Nephthytis Production Guide

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CFREC-A Foliage Plant Research Note RH-91-23

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


NEPHTHYTIS

Syngonium podophyllum (Nephthytis podophyllum), also called nephthytis and arrowhead vine, is indenenous to tropical America. The plant produces climbing vines with 3-parted leaves on long petioles when mature. Virtually, all the plants produced for the foliage plant industry are in juvenile condition. In the juvenile state, plants develop with arrowhead-shaped leaves. As most of these plants grow in size, and particularly as they climb on a supporting element under bright light conditions in a greenhouse or in a tropical landscape, the younger leaves become divided in a palmate pattern, at which time the foliage reaches mature condition. Under interiorscape environments plants usually remain in the juvenile state with arrowhead-shaped leaves.

Nephthytis can be used as a specimen in small containers up to 8 inches in diameter and the very small plants in cell packs or small individual containers are frequently used in combination planters, such as dish gardens. One of the most popular usage of the plant is in hanging baskets from 5 1/2 to 12-inch diameter. Commercial interiorscapers use nephthytis in a variety of other cascading applications and occasionally as ground covers. Although few producers grow it as a totem, it is an excellent candidate for this application.


SPECIES AND CULTIVARS

During the 1970's Florida foliage nurserymen listed several cultivars of S. podophyllum which included: Cream, Emerald Gem, Green Gold, Variegatum, White Butterfly and Xanthophyllum. By 1990, the cultivar emphasis had shifted considerably to include: Compacta, Cream, Emerald Gem, Jenny, Lemon Lime, Maxima, Maya Red, Patricia, Pink Allusion, Pixie, Robusta, Variegatum and White Butterfly. Many producers indicate that Compacta, Lemon Lime and Maxima are essentially the same compact, self-branching selections made from White Butterfly. Syngonium wendlandii, another nephthytis species, was also listed in 1990.


PRODUCTION

Nephthytis traditionally has been propagated by seed or leafless, single-node stem cuttings, depending upon the cultivar. Most of the highly variegated cultivars must be propagated vegetatively to retain the characteristics typical of each. Recently, many growers have adopted the use of tissue-cultured plants established as plugs. Since the plug plants are usually multi-branched and in vigorous condition as received by the finished plant grower, production time is minimized.

The potting medium should have good aeration and water-holding capacity. Syngonium will tolerate a moisture deficit in the soil, but will grow more vigorously if soil is not allowed to dry. Most growers are successfully using one of the commercially available, preformulated, light weight peat-based potting blends. Most of the greenhouse blends have good physical and chemical properties and are available in bags or in bulk.

Suggested light levels for potted plant production are 1500-3000 foot-candles which can be obtained with 70 to 80 percent light reduction during Florida summers.

Excellent growth can be obtained with 3-1-2 (N-P2O5-K2O) ratio of liquid or slow-release fertilizers when applied at the rate of 2.9 pounds of actual nitrogen per 1,000 square feet per month. If irrigation is adjusted to near zero leaching at each irrigation the fertilization rate can be decreased. Conversely, if water use on the crop is excessive, additional fertilizer will be required to maintain proper color and vigor. The latter practice is discouraged. Lower fertilizer rates can also be used in winter with lower light levels and night temperatures which can be dropped to 60F. Slightly higher rates may be needed during the summer months when temperatures and light levels are higher.

Irrigation procedure is important with this crop because of the ease when certain bacterial pathogens are spread with overhead-applied water splashing off the foliage of infected plants. Drip irrigation works well for hanging baskets and large, widely-spaced containers. Hanging plants should not be placed directly over benches of nephthytis because water leaking from the hanging materials can also spread the bacterial blight. If feasible, one of the sub-irrigation systems should be employed for small, closely-spaced plants. The sub-irrigation systems avoid wetting the foliage and provide an opportunity to recirculate the unused irrigation water. Use of solid cover structures (greenhouses) is recommended for this crop.

Although nephthytis will survive temperatures near freezing, they grow best between 70 and 95F. Night temperatures can be dropped to 60F without loss of quality or significantly adding to the production time of established plants. Plants being propagated from seed, leafless cuttings or micro-cuttings from tissue culture do benefit from bottom heat of approximately 70F in the root zone.


