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Group Title: Black speck of cabbage, progress of research and results of cabbage variety trials ...
Title: Black speck of cabbage, progress of research and results of cabbage variety trials.
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Title: Black speck of cabbage, progress of research and results of cabbage variety trials.
Series Title: Mimeo report - University of Florida Central Florida Experiment Station ; 68-4
Physical Description: Serial
Language: English
Creator: Strandberg, J. O.
Publisher: University of Florida, Central Florida Experiment Station
Publication Date: 1968
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Bibliographic ID: UF00075819
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 144607800

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida







,"HU'E L!3i";"ARY j
e r- CENTRAL FLORIDA EXPERIMENT STATION
Sanford, Florida MAY 16 1968

Mimeo Report CFES 68-4 April 12, 1968
I.F.A.S. Univ. of Florida
BLACK SPECK OF CABBAGF--
PROGRESS OF RESEARCH AND RESULTS OF CABBAGE VARIETY TRIALS, 1967-68

J. O. Strandberg, Assistant Plant Pathologist

The disease of winter cabbage known as "Black Speck" continues to cause
substantial losses to growers in Florida. The causes of Black Speck are not
entirely known at this time. However, a thorough knowledge of the causes will
be necessary if economical methods for disease control are to be found. For
this reason, research to determine the factors which cause black speaking re-
mains a primary concern.

Black Speck appears as numerous, dark specks on the interior leaves of the
cabbage head. The leaves look as though black pepper had been sprinkled on
them. These symptoms have given rise to another popular name; "Pepper Spot".
The specks may be present on the cabbage at harvest time but more commonly,
become evident after the cabbage has been stored at a cool temperature. Damage
to the heads is due entirely to the unsightliness of the dark specks which
increase in number with storage time.

Black Speck is presumed to be a physiological disease since no micro-
organisms have been implicated as causal agents. Present evidence indicates
that interactions of certain soil factors, weather and the physiology of the
cabbage plant itself are responsible for the condition.

The individual specks on the cabbage leaf are minute areas in which the
leaf cells have been killed. Through observations of specially prepared tissue
samples under the light microscope, it has been determined that the epidermal
or outer layer of cells are killed first. Death and collapse of additional
cells proceeds inward, resulting in a small, sunken area on the leaf surface.
The death and collapse of these cells is usually accompanied by a darkening of
the dead tissues. Each necrotic area is associated with one or more stomata,
the tiny "breathing pores" present on the leaves and stems of plants. The two
guard cells of the stomata which are directly responsible for the opening and
closing of these pores, are killed first. Then the subsidiary, or adjacent
epidermal cells are killed. This is followed by the death of the mesophyll
cells lining the sub-stomatal chamber, which is in the interior of the leaf
directly beneath the stomata.

In addition to their role in gas exchange between the leaf and the atmos-
phere, stomata can secrete or guttate water. This guttation fluid may be seen
on foliar cabbage leaves under conditions of high humidity in the form of tiny
droplets. They are much more abundant on leaves in the interior of the cabbage
head and may be found there at any time during growth or post-harvest storage.
Guttation fluid is not pure water but contains many salts, sugars, amino and
organic acids in solution. Under conditions of low soil or atmospheric moisture,
the plant may re-absorb part of this fluid via the stomata. It is proposed
that the solutes become concentrated in the guttation fluid until levels are


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reached which are toxic to the plant cells. This phenomenon may be intensified
by the large quantities of many salts taken up by plants as direct result of
their presence in large concentrations in many of our Florida soils and ground
water. Copper has been implicated and we have produced black speck symptoms
in the laboratory by placing dilute solutions of sodium phosphate,copper sulfate,
and other salts on pieces of cabbage leaves. It is probable that no single
element or compound is entirely to blame.

Further experiments at this station have shown that initial cell damage
occurs in the field and that tissue darkening is brought about by storage of
the cut heads, especially at cool temperatures. This fact may complicate disease
control through regulation of storage conditions.

