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Effects of Light Level and Nitrogen Fertilization
on Growth of Heart-leaf Philodendron Stock Planits' c
and Severity of Red-Edge Disease' '
A.R. Chase and R.T. Poole1
CFREC-Apopka Research Report RH-93-9
Philodendron scandens oxycardium stock plants with red-edge disease, caused by
Xanthomonas campestris pv. dieffenbachiae, were grown under 1500, 3500 or 5500 ft-c light
intensity and fertilized with 19-6-12 Osmocote at 4, 8 or 12 g/6-inch pot/3-months. Two cutting
crops were propagated from the stock plants in each of two experiments. Stock plant
fertilization rate was more important than light intensity for subsequent growth and quality of
cuttings. Best quality crops were grown from cuttings harvested from stock plants fertilized at
8 or 12 g/6-inch pot. Stock plants grown under 1500 ft-c had significantly lower levels of red-
edge disease compared to plants grown under 3500 or 5500 ft-c. Stock plant fertilization rate
did not affect severity of red-edge disease on stock plants or plants grown from their cuttings.
Light and fertilizer levels for producing good quality acclimatized foliage plants have
been published for most economically important species (6, 7). Less information is available
on growth parameters for containerized stock plants grown in commercial type soilless media
(5, 12). The following experiments were conducted to determine optimum light intensities and
fertilizer levels for Philodendron scandens oxycardium (heart-leaf philodendron) container grown
stock plants to produce high quality cuttings. The effects of light intensity and fertilizer level
on severity of red-edge disease caused by the bacterium Xanthomonas campestris pv.
dieffenbachiae were also evaluated.
'Professor of Plant Pathology and Professor of Plant Physiology, respectively, Central Florida Research and
Education Center, 2807 Binion Road, Apopka, FL 32703.
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational
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COOPERATIVE EXTENSION WORK IN AGRICULTURE, HOME ECONOMICS, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA,
U.S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING.
q3 Central Florida Research
UFLORIDA and Education Center
Institute of Food and Agricultural Sciences Research Report
Materials and Methods
Experiment 1. Research was initiated on February 28, 1991, when rooted heart-leaf
philodendron cuttings, three per 3-inch pot, were repotted into 6-inch containers, using Vergro
Container Mix A without superphosphate (Verlite Co., Tampa FL 33680). These stock plants
were grown in a shadehouse in a 3 x 3 factorial experiment with 5 replications (pots) per
treatment. Plants were arranged in a randomized block design under polypropylene shadecloth
providing 45, 60 or 75% shade so that the maximum light intensity at plant level was 5500,
3500 or 1500 ft-c, respectively. Minimum and maximum air temperatures at bench level in the
shadehouse during the course of the experiment were 650F and 950F, respectively.
Pots were top-dressed with 4, 8 or 12 g/6-inch pot 19-6-12 Osmocote (Grace/Sierra Co.,
Milpitas, CA 95053), on February 28 and again on May 21, 1991. Plants were watered
overhead three times per week. Symptoms of red-edge disease (necrotic reddish-brown leaf
margins) were first observed on foliage shortly after placement in the shadehouse. Naturally
occurring infection by Xanthomonas campestris pv. dieffenbachiae, the bacterium causing red-
edge disease in philodendron, was confirmed by isolation of the pathogen.
Cuttings were harvested from stock plants on May 14 (crop la) and July 31, 1991 (crop
lb). Stock vines were cut back to the pot rim during harvest. Cuttings were rooted by placing
five single-eye nodes per 5-inch pot, in Vergro Container Mix A. Cuttings were placed under
intermittent mist in a greenhouse where maximum light intensity at bench level was 2000 ft-c
and temperatures ranged from 650F to 950F. Cuttings harvested on May 14 were removed from
mist on June 25, those obtained on July 31 were removed on September 10, 1991. Cuttings
were fertilized with 5 g/5-inch pot 19-6-12 Osmocote shortly before plants were moved to the
shadehouse. After removal from mist, cuttings were placed under 1500 ft-c maximum light
intensity in the same shadehouse as stock plants.
