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Effects of Host Nutrition on Growth and Susceptibility of Anthurium
scherzeranum to Xanthomonas Leaf Spot
A. R. Chase and R. T. Poole
University of Florida, IFAS
Agricultural Research and Education Center Apopka
AREC-Apopka Research Report RH-86-4
Anthurium spp. are becoming more popular in Florida as potted',,
flowering or foliage crops. Anthurium andraeanum is grown in Hawai2-as--a-
cut flower crop. One of the most serious problems encountered by Hawaiian
producers is Xanthomonas leaf spot and blight. This disease has also
become a serious problem for Florida producers of many species and
cultivars of anthurium. Although disease control and cultural procedures
have been developed for production of this crop in Hawaii, they are often
unsuccessful due to low efficacy of available bactericides or not
applicable under Florida conditions. The following research was initiated
to partially evaluate potential for producing A. scherzeranum with
different fertilizer levels to maximize both plant quality and resistance
to Xanthomonas leaf spot and blight.
Two experiments were performed with seedling A. scherzeranum. Plants
were established in a steam-treated potting medium consisting of 50%
Canadian peat and 50% pine bark. The medium was amended, after steaming,
with 1 lb Micromax and 7 Ibs dolomite per cubic yard. Plants were
fertilized with a top-dressing of Osmocote 19-6-12 at the following rates
(Exp. 1): 1, 3, 5, 7, 9, 11, 13, and 15 g/6" tub every 3 months. In the
second test the rates were: 1, 5, 9, 13, and 17 g/6" tub every 3 months.
The first experiment was conducted in a shadehouse with a maximum of
approximately 3500 ft-c light intensity between 3-1-85 and 8-26-85. The
second experiment was conducted in a greenhouse with a maximum of about
1000 ft-c light intensity between 7-16-85 and 1-31-86. Plants were
evaluated bimonthly for number of leaves and flowers, length of the most
recently matured leaf and soluble salts of the potting medium. At the
final rating, an overall quality grade was also recorded. All plants were
then moved into a greenhouse on a bench receiving intermittent mist (5
sec/30 min for 12 hr/day) and inoculated with a suspension of Xanthomonas
campestris pv. dieffenbachiae. Misting was initiated 24 hr prior to
inoculation and continued until the end of the test. The number of leaves
showing symptoms of Xanthomonas blight was recorded approximately 1 month
Anthuriums produced under 3500 ft-c were able to utilize a relatively
high amount of fertilizer. Mean number of leaves and flowers and mean
quality grade were highest when plants were fertilized at levels from 7 -
13 g and grown in higher light (Table 1). Mean length of the most recently
matured leaf was not affected by fertilizer treatments. Plants treated
1Associate Professor of Plant Pathology and Professor of Ornamental
Horticulture, respectively, Agricultural Research and Education Center,
2807 Binion Road, Apopka, FL 32703.
F /cp 367?
with the lowest amount of fertilizer had the lowest number of leaves with
Xanthomonas blight. Soluble salts levels changed according to the
fertilizer treatment and the amount of time from the last application.
Plants in the highest fertilizer treatment had reduced growth (Table 1).
Anthuriums produced under greenhouse conditions may not have required
as much fertilizer as those grown in shadehouse conditions. In this
experiment, mean number of leaves, leaf length and quality grade were all
affected by fertilizer treatment (Table 2). Only plants treated with the
highest amount of fertilizer had reduced numbers of leaves, although leaf
length was reduced for fertilizer levels of 11 or 17 g. Plant quality was
reduced at fertilizer levels of 11 and 17 g/pot. Optimal fertilizer levels
ranged from 1 9 g for these plants produced under low light conditions.
The mean number of leaves with Xanthomonas leaf spot was unaffected (Table
2). Since these plants were not utilizing high amounts of fertilizer or
water, the soluble salts levels remained relatively high throughout the
test in all treatments.
As one would expect, the amount of fertilizer required to produce high
quality A. scherzeranum differed according to the light levels of
production. Under higher light conditions (3500 ft-c), high quality plants
utilized from 7 13 g Osmocote 19-6-12/6" pot every 3 months. Under lower
light conditions (1000 ft-c), highest quality plants were produced with
significantly lower amounts of fertilizer (rates from 1 9 g Osmocote
19-6-12/6" pot every 3 months). The affect of fertilizer level on
resistance of the host to Xanthomonas leaf spot and blight is probably due
to the production of susceptible leaves at these rates. Rates which favor
production of many new leaves concurrently favor disease development, since
these leaves are most susceptible to X. campestris pv. dieffenbachiae. In
this case, reducing susceptibility to Xanthomonas leaf spot and blight
through alteration of host nutrition is not feasible..
Additional Literature References
1. Nishijima, W. T., and D. K. Fujiyama. 1985. Bacterial blight of
Anthurium. Hawaii Coop. Ext. Serv. HITAHR. Commodity Fact Sheet AN-4(A)
2. Poole, R. T., and B. A. Greaves. 1969. N, P, and K fertilization of
Anthurium andreanum 'Nitta' and 'Kaumana'. Proc. Trop. Reg. Amer. Soc.
Hort. Sci. 13:367-372.
Table 1. Effect of fertilizer rate on growth of Anthurium scherzeranum
grown in a shadehouse and subsequent severity of Xanthomonas blight.
g Osmocote/ Mean Mean leaf Mean Mean Mean No. Soluble
6" pot/ 3 mo No. length No. quality diseased salts
3-1 and 5-20 leaves (inches) flowers grade leaves 7-2 7-31
1 9.8*b 7.0ns 2.4* 2.4** 0.6* 53** 91**
3 13.8 6.9 4.1 3.2 1.4 84 110
5 12.1 7.3 3.2 3.0 1.6 185 108
7 15.2 6.8 4.9 3.5 1.5 188 115
9 14.7 7.1 3.4 3.4 1.9 250 145
11 15.9 7.0 4.6 3.4 1.8 300 104
13 17.2 7.4 5.6 3.6 2.1 519 124
15 13.5 7.4 3.8 3.1 1.6 488 126
aMean quality grade for 10 plants was rated as follows:1 = dead; 3 = good,
salable; 5 = excellent, highly salable.
Significance of the F test was denoted as not significant (ns) or
significant at the 5% (*) or 1% (**) level.
Table 2. Effect of fertilizer rate on growth of Anthurium scherzeranum
grown in a greenhouse and subsequent severity of Xanthomonas blight.
g Osmocote/ Mean Mean leaf Mean Mean Mean No. Soluble
6" pot/3 mo No. length No. quality diseased salts
7-16 and 10-8 leaves (inches) flowers grade leaves 12-30
1 30.7* 6.8* 4.7ns 4.0** 3.3ns 1168*
5 28.4 6.1 3.4 3.7 1.5 2150
9 28.5 6.5 4.5 3.9 2.3 3038
11 30.6 5.5 3.5 3.2 2.3 3548
17 22.1 5.4 3.6 2.8 1.9 3735
salable; 5 =
grade for 10 plants was rated as
excellent, highly salable.
follows: 1 = dead: 3 = good,
bSignificance of the F test was denoted as not significant (ns) or
significant at the 5% (*) or the 1% (**) level.