S. fruoticola, irhiie
2ï! were due to
TYPES OF BROWN-ROT TWIG-BLIGHT
ON PEACH IN OREGON CAUSED
BY SPECIES OF
SC LERO TI NIA
by
WANG, CITUANG
A THESIS
submitted to the
OREGON STATE COLLEGE
in partial fulfillment of
the requirements for the
degree of
MASTER OF SCIENCE
June 1941
APPROVED:
Professor of Botany
In Charge of Major
Head of Department of Botany
Chairman of School Graduate Committee
Chairman of State College Graduate Council
AC KNO WLEDGMENT S
I
wish to express my appreciation to Dr. C. E.
Owens, Dr. S. M. Zeller, Dr. T. C. Llu, Mr. A. J.
Braun and Mr. A. W, Evans for assistance of various
kinds in carrying out this investigation and
pre-
paring the thesis.
Dr. Owens is largely responsible for the detailed
correction of the thesis.
Thanks are due the following farm owners for per-
mission to collect material for study from their peach
orchards:
George Hesler, J. H. Tompkins, Louis Will
and C. A. Rockhill of Yanthill County, and W. L. Powell
of Benton County.
Contents
I ntrod.uc tian
.
.................
.
Review of Literature
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Occurrence of two Types of Twig Blight in Oregon
Page
i
.
.
2
.
.
5
Early Blossom-infection Type
Late Fruit-infection Type
ßource of Material
.
.
.
.
.....
.
Method of Determining Species
.
Species of 3clerotinia Concerned
Percentage of
Literature Cited
.
.
P lates
.
.
.
.
.
.
.
.
7
.
.
.
.
.
.
.
.
.
.
7
.
.
.
.
.
.
.
.
.
.
8
.
.
.10
ch bpecies in Liaterial
Summary and Conclusions
Tables
.
.
.
.
.
.
.
.
tudled
.
.
.
.
.
.
.
.
.
.
.
.10
.
.
.
.
.
.
.
.
.
.
.
.12
.
.
.
.13--30
.
.
.
.31--33
............
...............
.
.
.
TYPES OF BROWN-ROT TWIG-BLIGHT ON PEACH IN OREGON
CAUSLD BY SPECIES OF SCROTINIA
Introduction
Brown rot, caused by species of Sclerotinia, is an
important disease of stone fruits in Europe, America,
and various other parts of the world.
In Europe and
especially in Britain the pome fruits also are seriously
attacked by certain species.
In America the ponie fruits
are sometimes affected but here the trouble is primarily
one occurring on stone fruits.
The occurrence of a twig blight on peaches in Oregon
due to the brown rot fungus has been observed over a
period of many years.
The conionly occurring type of
blight is that resulting from blossom infection and
affects a relatively short length of twig, usually killing from about two or three to five or six inches of the
terminal part of the twig.
During the late sunnner of 1940 a type of twig blight
was observed which apparently resulted from the spread of
the brown rot fungus from rotting fruits into the twig.
Many twigs were girdled at the point of attachment of the
rotting fruit thus killing all the twig growth beyond
this point.
2
The purpose of this investigation was to determine
the species of Scierotinia causing these two types of twig
blight, the one resulting from the early blossom infections, the other from the late fruit infections.
Review of Literature
Since the time of Persoon, who published what appears
to be the first authentic description of any of the brown
rot fungi under the name Torula fructigena (9), and later
Monilia fructigena (10), considerable confusion has existed in both Europe and America as to the exact identity
of the various
of disease.
species of Scierotinia causing this type
Not until Harrison (4, 5) made a thorough
review of the literature and studied all of the material
available in Europe, America, and Australia was the con-
fusion cleared up and the identity of the several species
clearly established.
From Harrison's work it appears
that there are three distinct species of Scierotinia causing a "brown rot" disease of fruits, as follows:
S.
(a)
fructigena (Ader. and Ruhi.) causes fruit rot of both
pone and stone fruit in Europe and the British Isles.
is said to occur also in China and Japan.
(b)
S.
It
laxa
(Ader. and Ruhi.) causes fruit rotting mainly in the stone
fruits, but also causes blossom blight, twig and spur
blight, and twig canker in stone fruits and sometimes in
3
pears and quinces as well.
Europe, Britain,
of North America.