Total number of nodes on vines of stock plants was recorded when cuttings were
harvested. Electrical conductivity (Ixmhos/cm) and pH of medium leachate from stock plants
were measured on March 7 and June 28, 1991 using the pour through nutrient extraction
procedure (13). Plant grade (based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 =
fair quality, salable, 4 = good quality and 5 = excellent quality) and total vine length were
determined on August 9 (crop la) and on October 15, 1991 (crop lb). The severity of
symptoms of red-edge disease on stock plants and plants grown from crop la cuttings were
determined on June 14 and August 15, 1991, respectively.
Experiment 2. Experiment 2 began on October 15, 1991, when cuttings were potted and placed
under the same shade levels as in Experiment 1. Containers were top-dressed on October 16,
1991 and again on January 29, 1992 with the same rates of 19-6-12 Osmocote as used in
Experiment 1. Stock plants were graded based on the same scale as used in Experiment 1, on
May 11, 1992. The pour-through method was used to determine electrical conductivity and pH
of stock plant medium leachate on March 6 and May 15, 1992.
Two cutting crops were harvested and propagated under intermittent mist in the same
manner as in Experiment 1. Crop 2a was harvested and propagated on January 10 and crop 2b
on May 15, 1992. When adequately rooted (crop 2a on March 16, crop 2b on July 9, 1992)
cuttings were placed under 60% shade in the shadehouse where stock plants were maintained.
Both crops were fertilized with 5 g/5-inch pot 19-6-12 Osmocote on the day plants were moved
to the shadehouse.
Plant grades, total vine length and number of nodes per vine on the 5-inch pots of heart-
leaf philodendron grown from cuttings were recorded on March 27 (crop 2a) or on August 14,
1992 (crop 2b). The number of leaves damaged by red-edge disease on stock plants and plants
grown from cutting crops was determined on January 10, May 12 and August 13, 1992,
Heart-leaf philodendron vines produced more nodes when grown under 1500 ft-c
compared to plants grown in the two higher light intensities but fertilizer rate had no effect
(Table 1). Total number of nodes per plant on crop lb heart-leaf philodendron plants harvested
on July 30, however, was not affected by light intensity or fertilizer level (data not shown).
Although crop 2a plants receiving the highest fertilizer rate were slightly shorter when compared
to those grown at the lower rates, fertilizer rate did not significantly affect other growth
parameters in either experiment (Table 1).
Plant grades from crop la and lb cuttings, as well as total length of vines from crop la
cuttings, were not affected by light intensity (Table 2). Crop lb cuttings produced the longest
vines when harvested from stock plants grown in the lowest light.
Fertilizer rate affected plant grade and vine length of plants grown from both la and lb
cutting crops (Table 2). In general, plants grew more and received higher plant grades when
either 8 or 12 g/6-inch pot rates of fertilizer were used.
Number of nodes per vine on plants grown from crop 2a cuttings was influenced by an
interaction of light intensity and fertilizer rate on the stock plants (Figure 1). Plants with more
nodes per vine were produced from stock plants grown under 60% shade (2500-3500 ft-c)
receiving 12 g/6-inch pot of 19-6-12. As light intensity in stock plant area increased, more
fertilizer was required to maintain the same node per vine ratio obtained with low light and low
As in Experiment 1, one cutting crop (2a) was similarly affected by light intensity in
stock plant areas, with longest vines grown from cuttings of stock plants under 75% shade (5500
ft-c) (Table 3). Overall, plant grade of 2a cuttings was best when stock plants received 8 or 12
g/6-inch pot 19-6-12. Total vine length of both 2a and 2b crops and number of nodes on vines
of 2b cuttings increased as fertilizer rate of stock plants increased.
Light intensity influenced severity of red-edge disease on heart-leaf philodendron stock
plants in both experiments (Figure 2). Stock plants grown under the lower light level had
significantly fewer leaves with symptoms of red-edge disease than those grown under the two
higher light levels. In addition, there was a direct correlation between the severity of infection
for stock plants and the severity of infection on the plants propagated from them. Severity of
red-edge disease on either stock plants or plants grown from their cuttings was not influenced
by fertilizer rate.
