| Material Information
||Fertilizer level does not affect severity of Helminthosporium leaf spot of Calatheas
||AREC-Apopka research report
||2 p. : ; 28 cm.
||Chase, A. R ( Ann Renee )
Agricultural Research and Education Center (Apopka, Fla.)
||University of Florida, IFAS, Agricultural Research and Education Center-Apopka
||Place of Publication:
||Calathea -- Diseases and pests -- Control -- Florida ( lcsh )
Leaf spots -- Control -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
bibliography ( marcgt )
non-fiction ( marcgt )
||Includes bibliographical references (p. 2).
||Statement of Responsibility:
| Record Information
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 70669449
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
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
_-,') I 1
Fertilizer Level Does Not Affect Severity of Helminthosporium
Leaf Spot of Calatheas
A. R. Chase I
University of Florida, IFAS Ce ntral Science
Agricultural Research and Education Center Apopka Library
AREC-Apopka Research Report RH-86-9.
Fertilizer level has been shown to affect the susceptj)i,i;lm of, many
plants to leaf spot diseases. Sometimes increasing fertilizer rdsi1'ttiid
greater disease development while at other times the reverse'-ccurs: he-------
following research was performed to determine the relationship between
fertilizer level and susceptibilityof four Calathea cultivars to leaf spot
caused by Bipolaris setariae (=Helminthosporium setariae and Drechslera
setariae) (3). Previous research with the same pathogen on Areca palms
(Chrysalidocarpus lutescens) showed that disease development was not
affected by fertilizer level (1),..
Rooted divisions of four Calathea species or cultivars were planted in
6" pots using a potting medium consisting of 50% Canadian peat and 50% pine
bark (v/v). After steaming, the medium was amended with 7 lbs dolomite and
1 lb Micromax (micronutrient source) per cubic yard. Ten pots of each
species or cultivar were then top dressed with Osmocote 19:6:12
(slow-release fertilizer) on 25 April (Test 1) or 12 June 1986 (Test 2) at
each of the following rates: 2, 5, 8, 11, and 14 g/6" pot. The recommended
rate for Calathea is approximately 4 g/6" pot (2). Tests were performed in
a shaded glasshouse where plants received a maximum of 1500 ft-c natural
light and temperatures ranged from 70" to 100'F. After 8 weeks, plants
were moved to a bench where they were misted intermittently (5 sec/30 min
for 12 hours/day). After 1 day of misting, they were inoculated with a
conidial suspension of Bipolaris setariae (1 x 10 conidia/ml) by spraying
to runoff and then placed in a plastic bag. The bags were removed after 2
days, and misting continued until the end of the test. The number of leaf
spots per plant was recorded approximately 2 weeks after inoculation.
Calathea argentea, C. argentea cv. Vandenheckei, C. roseo-picta, and C.
makoyana were included in the first test. In the second test, only C.
argentea and C. argentea cv. Vandenheckei were included.
The number of leaf spots was not affected by fertilizer level on any
of the cultivars tested in either test (Table 1). Differences in plant
growth were noted as well as differences in soluble salts levels of pot
leachates, indicating that differences in the plant fertility did occur.
This research on Calatheas supports earlier research on Areca palm which
also showed that fertilizer level did not affect Helminthosporium leaf spot
of that plant.
Associate Professor of Plant Pathology, Agricultural Research and
Education Center, 2807 Binion Road, Apopka, FL 32703.
1. Chase, A. R., and R. T. Poole. 1983. The feasibility of controlling
Areca palm leaf spot by altering host nutrition. Proc. Fla. State
Hort. Soc. 96:278-280.
2. Conover, C. A., and R. T. Poole. 1985. Light and fertilizer
recommendations for production of acclimatized potted foliage plants.
Foliage Digest 7(8):1-6.
3. Simone, G. W., and D. D. Brunk. 1983. New leaf spot disease of
Calathea and Maranta spp. incited by Drechslera setariae. Plant
Table 1. Effect of fertilizer level on number of leaf spots caused by
Bipolaris setariae on Calathea species and cultivars.
Fertilizer level Mean number of leaf spots/10 plants
g Osmocote 19:6:12 argentea 'Vandenheckei roseo-picta makoyana
per 6" potz Test 1 Test 2 Test 1 Test 2 Test I Test I
2 17.4nsy 19.5ns 8.9ns 29.5ns 1.9ns 8.4ns
5 20.1 40.0 10.7 31.0 3.7 10.7
8 5.3 34.5 15.0 35.0 4.8 7.2
11 17.7 38.0 9.5 23.5 1.9 9.4
14 11.2 39.5 11.7 22.0 2.9 8.3
zRecommended rate is approximately 4 g/6" pot.
YNo significant differences among treatments in a column.