This species is known in
China, Japan, and the Pacific Coast region
(e)
S.
fructicola (Wint.) Rehm.,
commonly referred to as the American brown rot fungus,
causes fruit rot, but may also cause blossom and twig
blight and canker on most stone fruit trees.
occasionally affect pone fruits also.
It may
This species is
known to occur throughout North America and is the only
brown rot fungus found in Australia and New Zealand.
Since Harrison has so thoroughly reviewed the literature this account will be confined to the situation on
the Pacific coast of North America and particularly to
Oregon and California, where both S. fructicola and S.
laxa are known to occur.
Apparently the brown rot disease has been known in
Oregon since the latter part of the 19th century when
Hedrick
(6)
reported it on prunes.
It apparently was not
suspected that there night be more than one form present
in this state until Barss and Posey made a study of
strains collected on various stone fruits, pears, and
quinces, and became convinced that there were two distinct
strains, or possibly species, occurring in Oregon.
Posey
(li) wrote a master's thesis on the subject which was
mitted in 1915.
Thj
sub-
thesis was not published but a brief
4
abstract covering the essentials of this investigation was
published In Science, October 22, 1915.
Barss (i) later
published a circular on brown rot in Oregon and suggested
the naine iJonilia oregonensis for the strain which differs
from the common American brown-rot species, since at that
time the confusion over the various species occurring in
Europe and America had not yet been cleared up.
As in-
dicated above, Harrison has since demonstrated that this
form is identical with the European S. laxa.
states that the ttordinarytT brown rot fungus,
Barss further
now known to
be the American brown-rot species, S. fructicola, causes
the severe attacks of fruit rot of stone fruits in Oregon,
and also causes blossom blight as well.
On the other hand
he states that the newly described species, now known to
be S. laxa, causes very severe attacks of blossom and spur
blight and twig cankers on all kinds of stone fruits and on
certain varieties of pears.
However, the latter species
causes less rotting of fruit than S. rructicola according
to Barss.
No apothecia of S. laxa have ever been found in
Oregon, but those of S. fructicola are common.
In California Bioletti (2) published the earliest
account of brovm rot of fruits.
Other accounts of the
occurrence of brown rot in California were published by
Smith (13), Howard and
Home
(8),
and Rudolph (12).
These
earlier writers mentioned both fruit rot and blossom and
5
twig blight but gave no indication that they suspected the
presence of two species of brown rot fungi.
No apothecia
of Scierotinia were reported by any of these writers.
Smith called attention to the blossom and twig blight and
Rudolph emphasized this phase, especially on apricots.
Rudolph sent specimens to Ezekial
both
S.
(3)
who described
laxa and S. fructicola thus indicating that at
that date both species were present in California even
though no one had reported apothecia up to that time.
Hewitt and Leach
(7)
were the first to definitely
Apothecia of
report S. fructicola from California.
Selerotinia fructicola were found in California in 1936,
apparently for the first time.
According to them S. laxa
is still the most widespread species in that state, causing
blossom and twig blight and also fruit rot of apricot,
prune, nectarine, peach and cherry.
S.
fructicola occurs
in many localities but apparently is not very abundant
except in certain circumscribed areas such as the Sacramento valley.
Occurrence of Two Types of Twig Blight on
Peach in Oregon
Two types of brown rot twig blight on peaches have
been observed in the Vvillamette valley of Oregon, namely
the early type entering through blighted blossoms, and the
late type entering from rotted fruits.
The typical twig
bUCht resulting from blossom infec-
tion appears shortly after blossoming, sometinies before
the terminal tuft of leaves is full grovm and before new
shoot growth has proceeded very far.
Any blossom on a
twig may be killed by the brown rot fungus and in many
cases the fungus grows from the blossom back into the twig
and girdles it.
Vhen this happens that part of the twig
beyond the girdle dies, giving rise to the common and
often observed twig blight (Plate I).
The length of twig
killed depends upon which blossom is infected.
If the
girdle results from ïnfection of a blossom near the tip
of the twig the blighted tip will be quite short.
On the
other hand if a blossom near the base of the blossom-
bearing shoot is infected and results in girdling, a longer
length of twig will be killed.
It is usually quite easy
to identify this early, blossom-type of twig blight.
Often
the blighted blossom dries up and hangs on, or if it falls
off, the girdling canker will be located at the node
where the blossom occurred and the relationship can always
be recognized.
