Philodendrons - Self-Heading Types

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CFREC-A Foliage Plant Research Note RH-91-27

R.W. Henley, A.R. Chase and L.S. Osborne
University of Florida, IFAS
Central Florida Research and Education Center - Apopka
2807 Binion Road, Apopka, FL 32703-8504


PHILODENDRONS - SELF-HEADING TYPES

There are some 200 species of Philodendron in the aroid family, Araceae. These tropical herbs are indigenous to tropical America. Although most philodendron are distinctly vine-like, a number of species and cultivars have leaves spaced so close together that the stem is not visible until some of the lower (older) leaves abscise (fall off). Using the foliage industry language, plants in the latter category are called self-headers. Horticulturists and botanists describe some of the self-heading philodendrons as being arborescent types (those which have large, stiff stems, rigid enough to hold the plant top upright for several years).

The self-heading philodendrons are most typically grown as specimen plants which can be used at table top level in small sizes and the larger plants are frequently placed at floor level for maximum design impact. The self-headers can also be massed in large in-ground planters to create the effect of a grouping of shrubs. Occasionally self-heading philodendrons are use indoors in hanging planters, but this treatment is rather rare because many of the plants do not have leaves which reflex over the container.


SPECIES AND CULTIVARS

Thanks to a few serious plant breeders there are now numerous hybrids which have more refined growth characteristics than most of the species. Some of the self-heading philodendrons are listed below with the preferred method of commercial propagation (Table 1).

Table 1. List of self-heading Philodendron species and cultivars with the preferred method of propagation of each indicated.


                                                                                                                     
Horticultural Name					Preferred 
			Common Name		    Propagation Method
                                                                                                                      

Philodendron bipinnatifidum				Seed

Philodendron `Black Cardinal' (Pat. no. 5355)		Tissue culture
		Black Cardinal Philodendron

Philodendron `Emerald Prince'				Tissue culture
		Emerald Prince Philodendron

Philodendron `Imperial Green'	(Pat. no. 6086)		Tissue culture
		Imperial Green Philodendron

Philodendron `Imperial Red' (Pat. no. 6337)		Tissue culture   		  		
		Imperial Red Philodendron

Philodendron martianum (P. cannifolium)			Seed

Philodendron `Moonlight'				Tissue culture
		Moonlight Philodendron

Philodendron `Prince Albert'				Tissue culture
		Prince Albert Philodendron

Philodendron `Prince of Orange' (Pat. no. 6797)		Tissue culture
		Prince of Orange Philodendron

Philodendron selloum					Seed
		Lacy-tree Philodendron

Philodendron wendlandii   			 	Seed

Philodendron `Xanadue'					Tissue culture
		Xanadue Philodendron


PRODUCTION

Florida nurserymen propagate certain self-heading philodendrons from commercially packaged seeds. A few Florida growers, primarily P. selloum growers, have maintained blocks of mature plants for seed production. This practice is labor intensive and the seed has limited longevity unless it is properly processed and vacuum packed.

The tiny seeds are sown on the medium surface and covered with a fine layer of screened sphagnum moss or sphagnum peat. Seeds germinate best at 75 to 80F and the upper layer of medium must be kept moist and low in soluble salts or the germinating seeds will be killed. Various techniques can be used to stabilize moisture in the germination medium. Fine mist nozzles located above the germination flats, sleeves of translucent polyethylene placed around the flats, or rigid plastic covers designed to fit the over the top of a flat will help maintain a desirable moisture level in the germination medium. Shaded greenhouses or germination rooms illuminated with cool white fluorescent lamps can be used for germination with the latter type facility preferred by some nurserymen because more uniform light and temperature regimes can be achieved. Usually light levels of 300-600 foot candles are sufficient for germination. After seedlings develop about two leaves the light level should be increased to 1500-2500 foot candles to maximize growth and keep plants compact. Plants produced in liner trays which have plugs 1 or more across will transplant with less shock than those grown in community flats or propagation beds and then transplanted to finishing pots. Many plant finishers prefer to purchase seedlings in plug form from propagation specialists and be free of the chore of managing plants through the delicate germination and early development stages.

Self-heading philodendron are not propagated by conventional cutting propagation procedures because of their short internodes and large stems and leaves. Within the past 12 years, hybrid self-headers which do not produce true-to type seeds have been propagated through tissue culture (TC). This innovation has not only provided a means of mass propagation for a number of useful hybrids, but it has essentially generated a new product line. Most philodendron grown from seeds or conventional cuttings produce few side shoots. Most of the philodendron plants from TC have basal shoots which help produce compact plants, even in small pots. Tissue-cultured philodendron are available as plugs from 3/4 to 1-inch across, and in some cases, as nonestablished microcuttings. The type of propagule used by the plant finisher will depend upon the degree environment control achievable in the production area, the ability of the nursery staff and the availability of desired plant material. The majority of nurseries start with plugs, thus avoiding the tedious job of rooting microcuttings in a potting medium.

