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P 9 -" Effect of nitrogen source on growth and susceptibility of
Anthurium hybrids to Xanthomonas campestris pv. dieffenbachiae
A. R. Chase and R. T. Poole'
University of Florida, IFAS L
Central Florida Research and Education Center Apopka
CFREC-Apopka Research Report, RH-90-20 2 1 1 799
One of the most damaging diseases of Anthuriums worldwide is Xanthomonas blight..
caused by X. campestris pv. dieffenbachiae. This disease has caused losses in the millions in
the Hawaiian cut flower industry and affects production of all types of anthuriums including
those grown as potted plants. This disease is characterized by marginal infections which are
yellow initially, later turning brown and spreading into the centers of the leaves. Flowers
may be affected as well. The bacterium which causes the disease is easily splashed with
overhead irrigation or rainfall and is very difficult to control under any growing system
which includes overhead irrigation. Use of bactericides has proven a poor control method
since many cultivars of the anthurium are sensitive to copper and streptomycin sulfate
compounds. Research during the past few years has shown that while fertilizer level affects
susceptibility of anthurium to this pathogen it also affects flowering and growth of the plant.
The best fertilizer level for growth of the plant, unfortunately, results in the highest
* susceptibility to the pathogen (1, 2). Additional research on the source of nitrogen was
suggested to determine its potential for disease control. Two anthurium hybrids, 'Princess'
and 'Southern Blush', were tested with nitrate and ammonium sources of nitrogen for growth
response and susceptibility to X. campestris pv. dieffenbachiae.
Anthurium plants originally from tissue culture were obtained from commercial
growers. Plants were established in a mixture of Vergro and pine bark (1:1 by volume) and
utilized in tests when they reached about 6 inches tall. Fertilizer was applied once a week
in a liquid form and consisted of 50 ppm nitrogen (from different sources), 25 ppm
potassium (from KC1), and 7 ppm phosphorous (from H3P04). Nitrogen treatments were
as follows: 100% ammonium [(NH4)2SO4], 50% ammonium and 50% nitrate (NH4N03), and
100% nitrate [KNO3, NaNO3, and Ca(N03)2]. Plant ratings included number of leaves, height,
and top quality at test completion. Top quality was rated as follows:1 (dead), 2 (poor,
unsalable), 3 (good, salable), 4 (very good, salable), and 5 (excellent, salable). Plants were
inoculated using standard methods with a suspension of the pathogen and plants were placed
under intermittent mist for about 3 weeks to promote disease development. Disease severity
was rated as the percentage of the foliage with symptoms of blight and/or the number of
1 Professor of Plant Pathology and Environmental Horticulture, respectively. Central
Florida Research and Education Center, 2807 Binion Rd., Apopka, FL 32703.
leaves with symptoms of blight. The first test was conducted with 'Princess' and started on 9
November 1989 with disease ratings on 19 March 1990. The second test included 'Southern Blush'
and 'Princess' and started on 9 April with disease ratings on 13 July 1990.
Nitrate nitrogen resulted in a slight reduction of height for 'Princess' in test 1 but gave a
slight increase in height in test 2 with height of 'Southern Blush' unaffected by nitrogen source
(Tables 1, 2 and 3). Number of leaves was not affected for either anthurium hybrid in these tests
although 100% ammonium resulted in some leaf damage due to chlorosis of lower leaves in the
summer test on 'Princess' (Table 2). Top quality was only affected in test 2 for the 'Princess' and
was slightly better for plants receiving the 100% nitrate source of nitrogen (Table 2). Overall, plant
growth was not consistently or significantly affected by these fertilizer treatments.
The disease response was similar in that fertilizer source did not consistently affect severity
of Xanthomonas blight. In the first test on 'Princess' disease severity was slightly higher for plants
receiving the 100% nitrate fertilizer compared to the 50-50 mixture and the 100% ammonium
source (Table 1).
'Princess' and 'Southern Blush' plants grew equally well when fertilized with 100%
ammonium, 50% ammonium and 50% nitrate, or 100% nitrate nitrogen. Although disease severity
was affected by fertilizer treatment in one of three tests, the response was slight and is apparently
not reliable. Unfortunately, anthurium producers cannot affect severity of Xanthomonas blight by
altering the fertilizer program with respect to either rate or source of nitrogen.
1. Chase, A. R. 1989. Effect of fertilizer rate on growth of Anthurium andraeanum and
susceptibility to Xanthomonas campestris pv. dieffenbachiae. pp. 48-49 In Proc. Second
Anthurium Blight Conference. Hawaii Inst. Trop. Agric. and Hum. Resour. 02-22-89.
2. Chase, A. R., and R. T. Poole. 1986. Effects of nutrition on growth and susceptibility of
Anthurium scherzeranum to Xanthomonas leaf spot. Nurseryman's Digest 20(6)-58-59.
Table 1. Effect of nitrogen source on growth ofAnthurium 'Princess' and severity of Xanthomonas
blight caused by Xanthomonas campestris pv. dieffenbachiae (Test 1).
Treatment No. Height Top quality Percent No.
leaves (in) 20 Feb diseased diseased
14 Feb 14 Feb 19 March leaves
100%Ammonium 24.2 5.0 4.3 4.9 2.3
SSignificance of the F test was denoted as ns (not significant) or (significant at the 1% level).
Table 2. Effect of nitrogen source on growth of Anthurium 'Princess' and severity of Xanthomonas
blight caused by Xanthomonas campestris pv. dieffenbachiae (Test 2).
Treatment No. No. bad Height Top No.
leaves leaves (in) quality diseased
29 May 11 June 29 May 11 June leaves
100%Nitrate 20.1ns 1.8** 7.7* 3.7** 2.7ns
50%Nitrate 20.1 1.5 8.1 3.3 3.5
100%Ammonium 18.9 3.9 7.2 2.9 4.1
Significance of the F test was denoted as ns (not significant) or significant at the 1% ("*) or 5%
Table 3. Effect of nitrogen source on growth of Anthurium 'Southern Blush' and severity of
Xanthomonas blight caused by Xanthomonas campestris pv. dieffenbachiae.
Treatment No. No. bad Height Top No. No.
leaves leaves (in) quality flowers diseased
29 May 11 June 29 May 11 June 11 June leaves
100%Nitrate 49.4ns 0.7ns 6.9ns 3.5ns 1.5ns 6.9ns
50%Nitrate 50.7 1.1 7.3 3.5 1.4 6.9
100%Ammonium 50.9 0.8 7.2 3.4 1.3 6.2
Significance ot the F test was denoted as ns (not significant) or significant at the 1% (*) or 5%