In a recent study Philodendron scandens oxycardium plants with leachate electrical
conductivity measuring 1040 to 1460 pmhos/cm maintained their attractiveness when placed
indoors for up to two months (11). The electrical conductivity measurements observed here for
plants receiving 8 or 12 g/6-inch pot, 1050 and 1602 /mhos/cm are close to that range.
Stock plant fertilization rate was more important than light intensity in the growth and
quality of heart-leaf philodendron crops produced in these two experiments. Best quality crops
were produced when stock plants received 8 or 12 g/6-inch pot rather than 4 g/6-inch pot of
19-6-12 Osmocote every 3 months.
Earlier research has shown that fertilizer rate can affect severity of bacterial disease
infection of some foliage plants (2, 3, 4, 8). The fertilizer rates tested in these experiments
were lower than those utilized when disease was evaluated in the above mentioned research and
they did not influence disease severity on heart-leaf philodendron. Preinoculation light levels
did not significantly influence bacterial disease expression on Syngonium podophyllum with
Xanthomonas blight (1) or Schefflera arboricola with Pseudomonas leaf spot (3). However,
light level was shown to affect severity of expression of Pseudomonas leaf spot on
chrysanthemums (9) as well as red-edge disease in this report. Bactericides alone have so far
provided very limited control of most bacterial diseases (10). Effective control is obtained with
use of integrated disease control programs based on use of pathogen free plant material, proper
sanitation practices and bactericides when needed. In the future, environmental manipulation
should become an important part of integrated disease control programs.
1. Chase, A.R. 1988. Effects of temperature and preinoculation light level on severity of
Syngonium blight caused by Xanthomonas campestris. J. Environ. Hortic. 6(2):61-63.
2. Chase, A.R. 1989. Effect of nitrogen and potassium fertilizer rates on severity of
xanthomonas blight of Syngonium podophyllum. Plant Disease 73:972-975.
3. Chase, A.R. and J.B. Jones. 1986. Effects of host nutrition, leaf age, and
preinoculation light levels on severity of leaf spot of dwarf schefflera caused by
Pseudomonas cichorii. Plant Disease 70:561-563.
4. Chase, A.R. and R.T. Poole. 1987. Effects of fertilizer rate on severity of
xanthomonas leaf spot of schefflera and dwarf schefflera. Plant Disease 71:527-529.
5. Conover, C.A. and R.T. Poole. 1972. Influence of shade and nutritional levels on
growth and yield of Scindapsus aureus, Cordyline terminalis 'Baby Doll' and
Dieffenbachia exotica. Proc. Trop. Reg. Amer. Soc. Hort. Sci. 16:227-281.
6. Conover, C.A. and R.T. Poole. 1974. Influence of shade and fertilizer source and level
on growth, quality and foliar content of Philodendron oxycardium Schott. J. Amer. Soc.
Hort. Sci. 99(2):150:152.
7. Conover, C.A. and R.T. Poole. 1990. Light and fertilizer recommendations for the
production of acclimatized potted foliage plants. Nursery Digest 24(10):34-36, 58-59.
8. Harkness, R.W. and R.B. Marlatt. 1970. Effect of nitrogen, phosphorus and potassium
on growth and xanthomonas disease of Philodendron oxycardium. J. Amer. Soc. Hort.
9. Jones, J.B., A.R. Chase, B.K. Harbaugh and B.C. Raju. 1985. Effect of leaf wetness,
fertilizer rate, leaf age, and light intensity before inoculation on bacterial leaf spot of
chrysanthemum. Plant Disease 69:782-784.
10. Knauss, J.F., W.E. Waters and R.T. Poole. 1971. The evaluation of bactericides and
bactericide combinations for the control of bacterial leaf spot and tipburn of Philodendron
oxycardium incited by Xanthomonas dieffenbachiae. Proc. Fla. State Hort. Soc. 84:424-
11. Poole, R.T. and C.A. Conover. 1990. Leachate conductivity and pH for ten foliage
plants. J. Environ. Hort. 8(4):166-172.
12. Reyes, T., A.R. Chase and R.T. Poole. 1990. Effect of nitrogen level and light
intensity on growth of Epipremnum aureum. Proc. Fla. State Hort. Soc. 103:176-178.
