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Group Title: AREC-Apopka research report - Agricultural Research and Education Center - RH-84-13
Title: Alternaria leaf spot control with chemicals
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Permanent Link: http://ufdc.ufl.edu/UF00066559/00001
 Material Information
Title: Alternaria leaf spot control with chemicals
Series Title: AREC-Apopka research report
Physical Description: 4 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Agricultural Research and Education Center (Apopka, Fla.)
Publisher: University of Florida, Agricultural Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1984
 Subjects
Subject: Alternaria diseases -- Control -- Florida   ( lcsh )
Foliage plants -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 2).
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00066559
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 71324720

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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








ALTERNARIA LEAF SPOT CONTROL WITH CHEMICALS


A. R. Chase HU; LIBRARY
Agricultural Research and Educatio Center
University of Florida JAlN i;0,
AREC Apopka Research Report, RH 84-13

ifA Univ. of Florr-.
One of the most important groups of foliage plants produed-itn -Florida
is comprised of members of the Araliaceae family. This group includes
schefflera (Brassaia actinophylla), dwarf schefflera (Schefflera
arboricola), Japanese aralia (Fatsia japonica), tree ivy (Fatshedera sp.),
false aralia (Dizygotheca elegantissima) and many species of aralia
(Polyscias spp.). The most common disease of this group is a leaf spot
caused by Alternaria panax which was originally described on the
schefflera, but is now known to occur on all of the members of this group
of foliage plants.

Control of Alternaria leaf spot has been difficult on certain members
of this plant group due to their sensitivity to many pesticides.
Nevertheless, many fungicides are effective in controlling Alternaria leaf
spot and several are registered for use on schefflera and a few for use on
same of the other crops. Table 1 is a brief summary of research
information regarding the fungicides used to control Alternaria leaf spot
on scheffleras and their relatives. The table attempts to review published
information on the efficacy, phytotoxicity and registration status of many
fungicides which can be used to control Alternaria leaf spot. In some
cases, the efficacy or phytotoxicity information is unknown, but if the
fungicide is registered for use on a crop it may be assumed that it is
efficaceous and normally safe.

In an attempt to further establish the efficacy of some of these
chemicals, several experiments were conducted on Alternaria leaf spot
disease. The first experiment was conducted using Fatsia japonica as the
host and several rates of Daconil 4.17 F (chlorothalonil). Plants were
sprayed once with the treatments and then inoculated three days later with
spores of the pathogen, Alternaria panax. Retreatment of the plants
occurred on a weekly basis for a total of four applications. Plants were
evaluated twice during the experiment for disease severity (Table 2). At
the first rating, about ten days after inoculation, only the highest rate
of Daconil provided excellent control of the leaf spot. However, all three
rates proved excellent in leaf spot control by the end of the test. No
signs of phytotoxicity were noted during the test.

The second experiment was conducted three separate times using
scheffleras and several fungicides. The fungicides were applied once three
days before inoculation of the plants with spores of Alternaria panax, and
plants were rated for disease severity one week later. In each test, all
of the fungicides provided excellent control of Alternaria leaf spot of
schefflera (Table 3). Since the duration of the tests were so short, no
real evaluation of the phytotoxicity could be made. Certainly, the plants
developed no symptoms in the ten days of the test, but phytotoxicity such
as stunting or distortion of new growth cannot be evaluated in ten days.








There appear to be many fungicides which are both labelled for use on
members of the Araliaceae family and can control Alternaria leaf spot of
these plants. Choosing the best fungicide for each crop should be based on
registration, efficacy, and phytotoxicity information since these factors
vary greatly from one plant genus to another.


REFERENCES

1. Chase, A. R. 1983. Phytotoxicity of some fungicides used on tropical
foliage plants. Florida Nurseryman 30(5):26-27,47.
2. Simone, G. W. and A. R. Chase. 1984. Disease control pesticides for
foliage production. Florida Foliage 10(4):28-37.


Mention of a product name in this report is not meant as either an
endorsement or a recommendation of that product by the author or the
University of Florida.








Table 1. Registration, efficacy and phytotoxicity of some fungicides for
control of Alternaria leaf spot of schefflera and related plants.


Host Fungicide Registrationa Efficacyb Phytotoxicity

Aralia Kocide 101 yes unknown unknown
Zyban 75 WP yes yes safe

Brassaia Chipco 26019 yes (but not for yes variable
(schefflera) Alternaria) safety
Daconil 4.17 F no yes unsafe
Manzate 200 yes yes safe
Zineb 75 WP no yes safe
Zyban 75 WP yes yes safe

Dizygotheca Chipco 26019 yes (but not for unknown safe
Alternaria)
Daconil 4.17 F no unknown safe

Fatsia Daconil 4.17 F no yes safe
Zyban 75 WP yes unknown unknown

aIf a fungicide is registered for use on the plant, it is generally safe to
assume that it can be safely used on that crop.
bA fungicide which controls a leaf spot disease on one crop generally
provides similar control of the same disease on another crop.



Table 2. Efficacy of Daconil 4.17 F in controlling Alternaria leaf spot of
Fatsia japonica (Japanese aralia).


Rate Severity ratinga Number lesions
Treatment (pint/100 gal) 4-13-84 4-26-84

Noninoculated
control 1.1 a 0.0 a

Inoculated
control -- 4.1 c 51.7 b

Daconil 4.17 F 2 1.9 b 6.9 a
Daconil 4.17 F 4 1.8 b 1.1 a
Daconil 4.17 F 8 1.2 a 0.1 a

aDisease severity was rated as follows: 1 = no lesions, 2 = 1-10 lesions,
3 = 11-25 lesions, 4 = 26-50 lesions, and 5 = 51 or more lesions with
some distortion due to coalescing.








Table 3. Efficacy of fungicides in controlling Alternaria leaf spot of
schefflera (Brassaia actinophylla).


Rate Severity ratinga

Treatment (lb/100 gal) Test 1 Test 2 Test 3

Noninoculated
control -- 1.0 a 1.1 a 1.1 a

Inoculated
control -- 3.3 b 2.6 b 2.7 b

Manzate 200 1.5 1.2 a 1.0 a 1.0 a

Zyban 75WP 1.5 1.1 a 1.0 a 1.0 a

Carbamate 75WP 1.5 1.0 a 1.0 a 1.1 a

Chipco 26019 0.5 1.2 a 1.0 a 1.2 a

aDisease severity was rated as follows: 1 = no lesions, 2 = 1-10 lesions,
3 = 11-25 lesions, and 4 = 26 or more lesions.


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