Group Title: CFREC-Apopka research report - Central Florida Research and Education Center-Apopka ; RH-91-3
Title: Control of some fungal diseases of ornamentals with Agribrom
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Permanent Link: http://ufdc.ufl.edu/UF00065851/00001
 Material Information
Title: Control of some fungal diseases of ornamentals with Agribrom
Series Title: CFREC-Apopka research report
Physical Description: 3 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: 1991
 Subjects
Subject: Plants, Ornamental -- Diseases and pests -- Control -- Florida   ( lcsh )
Fungal diseases of plants -- 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.
 Record Information
Bibliographic ID: UF00065851
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70287573

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0 H Control of Some Fungal Diseases of Ornamentals with Agribroml

A. R. Chase1 Marston Science
Library
University of Florida, IFAS SEP 3
Central Florida Research and Education Center Apopka994
CFREC-Apopa Research Report, RH-91-3 Univers of Florida

Fungal diseases cause substantial losses in many floral, foliage and landscape crops.
Losses may occur during any stage of production from rooting of cuttings to finishing the crop.
Currently available fungicides have different levels of efficacy depending on each type of
pathogen. In addition, considerations of labeling and phytotoxicity limit use of some of these
products. Use of fungicides during the rooting process is not always successful due to the
excessive amounts of foliar wetting needed during this time. A compound which can be added
to the irrigation water which would restrict development of plant pathogens would be beneficial.
Agribrom (Great Lakes Chemical Corp., West Lafayette, IN 47906) has been labeled for water
treatment as an algicide for several years (5). Although some claims have been made regarding
its effectiveness in controlling both fungal and bacterial diseases, little data have been developed
in this area (1,2,3,4). The following research was conducted to partially evaluate its potential
for fungal disease control on eleven different ornamental crops under a mist system.

Two benches in a fiberglass-covered greenhouse were used for all tests. One bench
received the Agribrom treatment while the other bench served as the nontreated control. An
Agribrom stock solution was prepared every three or four days by adding 10 g of the powder
per gallon of hot tap water and placing on a hot plate until completely dissolved (usually 1
hour). The stock was then stored in a holding tank shielded from light exposure and added to
the mist system by a Dosatron proportioner (Dosatron International, Inc. Clearwater, FL 34615)
set at 4% which diluted the solution delivered to the leaf surface to about 50 to 60 ppm. The
mist system operated for 35 sec every half hour for 12 hours per day. This treatment was
started three days prior to inoculation and continued until test completion (up to one month).

Plants were obtained as seedlings or were rooted from cuttings. They were grown in
Vergro potting medium usually in a 4-inch pot until they were well established. Fertilizer was
applied once at planting at 1.5 g/pot of Sierra 17-6-12 controlled-release fertilizer (Grace-Sierra,
Milpitas, CA 95035). A minimum of 10 plants was used for each of the following treatments:
1) noninoculated control, 2) inoculated control, 3) noninoculated Agribrom treated, and 4)
inoculated Agribrom treated.

Inocula were grown for various periods of time on potato dextrose agar'medium and
adjusted to concentrations between 1 x 104 and 1 x 106 depending upon the pathogen and disease
pressure desired. Plants were removed from mist, inoculated by spraying to drip with a conidial
suspension and returned 2 hours later. Disease severity was determined after 2 days to 4 weeks


'Professor of Plant Pathology, University of Florida, IFAS, Central Florida Research and
Education Center-Apopka, 2807 Binion Road, Apopka, FL 32703.






according to its development and was reflected by the number of lesions per plant or the
percentage of the foliage or flowers with symptoms. The plants and pathogens included are
listed in Table 1.