PHYSIOLOGICAL PROBLEMS

1.) Water-soaked leaves

Symptoms -
- Portions or entire leaves appear wet or water-soaked. This symptom almost always occurs on young leaves and occurs primarily in early morning during winter when sunlight first strikes the foliage and warms the leaf tissue, but the potting medium is still cold. This temporary condition causes a water imbalance in the plant, but as the soil warms, symptoms disappear.

Control -
To control the problem, maintain root temperatures at 65F or above or increase air temperature slowly.

2) Long, thin internodes

Symptoms - Internodes are elongated with wide spaces between leaves.

Control -
This condition is caused from lack of sufficient light as the stems elongate. Increase the light levels to those recommended. There is also a strong species/cultivar influence on the internode length under a standard set of conditions. Most of the newer cultivars are more compact than the plants common to the industry 20 years ago.

3) Loss of cutting from non-pathogenic means

Symptoms -
Single-node (eye) cuttings rot in the propagating beds.

Control -
Select only healthy, mature node cuttings and place in a well aerated propagating medium. Maintain water and nutrients applications to stock plants at appropriate levels and high quality cuttings will be produced. This problem is rare today because most of the finished product is derived from tissue-cultured plants.

Reference Pest Control Guides Here


BACTERIAL PROBLEMS

1) Bacterial leaf spots - (Erwinia spp. or Pseudomonas cichorii)

Symptoms -
Symptoms first appear as small water-soaked lesions which can be translucent. Sometimes they are confined between leaf veins and other times they expand irregularly across the veins. If Erwinia causes leaf spot the centers may become mushy and drop out. The color of spots is usually tan to dark-brown depending upon moisture conditions and activity. Tan lesions are common when the weather is dry and indicates a relatively inactive infection.

Control -
Bacterial leaf spot control should be based upon use of pathogen-free cuttings or tissue-culture plantlets since bacteria can be carried on the surface or within stems of asymptomatic plants. Minimizing overhead water is also very important since bacteria need water to spread and infect plants.

2) Erwinia cutting rot (Erwinia spp.)

Symptoms -
Rapid decay of cuttings of syngonium occurs when cutting ends are contaminated with Erwinia spp. or the pathogen moves from an infected leaf into the stem. The mushy rot usually starts on the cutting stem and advances until the entire cutting disintegrates. Sometimes the rot stops and remaining portion of the cutting produces roots.

Control -
Use of pathogen-free cuttings is paramount.

3) Xanthomonas blight (Xanthomonas campestris pv. dieffenbachiae)

Symptoms -
Xanthomonas blight symptoms on syngonium occurs on first on the leaf margins where the bacterium enters through hydathodes. Lesions are first translucent, yellowish and water-soaked. They may take a long time to enlarge but eventually they can encompass the entire leaf margin, invade the center of the leaf and even cause leaf abscission. Mature lesions are papery and tan and can be surrounded by a bright yellow halo. If the plant becomes systemically infected, it will show signs of yellowing, stunting and loss of lower leaves. Eventually systemically infected plants die.

Control -
Use of bactericides for control of even the foliar phase of Xanthomonas blight is rarely effective. Avoidance of this disease is the most effective control. Scout the crop routinely and frequently to detect early symptoms of Xanthomonas blight. Use of vinegar (1 gal/100 gal) has occasionally been effective in reducing disease spread. Copper compounds (Kocide 101) are as effective, although no bactericides can control this disease once plants become systemically infected. Limit overhead irrigation to reduce pathogen spread and keep in mind that most of the commonly produced aroids (dieffenbachia, aglaonema and anthurium) are also hosts of this pathogen.

Reference Pest Control Guides Here


FUNGAL PROBLEMS

1) Black cane rot or Ceratocystis blight (Ceratocystis fimbriata)

Symptoms -
The disease appears as a black, water-soaked area sometimes girdling the stem. Leaves gradually become chlorotic and die. Leaf spots caused by this pathogen occur as well as root rot and stunting.

Control -
Hot water treatment of infected stem cuttings for 30 minutes at 120F has been effective in eradicating this pathogen. Use of pathogen-free cuttings is also recommended.

2) Cephalosporium leaf spot (C. cinnamomeum = Acremonium crotocinigenum)

Symptoms -
Lesions on leaves and petioles are small, reddish-brown, circular to irregularly shaped and have a slightly yellow border. Disease is more common where plants are grown in ground beds and exposed to rainfall or overhead irrigation.

