Potho Production Guide

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CFREC-A Foliage Plant Research Note RH-1991-29

R.T. Poole, A.R. Chase and L.S. Osborne

University of Florida, IFAS
Central Florida Research and Education Center - Apopka

2807 Binion Rd., Apopka, FL 32703-8504


POTHOS

This plant must have a criminal background, it has so many aliases. Exotica and Tropica show pictures of several Scindapsus and Epipremnum species and Hortus III also lists species of Scindapsus and Epipremnum. Sales catalogs feature names like Devil's Ivy and Golden Pothos. The current name is Epipremnum aureum (alias Scindapsus aureus alias Pothos aureus). `Golden Pothos' is a golden, yellow-green variegated vine with waxy leaves. When grown in optimum conditions, such as the tropics, leaves will grow to two feet in length. `Marble Queen' has smooth waxy leaves with white variegation. A third "Pothos" is still botanically described as Scindapsus. Scindapsus pictus usually goes by the name of Pictus and has thick leatherlike leaves, obliquely ovate, dark green with green-silver blotches.


PRODUCTION

Stocks plant are best grown at 5,000 foot-candles (ft-c). Number of cuttings and weight of cuttings are larger than those from stock plants grown at 2,000 ft-c. Pothos cuttings will have rapid shoot and root growth if light is 3,000 ft-c and the temperature is 80F. Rooting occurs within 3-4 weeks and buds can start to grow in 1-2 weeks. There was no benefit from indolebutyric acid (IBA). Cuttings can be stored at 50-65F, but they should be placed in the mist bed as soon as possible. Cuttings will root equally well in an organic medium such as peat or an inorganic medium such as calcined clay.

Pothos will survive a wide range of environmental conditions, but grows best at 70- 90F. Minimum temperatures below 70F and maximum temperatures above 90F will greatly retard growth. Plants should be supplied the equivalent of 5 lbs of nitrogen/1000 ft2 monthly from a 3-1-2 analysis or 7 grams of 19-6-12 per 6" pot per 3 months. Slow release and liquid have been successfully used. Micronutrients such as copper, iron, manganese and zinc are needed in such small quantities that the impurities in water and micronutrients supplied by the medium are usually sufficient. Tissue composition of good quality foliage plant has been found to be: N, 2.5-3.5% dry weight; P, 0.20-0.35%; K, 3.0-4.5%; Ca, 1.0- 1.5% and Mg, 0.3-0.6%. The growing mix should be well aerated and overwatering avoided. Pothos have been watered with sewage effluent with no harmful effect. Plants growth is modified easily with the growth retardants B-Nine at 10,000 parts per million (ppm) spray and 100 ppm of an ancymidol (A-REST) spray or 0.6 milligrams (mg) of ancymidol per square foot and 100 mg per 600 milliliter pot of paclobutrazol (Bonzi).

Pothos are very tolerant of atmospheric fluoride and ethylene (C2H4) and can be shipped for 2 weeks without loss of quality if temperatures are maintained between 55-60F. Pots containing pothos with an electrical conductivity (EC) range of 1,000 - 6,000 mhos/cm as determined by the pour-through method maintained an attractive appearance for 6 weeks after placement in rooms with 125 ft-c for 12 hours daily. While indoors plants should be watered 1 - 2 times weekly.


PHYSIOLOGICAL PROBLEMS

1) Loss of variegation

Symptoms -
Stock plants begin to lose variegation with leaves becoming predominantly green.

Control -
Frequently cutters remove the most desirable vines for propagation, leaving poorly variegated vines to expand. To maintain best leaf color in the stock beds, cut above a node with a leaf of the proper variegation. Occasional rouging of undesirable vines maintains desirable variegation. Light intensities of less than 1000 ft-c also contributes to loss of variegation.

2) Discolored leaves

Symptoms -
Leaves have scattered brown patches, usually located in the center of the leaf.

Control -
Low temperatures or abrupt change from very high temperatures to moderate temperatures can cause this discoloration, especially if plants are succulent and growing vigorously. Maintain even, warm temperatures.

3) Small leaves

Symptoms -
New growth produces medium size to small leaves.

Control -
This phenomenon, caused by lack of fertilizer and/or low light, rarely occurs in the nursery and can be controlled by fertilizer application and increased light.

4) Decaying roots

Symptoms -
Roots brown or nonexistent.

Control -
If not caused by pathogens, reduce irrigation frequency and/or improve aeration of the soil mix.


BACTERIAL PROBLEMS

Reference Pest Control Guides Here

1) Bacterial leaf spot - (Pseudomonas cichorii, Erwinia carotovora, and E. chrysanthemi)

Symptoms -
Bacterial leaf spot diseases are characterized by rapidly spreading water- soaked lesions formed anywhere on the leaves. Under wet conditions, the centers of these spots may fall out. Sometimes leaf spots have a yellow border.

