Philodendron - Vining

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Heart-leaf philodendron is still one of the most popular and best foliage plants available and is often utilized for potted plants, totem poles and hanging baskets.Its proper botanical name is now Philodendron scandens oxycardium, but over the years this plant has also been known as Philodendron oxycardium and Philodendron cordatum.

Heart-leaf philodendron stock plants require slightly higher light levels (2500-3000 ft-c) than potted plants (1500-3000 ft-c). Best quality stock is produced at about 3000 ft-c and most attractive potted plants at 2000 ft-c. Excellent growth can be obtained with a 3-1-2 (N-P2O5-K2O) ratio liquid or slow release fertilizer when applied at a rate of about 1500 lb N/A-yr (equivalent to 34.5 lb N/1000 ft2/yr).

Potting media utilized for hear-leaf philodendron should have high water holding capacity and excellent aeration. Amendments should include micronutrients and dolomite to supply calcium and magnesium. Good plant growth will be obtained when soil temperatures are at least 65°F and air temperatures 70°F or above. Air temperatures as high as 105°F are not damaging to hear-leaf philodendron, as long as soil moisture is adequate and proper light levels provided.

1) Chlorotic leaves

Symptoms -

Two types of chlorosis are somewhat common on heart-leaf philodendron. Type I appears near the petiole attachment on the outer lobe margins. Type II appears on the lower margins opposite the petiole with some streaks extending upward; sometimes some marginal chlorosis is associated with this type.

Control -

Type I chlorosis is due to magnesium deficiency and can be prevented in incorporation of dolomite into the potting media at 7 lb/yd3. Once Type I chlorosis appears on foliage, it cannot be fully corrected, but further damage can be prevented by use of magnesium sulphate (MgSo4) at 3 to 5 lb/100 gallons. Type II chlorosis is suspected to be due to micronutrient imbalance, but the specific cause is unknown at present.

2) Oversized leaves

Symptoms -

Stock plants growing under proper light levels and receiving high levels of fertilizer may produce leaves that are too large to utilize easily in propagation.

Control -

Reduce fertilizer levels to reduce leaf size, but do not lower level so much it reduces leaf color. If large leaves are still a problem after reducing fertilizer level, reduce the light level slightly.

3) Poor plant vigor

Symptoms -

Leaves and stem caliper small and weak. Cuttings root poorly and do not grow off rapidly.

Control -

Increase light level and fertilizer level if leaf color is light green after increasing light level. This will increase leaf and stem caliper and carbohydrate level within the plant which will improve rooting and initial growth.

4) Crippled leaves

Symptoms -

Leaves have a wrinkled line beginning at the top of the heart-shaped lobes extending to the lower margin on the same side. The wrinkled area may be green, slightly chlorotic or sometimes have some necrotic spots.

Control -

The problem is induced by a phytotoxic reaction to pesticides or liquid fertilizer allowed to dry within the partially folded leaf. Liquid fertilizers applied overhead should be washed from leaves after application or applied at rates equivalent to 2 lb 20-20-20/100 gallons or less at each application. Phytotoxic pesticide reactions are not common if proper rates are utilized.

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BACTERIAL PROBLEMS

Reference Pest Control Guides Here

1) Bacterial leaf spot (Erwinia carotovora and E. chrysanthemi)

Symptoms -

Lesions initially appear as small water-soaked, irregularly shaped areas which rapidly become necrotic and sometimes encompass the entire leaf blade. Lesions may also occur on leaf petioles and stems. Many times the center of a lesion fall out or becomes mushy. This disease is most severe under conditions of high moisture and temperature. The bacterium appears to be dormant during the cool winter months.

Control -

Removal and destruction of infected tissue is most desirable and infected plants should never be used as a cutting source.

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 lower 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.

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FUNGAL PROBLEMS

Reference Pest Control Guides Here

1) Dactylaria leaf spot (Dactylaria humicola)

Symptoms -

Pinpoint water-soaked lesions on young leaves are the first symptom of this disease. Lesions turn chlorotic and then tan, have depressed centers, and usually remain quite small (less than 1/8" wide).

Control -

This disease is not commonly found in the industry except in ground beds exposed to overhead irrigation.

2) 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.

3) 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.

4) 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.

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NEMATODE PROBLEM

Reference Pest Control Guides Here

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.

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VIRAL PROBLEM

Reference Pest Control Guides Here

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.

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INSECT AND RELATED PROBLEMS

Reference Pest Control Guides Here

The major arthropod pests of this plant species include aphids, moths (worms), fungus gnats, mealybugs, mites, scales, and thrips. Mealybug, mite, and scale infestations are typically the result of bringing infested plant material into the greenhouse. Aphids, moths, fungus gnats 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.

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 -

Several products are effective for worm control.

2) 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.

3) 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.

4) 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 2mm 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. Coccus hesperidum Linnaeus (brown soft scale) and a hard scale Hemiberlesia lantania (Sign.) (lantania scale) have been reported as pests of this plant specifically.

Control -

See Mealybugs

5) 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 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.

6) Slugs

Symptoms -

Slug and caterpillar damage are similar and determining which pest is present can be difficult. Snails and slugs are voracious feeders, with small stages feeding on surface tissue and larger ones eating irregular holes in foliage. Generally, the culprit can be found on close examination of the plant. Slugs often live under benches or in dark, moist protected places close to the damage. These pests are nocturnal and can be found feeding at night.

Control -

Sprays or baits applied to moistened soil around plants are effective. Repetitive applications are necessary. Good sanitation with removal of extraneous plant material and debris which might shelter these pests aids in control.

7) Thrips (Western Flower Thrips and Banded greenhouse 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.

Reference Pest Control Guides Here

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

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

3. 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.

4. 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.

5. Short, D.E., J. Price and L.S. Osborne. 1989. Sweetpotato whitefly on ornamental plants. Extension Entomology Report #73.

6. Simone, G.W. 1989. Disease control pesticides for foliage production (Revision #4). Plant Protection Pointer. Extension Plant Pathology Report #30. [also in Foliage Digest 12(9):1-8]