Other possibilities for disease control are through varietal resistance
and soil management or amendments. Both are being explored at present. It
is known that resistance to black speck is inherited. The genetics of re-
sistance are being investigated in cooperation with Dr. P. H. Williams of the
University of Wisconsin. Experiments carried out during the winter and spring
of 1967-68 have demonstrated the existence of various levels of resistance to
black speck among several cabbage lines and varieties. Preliminary data from
crosses between highly resistant and highly susceptible lines indicate that
resistance is inherited as a recessive trait. Therefore, both parental lines
must be resistant if a resistant hybrid is to be produced. It is proposed that
interested plant breeders submit their inbred and parental lines to be evaluated
for resistance to black speck.

As a continuation of work begun in 1965, several lines and varieties of
hybrid and open-pollinated cabbage were evaluated for resistance to black speck
during the 1967-68 season. Bacterial and fungal diseases were not prevalent
during these tests and no evaluations of resistance to parasitic diseases were
made. Yields and some varietal characteristics were recorded. Results of the
early trial (No. 1) and late trial (No. 2) are summarized in tables 1 and 2.

It should be noted that several widely accepted and promising new varieties
were included in both trials one and two. In almost all cases, damage from black
speck was much more severe in the first trial than in the second. Many varieties
showing a low incidence of black speck in previous trials and even in trial two
of this year sustained a high incidence of black speck in trial one. Only one
variety (Hybrid 21) was completely free of black speck in this trial. These
results indicate that weather conditions can have a profound influence on the
development of this disease. Weather data from the present season and from
previous years are being analyzed to determine which aspects of weather most
affect disease severity.

These tests were carried out under the same field conditions encountered in
commercial production. However, the black speck ratings were made under severe
storage conditions which had previously been shown to be optimum for symptom
development. In practice, several commercially available hybrid varieties of
cabbage can be expected to produce a crop which is free from objectionable levels
of black speck under average growing and storage conditions. In our tests, the
hybrid varieties; Hybrid 18, Little Rock and Rio Verde have performed best in
this respect.








-3-


Future research on the cause and control of black speck will be directed
toward determining the specific factors which cause the disease to occur. The
most economic means of control appears to be varietal resistance. The develop-
ment of varieties resistant to black speck is feasible and will continue to be
a primary objective.

Over the past three years, Dr. R. B. Forbes, Associate Soils Chemist at
this Station, has conducted experiments with soil amendments, special fertili-
zation practices, and foliar sprays. None of the soil amendments which included
hydrated lime, dolomite, basic slag, sulfur, gypsum, various minor elements, and
chelates showed any significant effect on the incidence of black speck, nor did
there appear to be any relationship between soil pH and black speck. Whether
the cabbage was grown on old or new land made no difference.

Copper applied as a foliar spray increased the severity of black speck.
Black speck was also increased by above normal rates of a complete fertilizer.
Significant decreases in black speck were produced by foliar sprays and soil
applications of potassium chloride. Applying rates of 0, 100, 300, and 600
pounds of KO per acre resulted in a progressive decrease in black speck with
each added level of K20.

Research on the soil factors involved in black speck will be continued.






Table 1.- Summary of data from Cabbage Variety Trial No. 1. Seeded 9/1/67 and transplanted 10/2/67 at
Central Florida Experiment Station, Sanford. Black Speck ratings for the previous two years
are included where available.