Control -

3) Myrothecium leaf spot and petiole rot (M. roridum)

Symptoms -
Myrothecium leaf spot and petiole rot occur commonly on small, tissue-cultured plantlets. As few as three leaf spots can result in their loss, although the petiole rot is most common on newly established plantlets. Lesions start as small water-soaked areas which are greasy appearing. These spots are generally circular and when mature contain black and white fruiting bodies on the undersides of the leaves or at petiole bases.

Control -
Minimizing foliage wetting and wounding greatly reduce the severity of this disease especially on the tissue-cultured plantlets. Additionally, avoid applications of higher than necessary amounts of fertilizer since this can increase the plant's susceptibility to M. roridum.

4) Rhizoctonia aerial blight and leaf spot (R. solani)

Symptoms -
Rhizoctonia aerial blight of syngonium usually appears as small, irregularly- shaped, water-soaked lesions on lower leaves or leaf edges in contact with the potting medium. Lesions are brown and may be accompanied by the web-like mycelium of the pathogen which is also reddish-brown.

Control -
Since the pathogen is soil-borne, plant roots must be treated for optimal disease control. Always use pathogen-free potting media, pots and plants and grow plants on raised benches to avoid infections. Since the disease occurs during the hot, humid summer months special precautions should be taken then to prevent infections.

Reference Pest Control Guides Here


INSECT AND MITE PROBLEMS

The major arthropod pests of this plant species include aphids, moths (worms), fungus gnats, mealybugs, mites, scales, thrips and whiteflies. Mealybug, mite, and scale infestations are typically the result of bringing infested plant material into the greenhouse. Aphids, caterpillars, fungus gnats, thrips and whiteflies 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. Because of the numerous Syngonium cultivars grown in the greenhouse, a small group of plants from each cultivar should be tested for phytotoxicity prior to treating the entire crop. The list given in this section should be used only as a guide to the sensitivity of this plant to pesticides.

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 -

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 antennas 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) Mites

Symptoms -
Mites are very small and go unnoticed until plants become severely damaged. Damaged foliage begins to turn yellow or become speckled due to the feeding of mites. Webbing, loss of leaves and plant death can occur when mite populations reach high levels. Often the presence of this pest is overlooked because the cast skins and webbing produced by this mite are confused for dust on undersides of leaves. The mite that is often found on this plant closely resembles the two-spotted spider mite but is cherry red in color.

Control -
The critical point in any control program is thorough coverage with the pesticide. The best control program is to minimize the possibility of introducing mites into the growing area on infested plant material. Biological control programs have worked in small scale studies but remain unproven in commercial greenhouses.

6) 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

7) Shore flies

Symptoms -
Shore flies are 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 antennas. 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.

8) Snails and slugs

Symptoms -
Snail, 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.

9) 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.

10) Whiteflies

Symptoms -
Infested leaves often have small yellow spots where adults or immature whiteflies have fed. When populations become dense the leaves become yellowed and lower leaves are covered with black sooty mold. The immature stages of the sweetpotato whitefly are small scale-like insects and can be found on the undersides of infested leaves.

Control -
Many materials are registered and effective at controlling whiteflies. To minimize additional resistance problems, insecticides should be applied two times per week throughout one life cycle (3 weeks) to control an established infestation. Monitor the population to determine if the particular insecticide being applied is reducing whitefly numbers. Some populations may be resistant to one or more insecticides. If the infestation persists, use another compound following the same schedule. Do not apply tank mixes as they may enhance resistance. If low numbers of whiteflies persist, apply one of the above insecticides once per week for 3 weeks, then switch insecticides. Undersides of leaves must be covered thoroughly to achieve satisfactory control. For additional information on this pest please consult Plant Protection Pointer #73 (Sweetpotato whitefly on ornamental plants).



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 staff. 1976. Hortus Third. MacMillan Publishing Company, Inc., New York, NY. 1290 pp.

2. Chase, A.R. 1983. Phytotoxicity of some fungicides used on tropical foliage plants. ARC- Apopka Research Report, RH-83-2.

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

4. 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. 13 pp.

5. Poole, R.T. and A.R. Chase. 1987. Syngonium guide. Greenhouse Grower. (1):28-29.

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

7. 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.

8. 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.

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

10. Simone, G.W. and A.R. Chase. 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]

11. Spinazzola, Lisa (Editor). 1990. Florida Foliage Locator 1990-91. Florida Foliage Association, Apopka, FL. 144 pp.