Spathiphyllum Production Guide

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CFREC-A Foliage Plant Research Note RH-91-32

R.J. Henny, 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


SPATHIPHYLLUM

Spathiphyllum are attractive indoor foliage plants which tolerate very low light levels. Spathiphyllum produce a showy white inflorescence, consisting of a hood-shaped spathe surrounding the spadix, which adds to their ornamental value. For this reason, Spathiphyllum are often called Peace Lilies and or White Anthuriums. There are 26 Spathiphyllum cultivars listed in the 1990-91 Foliage Plant Locator (Table 1).

Table 1: Spathiphyllum cultivars listed in the 1990-91 Florida Foliage Plant Locator.


S. florabundum			S. `Deneve'

S. `Don Juan'TM			S. `Green Velvet'

S. `Gretchen'			S. `Kathylyn'TM

S. `Kristina'TM			S. `Lilian'

S. `Londonii'R 			S. `Lord Nelson'

S. `Lynise'TM (Pat #6145)	S. `Mauna Loa'

S. `Mauna Loa Superba'		S. `Mauna Loa Supreme'

S. `Mini'			S. `Petite'

S. `Phoenix'TM			S. `Princess'TM

S. `Regency'			S. `Sensation'TM (Pat #6964)

S. `Starlight'TM		S. `Supreme'

S. `Tasson'			S. `Viscount'TM

S. `Viscount Prima'TM		S. `Wallisii'

Spathiphyllum will not tolerate high light intensities without reduction in quality and should be grown under 1500 to 2500 foot-candles. A fertilizer ratio (N-P2O5-K2O) of 3-1-2 applied at a rate of 1500 lb N/A/yr (3-1/2 pounds of nitrogen per 1000 square feet monthly during the warm growing season and 2-1/2 pounds of nitrogen during the winter months) produces high quality plants. Slow release fertilizers and constant feed fertilization are equally effective methods of applying nutrients. A potting soil with good aeration and high water holding capacity is necessary. Spathiphyllum will survive between temperatures of 40-100F, but should be maintained between 65-90F for best growth. Good quality Spathiphyllum will ship at 55-60F for 2 weeks without damage.


PHYSIOLOGICAL PROBLEMS

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1) Saturated soil medium

Symptoms -
Leaves are wilted or collapsed and sometimes necrotic along leaf margins. Roots are sparse, sometimes with black tips.

Control -
Reduce irrigation frequency to improve soil aeration or utilize a potting medium with a higher pore space percentage. This problem is more likely to occur during cold weather when plant water needs decrease.

2) Micronutrient deficiency

Symptoms -
Reduced growth and chlorotic leaves are common symptoms of micronutrient deficiency. This disorder frequently occurs during winter months when soil is cold. Both iron (Fe) and manganese (Mn) deficiencies have been observed in the past.

Control -
Increase soil temperature and improve soil aeration. If soil is cold, application of additional micronutrients will have little benefit. Keep soil temperatures above 65F to avoid this problem.

3) Excess light or temperature

Symptoms -
Leaves may be curled, pale, and chlorotic to necrotic. Often leaves have burned (necrotic) margins and tips.

Control -
Reduce the light level to 2500 ft-candles or below and/or the temperature to 90F or lower. An increase in fertilizer will improve plant color, but may result in excessive levels of soluble salts and some damage.

4) Young immature plants - no flowers

Symptoms -
Lack of flowering is especially common on young plants.

Control -
Plants grown for 9 to 15 months will usually bloom between February and April, depending on winter growing temperatures. Younger plants may be induced to flower using a foliar spray of 250 ppm of GA3 (Gibberellic acid). Flower size on GA3-treated plants is generally smaller than on plants blooming naturally. Plants normally have open blooms 12 to 16 weeks after treatment with GA3 depending upon their growth rate; plants flower sooner in the summer than during the winter.


FUNGAL PROBLEMS

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1) Aerial blight (Phytophthora sp.)