Twigs blighted by the brown rot fungus
have a characteristic appearance which can be recognized
with considerable certainty.
The late tipe of brown rot twig blight appears when
the fruit is nearly or quite mature and results when the
7
fungus migrates frani a rotted fruit back through the
pedicel and girdles the twig.
Twigs girdled and killed
at this stage are usually longer and more conspicuous
than the twigs blighted earlier because, at the later date,
the new, current season's twig growth has developed and
therefore there is a much longer extension of twig beyond
the point where the rotten fruit is attached and where the
girdling has occurred (Plate II).
This additional length
of blighted twig with its numerous, dead, brown leaves
is quite conspicuous, and in serious cases the tree may
be covered with these dead twigs or tTflagsU which are
visible for comparatively long distances.
Source of Material
Material for this study was collected during the fall,
winter, and spring of 1940-41 fron several localities in
the
illamette valley of Oregon.
Orchards from which
specimens were collected include the following:
Yanthill County::
George Hesler, Dayton
J.
H. Tompkins,
Grand Island
Louis Will, Grand Island
C. A. Rockhill,
Grand Island
Benton County:
I,
L. Powell,
Kiger Island
Ilethod Used in Determining Species
The species concerned in each
determined by the culture method.
te
of blight was
Barss, Posey, Harrison,
Hewitt and Leach, and others have noted that each species
of Scierotinia causing brown rot has its own character-
istic appearance when grown upon potato dextrose agar
and other media.
The fungus concerned was isolated by
the ordinary method; i.e.,
sterilizing the surface of the
diseased twig with mercuric chloride, l-1000, then, with
sterile instruments, removing bits of the diseased tissue
from beneath the bark and plating on agar.
Plate III shows
the characteristic growth of S. fructicola and S. laxa on
potato dextrose agar and on Cook's agar in Petri dishes.
It will be noted, as many previous investigators have
observed, that the former makes a much more rapid and
luxuriant growth than the latter.
S.
fructicola makes a
uniform growth with conspicuous concentric rings.
The
niycélial mat is covered with a dense growth of conidio-
phores and conidia giving the zoned surface an ashy gray
color and a very fluffy and pulverulent appearance.
S.
laxa, on the other hand, grows slowly, in an irregular
manner, has a whiter color and does not produce such conspicuous concentric zones as does S. fructicola, and pro-
duction of conidia is very scant.
Species of Scierotinia Concerned
These studies showed that the two species associated
with the types of twig blight concerned were
and S. laxa.
S.
fructicola
There were 244 specimens collected and one
to four attempts at isolation were made from each specimen.
Many of the tissue plantings failed to produce a growth of
Scierotinia but from the total number of specimens from
which attempts to isolate a fungus were made, one or
more cultures were secured from 154 different blighted
twigs.
Table i shows in detail the number of specimens
collected, place and time of collection, attempts at
isolating the fungus, and the species isolated in each
te
case from the early type or late
tively.
of twig blight respec-
The tabulation shows that in a great majority of
cases the early or blossom infection type yielded cultures
of S. laxa while the late or fruit type of blighted twigs
yielded a high percentage of
Table
2
S.
fructicola.
gives a summary of the incidence of the two
species of Scierotinia on the two types of blighted twigs.
At least on peaches these studies
confirm the statement of
Bars s that most of the blossom blight is caused by S. laxa
while most of the fruit rot is caused by S. fructicola.
Thj
conclusion is based upon the fact that of 82 twïgs
lo
showing the early or blossom infection type of blight 79,
or 96 percent yielded cultures of S. laxa while only 3,
or 4 percent gave cultures of S. fructicola.
On the other
hand, of 72 twigs exhibiting the late or fruit infection
type of blight 51, or 71 percent gave S. fructicola and 21,
or 29 percent yielded S. laxa.
There is a possibility that the high percentage of
S.
laxa secured in cultures made from the late or fruit
infection type of blighted twigs may be due to error in
determining the identity of species because of contsminated
cultures.
Suimnary and Conclusions
1.
Two types of twig blight due to infection by
species of Sclerotinia have been observed on peaches in
Oregon, an early type resulting from blossom infection, and
a late type caused by the spread of the fungus from rotten
fruits into the twigs.
2.