13. Wright, R.D. 1986. The pour-through nutrient extraction procedure. HortScience
Growth and plant grade of Philodendron scandens oxycardium stock plants grown with three shade levels and three
fertilizer rates, in two experiments.
Maximum Experiment 1, crop laz Experiment 2, crop 2a
light intensity (ft-c) Number of nodes Plant grade, Vine length (in) Number of nodes
1500 36**x 4.0" 66.4* 49.
3500 33 4.8 61.6 41
5500 30 4.8 54.4 41
19-6-12, g/6-inch pot"
4 33"s 4.5"n 64.4* 43"
8 33 4.7 65.6 47
12 34 4.5 52.0 41
zStock plants (three rooted cuttings per 6-inch pot) were started on February 28 and cutting crop la harvested on May 14, 1991.
Crop 2a, harvested on January 10, 1992, was obtained from stock plants started on October 15, 1991.
YPlants were graded on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 =
xns, *,**; Results nonsignificant, significant at P = 0.05 and significant at P = 0.01, respectively.
"Plants received 19-6-12 Osmocote at the rates indicated on February 28 and June 25 1991, in experiment 1 and on October 16,
1991 and January 29, 1992 in experiment 2.
Growth of cuttings obtained from Philodendron scandens oxycardium stock plants
grown with various shade and fertilizer levels from February 28 until October 15,
Stock plant Crop la, harvested May 14, Crop lb, harvested Jul 31,
production area evaluated Aug 9, 1991 evaluated Oct 15, 1991
intensity (ft-c) Vine length Vine length
Plant grades (in) Plant grade (in)
1500 4.3ns 44.0" 4.6" 33.2"
3500 4.4 37.6 4.6 30.4
5500 4.1 41.2 4.7 28.4
4 3.7" 30.0" 4.2*" 25.6"
8 4.5 44.0 4.9 34.8
12 4.7 48.8 4.8 32.0
zPlant were graded using a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality,
salable, 4 = good quality and 5 = excellent quality.
Yns, **; Results nonsignificant and significant at P = 0.01, respectively.
xStock plants received 19-6-12 Osmocote at the rates indicated on February 28 and June 25
Vine length, number of nodes and plant grade of two crops of Philodendron scandens oxycardium cuttings harvested
from stock plants grown with three light levels and three fertilization rates from October 15, 1991 until May 15, 1992.
Crop 2a harvested Jan 10, Crop 2b harvested May 15,
Stock plant production evaluated Mar 27, 1992 evaluated Aug 14, 1992
area light intensity
a ft i Plant grades Vine length (in) Plant grade Vine length (in) No. of nodes
1500 3.7"n 15.6" 3.0"' 27.2"n 19"'
3500 3.7 13.2 3.4 30.8 20
5500 3.3 10.4 3.3 27.6 21
19-6-12, g/6-inch potx
4 2.8" 10.8' 3.0" 26.4' 19*
8 4.0 14.0 3.1 25.2 18
12 4.0 14.4 3.6 33.6 23
zPlants were graded on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 =
Yns, *, **; Results nonsignificant, significant at P = 0.05 and significant at P = 0.01, respectively.
xStock plants received 19-6-12 Osmocote at the rates indicated on October 16, 1991 and January 29, 1992.
Figure 1. Light and fertilizer levels
in stock plant areas affect growth of
heart-leaf philodendron cuttings.
1500 ft-c 3500 ft-c 5500 ft-c
- 4 g/6-inch pot
8 g/6-inch pot
I 12 g/6-inch pot
Stock plants fertilized with Osmocote
19-6-12 at the rates indicated on Oct
16, 1991 and Jan 29, 1992.
f > I
* A -,
Figure 2. Number of leaves with symptom
of red-edge disease on heart-leaf
philodendron stock plants and cuttings.
Stock pits, Exp. 1
SStock pits, Exp. 2
M Cuttings, Exp. 1
M Cuttings, Exp. 2
Damage rated for exp. 1 stock-Jun 14 and
cuttings-Aug 2, 1991; for exp. 2 stock-
May 12 and cuttings-Aug 13, 1992.