Title: Results of 1972-73 blackrot inoculation study
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 Material Information
Title: Results of 1972-73 blackrot inoculation study
Physical Description: Book
Creator: Weingartner, David Peter,
Publisher: Agricultural Research Center,
Copyright Date: 1973
 Record Information
Bibliographic ID: UF00076348
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: 144719374 - OCLC

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SHUME I BRARY

AGRICULTURAL RESEARCH CE T1 O qQ
IOCT 2 9 1913
T ASTI7GS, FLORIDA

1imeo Research Report PR-1973Xa Octob 1973
,v. of Florida
RESULTS OF 1972-73 BLACKROT INOCULATICf 'STU-DYT----- -...
D. P. Weingartner, Asst. Plant Pathologist
J. R. Shumnaker, Assoc. Horticulturist

INTPODUCTION: Blackrot is currently the most important disease problem on cabbage
grown in Florida and probably the U. S. Efforts are being made across the country
to effectively control the disease. The nost promising method for controlling
blackrot is disease resistance. Recently Dr. Paul 'illiass, University of Wisconsin,
determined how resistance is inherited in cabbage. Currently, seed companies are
attempting to incorporate resistance to blackrot into their new varieties. It will
be several years, however, before such resistance is available in commercial varie-
ties adapted to Florida's growing conditions.

During the past several years, differences in tolerance of commercially available
cabbage varieties to blackrot have been observed. All connercial varieties are
susceptible to the disease, however, symptoms in some cultivars do not progress
so rapidly as in varieties such as ilarket Prize.

During the 1972-73 cabbage season, an experiment was performed to test tolerance
of 23 cabbage varieties to blackrot. All varieties were transplanted in four
replications December 11, 1972.

A single isolate of blackrot bacteria obtained from Fastings area cabbage was
grown in laboratory cultures. During late February, when cabbage was forming~ heads,
several quarts of 72 hour cultures of bacteria were added to 20 gallons of water in
a weed sprayer. The bacterial suspension was sprayed over the entire bed, at
a rate of 40 GPA, during a light rain which lasted for several hours. One week
later, the cabbage were sprayed with bacteria during the eveninC when dew was
forming on the plants. Severity of blackrot was rated 107 (3/28/73), 113 (4/3/73)
and 133 (4/23/73) days after transplanting.

Significant differences in blackrot severity (Table 1) vere observed on all three
dates. Although cabbages were not harvested, ratings made on 4/3/73 best represent
severity at hypothetical harvest.

The speciality varidy Savoy King, illustrated tolerance to the disease on all
three dates. Red Iead hybrid was moderately affected.

Varieties suited for general commercial use which were significantly less affected
than TMarket Prize on 4/23 were: Atlas No. 70, Saf-Gard To. 18, Rio Verde, A & C
No. 5, Sentinel To. 19 and Greenboy. Varieties illustrating tolerance on 4/3 in-
cluded: Rio Verde, Sentinel No. 19, Hybrid 15, Greenboy, and Blue Chip.

Cultural characteristics of several blackrot tolerant varieties which have been
tested for several years at Hastings are surmaarized and compared to Market
Prize in Table 2. These cultivars may provide substitutes for highly susceptible
varieties until genetic resistance is available in commercial varieties more
suited to Hastings growing conditions.


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Table 1. Differences in varietal susceptibility to blackrot.
1973 inoculation experiment.


Results of


Blackrot Rating I/

Variety
3/28 (107d) 4/3 (113 d) 4/23 (133 d)

Atlas No. 70 1.8* 3.8* 4.3*
Savoy King 2.0* 5.0* 5.0*
Saf-Gard No. 18 2.3* 4.3" 5.3*
Rio Verde 2.5* 5.3 6.0"
A & C No. 1400 2.5* 4.3* 6.3*
Sentinel No. 19 3.5 5.8 6.5*
Greenboy 3.5 6.3 6.5*
A & C No. 5 3.5 6.8 7.0
Blue Chio 4.0 6.5 7.3
Red Head Hybrid 1.5* 5.3 7.3
Hybrid 15 2.5* 4.8 7.5
Stonehead 3.8 6.8 8.3
!Market Topper 3.3 6.8 8.3
Harvester Queen 4.3 7.3 8.5
King Cole 5.7 8.7 8.7
Market Prize 4.5 7.5 8.8
Round Up 5.0 9.0 8.8
Gourmet 5.8 8.3 9.3
Greenback 4.8 7.8 9.5
Superette 4.3 7.8 9.5
Prime Pak 6.3 9.5 10.0
Banner 5.3 7.8 10.0


LSD .01 2.3 3.3 3.0
LSD .05 1.8 2.5 2.3


1/ Rated on 1-11 scale with 1 = no disease and 11 = all heads severely
lesioned and non-marketable. Number of days between transplant and
date of rating are indicated in parentheses. Indicates varieties
significantly (P = 0.05) less affected than Market Prize.













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Table 2. Comparison of varietal characteristics in five blackrot "tolerant" varieties to those of Market Prize.l/


Blackrot3/
Rating


Yield
(CTt/A)


Average
dead WTt.


Qualitye/r

External Internal Uniformity&/


Days From
Transplant
To Harvest


Atlas To. 70 TS 4.3 242 2.2 3.8 2.4 3.5 104
Saf-Gare o. 18 TS 5.3 247 2.5 4.0 3.0 3.4 114
Rio Verse 6.0 307 2.6 4.3 3.1 3.7 114
Sentinel no. i; TS 6.5 247 2.9 4.0 3.4 3. 114
Greenboy NE 6.5 284 2.8 3.8 3.7 3.6 114

Market Prize JH 8.8 215 2.2 4.0 4.4 3.8 114


1/ Blackrot ratiigr one year's data; yield, average head weight and days from transplant to harvest are average of
three year's (1969-1970, 1970-1971 and 1971-1972) data; quality and uniformity based on twro year's (1970-1971
and 1971-1972) data.

2/ TS T. SahatE (Herbst Eros.); FK Northup King; JF Joseph Harris.

3/ Blachrot ratirfs: 1 = no disease and 11 = all plants severely lesioned and non-marketable; External quality
associated with appearance of wrapper and top leaves; Internal quality associated with core size, head composi-
tion, etc.; Uniformity associated with inbreds and genexpl off-types in each population. All quality and unifor-
mity rated 1 = poor and 5 = desirable.


Variety


Seed
Source




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