First Harvest Data
Average
Identi- Days Yield
fiction After % 50 lb Wt/ No. Black Speck
Seed or Lot Trans- Heads units/ Head Heads/ Leaf Head Rating Holding
Variety Source Number plant Ready acre lbs 50 lb Color Shape 1956 1967 1968 quality
(1) (2) (3) (4) (5)


128A
130A
132C
132E
134A
Little Rock*
Superette*
Hybrid 901*
Rio Verde*
Emerald Cross*
A-S Cross
B-A Cross
M-S Cross
N-S Cross
0-S Cross
R-A Cross
R-C Cross
R-K Cross


Clemson TCES
Clemson TCES
Clemson TCES
Clemson TCES
Clemson TCES
Clemson TCES
Ferry-Morse
Ferry-Morse
Northrup-King
Northrup-King
Takii
Takii
Takii
Takii
Takii
Takii
Takii
Takii
Takii


10820-11613
11659
165/wl
180/02
Ukawa
Sano
Yasaka
Yoshihara
Kaya
Kawakami
Kumi
Yohro
Kyoto


122
122
122
122
122
111
88
103
123
99
103
104
123
103
111
123
123
123


-- -- G Var
S Var Var
S BG Var
S YG Var
S G Var
S YG Var
97 716 2.1 24 BG S
55 528 2.7 19 I R
77 672 2.5 20 I SR
94 970 3.1 16 BG SR
53 364 1.9 21 I SR
80 771 2.7 19 BG F
71 654 2.6 19 BG F
84 885 3.0 17 BG F
80 657 2.3 22 BG S
79 714 2.6 19 YG F
92 850 2.6 19 BG F
89 820 2.6 19 I F
87 881 2.9 17 I F


-- 1.6
-- 1.5
S 3.0
-- 0.9
-- 1.3
2.0
0.1 1.1
-- 0.6 2.7
-- 2.4 2.8
-- 0.2 0.8
-- 2.5
2.1
-- 1.3
-- 0.4
-- 1.6
-- 1.2
-- 1.5
-- 2.3
-- 1.4


Poor
Poor
Poor
Poor
Poor
Poor
Good
Good
Good
Exlt.
Good
Poor
Good
Good
Good
Fair
Poor
Poor
Good







Table 1. Cont'd.


First Harvest Data


Variety

R-O Cross
S-D Cross
Hybrid 18*
Hybrid 21*

Globelle*
Marion Mkt.*
Hybrid 18*
Hybrid 31
Hybrid 42*
Pack-Rite (39)*
Harvest Queen*
Hybrid 21*
Market Prize
Globe 62M*
TBR Globe*
Resistant Glory
G-71
G-73


Identi-
fication
or lot
Number


Days
After
Trans-
plant


Seed
Source
(1)
Takii
Takii
SRS-Niagara
SRS-Niagara

SRS-Niagara
SRS-Niagara
Sakata
Sakata
Sakata
Sakata
Sakata
Sakata
Harris
Keystone
Northrup-Kinj
Ferry-Morse
Cornell Univ,
Cornell Univ,


Heads
Ready


50 lb
units/
acre


827
970
735
861

655
820
630
945
783
494
641
708
689
634
722
608


Wt/
Head
lbs


2.6
3.1
2.2
2.7

2.6
2.9
2.1
2.9
2.7
2.2
2.6
2.6
2.7
2.5
2.5
2.4


No.
Heads/ Leaf


50 lb


19
16
23
19

19
17
24
17
19
23
19
19
19
20
20
21


Color
(2)
BG
YG
I
Y

BG
I
I
I
YG
I
I
Y
I

BG
BG
I


Head


*Variety also included in Variety Trial No. 2.


Holding
quality
(5)
Good
Good
Fair
Poor


Shape
(3)
F
F
F
F

R
S
F
SR
SR
R
R
F
SR
S
S
R
Var
Var


___ __


Black Speck
Rating
1966 1967 1968
(4)
-- 5.0
-- 1.9
0.0 0.7
-- 0.0 0.0

1.6 2.2 3.2
1.7 0.5 1.1
-- 1.4
1.1
-- 1.5
1.0
-- 0.7
0.2
1.8 1.2 2.6
-- 1.2 0.4
0.8 0.2 2.2
-- 1.9 1.4
-- 3.1
-- -- 35