Control -
Bacterial leaf spot can be controlled through elimination of water on leaves. This is almost impossible during rooting of cuttings and preventative applications of streptomycin sulfate (Agri-Strep 21.2%) may aid control. Choice of clean cuttings and strict sanitation are probably the most important control measures.

2) Cutting soft rot - (Erwinia carotovora and E. chrysanthemi)

Symptoms -
A mushy soft rot of the lower end of a cutting. Sometimes the plants have a fishy, rotten odor, characteristic of Erwinia infections.

Control -
Same as above except use of bactericides is not recommended due to very poor efficacy.


FUNGAL PROBLEMS

Reference Pest Control Guides Here

1) Pythium root rot (Pythium splendens)

Symptoms -
Cuttings usually show poor rooting and have yellow leaves. Examination of the stem and roots reveals a mushy black rot extending from the cut end into the upper portions of the stem and leaves. Root and stem rots usually occur in patches on a propagation bench where it spreads into uninfected cuttings.

Control -
Control should be based on use of disease-free propagation material, sterilized potting media and raised benches. Reducing water applications to the minimum level for good rooting also reduces root and stem rot diseases.

2) Rhizoctonia foot rot (Rhizoctonia solani)

Symptoms -
A mass of brownish mycelium covers the infected plants. Growth of mycelium from the potting medium onto the plant can escape notice and give the appearance that plants have been infected from an aerial source of inoculum. Close examination, however, generally reveals the presence of mycelium on stems prior to development of obvious symptoms. Rhizoctonia mycelia are usually reddish-brown in color and have the consistency of a spiderweb.

Control -
Chemical control of diseases caused by Rhizoctonia has been investigated on many plants using a variety of fungicides.

3) Southern blight (Sclerotium rolfsii)

Symptoms -
The pathogen attacks all portions of the plant, but is most commonly found on stems and leaves. Initially, symptoms on stems are confined to water-soaked, necrotic lesions at or near the soil line. White, relatively coarse mycelium grow in a fan-like pattern and may be seen on the soil surface, leaves or stems. The round sclerotia form almost anywhere on the affected portions of the plant or the soil surface. They are initially white and cottony and approximately the size of a mustard seed. As sclerotia mature, they turn tan and eventually dark brown and harden. Mycelia and sclerotia generally develop concurrently with stem rot and wilting, allowing an accurate diagnosis of the problem. A cutting rot can develop on contaminated plant materials during the summer months.

Control -
Although this disease can be avoided using proper cultural methods, it continues to cause losses in production of foliage plants today. Chemical control of Southern blight has been investigated on several different foliage plants as well as non-ornamental crops.


INSECT AND RELATED PROBLEMS

Reference Pest Control Guides Here

Insects and mites are seldom serious problems on Pothos. The major arthropod pests include caterpillars, mealybugs, mites, scales and thrips. Mealybug, mite and scale infestations are typically the result of bringing infested plant material into the greenhouse. Moths 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) 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 -

2) 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.

3) Mites

Symptoms -
Spider 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. Mites have round pale yellow to reddish eggs deposited on the under surfaces of leaves; nymphs and adults have two dark patches on either side of there bodies or they are brick red in color depending on the species.

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.

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 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

5) 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



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.


REFERENCES

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

2. Chase, A.R. and R.T. Poole. 1990. Effect of variegation on growth and chilling sensitivity of `Marble Queen' pothos. CFREC-Apopka Research Report RH-90-17.

3. Conover, C.A. and R.T. Poole. 1984. Use of sewage effluent as an irrigation source for foliage plants. AREC-A Research Report RH-84-17.

4. Conover, C.A. and R.T. Poole. 1984. Influence of shipping temperature and duration on simulated shipping of small potted foliage plants. Proc. Fla. State Hort. Soc. 97:280-282.

5. McConnell, D.B. and R.T. Poole. 1972. Vegetative growth modification of Scindapsus aureus by ancymidol and PBA. Proc. Fla. State Hort. Soc. 85:387-389.

6 Poole, R.T. and C.A. Conover. 1982. Growth of foliage plants at various night temperatures. CFREC-Apopka Research Report RH-82-26.

7. Poole, R.T. and C.A. Conover. 1987. Heat stress of foliage plants. CFREC-Apopka Research Report RH-87-2.

8. Poole, R.T. and C.A. Conover. 1988. Storage of Philodendron and Pothos cuttings. Proc. Fla. State Hort. Soc. 101:313-315.

9. Short, D.D. 1978. Phytotoxicity of insecticides and miticides to foliage and woody ornamental plants. Extension Entomology Report #57.

10. Short, D.E., L.S. Osborne, and R.W. Henley. 1982. 1982-83 Insect and related arthropod management guide for commercial foliage and woody plants in Florida.
Extension Entomology Report #52.

11. 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]

12. Wang, Ying-Tung. 1987. Effect of warm medium, light intensity, BA and parent leaf on propagation of Golden Pothos. HortScience 22(4):597-599.