Varying degrees of disease control were achieved with the Agribrom treatment (Table
1). Control ranged from 71 to 93% for the majority of the leaf spotting fungi (Alternaria,
Corynespora, Drechslera, and Fusarium leaf spots). In addition, Rhizoctonia petiole rot of
pothos (E. aureum) and Rhizoctonia aerial blight of Boston fern (N. exaltata) were controlled
88 and 93%,, respectively. Botrytis blight of flowers on geranium (P. hortorum) and leaves on
African violet (S. ionantha) showed some control but could not be expected to control disease
significantly on all affected portions of these plants (Table 1). Although Myrothecium petiole
rot was not controlled on nephthytis (S. podophyllum), Myrothecium leaf spot of creeping fig
(F. pumila) showed significant reduction when treated with Agribrom (Table 1).

Phytotoxicity occurred on several plants during these trials and during similar trials with
Agribrom to evaluate bacterial disease control. A summary of the plants affected and the
symptoms which developed as a result of Agribrom treatment, presumably due to bromine
toxicity, are given in Table 2. Earlier work showed that while 50-60 ppm of bromine could
cause severe phytotoxicity on some crops, a reduced rate of 25 ppm was apparently safe (1).

Agribrom shows good activity against a number of important fungal and bacterial
pathogens (1) of ornamentals. Although its use in mist systems seems warranted, one cannot
expand this efficacy to weekly or even daily foliar sprays. Previous research has indicated that
bromine should be available on the leaf surface almost continually to afford maximum control
of plant pathogens.

Literature Cited

1. Chase, A.R. 1990. Control of some bacterial diseases of ornamentals with Agribrom.
Proc. of the Fla. State Hort. Soc. 103: (In Press)

2. Chase, A.R. 1988. Controlling cutting rot of marble queen pothos. CFREC-Apopka
Research Report, RH-88-4.

3. Nishijima, W. 1990. Chemical control, pp. 39-40 In. Proceedings of the Third
Anthurium Blight Conference. A. Alvarez, editor.

4. Powell, C.C. and S. Ashley Smith. 1989. The use of Agribrom on Cyclamen. Ohio
Florists' Assn. Bull. No. 716. pp 1-3.

5. Rickard, D.A. and H.K. Tayama. 1990. Bring algae down and plug profits up with
Agribrom. Grower Talks 54(8):82, 84, and 89.








Table 1. Efficacy of Agribrom at 50 60 ppm bromine on some fungal diseases
of ornamentals.


Scientific name
Aeschynanthus pulcher
Brassaia actinophylla
Dracaena marginata
Epipremnum aureum
Ficus pumila
Maranta leuconeura
Nephrolepis exaltata
Pelargonium hortorun

Polyscias fruticosa
Saintpaulia ionantha


Common name


lipstick vine
schefflera
red-edge dracaena
pothos
creeping fig
prayer plant
Boston fern
geranium

parsley aralia
African violet


Syngonium podophyllum nephthytis
'Phytotoxicity occurred on these plants (see Table 2


Pathogen


Corynespora cassiicola
Alternaria panax
Fusarium moniliforme
Rhizoctonia solani
Myrothecium roridum
Drechslera setariae
Rhizoctonia solani
Botrytis cinerea

Alternaria panax
Botrytis cinerea

Myrothecium roridum


Percent
control
93"
82
80Y
88
77
71
93
15 (flowers)
3 (leaves)
90
60 (flowers)'
0 (leaves)
0


for symptom descriptions).


Table 2. Phytotoxicity response of some ornamentals to 50 60 ppm bromine.


Scientific name Common name


Aeschynanthus pulcher

Dracaena marginata
Ficus benjamin
Hedera helix
Hibiscus rosa-sinensis

Saintpaulia ionantha
Schlumbergera truncata


lipstick vine

red-edge dracaena
weeping fig
English ivy
hibiscus

African violet
holiday cactus


Phytotoxic symptom response
distortion of immature leaves and
abscission with severe necrosis
chlorotic tip burn on older leaves
chlorotic etching on immature leaves
chlorotic etching on immature leaves
chlorotic etching on immature leaves
and stunting of cutting growth
white spots on flowers
white spots on flowers




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