Sano 104
Oci 111
6311-7495 123
6313-7531 111

6300/6134 104
6408/5009 111
1695 111
1924 104
6586 104
6607 79
6610 96
8921 104
2005A 88
1412-21 103
g 131-2 104
10440-11672 96
S 11-1-1 123
S 15-5-2 123


Good
Good
Fair
Fair
Fair
Poor
Good
Poor
Good
Fair
Fair
Fair
Poor
Poor


Average
-- _------






Table 2. Summary of data from Cabbage Variety Trial No. 2. Seeded 9/21/67 and transplanted 11/1/67 at
Central Florida Experiment Station, Sanford. Black Speck ratings for 1966, 1967, and two
trials in 1968 are included.

First Harvest Data


Variety


Market Topper
Improved Globe
Hybrid Emerald
Hybrid 63
Globelle

F1 Hybrid
Little Rock
Superette
Fl Hybrid
Rio Verde
FI1 Hybrid
Hybrid 41
Hybrid 42
Hybrid 59
Hybrid 63
Hybrid 68
Hybrid 70
Sanibel
Sanibel


Seed
Source
(1)


J. Harris
Northrup-King
Northrup-King
Northrup-King
Northrup-King

Keystone
Ferry-Morse
Ferry-Morse
Keystone
Northrup-King
Keystone
Sakata
Sakata
Sakata
Sakata
Sakata
Sakata
UW
UW


Identi-
fication
or Lot
Number


1934
170/68
177/58
Q--

6177ME

9477
10820-11613
11659
9478
180/02
9479
6220
6588
6610
7068
1955
2505
1967
25-812A


Days
After
Trans-
plant


114
120
94
133
121

114
121
114
114
122
121
114
114
120
133
120
114
120
114


%
Heads
Ready


90
95
95
95
74
100
95
94
87
96
97
98
97
97
98
99
99
95
97


Average
Yield


50 lb
units/
acre


872
1140
721
1386
654

907
907
1043
757
1395
1038
1117
967
1112
1365
1130
1145
1095
1092


Wt/
Head
lbs


No.
Heads/ Leaf


50 lb


2.8
3.4
2.2
4.2
2.5
2.6
2.8
3.2
2.5
4.2
3.1
3.3
2.9
3.3
4.0
3.3
3.3
3.3
3.2


Color
(2)

I
BG
I
I
BG
G
BG
I
G
BG
BG
YG
YG
YG
I
BG
I
I
I


Black Speck
Rating
Head 1968 Holding
Shape 1966 1967 1 2 quality
(3) (4) (5)

S 2.1 1.2 -- 0.7 Good
R -- -- 0.4 Good
SR -- -- 0.5 Poor
SR -- -- 0.7 Good
R 1.6 2.2 3.2 0.2 Good
SR -- -- 0.7 Fair
S -- 0.1 1.1 0.0 Good
R -- 0.6 2.7 0.4 Exclt.
F -- -- -- 0.0 Good
SR -- 0.2 0.8 0.1 Good
F -- -- 0.05 Good
F -- -- 0.5 Poor
SR -- -- 0.4 Fair
SR -- -- 0.2 Good
SR -- -- 0.7 Good
F -- -- 1.1 Fair
F -- -- 1.3 Poor
S 0.8 1.4 -- 1.1 Good
S 0.8 1.4 -- 0.7 Good


-- -- -- -






Table 2. Cont'd.