Florida nurserymen finish self-heading philodendron plants in container sizes from 6 to 14 inches in diameter. Most of the plants in 6 to 10-inch pots are sold through retail outlets. A few of the 8 and 10-inch and most of the larger plants are sold to the interiorscape market. A few growers produce a limited quantity of 3 to 5-inch pots of self-headers for the retail trade, usually starting from non-established microcuttings.

Plants should be grown in a well drained potting medium with high water holding capacity. Most nurseries growing plants in greenhouses use pots up to 8-inch diameter filled with high quality, preblended mixes composed of over 50 percent Canadian peat and other clean amendments. Under shadehouse conditions growers frequently utilize potting mixes which include some Florida sedge peat plus some bark and sand. Calcium and magnesium are normally supplied through additions of dolomite blended with the potting medium at the rate of 4 to 10 pounds per cubic yard to adjust the pH to approximately 6.0. The amount of dolomite used will vary depending upon the initial acidity of the mix and the projected impact of the fertilization programs and irrigation water on the mix pH. A microelement blend can be added at the time of mixing or as a post-plant application with a soluble microelement mix. Microelements should also be applied periodically during crop development as part of a liquid fertilizer program. A fertilizer with approximately a 3-1-2 or 2-1-2 ratio should be used at the rate of 2.9 to 3.4 pounds of nitrogen per 1000 square feet per month.

Although Philodendron selloum and a few of the species will tolerate full sun exposure in Florida landscapes, they have more attractive foliage when grown under shade levels of 3000 to 5000 foot-candles. Most of the hybrid philodendrons from tissue culture do best under 1500 to 2500 foot-candles. Philodendrons grow rapidly when the atmosphere in the production structure is between 70 and 85F.


PHYSIOLOGICAL PROBLEMS

1) Pale coloration

Symptoms -
Leaves lack the characteristic dark green color.

Control -
Winter chilling produces some chlorosis on lower leaves first. Avoid chilling through various cold protection measures. Light color can also be attributed to excessively high light levels or low nutrition. Use of recommended light levels and the recommended fertilizer application rates will assure good plant color.

2) Plants have excessively open appearance

Symptoms -
Petioles long and species which usually have lobed leaves without normal amount of deep lobes.

Control -
Plants should be grown under higher light intensity.

Reference Pest Control Guides Here


BACTERIAL PROBLEMS

1) Erwinia blight (E. chrysanthemi and E. carotovora subsp. carotovora)

Symptoms -
Erwinia blight appears initially as tiny water- soaked areas primarily on leaves. The disease can affect plants of many ages but appears to be less severe on large plants, such as those established in the landscape. Lesions on smaller plants expand rapidly into irregularly shaped tan to black areas. The bacterium spreads from leaf lesions into petioles causing complete collapse of infected leaves. Leaf and petiole disintegration are characteristic for Erwinia blight and can occur in as little as two days. Infected plants produced in an enclosed area, such as a greenhouse, have a characteristic unpleasant odor associated with the disease.

Control -
Considerable research has been conducted on this problem in an effort to identify a cultural means of control. Free moisture on leaf surface is needed for infection, but wounding of the tissue is not required. Unlike some other bacterial diseases, extended periods of misting are not necessary for infection to occur on P. selloum, although these conditions do increase disease severity. Disease severity also increases as temperature increases and is most severe on plants with either too little or too much fertilizer. Use of bactericides such as copper-mancozeb or streptomycin sulfate is not recommended since the degree of control is so poor. Minimizing water applications, using the recommended rate of fertilizer and spacing plants to allow rapid drying of leaves are recommended controls for Erwinia blight. The wide host range of these bacteria make it necessary to control the disease on all susceptible plants to reduce spread from one crop to another.

2) Pseudomonas leaf spot (Pseudomonas cichorii)

Symptoms -
This disease appears similar to Erwinia leaf spot except that lesions rarely become mushy and do not appear water-soaked.

Control -
Same as for Erwinia leaf spot (above).

3) Red-edge (Xanthomonas campestris pv. dieffenbachiae)

Symptoms -
Reddish-brown margins on edges of leaves is the most common symptom. Under wet and warm conditions, bacteria also spread into leaf centers and lesions expand until they reach a leaf vein. Sometimes lesions are also small, water-soaked specks which enlarge into irregularly shaped areas.

