Group Title: CFREC-Apopka research report - Central Florida Research and Education Center-Apopka ; RH-88-4
Title: Controlling Erwinia cutting rot of Marble Queen pothos
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Permanent Link: http://ufdc.ufl.edu/UF00065967/00001
 Material Information
Title: Controlling Erwinia cutting rot of Marble Queen pothos
Series Title: CFREC-Apopka research report
Physical Description: 5 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Central Florida Research and Education Center--Apopka
Publisher: University of Florida, IFAS, Central Florida Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1988
 Subjects
Subject: Plants -- Diseases and pests -- Control -- Florida   ( lcsh )
Bacterial diseases of plants -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065967
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70950522

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-" Controlling Erwinia Cutting Rot of Marble Queen Pothos

A. R. Chase1
Central Science University of Florida, IFAS
Library Central Florida Research and Education Center Apopka
CFREC-Apopka Research Report, RH-88-4
*MAR 9 1E'
SSamples of diseased Marble Queen pothos cuttings examined over the
UniversitypattlF yars were found to be infected with either Erwinia carotovora pv.
--..carotovora or E. chrysanthemi, two closely related bacterial pathogens.
Symptoms included wet and mushy leaf and petiole lesions. When the leaves
were allowed to dry, the lesions also dried and were not as typical in
appearance as the wet phase of this disease. The goals of this study were
1) identify potential compounds for control of Erwinia during shipping, 2)
determine rate of use of these compounds, 3) determine effects of dipping
time on efficacy of these compounds, and 4) determine effects of
temperature on efficacy of the dip treatments. Inoculation of healthy
plants with isolates of both E. carotovora pv. carotovora and E.
chrysanthemi allowed us to choose the most virulent isolate for further
study. Cuttings of Marble Queen were obtained from local producers and
used for all experiments described below. All tests were performed by
immersing cuttings in a chemical-water mixture for 15 minutes. Cuttings
were then stuck in flats containing Vergro potting medium and watered in.
Twenty-four cuttings were used in each treatment. Following watering in,
* cuttings were inoculated by spraying lightly a suspension of E.
chrysanthemi over the leaf surface. Flats were then placed under
intermittent mist and evaluated after 3 to 7 days for signs of cutting rot.
All data are presented as the number of rotted cuttings (total of 24
possible). Tests were repeated.
Potential compounds for controlling Erwinia on Marble Queen cuttings -

A series of tests were performed to identify potential compounds for
controlling Erwinia cutting rot using a dip treatment. Initial testing
during the winter months indicated that Agri-Brom could provide good
control of this disease (Table 1), but under summer testing the compound
failed to provide control of this disease (Table 2). Kocide failed to give
good control in this test when used alone but gave excellent control when
used with Manzate 200 (Table 1).

A second general experiment evaluated efficacy of Cyprex, Kocide,
Captan, and Aliette. In this test, none of the compounds gave any disease
reduction with the exception of Kocide applied at 2.25 g/gallon (Table 3).

The last compound tested was Abcure benzoyll peroxide). This compound
previously demonstrated good activity against the citrus canker bacterium

1Associate Professor of Plant Pathology, Central Florida Research and
Education Center, 2807 Binion Road, Apopka, FL 32703.
This research was paid for in part by a grant from Horticultural
Enterprises. Special thanks to Green Mansion for supplying plant material
A for this work.











when tested in the laboratory. In this study, control of Erwinia cutting
rot was not achieved with any of the rates tested (Table 4).
Rates of compounds to use -

The compounds which gave the best control, Agri-Strep and Kocide, were
included in additional tests to evaluate rates of use. Rates of 2.25, 4.5,
and 9.0 were compared. All rates of both compounds gave good disease
control (Table 5).

The use of Manzate with Kocide has been recommended for bacterial
control for many years. The next test was performed to evaluate the
benefit of mixing the two compounds in different ratios. All combinations
of these compounds gave excellent disease control in two trials (Table 6).
Effect of dip time on efficacy of Kocide -

The effect of dip time on the efficacy of Kocide 101 at the rate of
4.5 g/gal was tested. A five minute dip in a 72F solution was sufficient
to control Erwinia cutting rot on Marble Queen pothos (Table 7).
Effect of dip temperature on efficacy of Kocide -

Temperatures between 60 and 860F were tested. In this range efficacy
of Kocide was unaffected (Table 8).
Conclusions -

Optimal control of Erwinia cutting rot of Marble Queen pothos can be
achieved as follows.