First Harvest Data


Average
Yield


Wt/
Head
lbs


No.
Heads/
50 lb


Leaf Head
Color Shape
(2) (3)


Black Speck
Rating
1968
1966 1967 1 2
(4)


Hybelle
Globelle
Hybrid 18
Hybrid 21
BI4 x Globelle
Badger Belle
Hybrid 18

Badger Inbred 10
Badger Inbred 10
Pack Rite
Badger Blueboy
Hybrid 21
Head Start
Globe 62M
TBR Globe
Early Glory 215
Marion Market
Badger Belle
Resistant Danish
W5


UW
Uw
SRS-Niagara
SRS-Niagara
UW
UW
Sakata

UW
U1w
Sakata
Asgrow
Sakata
Asgrow
Asgrow
Northrup-King
Asgrow
Asgrow
Asgrow

J. Harris


Hybrid 15 UW


25-973A
3565R
6311-7495
6313-7531
25-967A
BI-12
1695

25-45S
25-46S
6607
90505
8921
27008A
30502A1
183/L50
10500
50501
S90504

1946
1967


120
114
133
114
114
133
114

114
114
94
120
120
120
133
120
114
114
114


1147
704
1232
873
413
677
778
467
565
652
772
908
612
1180
787
714
768
562


133 92
114 88


3. 1. 25-- 1,0-~


3.4
2.7
3.9
2.8
3.0
2.3
2.4

2.0
1.8
2.1
2.9
2.8
2.3
3.6
3.1
2.6
2.8
2.3


1.5 2.5 -- 1.0
1.6 2.2 3.2 0.5
-- 0.0 0.0 0.0
-- 0.0 0.0 0.0
- -- 0.3
4.7 4.8 -- 4.3
-- 1.4 0.0
-- -- -- 0.6
--- -- 0.6
---- 1. 0.4

1.3 1.4 -- 1.5
-- 0.2 0.0
--- -- 0.2
1.2 -- 0.4 0.9
0.6 0.8 2.2 0.7
1.6 1.8 -- 0.7
1.7 0.5 1.1 0.3
4.7 4.8 -- 5.0


1092 3.4 15
-- 2.7 19


Good
Good
Fair
Poor
Exclt.
Good
Fair
Poor
Poor
Pcor
Fair
Peor
Poor
Fair
Fair
FGir
Good
Fair


0.3 1.4 -- o,1 Exclt.
- -- 0.5 No reading


Variety


Seed
Source
(1)


Identi-
fication
or Lot
Number


Days
After
Trans-
plant


CAo
Heads
Ready


50 lb
units/
acre


Holding
quality
(5)


-II -








- 8 -


(1) Seed Sources Asgrow Seed Co., Orange, Conn.; Clemson TCES, W. C. Barnes,
Truck Crop Experiment Station, Clemson Univ., Charleston, S. C.; Cornell -
M. H. Dickson, Dept. of Vegetable Crops, Cornell Univ., Ithaca, N. Y.; Ferry-
Morse Seed Co., Inc., Moreton Farms, Rochester, N. Y.; Keystone Seeds, Corneli
Seed Co., 101 Chouteau Ave., St. Louis, Mo.; Northrup King & Co., 1500 Jackson
St., N. E. Minneapolis, Minn.; T. Sakata & Co., P. O. Box Kanagawa No. 11,
Yokohama, Japan; SRS Seeds, FMC Corp., Niagara Chemical Division, Modesto,
Calif.; Takii & Co. Ltd. P. 0. Box 7, Kyoto, Japan; University of Wisconsin,
P. H. Williams, Dept. Plant Pathology, Madison, Wisconsin.

(2) Leaf Color BG = Blue-Green; G = Green; YG = Yellow-Green; I = Intermediate
between YG and BG; Var = Variable.

(3) Head Shape F = Flattened; R = Round; S = Spherical; SR = Semi-round;
Var = Variable.

(4) Black Speck Rating Incidence of black speck on 20 heads, 5 from each
replicate, were recorded after 2 weeks of storage at 40C. Ratings were
0 = none to 5 = very severe extending to center of head.
1966 and 1967 are results from previous years. 1968-1 = Variety Trial No. 1
(early) and 1968-2 = Variety Trial No. 2 (late).

(5) Holding Quality Evaluation of line for freedom from bursting at two weeks
after first harvest. Rated Poor, Fair, Good, Excellent.




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