Control -
Use of raised benches and minimizing foliage wetting are two of the most important cultural controls of red-edge disease.

Reference Pest Control Guides Here


FUNGAL PROBLEMS

1) Phytophthora leaf spot (Phytophthora parasitica)

Symptoms -
Lesions are dark brown, water-soaked, irregularly shaped, and 1/2 to 1" wide. The disease is most severe in the summer months in ground beds of philodendron.

Control -
Growing plants in sterilized potting media on raised benches eliminates much of the source of this disease.

2) Pythium root and stem rot (Pythium spp.)

Symptoms -
One of the first symptoms of Pythium root rot on this philodendron is yellowing of leaves on rooted cuttings. Leaves turn brown and usually remain attached to the stems while leaves farther up on the vine may wilt. Stems are easily removed from pots to reveal few healthy roots. The roots themselves are blackened and mushy and the cortex of an infected root is readily stripped from the inner core.

Control -
Always use sterilized potting media and grow on raised benches. Soil drenches are effective.

3) Southern blight (Sclerotium rolfsii)

Symptoms -
Plants with southern blight may initially appear similar to those infected with many stem or root infecting fungi. As the disease advances, however, the white cottony masses of mycelia and brown seed-like sclerotia set this disease apart. The sclerotia usually form on the basal portion of stems of infected plants but may also be found on infected leaves. Eventually the entire cutting or plant may be covered with the fungus.

Control -
Southern blight must be controlled through prevention. Use pathogen-free potting medium, pots and planting materials.

Reference Pest Control Guides Here


NEMATODE PROBLEM

1) Burrowing nematode (Radopholus similis)

Symptoms -
Small root systems, reduced vigor and reduced yields of cuttings from stock plants are common symptoms of burrowing nematode infestations. Plants may appear similar to those infected with root rotting fungi, and diagnosis is very important for all root problems. The nematode lives inside the roots and does not form any obvious outward structures such as galls.

Control -
A combination of cultural controls is the best way to avoid nematode infestations. Methods listed for the fungal root and stem rotting pathogens are effective.

Reference Pest Control Guides Here


VIRAL PROBLEM

1) Dasheen mosaic virus (DMV)

Symptoms -
Chlorotic streaking and mosaic patterns as well as distortion of new leaves are found in philodendron infected with DMV. Growth of infected plants is reduced compared to healthy plants even when obvious symptoms are not present.

Control -
This virus is also a pathogen of Aglaonema, Dieffenbachia and Spathiphyllum, and control practices should include these genera as well. Elimination and destruction of infected plants is the only way to stop spread of the virus. Aphid control and sterilization of cutting instruments periodically also are important ways to minimize virus spread since the virus may be vectored by either method.

INSECT AND RELATED PROBLEMS

The major arthropod pests of this plant species include aphids, moths (worms), fungus gnats, mealybugs, scales, shore flies and thrips. Mealybug, mite, and scale infestations are typically the result of bringing infested plant material into the greenhouse. Aphids, moths, fungus gnats, shore flies and thrips have the ability to fly and thus invade the greenhouse from weeds and other infested plants outside. In the control section for each pest, a few of the many registered and effective pesticides will be listed. For a complete listing please consult the references at the end of this report.

1) Aphids

Symptoms -
Aphids are pear-shaped, soft-bodied insects which vary in color from light green to dark brown. Infestations may go undetected until honeydew or sooty mold is observed. Aphids can cause distortion of new growth or, in extreme cases, infested plants can be stunted.

Control -
Aphids are relatively easy to control with many registered materials. Phytotoxicity to this plant has been caused by many different chemicals. Please conduct your own tests to see what is safe under your conditions. Root aphids have been controlled with soil drenches of Diazinon.

2) Caterpillars (worms)

Symptoms -
Infestations are easy to detect because worms, their excrement and the damage they cause, are usually quite visible to the unaided eye. Damage appears as holes in the center or along the edges of leaves. Damage by worms is often confused with slug or snail damage. The only way to determine which pest is involved is to find a specimen. Old damage can be distinguished from new by the calloused appearance of the older damaged areas (worms are usually gone by this time).

Control -

3) Fungus gnats

Symptoms -
Fungus gnats are small black flies (1/8 inch long) and are frequently observed running around the soil surface or on leaves and are often confused for Shore flies (see later section). The adults have long bead-like antennae and their legs hang down as they fly. These insects are very weak fliers and appear to "flit" around randomly. The larvae are small legless "worms" with black heads and clear bodies that inhabit the soil. The larvae spin webs on the soil surface which resemble spider webs. Damage is caused by larvae feeding on roots, root hairs, leaves in contact with the soil and lower stem tissues. Feeding damage may predispose plants to disease and they are often found in close association with diseased plants or cuttings. Adults do not cause any direct damage, but are responsible for many consumer complaints to growers. Adults emerge and fly around in retail shops, homes, or offices and are therefore a nuisance. For further information please consult Extension Entomology Report #74 (Management of fungus gnats in greenhouse ornamentals).