Symptoms -
Large (up to 1 inch wide) black or brown dead spots form on leaf margins and centers. Spots are wet and mushy under moist conditions but may dry if plant foliage is kept dry.

Control -
Keep plant foliage dry and grow plants in a sterilized potting medium on raised benches away from the native soil. Always treat both soil and foliage since the pathogen moves from the potting medium onto the foliage.

2) Cylindrocladium root rot (Cylindrocladium spathiphylli)

Symptoms -
One of the first symptoms of this root rot disease is yellowing of lower leaves, sometimes accompanied by slight wilting. Elliptical dark brown spots may be found on leaves and petioles and lower portions of petioles frequently rot. At this stage, plant roots are severely rotted and few healthy roots are found. Tops of such plants are easily removed from the pot without any adhering roots.

Control -
Control of this root rot disease must be based first upon use of pathogen-free plants from either tissue culture or seed sources. Use of sterilized potting medium and pots and growing plants on clean or "sterilized" raised benches are also important in reducing the chances of disease development and spread. The Spathiphyllum cultivars tested to date have been very susceptible to Cylindrocladium root rot with the exception of S. floribundum. This species is a host of the pathogen, but is highly resistant and shows little root loss when infected with Cylindrocladium spathiphylli. Chemical treatments are not completely effective unless disease pressure is very low.

3) Myrothecium leaf spot (Myrothecium roridum)

Symptoms -
Brown to black circular lesions form on leaf margins and centers. The lesions may have concentric rings of light and dark tissue or they may be water-soaked and uniformly black in color. The lower surface of the spot frequently has the fungal fruiting bodies present, which are irregularly shaped, black and have a white fringe around the borders.

Control -
Small, tissue-cultured plantlets are highly susceptible to this disease and may be lost if precautions are not taken. Disease severity is highest during periods of the year when air temperatures are between 60 and 85F. Little, if any, disease occurs at other times.

4) Pythium root rot (Pythium sp.)

Symptoms -
Roots are blackened and mushy and the outer cortex is easily removed from the inner core. This stage looks identical to the root rot symptom caused by Cylindrocladium spathiphylli and diagnosis by a plant pathology laboratory is mandatory to distinguish between the diseases. Foliage of plants with Pythium root rot is frequently chlorotic and wilted.

Control -
Use the cultural controls listed under Cylindrocladium root rot. Several products are available for pythium.


VIRAL PROBLEM

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1) Dasheen Mosaic Virus (DMV)

Symptoms -
A mosaic pattern of light green to yellow is found on the new leaves of infected plants at various times during the year. No leaf distortion normally occurs. This disease does not appear to cause economically significant losses in Spathiphyllum production for the majority of growers.

Control -
Other aroids (dieffenbachia, anthurium and philodendron) are susceptible to DMV and can be sources of infection for Spathiphyllum. Always discard and destroy plants with these symptoms and control aphids since they serve as vectors of the virus. Sometimes genetic disorders appear similar to DMV.


INSECT AND MITE PROBLEMS

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The arthropod pests of Spathiphyllum are of relatively minor importance, but include caterpillars, mealybugs, scales, and thrips. Mealybug and scale infestations often begin by bringing infested plant material into the greenhouse. Moths and thrips invade the greenhouse by flying in from weeds and other infested plants outside. In the control section for each pest a few of the many registered and effective pesticides are 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.

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.

5) Scales

Symptoms -
Infested plants become weakened or stunted and begin to die. Scales can be found feeding on leaves, petioles or stems. Their shapes, sizes and colors are variable and many are hard to distinguish from the plant material on which they are feeding.

Control -
See mealybugs.

6) 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 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 (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.

8) 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, one insecticide 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 of these 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 the 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. Chase, A.R. 1990. Phytotoxicity of bactericides and fungicides on some ornamentals - 1990 update. 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. 1989. 1989-90 Insect and related arthropod management guide for commercial foliage plants in Florida. Extension Entomology Report #53.

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

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