1. Use Kocide 101 77WP or Agri-Strep 21% at rates between 2.25 and 4.5
g/gallon. If resistance is suspected Manzate 200 (2.25 g/gallon)
can be used in conjunction with Kocide 101 at the same rate.

2. Dip cuttings for 5 to 15 minutes depending upon time of year and
presence of Erwinia on stock plants.

3. Keep dip mixture temperature between 60 and 860F.


-2-









Table 1.

Treatment


g per gallon


No. rotted cuttings/24


Noninoculated control -- 1
Inoculated control -- 10
Agri-Strep 21% 4.5 3
Kocide 101 77WP 4.5 8
Kocide 101 77WP 4.5
and Manzate 200 75WP 4.5 1
Agri-Brom* 0.01 0
Agri-Brom 0.02 1
Agri-Brom 0.03 5
Agri-Brom 0.04 1

*Agri-Brom was applied as the active ingredient of the commercial
compound.


Table 2.

No. rotted cuttings/24
Treatment g per gallon Test 1 Test 2

Noninoculated control -- 1 0
Inoculated control -- 7 7
Agri-Brom* 0.01 9 7
Agri-Brom 0.02 8 8
Agri-Brom 0.03 14 3
Agri-Brom 0.04 10 5
Agri-Brom 0.05 17 3
Agri-Brom 0.06 10 5

*Agri-Brom was applied as the active ingredient of the commerical
compounds.



Table 3.

Treatment g per gallon No. rotted cuttings/24

Noninoculated control -- 0
Inoculated control -- 24
Cyprex 65 WP 2.25 24
Kocide 101 77WP 2.25 13
Captan 50WP 2.25 24
Aliette 80WP 2.25 24
Aliette 80WP 4.50 23
Aliette 80WP 9.00 19


-3-









Table 4.


Treatment


ml per gallon


No. rotted cuttings/24
Test 1 Test 2


Noninoculated control -- 0 0
Inoculated control -- 4 15
Abcure 10 7 13
Abcure 20 4 7
Abcure 30 3 12
Abcure 40 4 18
Abcure 50 16 16
Abcure 60 3 12




Table 5.

Treatment g per gallon No. rotted cuttings/24

Noninoculated control -- 0
Inoculated control -- 10
Agri-Strep 2.25 1
Agri-Strep 4.5 4
Agri-Strep 9.0 1
Kocide 101 2.25 2
Kocide 101 4.5 2
Kocide 101 9.0 0



Table 6.

Treatment No. rotted cuttings/24
g/gal Test 1 Test 2

Noninoculated control -- 0 0
Inoculated control -- 11 10
Kocide 2.25 and Manzate 2.25 2 2
Kocide 2.25 and Manzate 4.5 0 1
Kocide 4.5 and Manzate 2.25 2 2
Kocide 4.5 and Manzate 4.5 1 3
Kocide 4.5 and Manzate 9.0 0 1
Kocide 9.0 and Manzate 4.5 2 2
Kocide 9.0 and Manzate 9.0 0 1


-4-











Table 7.

Treatment


Noninoculated control 30 min 0
Inoculated control 30 min 16
Kocide* 5 min 1
Kocide 10 min 0
Kocide 15 min 2
Kocide 20 min 0
Kocide 25 min 0
Kocide 30 min 0

*Kocide was applied at the rate of 4.5 g/gal in all treatments.



Table 8.


No. rotted cuttings/24


Solution
temperature OF


Treatment


No. rotted cutting/24


Noninoculated control 86 0
Inoculated control 86 17
Kocide* 86 0
Kocide 77 0
Kocide 68 1
Kocide 60 2

*Kocide was applied at the rate of 4.5 g/gal in all treatments.


-5-


Time of dip












4




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