Cultures of the causal fungus isolated from the
two types of blighted twigs revealed that two different
species of brown rot fungi were concerned, S. laxa, causing
nearly all of the early type of twig blight, and S.
fructicola, causing most of the late type of blight.
were exceptions to the rule in both cases.
There
11
3.
Of a total of 82 cultures secured from the early
or blossom-infection tipe of blighted twigs, 96 percent
were S. laxa, while of 72 cultures isolated from the late
or fruit infection type of blighted twigs, 71 percent were
S. fructicola.
4.
Based upon the data secured in these investiga-
tions it is concluded that nearly all of the blossom
in-
fection type of twig blight on peaches in the Willamette
valley, Oregon is caused by S. laxa, while the late or
fruit rot type is caused quite largely by S. fructicola.
12
LITERATURE CITED
1.
Barss, H. P. Brown rot and related diseases of stone
Ore. Agr. Exp. Sta. Cir. 53. 1923.
fruits :in Oregon.
2.
Calif. Agr.
Bioletti, F. T. Brown rot of stone fruits.
1902.
Exp. Sta. Rept. (1898-1901) 2:330-331.
3.
The
Ezekial, W. N. Fruit rottinC Scierotinlas. II.
American brown-rot fungi. Md. Ar. Exp. Sta. Bui.
271:87-142. 1924.
4.
Harrison, T. H. Brown rot of fruits and associated
Historical
diseases of deciduous fruit trees. I.
taxonomy
concerning
critical
remarks
review and
Jour.
and nomenclature of the causal organisms.
S.
1933.
N.
a1es 67:132-177.
Roy. Soc.
5.
Brown rot of fruits and associated
______________.
diseases of deciduous fruit trees. II. The apothecia
Jour. Roy. Soc. N. S.
of the causal organisms.
1934.
Viales 68:154-176.
6.
Brown rot of prunes.
Hedrick, U. P.
1895.
Sta. Bui. 47.
7.
Brown rot Scierotinias
Hewitt, W. B. and L. D. Leach.
distribution on
their
California
and
occurring in
Phytopath. 29:337-351. 1939.
stone fruits.
8.
Brown rot of apricots.
Howard, W. L. and W. T. Home.
Calif. Agr. Exp. Sta. Bui. 326:73-88. 1921.
9.
Persoon, C. H. Torula £ructirena in Observ. Mycol.
Lypsiae., p. 26. 1796.
10. ______________.
1801.
Ore. Agr. Exp.
Synopsis Methodica Fungorum p. 693.
B.
Studies of Lionilia blight of fruit trees.
1915.
Science N. S. 42:583.
11. Posey, G.
12. Rudolph, B. A. Lionilia blossom blight (brovm rot) of
1925.
apricots. Calif. Agr. Exp. Sta. Bul. 383.
13. Smith, R. E. Report of the plant pathologist to July 1,
1907.
Calif. Agr. Exp. Sta. Bui. 184.
1906.
TABLE 1. -- Isolations from b1ihted twigs, both early (blossom) and late (fruit) tï,e of
lace of collections and host variety,
infection, showing the number and date of collections,
which
a brovm rot organism was rein
instances
of
attempted,
number
number of isolations
of
infection in each case.
and
type
the
present,
or
Sclerotinia
covered, the soecies
Juber and
Date of
Collection
Place of Co1-Number of
Isolations
lection and
Variety
Attempted
iost
Number of
Cultures
Recovered
i
Species of Sclerotinia
Present
S.
laxa
S.
fructicola
Type of Infection
Early
lossoxn
Infection
j_______________
I
Lete
Fruit
Infection
Geo. Ilesler
1
2
D-28-40
u
3
0
-
-
-
-
4
0
-
-
-
-
3
1
x
-
x
-
"
3
2
x
-
x
-
Dayton
Cling
Geo. Nesler
ayton
Craford
3
II
4
5
"
"
3
2
x
-
x
-
6
"
"
2
0
-
-
-
-
lt
tI
3
2
x
-
x
-
"
"
3
2
x
-
x
-
"
"
i
O
-
-
-
-
7
8
9
TABLE 1. (Continued)
10
!'.
u
3
0
-
-
-
-
2
2
x
-
x
-
1
x
-
x
-
11
"
12
"
"
13
"
"
2
0
-
-
-
-
14
"
3
0
-
-
-
-
15
"
3
2
x
-
x
-
16
"
4
0
-
-
-
-
"
2
2
x
-
x
-
"
3
2
-
x
-
17
"
18
1
"
"
2
1
x
-
x
-
20
"
"
3
1
x
-
x
-
21
"
"
2
2
x
-
x
-
"
1
1
x
-
x
22
23
II
2
3..
x
-
x
-
24
"
2
0
-
-
-
-
"
3
1
x
-
x
-
25
"
TABlE 1.
