Anthurium Production Guide

ANTHURIUM

CFREC-Apopka Foliage Plant Research Note RH-91-3 This publication is a revision of AREC-A Foliage Plant Research Note RH-83-F.

R.J. Henny, A.R. Chase and L.S. Osborne Professor, Plant Genetics, Professor, Plant Pathology and Associate Professor, Entomology, respectively. University of Florida, IFAS Central Florida Research and Education Center 2807 Binion Road, Apopka, FL 32703-8504

Reference to University of Florida/IFAS Pest Control Guides

Interest in Anthurium as a potential crop is increasing as foliage growers look for new plants with color. There were 7 different Anthurium listings in the 1990-91 Foliage Plant Locator Table 1:

Table 1:

A. andraeanum      A. clarinervum
A. hookeri         A. hookeri `Alicia'
A. watermaliense   A. `Pink Princess'
A. species and cultivars

PRODUCTION

Best growth and flowering of anthuriums depend on many factors of which potting medium, fertilizer and light levels may be considered the most important. Due to their epiphytic nature anthuriums require well-aerated soil mixes, however, the mixes need to provide sufficient moisture as well as support for the plant. Mixes successfully used in Hawaii include wood shavings, tree fern chips, macadamia nut shells, volcanic cinder, taro peel and sugarcane bagasse. Other media that have provided good anthurium growth include mixtures such as 1:1:1 peat:perlite:bark or 1:1 peat:perlite. A medium of 2:1 peat:perlite has also been suggested as good for anthurium.

A light level of 1500 to 2000 ft-candles has been proposed as best for anthurium under Florida conditions. Anthurium `Lady Jane' liners from tissue culture grew better at 1200 ft-c than at 2400 or 3600. Best growth and flowering of Anthurium `Southern Blush' in 6-inch pots was obtained with a maximum light intensity of 2000 ft-c compared to 1000 ft-c. Studies in Hawaii with cutflower cultivars showed that flower peduncles were longer and spathe size was increased at lower light levels, while flower production was increased slightly with an increase in light.

The proper fertilizer level necessary to produce anthurium depends upon production light levels. Fertilizer requirements of Osmocote 19-6-12 was 7-13 gm for good quality 6-inch pots of A. scherzeranum at light levels of 3500 ft-c compared to 1-9 gm at 1000 ft-c. A level of 5 gm Osmocote 14-14-14 per 6-inch pot was suggested for anthurium grown at 1500-2000 ft-c.

PHYSIOLOGICAL PROBLEMS

1) Excess light

Symptoms -

Leaves appear bleached in the centers and may have brown tips.

Control -

Increase shade so as to reduce light level to 1800 - 2500 foot-candles.

2) Overfertilization

Symptoms -

Lower leaves become yellow and develop brown tips that gradually enlarge.

Control -

Reduce fertilization and leach soils thoroughly. Check roots for damage and possibility of secondary infection by fungus or bacteria.

3) Lack of flowering

Symptoms -

Mature plants produce many leaves but few flowers. No flowers on the lateral shoots.

Control -

Increase light level to 1800 - 2500 foot-candles. Maintain higher light intensity as long as leaves do not develop symptoms mentioned in 1) above.

BACTERIAL PROBLEMS

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1) Soft rot (Erwinia carotovora subsp. carotovora)

Symptoms -

Erwinia soft-rot symptoms appear at stem bases as a wet, mushy lesion. The tissue rapidly collapses, turns dark and can become rank smelling. Erwinia is most severe under hot wet conditions when controls are rarely effective.

Control -

Do not reuse pots or potting media from plants which have died from this disease since they can be contaminated with the pathogen.

2) Xanthomonas blight (Xanthomonas campestris pv. dieffenbachiae)

Symptoms -

Xanthomonas blight symptoms on anthuriums occur on all parts of the plant but usually start 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 black and usually surrounded by a bright yellow halo. If the anthurium becomes systemically infected, the plant will show signs of yellowing, stunting and loss of lower leaves. Eventually systemically infected plants die.

Control -

Avoidance of this disease is the most effective control. Scout the crop routinely and frequently to detect early symptoms of Xanthomonas blight. Some growers report effective control by removing symptomatic leaves, although this method has obvious drawbacks for potted foliage producers. Limit overhead irrigation to reduce pathogen spread and keep in mind that most of the commonly produced aroids (dieffenbachia, aglaonema and syngonium) are also hosts of this pathogen.

FUNGAL PROBLEMS

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1) Anthracnose (Colletotrichum gloeosporioides)

Symptoms -

Anthracnose symptoms start as tiny brownish spots on the flower spadix. During high humidity these spots enlarge, appear water-soaked and turn necrotic. Sometimes the entire spadix will turn black as lesions coalesce. The shape of most lesions is, however, angular due to the shape of the spadix tissue. As the disease becomes more severe, masses of orangeish spores form on necrotic areas. Leaves and spathes are rarely if ever infected.

