Group Title: AREC-Apopka Research Report - Agricultural Research and Education Center - RH-84-20
Title: Effects of light and fertilizer levels on Xanthomonas leaf spot of Scheffleras
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00066552/00001
 Material Information
Title: Effects of light and fertilizer levels on Xanthomonas leaf spot of Scheffleras
Series Title: AREC-Apopka Research Report
Physical Description: 3 p. : ; 28 cm.
Language: English
Creator: Chase, A. R ( Ann Renee )
Agricultural Research and Education Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research and Education Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1984
Subject: Xanthomonas diseases -- Control -- Florida   ( lcsh )
Plants -- Effect of light on -- Florida   ( lcsh )
Plants -- Fertilizers -- Testing -- Florida   ( lcsh )
Leaf spots -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: A.R. Chase.
General Note: Caption title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00066552
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 - 71316686

Table of Contents
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        Page 3
Full Text


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
of Florida


A. L. )i_4 ] l Ir
University of ia, Al
Agricultural Research and Education Center
AREC-Apopka Research Report, RH-84-20

Effects of light or fertilizer levels on severity of diseases have
been studied on several foliage plants including philodendron, dieffenbachia
and peperomia. Controlling bacterial diseases of foliage plants is diffi-
cult, since very few bactericides are both effective and safe. An inte-
grated approach to disease control of bacterial diseases would be desirable
and should include as many factors as possible. The information provided
in this paper relates results of tests on schefflera (Brassaia actinophylla)
infected with Xanthomonas campestris pv. hederae, the cause of a bacterial
leaf spot of scheffleras and related plants.

The effect of host nutrition was tested by growing scheffleras with
different amounts of Osmocote 19-6-12 (slow release fertilizer). A potting
medium consisting of Canadian peat (50%), pine bark (25%) and cypress
shavings (25%) was amended with dolomite and Micromax. The following rates
of Osmocote were added as a top dressing: 2, 4, 6, 8, and 10 g per 4 inch
pot. The recommended rate of fertilizer for this plant is about 2 g every
3 months. Plants were grown in a glasshouse for 4 to 6 weeks with about
1500 ft-c light and temperatures from 65 to 900F. Plant heights were re-
corded when the test was initiated and just prior to inoculation (4 to 6
weeks after initiation) to determine effects of fertilizer treatment on
plant growth. This test was performed twice using ten plants per fertilizer
treatment. Approximately 2 weeks after inoculation, plants were rated for
severity of Xanthomonas leaf spot by estimating percentage of foliage affected.

Fertilizer treatments did not affect height of test plants during the
trial (Table 1). In contrast, increasing fertilizer level decreased percen-
tage of Xanthomonas infection (Table 2). Since increases in fertilizer level
did not result in visible plant damage (color changes, burning, or leaf loss
were not noted), this may be a feasible way to reduce severity of Xanthomonas
leaf spot on this plant.

The effect of preinoculation light level on growth of schefflera and
susceptibility to Xanthomonas was tested in a shadehouse with plants grown
for 6 to 8 weeks under different light levels. The potting medium and pot
size previously described were used. In Test 1, shade levels of 80, 73, 63,
and 47% were used. In Test 2, shade levels were 70, 50 and 30%. Ten plants

1Associate Professor of Plant Pathology, Agricultural Research and Education
Center, 2807 Binion Road, Apopka, FL 32703.

were used per shade treatment in each trial. The tests were both performed
between June and August of 1984 when light intensities reached a yearly
maximum (about 15,000 ft-c in full sun). Air temperatures ranged from 75
to 1000F. As in previous tests, plant heights were recorded at initiation
of the trial as well as just prior to inoculation with Xanthomonas. Pe-
Xanthomonas infection was recorded 2 weeks after inoculation.

In both trials, shade level affected height of plants (Table 3).
plants in Test 1 were obtained under 73 or 80% shade while tallest plants in
Test 2 occurred under 30% shade. Other parameters such as foliage color were
unaffected. Results of these tests for percentage Xanthomonas infection were
confusing (Table 4). In Test 1, the highest percentage infection occurred
for plants grown under 73% shade, while in Test 2, the most severe degree of
disease occurred for plants grown at either 70 or 30%. In the first test,
disease severity decreased when shade level was decreased between 73 and 47%.
In the second trial, disease severity decreased between 70 and 50%, but in-
creased between 50 and 30% shade. These results indicate that more factors
were involved than those which were considered. Further testing of the
phenomenon should be conducted to elucidate the role of light level in
susceptibility of scheffleras to Xanthomonas leaf spot.

Table 1. Effect of fertilizer level on final height
of schefflera (Brassaia actinophylla).

level Average plant height (in)
(g/4" pot) Test 1 Test 2
2 6.6 9.7
4 6.6 10.6
6 6.8 11.3
8 7.1 11.0
10 6.9 10.6

Significance NS NS

Table 2. Effect of fertilizer level on percentage
infection of schefflera (Brassaia actinophylla)
inoculated with Xanthomonas campestris pv. hederae.

level Percentage infection
(g/4" pot) Test 1 Test 2
2 48.8 43.0
4 11.3 23.0
6 3.0 22.0
8 11.5 14.0
10 0.8 19.0

Significance 1% 5%
percentage of plant foliage with symptoms.

Table 3. Effect of shade level on height of schefflera
(Brassaia actinophylla)

Percentage Level Percentage Level
shade height (in) shade height (in)
80 8.7 -70 4.9
73 8.7 50 5.1
63 8.2 30 5.7
47 6.8

Significance 5% 5%

Table 4. Effect of shade level on percentage infection
of schefflera (Brassaia actinophylla) inoculated with
Xanthomonas campestris pv. hederae. (Tests performed
7/11/84 to 9/4/84).

Percentage Percentage Percentage Percentage
shade infection shade infection
80 34.5 70 72.7
73 50.5 50 54.7
63 37.5 30 76.0
47 32.5

Significance 10% 5%
percentage of plant foliage with symptoms.

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