(Continued)
"
26
27
28
"
29
"
2
1
x
-
x
-
ii
2
0
-
-
-
-
ti
3
0
-
-
-
-
4
0
-
-
-
-
4
3
x
-
-
x
4
0
-
-
-
-
4
0
-
-
-
-
Geo. llesler
30
'
31
"
32
Dayton
E iberta
Geo. Hesler
Dayton
Hale
i
33
Ii
tI
2
0
-
-
-
-
34
ii
it
2
1
x
-
-
x
35
ii
ti
2
2
-
x
-
x
ii
1
1
x
-
-
x
4
0
-
-
-
-
36
37
38
40
ii
n
it
3
1
x
-
x
-
n
it
2
2
x
-
X
-
1
0
-
-
-
-
ti
al
T.ABI
1.
41
"
(Continued)
2
0
-
-
-
-
3
2
-
x
-
x
2
1
-
x
-
x
2
0
-
-
-
-
i
O
-
-
-
-
2
1
-
x
-
x
4
1
-
X
-
x
3
0
-
-
-
-
3
2
-
x
-
x
50
3
1
-
x
-
x
51
4
3
-
x
-
x
4
0
-
-
-
-
3
i
-
x
-
x
3
1
-
x
-
x
3
0
-
-
-
-
J
42
"
43
lt
44
"
46
"
47
"
tl
II
tI
52
ft
53
55
11
tI
48
54
Grand Island
Unknovm
u
45
49
H. Tompkins
ft
11
II
ft
i-J
O)
TABLE 1.
(Coitinued)
56
2
0
-
-
-
-
3
0
-
-
-
-
57
H
It
58
u
U
4
2
-
x
-
x
59
U
H
3
1
-
x
-
x
60
"
8
2
1
-
x
-
61
"
2
1
-
x
-
2
i
-
x
-
62
'
8
x
63
"
2
0
-
-
-
-
64
"
2
2
-
x
-
x
II
3
3
-
x
-
x
11
4
1
-
x
-
x
-
x
-
x
i
-
x
65
66
"
67
"
68
"
69
3
U
It
70
71
lt
3
1
2
0
-
-
-
-
3
2
-
x
-
x
3
1
-
x
-
x
TABLE 1. (Continued)
ti
2
0
-
-
-
-
ti
2
0
-
-
-
-
2
0
-
-
-
-
4
1
-
x
-
x
76
3
3
-
x
-
x
77
3
0
-
-
-
-
.72
73
u
74
ti
75
'
II
H
78
"
2
0
-
-
-
-
79
"
3
0
-
-
-
-
80
'
11
2
0
-
-
-
-
81
It
3
2
-
x
-
x
82
II
3
0
-
-
83
t,
3
0
-
-
-
-
84
tI
3
2
-
x
-
x
85
it
i
-
86
ii
2
2
-
x
-
x
2
0
-
-
-
-
87
ti
-
-
TABlE 1. (Continued)
88
11
C.
89
"
í..
2
1
-
x
-
x
4
0
-
-
-
-
Rockhill
Grand Is land
7jnknovm.
90
'
"
3
0
-
-
-
-
91
"
"
3
0
-
-
-
-
92
"
H
3
0
-
-
-
-
93
tI
n
3
1
-
x
-
x
94
"
"
2
0
-
-
-
-
95
U
It
4
Q
-
-
96
"
"
2
0
-
-
-
-
97
It
lt
3
0
-
-
-
-
2
0
-
-
-
-
3
0
-
-
-
-
II
3
0
-
-
-
-
"
tI
2
1
-
x
-
x
't
lt
2
0
-
-
-
-
tI
98
99
Ii
100
101
102
II
I-J
TABLE 1.