Control -

In Hawaii, anthurium breeding programs for cut flower production routinely select for resistance to this disease. Resistance levels of the potted hybrid anthuriums have not been determined.

2) Phytophthora leaf spot, flower blight, and root rot (Phytophthora parasitica)

Symptoms -

Phytophthora leaf spot and flower blight are characterized by small water-soaked lesions on the leaves and/or spathe tissues. These lesions turn black and remain wet appearing as they enlarge. They can encompass the entire flower or leaf under conditions of both high temperature and moisture which are favorable to pathogen development. When conditions become drier or cooler lesions dry and can appear papery but usually remain quite dark in color.

Phytophthora root rot shows the same symptoms as many other root rot diseases. Leaves wilt, may turn yellow or pale green and eventually die. Plants are frequently stunted and examination of roots reveals their rotted condition. Initial infections of the roots appear as small water-soaked grayish or brown lesions. These lesions can rapidly expand to affect the entire root system. Severely infected plants may have no living roots remaining by the time they are examined.

Control -

Prevention is always the best control of a soil-borne pathogen like Phytophthora. Use clean pots, potting media, and grow plants on raised benches. Since anthuriums are rarely tolerant of heavy or poorly draining potting media, the appropriate mix is critical. Even regular fungicide applications to infected plants in a heavy potting medium will not control this disease on some potted anthuriums.

NEMATODE PROBLEMS

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1) Burrowing nematode decline (Radopholus similis)

Symptoms -

Stunting and poor growth are usually the first signs of burrowing nematode infestations. Plants also produce fewer and smaller flowers and appear nutrient deficient. Roots and lower stems poorly developed and can be rotted. Although many root pathogens can invade this dying tissue, the burrowing nematode can cause these symptoms in the absence of fungal pathogens.

Control -

Use of pathogen-free plants is vital and usually possible when tissue-cultured plantlets are purchased. Methods which reduce most root diseases, such as use of pathogen-free potting media and growing plants on raise benches, will aid in control of soil-borne nematodes as well. Hot water dipping of cuttings (50°C for 10 min) can reduce nematode populations in plant stems used for propagation but this method is not recommended unless the plant is especially rare or critical in a breeding program.

2) Foliar nematode (Aphelenchoides fragariae)

Symptoms -

Lesions appear as necrotic areas between leaf veins. If infestations are high, the leaves can appear striped with infested and healthy panels alternating. Reports of infestations have been made from seedlings primarily, since large plant appear to be resistant. Heavy infestations result in leaf loss and eventually plant death.

Control -

As always use pathogen-free seed or plantlets, pathogen-free potting media and grow plants on raised benches whenever possible. Discard infested flats of seedlings as good control may be difficult with the nematicides available. Even a few infested seedlings in a flat can result in loss of the entire flat so identifying the disease early and destroying infested plants are critical to disease control.

INSECT AND RELATED PROBLEMS

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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. However, 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) 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. 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) Mites (Twospotted spider mite)

Symptoms -

Two-spotted 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 their bodies.

Control -

The critical point in any control program is thorough coverage with a 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.

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 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

Symptoms -

Thrips are small (less than 1/20), thin insects. Adult thrips can be identified by a long fringe of hairs 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, 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. 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).

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. Nursery Digest 24(5):11.

2. Chase, A.R. and R.T. Poole. 1986. Effect of host nutrition on growth and susceptibility of Anthurium scherzeranum to Xanthomonas leaf spot. AREC-Apopka Research Report RH-86-4.

3. Conover, C.A. and R.T. Poole. 1988. Flowering crops for foliage growers. CFREC-Apopka Research Report RH-88-9.

4. Higaki, T. and R.T.Poole. 1978. A media and fertilizer study in anthurium. J. Amer. Soc. Hort. Sci. 100 1):98-100.

5. Higaki, T. and D.P. Watson. 1967. Anthurium culture in Hawaii. Univ. of Hawaii Coop. Ext. Serv. Circular 420.

6. Kamemoto, H. and H.Y. Nakasome. 1953. Effect of media on production of anthuriums. Hawaii Agr. Exp. Sta. Prog. Notes No. 94.

7. Nakasome, H.Y. and H. Kamemoto. 1962. Anthurium culture, with emphasis on the effects of some induced environments on growth and flowering. Hawaii Agr. Expt. Sat. Cir. 53.

8. Poole, R.T. and B.A. Greaves. 1969. N, P, and K fertilization of Anthurium andreanum `Nitta' and `Kaumana'. Proc. Tropical Region Amer. Soc. Hort. Sci. 13:367-372.

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

10. 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.

11. 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.

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

13. 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]