Control -
Reduce the amount of water applied to each pot where possible. Avoid algae growth where possible. Soil drenches or soil-surface sprays are effective at controlling the larvae. Nematodes that seek out insects in the soil are sold commercially and have been shown to control these pests without causing any negative effects to the host plants. Adults are very sensitive to most chemicals.

4) Mealybugs

Symptoms -
Mealybugs appear as white, cottony masses in leaf axils, on the lower surfaces of leaves and on the roots. Honeydew and sooty mold are often present and infested plants become stunted, and with severe infestations, plant parts begin to die.

Control -
Systemic materials are preferred. Control of root mealybugs is accomplished with soil drenches with an insecticide. When pesticides are applied to the soil, care must be taken to assure that the pots have good drainage and that no saucers are attached, or phytotoxicity may result.

5) Scales

Symptoms -
Infested plants become weakened or stunted and begin to die. Scales can be found feeding on leaves, petioles, or stems. They are usually distinct from the plant material on which they are feeding. Their shape (round to oval), size (pinpoint to 2 mm long), and color (light to dark brown) are quite variable and many scales are hard to distinguish from the plant material on which they are feeding.

Control -
See Mealybugs

6) Shore flies

Symptoms -
Shore flies small black flies (1/8 inch long) and are frequently observed sitting on the tips of leaves or on the soil surface feeding on algae. The adults have very short antennae. These insects are very strong fliers and exhibit directed flight (straight between 2 points). The larvae inhabit the soil and are small legless "worms" with clear bodies and no obvious heads. No known damage is caused by larvae. This insect is believed to feed only on algae. Adults do not cause any direct damage, but may be responsible for spreading plant pathogens, reducing value by defecating on the leaves (small black to green spots) and for many consumer complaints to growers. Adults emerge and fly around in retail shops, homes, or offices and are therefore a nuisance.

Control -
Reduce the amount of water applied to each pot where possible. Avoid algae growth on walkways, benches, and cooling pads. Chemicals are not believed to be very effective in the control of this pest.

7) Thrips

Symptoms -
Thrips are small (less than 1/20), thin insects. Adult thrips can be identified by a long fringe of hair around the margins of both pairs of wings. Color varies between species with western and other flower thrips being yellow to light brown and banded greenhouse thrips and a few other thrips that feed mainly on leaves being dark brown to black. Feeding takes place with rasping type mouth parts. Infested leaves become curled or distorted, with silver-gray scars or calloused areas where feeding has occurred. Thrips can transmit the tomato spotted wilt virus to many different ornamentals. Any unusual symptoms should be investigated.

Control -
Many materials are registered and effective at controlling thrips.


Pesticides should be applied according to label directions.

Regardless of the pesticide or mixture of pesticides used, it is
strongly recommended that the effects be evaluated on a few
plants, under your particular conditions before treating all plants.

Mention of a commercial or proprietary product in this paper
does not constitute a recommendation by the authors,
nor does it imply registration under FIFRA as amended.


Reference Pest Control Guides Here


REFERENCES

1. Bailey, L.H. Hortorum and staff. 1976. MacMillan Publishing Company, Inc. New York, NY. 1290 pp.

2. Chase, A.R. 1990. Phytotoxicity of bactericides and fungicides on some ornamentals. Nursery Digest 24:(5)11. 13 pp.

3. Conover, C.A. and R.T. Poole. 1990. Light and fertilizer recommendations for production of acclimatized potted foliage plants. CFREC-A Research Report RH-90-1.

4. Price, J., D.E. Short and L.S. Osborne. 1989. Management of fungus gnats in greenhouse ornamentals. Extension Entomology Report #74.

5. Short, D.E., L.S. Osborne and R.W. Henley. 1991. 1991-1992 Insect and related arthropod management guide for commercial foliage plants in Florida. Extension Entomology Report #52. 13 pp.

6. Short, D.E., L.S. Osborne, and R.W. Henley. 1984. Phytotoxicity of insecticides and miticides to foliage and woody ornamental plants. Extension Entomology Report #57.

7. Simone, G.W. and A.R. Chase. 1989. Disease control pesticides for foliage production. Extension Plant Pathology Report No. 30 (Revision #4). 54 pp.