103
"
104
105
108
It
3
0
-
-
-
-
"
2
0
-
-
-
-
'
2
0
-
-
-
-
8
2
0
-
-
-
-
"
2
1
x
-
x
-
"
2
0
-
-
-
-
3
1
-
x
-
x
3
0
-
-
-
-
106
107
(Continued)
"
'
L. 'i11
109
"
Grand Is land
Unknown
8
1.10
111
"
"
2
0
-
-
-
-
112
"
"
3
0
-
-
-
-
113
"
"
3
1
-
x
-
x
114
"
11
2
0
-
115
"
"
3
2
-
x
-
x
116
"
8
3
.
-
x
-
x
117
"
2
0
-
-
-
-
"
-
o
TABLE
1].8
1.
"
(Continued)
U
U
119
2
1
-
x
-
x
3
0
-
-
-
-
3
2
-
x
-
x
3
0
-
-
-
-
2
1
-
x
-
x
120
"
121
"
122
"
123
"
3
1
-
x
-
x
124
"
2
1
-
x
-
x
125
"
"
3
0
-
-
-
-
126
"
"
3
0
-
-
-
-
"
3
1
-
x
-
x
"
2
0
-
-
-
3
1
-
x
-
x
2
1
-
x
-
x
4
1
-
x
-
x
127
"
"
128
"
129
"
130
"
131
"
132
"
"
3
1
-
x
-
x
'
"
3
0
-
-
-
-
133
"
TABLE 1.
134
"
135
"
(Continued)
ï.
136 9-23-40
3
0
-
-
-
3
0
-
-
-
2
0
-
-
-
"
2
0
-
-
-
2
0
-
-
-
"
L. Powell
Kier
Island
Iale
137
"
138
"
tt
139
"
"
1
0
-
-
-
140
"
"
2
1
x
-
-
X
141
"
"
2
2
x
-
x
X
142
"
"
1
0
-
-
-
"
1
1
-
x
-
2
1
x
-
x
143
144
n
145
tt
1
0
-
-
-
146
"
i
O
-
-
-
"
i
O
-
-
-
tt
2
0
-
-
-
147
"
148
"
X
TABLE 1.
(Continued)
149
It
2
0
-
-
-
150
"
"
2
1
-
x
x
151
"
"
2
2
x
-
x
i
i
-
x
X
2
1
x
-
1
-
x
-
-
-
-
U
152
I.
153
"
Powell
L.
Kiger Islarul
2lberta
154
tI
3
155
tI
2
tt
156
157
158
"
U
It
159
160
16].
162
163
"
"
"
Ii
2
1
x.
-
x
2
0
-
-
-
3
1
x
-
x
2
1
x
-
x
3
2
X
-
X
2
2
x
-
x
1
1
x
-
x
1
1
x
-
x
X
TABLE 1.
164
"
(Continued)
W. L. Powe11
Kier Island
Crawford
It
166
'
167
"
168
"
It
ft
2
0
-
-
-
-
2
1
x
-
-
x
1
1
x
-
-
x
2
2
x
-
-
x
2
2
-
x
-
x
169
"
2
Q
-
-
-
-
170
11
2
1
x
-
-
x
171
"
2
0
-
-
-
-
172
"
2
1
x
-
x
-
173
"
"
2
0
-
-
-
-
"
W. L. Powell
Kiger Island
Slappy
2
1
x
-
x
-
175
2
0
-
-
-
-
176
3
1
x
-
x
-
177
1
3.
x
-
x
-
174
t',
TABLE 1.
178
"
179
(Continued)
"
i
i
x
-
x
11
1
1
x
-
x
2
2
-
x
x
2
1
x
-
x
180
"
181
"
182
"
2
1
i
-
x
183
"
i
i
x
-
i
184
"
2
2
i
-
x
185
"
i
O
-
-
-
186
"
2
2
x
-
x
187
"
2
i
x
-
i
188
"
2
2
i
-
x
189
"
2
2
i
-
x
190
',
2
0
-
-
-
19].
"
2
2
i
-
i
192
"
i
O
-
-
-
193
"
2
0
-
-
-
"
O)
TABLE 1. (Cpntinued)
1.94
1
"
L. Powell
Kiger Island
Rochester
2
1
x
-
x
-
2
2
-
x
-
x
2
1
-
x
-
x
3
1
x
-
-
x
2
1
-
x
-
x
2
2
x
-
-
x
t.
