| Material Information
||Suggestions for chemical control of Areca palm leaf spot
||2 p. : ; 28 cm.
||Chase, A. R ( Ann Renee )
Poole, R. T ( Richard Turk )
Agricultural Research Center (Apopka, Fla.)
||University of Florida, IFAS, Agricultural Research Center-Apopka
||Place of Publication:
||Areca -- Diseases and pests -- Control -- Florida ( lcsh )
Palms -- Diseases and pests -- Control -- Florida ( lcsh )
Leaf spots -- Control -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||A.R. Chase and R.T. Poole.
||ARC-A research report ;
|Table of Contents
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not reflect current scientific knowledge
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Copyright 2005, Board of Trustees, University
SUGGESTIONS FOR CHEMICAL CONTROL OF ARECA PALM LEAF SPOT.
A. R. Chase and R. T. Poole
University of Florida, IFAS
Agricultural Research Center-Apopka
Research Report RH-1982-24
Controlling Areca palm leaf spot is a continuing problem for many
growers producing plants under shadehouse conditions or with overhead
irrigations. There are several fungi which cause leaf spot of palms,
including Bipolaris setariae, Exserohilum rostratum, and the less common
Phaeotrichoconis crotalariae. Although these are distinctly different
pathogens, the symptoms they cause and the control measures required are
essentially the same. Two efficacy trials are reported here using various
chemicals available for use on some foliage plants.
The first test was performed in a greenhouse on Chrysalidocarpus
lutescens planted in 6" pots. The plants were free of symptoms initially.
The chemicals used included: Ornalin 50WP (1.5 and 3.0 lb/100 gal rates)
and Daconil 2787 4.17 F (1.5 lb/100 gal rate). Other treatments included
a noninoculated control and an inoculated control which received no chemical
sprays. The chemicals were applied once prior to inoculating the appropriate
plants with spores of Bipolaris setariae and then six additional times on
weekly intervals. Plants were watered from overhead to insure good disease
development. The degree of disease severity was rated twice, first after
four chemical applications and second after all seven applications. Daconil
provided excellent control at the 1.5 lb/100 gal rate and Ornalin provided
equivalent control at the 3.0 lb/100 gal rate (Table 1). Neither chemical
damaged the plants in any obvious manner.
The second efficacy trial was performed under shadehouse conditions on
plants similar to those used in the first test. In this case the plants were
naturally infected with Exserohilum rostratum during the course of the trial.
The following chemicals and suitable controls were included: Kocide 101 (1.5
lb/100 gal), Manzate 200 (1.5 lb/100 gal), Zineb 75WP (1.5 lb/100 gal) and
Carbamate (ferbam, 1.5 lb/100 gal). Sprays were made on a weekly basis between
6-15-82 and 9-28-82 for a total of 16 applications. Disease severity was rated
on 10-6-82 (Table 2). All fungicides provided good control of this leaf spot
and caused no symptoms of phytotoxicity with the exception of the Kocide. In
this case all the plants treated with Kocide showed symptoms of copper toxicity
similar to those seen on plants sprayed with excessive copper (necrotic areas
in new leaves and severe chlorosis and necrosis of older leaves).
These two tests indicate that many of the fungicides used to control palm
leaf spot at present can be effective even under shadehouse and overhead
irrigation conditions. The key to control of these leaf spot diseases is
eliminating or minimizing overhead watering and rainfall and thus the opportunity
for pathogen development. Use of a conscientious preventative fungicide program
is also quite effective and could include such fungicides as Daconil, Ornalin,
Carbamate, Manzate and Zineb. Since other fungicides are available with similar
Use of trade names does not imply a recommendation of those products over others
with similar active ingredients.
activities, these can be utilized as well. Removal of older leaves with
severe leaf spots is also recommended since they serve as a source of
inoculum for new infection.
As a final note, current studies at the ARC-Apopka have revealed that
microelement toxicity (especially copper) can also cause symptoms of leaf
spot which are indistinguishable from disease symptoms. Always be sure
that it is a disease you are treating and not nutritional imbalance or
Table 1. Control of Areca palm leaf spot caused by Bipolaris setariae.
Treatment Inoculation Disease rating:9-16-82 10-7-82
Water water 1.0 ab 1.0 a
Water spores 2.8 d 2.8 d
(1.5 lb) spores 1.8 bc 1.9 bc
(3.0 lb) spores 1.4 ab 1.6 ab
(1.5 lb) spores 1.2 ab 1.2 a
aA total of 12 plants was used for each treatment with 1 = no disease
to 4 = severe disease.
bNumbers in the same column followed by the same letter were not
statistically significant of 5% level using Duncan's multiple range test.
Table 2. Control of Areca palm leaf spot caused by Exserohilum rostratum
in a shadehouse.
Treatment Disease rating Quality rating
Water 2.4 bc 3.6 bc
(1.5 lb) 1.3 a 3.5 bc
Kocide (1.5 lb) 1.8 a 3.0 ab
(1.5 Ib) 1.2 a 3.5 bc
(1.5 lb) 1.4 a 4.0 c
aDisease rating was made for 5 plants per treatment with 1 = no disease and
4 = severe disease.
bQuality rating was made on a scale of 1 = poor, to 4 = good plant- salable.
CNumbers in the same column followed by the same letter were not statistically
different using Duncan's multiple range test at 5%.