195
"
196
U
197
198
"
199
200
"
3
3
x
-
-
x
201
"
3
1
x
-
-
x
2
2
x
-
x
-
2
2
x
-
x
-
2
1
x
-
x
-
2
2
x
-
-
x
1
1
x
-
-
x
x
-
-
x
x
-
-
x
202 1-20-41
ao3
W. .L. .Pawell
Kiger Island
Unknovm
"
204
ti
205
206
"
207
"
i
208
"
2
1
2
TABLE 1.
209
"
210
"
(Continued)
"
2
2
x
-
x
-
"
i
i
x
-
x
-
i
i
x
-
x
-
21].
212
"
"
i
i
x
-
x
-
213
"
"
i
i
x
-
x
-
214 3-7-41
"
2
0
-
-
-
-
215
"
"
2
0
-
-
-
-
216
"
"
2
0
-
-
-
-
"
2
1
x
-
-
x
"
"
2
1
x
-
-
x
t
"
3
2
x
-
-
x
217
210
219
220
"
"
2
1
x
-
-
x
221
"
1)
2
2
x
-
x
-
222
"
"
2
2
x
-
x
-
"
i
i
x
-
x
-
223
T&BLE 1. (Continued)
224
i
i
x
-
x
-
2
1
x
-
x
-
2
1
x
-
x
-
H
i
i
x
-
x
-
"
i
i
x
-
x
-
ti
1
1
x
-
x
-
2
1
x
-
x
-
2
1
x
-
x
-
2
1
-
x
-
i
i
x
-
x
-
1
1
x
-
x
-
"
225
226
'
227
225
"
229
"
230
231
"
232
233
"
234
"
H
235
it
i
i
x
-
x
-
236
ti
i
i
x
-
x
-
1
1
x
-
x
-
i
i
x
-
x
-
237
'
238
"
TABLE 1. (Continued)
239
240
x
-
x
-
2
1
x
-
x
-
1
1
x
-
x
-
i
i
x
-
x
-
It
i
i
x
-
x
-
11
2
i
x
-
x
-
11
'
243
244
1
"
241
242
2
1
"
(O
30
TABlE 2. Percentages of S. laxa and S. fructicola isolated
from the early blossom infection type and from the late
fruit infection type of blighted twigs respectively.
Species of Scierotinia Isolated
Place of
collection
"rom early infected twigs
$.
Ceo. Hesler
Dayton, Ore.
laxa
¡
S.
fructicola
From late infected twigs
fruoticola
laxa
S.
f
19
0
3
1
0
0
0
28
Louis Villi
Grand Island
0
0
0
14
Rockhill
Grand Island
1
0
0
2
N.
L. Powell
Kiger Island
59
3
18
6
Totals
79
3
21
51
Per Cent
96
4
29
71
J. H. Tompkins
Grand Island
C. A.
PLATE I.
Peach twigs showing the early or blossom infection
type of twig blight caused by Scierotinia laxa.
The
blighted, dried blossoms through which the fungus entered the twigs may be seen still attached to the twigs.
PLATE I.
PLATE II.
Peach twigs showing the late or fruit infection
type of twig blight caused by Sclerotinia fructicola.
The rotten peaches through which the fungus entered
the twigs may be seen still attached to the twigs.
All
of the growth beyond the girdle at the point of fruit
attacbment Is dead.
32
PLATE II.
PLATE III.
Cultures, grown on Cook's agar, of two species
Fig. 1.
of brown rot fungi concerned with the two types of twig
blight on peaches.
Left:
Culture of Scierotinia laxa isolated from a
peach twig showing the early or blossom infection type
of blight.
Culture of Sclerotinia fructicola isolated
Right:
from a peach twig exhibiting the late or fruit infection
type of blight.
Both cultures same age.
Cultures of the same two species of Sciero-
Fig. 2.
tinia shown in Fig. 1, but grown on potato dextrose agar.
Left:
Sclerotinia laxa.
Right:
Cultures
Sclerotinia fructicola
sanie
age as those shown in Fig. 1.
=
PLATE IV.
Fig. 1.
Peach twig showing. the early or blossom in-
fection type of twig blight with the clumps of conidiophores and conidiospores located near the tip of the twig.
Fig.
2.
Single spore cultures made from conidio-
spores such as those represented on the twig in Figure 1.
J
PLATE IV.
Fie.
Fig.
1.
2.